To see the other types of publications on this topic, follow the link: Mycobacteria.
Journal articles on the topic 'Mycobacteria'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Mycobacteria.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Harth, Günter, Saša Masleša-Galić, and Marcus A. Horwitz. "A two-plasmid system for stable, selective-pressure-independent expression of multiple extracellular proteins in mycobacteria." Microbiology 150, no. 7 (July 1, 2004): 2143–51. http://dx.doi.org/10.1099/mic.0.27113-0.
Full textAbstract:
Recombinant mycobacteria expressing Mycobacterium tuberculosis extracellular proteins are leading candidates for new vaccines against tuberculosis and other mycobacterial diseases, and important tools both in antimycobacterial drug development and basic research in mycobacterial pathogenesis. Recombinant mycobacteria that stably overexpress and secrete major extracellular proteins of M. tuberculosis in native form on plasmids pSMT3 and pNBV1 were previously constructed by the authors. To enhance the versatility of this plasmid-based approach for mycobacterial protein expression, the Escherichia coli/mycobacteria shuttle plasmid pGB9 was modified to accommodate mycobacterial genes expressed from their endogenous promoters. Previous studies showed that the modified plasmid, designated pGB9.2, derived from the cryptic Mycobacterium fortuitum plasmid pMF1, was present at a low copy number in both E. coli and mycobacteria, and expression of recombinant M. tuberculosis proteins was found to be at levels paralleling its copy number, that is, approximating their endogenous levels. Plasmid pGB9.2 was compatible with the shuttle vectors pSMT3 and pNBV1 and in combination with them it simultaneously expressed the M. tuberculosis 30 kDa extracellular protein FbpB. Plasmid pGB9.2 was stably maintained in the absence of selective pressure in three mycobacterial species: Mycobacterium bovis BCG, M. tuberculosis and M. smegmatis. Plasmid pGB9.2 was found to be self-transmissible between both fast- and slow-growing mycobacteria, but not from mycobacteria to E. coli or between E. coli strains. The combination of two compatible plasmids in one BCG strain allows expression of recombinant mycobacterial proteins at different levels, a potentially important factor in optimizing vaccine potency.
2
Chilima, Benson Z., Ian M. Clark, Sian Floyd, Paul E. M. Fine, and Penny R. Hirsch. "Distribution of Environmental Mycobacteria in Karonga District, Northern Malawi." Applied and Environmental Microbiology 72, no. 4 (April 2006): 2343–50. http://dx.doi.org/10.1128/aem.72.4.2343-2350.2006.
Full textAbstract:
ABSTRACT The genus Mycobacterium includes many species that are commonly found in the environment (in soil and water or associated with plants and animals), as well as species that are responsible for two major human diseases, tuberculosis (Mycobacterium tuberculosis) and leprosy (Mycobacterium leprae). The distribution of environmental mycobacteria was investigated in the context of a long-term study of leprosy, tuberculosis, Mycobacterium bovis BCG vaccination, and the responses of individuals to various mycobacterial antigens in Karonga District, northern Malawi, where epidemiological studies had indicated previously that people may be exposed to different mycobacterial species in the northern and southern parts of the district. A total of 148 soil samples and 24 water samples were collected from various locations and examined to determine the presence of mycobacteria. The detection method involved semiselective culturing and acid-fast staining, following decontamination of samples to enrich mycobacteria and reduce the numbers of other microorganisms, or PCR with primers specific for the mycobacterial 16S rRNA gene, using DNA extracted directly from soil and water samples. Mycobacteria were detected in the majority of the samples, and subsequent sequence analysis of PCR products amplified directly from soil DNA indicated that most of the products were related to known environmental mycobacteria. For both methods the rates of recovery were consistently higher for dry season samples than for wet season samples. All isolates cultured from soil appeared to be strains of Mycobacterium fortuitum. This study revealed a complex pattern for the environmental mycobacterial flora but identified no clear differences between the northern and southern parts of Karonga District.
3
Fol, Marek, Piotr Koziński, Jakub Kulesza, Piotr Białecki, and Magdalena Druszczyńska. "Dual Nature of Relationship between Mycobacteria and Cancer." International Journal of Molecular Sciences 22, no. 15 (August 3, 2021): 8332. http://dx.doi.org/10.3390/ijms22158332.
Full textAbstract:
Although the therapeutic effect of mycobacteria as antitumor agents has been known for decades, recent epidemiological and experimental studies have revealed that mycobacterium-related chronic inflammation may be a possible mechanism of cancer pathogenesis. Mycobacterium tuberculosis and non-tuberculous Mycobacterium avium complex infections have been implicated as potentially contributing to the etiology of lung cancer, whereas Mycobacterium ulcerans has been correlated with skin carcinogenesis. The risk of tumor development with chronic mycobacterial infections is thought to be a result of many host effector mechanisms acting at different stages of oncogenesis. In this paper, we focus on the nature of the relationship between mycobacteria and cancer, describing the clinical significance of mycobacteria-based cancer therapy as well as epidemiological evidence on the contribution of chronic mycobacterial infections to the increased lung cancer risk.
4
Kelley, Victoria A., and Jeffrey S. Schorey. "Mycobacterium's Arrest of Phagosome Maturation in Macrophages Requires Rab5 Activity and Accessibility to Iron." Molecular Biology of the Cell 14, no. 8 (August 2003): 3366–77. http://dx.doi.org/10.1091/mbc.e02-12-0780.
Full textAbstract:
Many mycobacteria are intramacrophage pathogens that reside within nonacidified phagosomes that fuse with early endosomes but do not mature to phagolysosomes. The mechanism by which mycobacteria block this maturation process remains elusive. To gain insight into whether fusion with early endosomes is required for mycobacteria-mediated inhibition of phagosome maturation, we investigated how perturbing the GTPase cycles of Rab5 and Rab7, GTPases that regulate early and late endosome fusion, respectively, would affect phagosome maturation. Retroviral transduction of the constitutively activated forms of both GTPases into primary murine macrophages had no effect on Mycobacterium avium retention in an early endosomal compartment. Interestingly, expression of dominant negative Rab5, Rab5(S34N), but not dominant negative Rab7, resulted in a significant increase in colocalization of M. avium with markers of late endosomes/lysosomes and increased mycobacterial killing. This colocalization was specific to mycobacteria since Rab5(S34N) expressing cells showed diminished trafficking of endocytic tracers to lysosomes. We further demonstrated that maturation of M. avium phagosomes was halted in Rab5(S34N) expressing macrophages supplemented with exogenous iron. These findings suggest that fusion with early endosomes is required for mycobacterial retention in early phagosomal compartments and that an inadequate supply of iron is one factor in mycobacteria's inability to prevent the normal maturation process in Rab5(S34N)-expressing macrophages.
5
Cayer, Marie-Pierre, Marc Veillette, Pascal Pageau, Richard Hamelin, Marie-Josée Bergeron, Anne Mériaux, Yvon Cormier, and Caroline Duchaine. "Identification of mycobacteria in peat moss processing plants: application of molecular biology approaches." Canadian Journal of Microbiology 53, no. 1 (January 1, 2007): 92–99. http://dx.doi.org/10.1139/w06-105.
Full textAbstract:
Peat moss processing plant workers are exposed to high concentrations of bioaerosols. Although mycobacteria have been cultured from peat moss, no study has examined the workers' exposure to mycobacterial bioaerosols. We evaluated the presence of mycobacteria in air samples from peat moss processing plants using molecular biology approaches (cloning-sequencing and polymerase chain reaction (PCR)) and the workers exposure using immunoglobulin G (IgG) complexes to mycobacteria. In addition, species detected in air samples and in peat moss were compared. Two peat moss processing plants were chosen among 14 previously studied. A total of 49 clones were sequenced. Real-time PCR was also performed on the same air samples to evaluate the airborne concentration of mycobacteria and estimate exposure levels. Several Mycobacterium species were present in the air samples (M. malmoense, M. smegmatis, M. graceum, M. bohemicum, and M. interjectum). Mycobacterium avium was recovered by culture in peat moss but not in the air using the molecular approach. Total airborne Mycobacterium concentration was estimated at 8.2 × 108/m3. Workers had IgG against the mycobacterial mix and M. avium, suggesting significant exposure. The findings from air samples, supported by IgG measurements, demonstrate that peat moss processing plant workers are exposed to mycobacteria in addition to other biological agents.Key words: exposure, peat moss, airborne mycobacteria.
6
Mah, Nancy, Carolina Perez-Iratxeta, and Miguel A. Andrade-Navarro. "Outer membrane pore protein prediction in mycobacteria using genomic comparison." Microbiology 156, no. 8 (August 1, 2010): 2506–15. http://dx.doi.org/10.1099/mic.0.040089-0.
Full textAbstract:
Proteins responsible for outer membrane transport across the unique membrane structure of Mycobacterium spp. are attractive drug targets in the treatment of human diseases caused by the mycobacterial pathogens, Mycobacterium tuberculosis, M. bovis, M. leprae and M. ulcerans. In contrast with Escherichia coli, relatively few outer-membrane proteins (OMPs) have been identified in Mycobacterium spp., largely due to the difficulties in isolating mycobacterial membrane proteins and our incomplete understanding of secretion mechanisms and cell wall structure in these organisms. To further expand our knowledge of these elusive proteins in mycobacteria, we have improved upon our previous method of OMP prediction in mycobacteria by taking advantage of genomic data from seven mycobacteria species. Our improved algorithm suggests 4333 sequences as putative OMPs in seven species with varying degrees of confidence. The most virulent pathogenic mycobacterial species are slightly enriched in these selected sequences. We present examples of predicted OMPs involved in horizontal transfer and paralogy expansion. Analysis of local secondary structure content allowed identification of small domains predicted to perform as OMPs; some examples show their involvement in events of tandem duplication and domain rearrangements. We discuss the taxonomic distribution of these discovered families and architectures, often specific to mycobacteria or the wider taxonomic class of Actinobacteria. Our results suggest that OMP functionality in mycobacteria is richer than expected and provide a resource to guide future research of these understudied proteins.
7
Durnez, Lies, Miriam Eddyani, Georgies F. Mgode, Abdul Katakweba, Charles R. Katholi, Robert R. Machang'u, Rudovik R. Kazwala, Françoise Portaels, and Herwig Leirs. "First Detection of Mycobacteria in African Rodents and Insectivores, Using Stratified Pool Screening." Applied and Environmental Microbiology 74, no. 3 (December 7, 2007): 768–73. http://dx.doi.org/10.1128/aem.01193-07.
Full textAbstract:
ABSTRACT With the rising number of patients with human immunodeficiency virus (HIV)/AIDS in developing countries, the control of mycobacteria is of growing importance. Previous studies have shown that rodents and insectivores are carriers of mycobacteria. However, it is not clear how widespread mycobacteria are in these animals and what their role is in spreading them. Therefore, the prevalence of mycobacteria in rodents and insectivores was studied in and around Morogoro, Tanzania. Live rodents were trapped, with three types of live traps, in three habitats. Pieces of organs were pooled per habitat, species, and organ type (stratified pooling); these sample pools were examined for the presence of mycobacteria by PCR, microscopy, and culture methods. The mycobacterial isolates were identified using phenotypic techniques and sequencing. In total, 708 small mammals were collected, 31 of which were shrews. By pool prevalence estimation, 2.65% of the animals were carriers of mycobacteria, with a higher prevalence in the urban areas and in Cricetomys gambianus and the insectivore Crocidura hirta. Nontuberculous mycobacteria (Mycobacterium chimaera, M. intracellulare, M. arupense, M. parascrofulaceum, and Mycobacterium spp.) were isolated from C. gambianus, Mastomys natalensis, and C. hirta. This study is the first to report findings of mycobacteria in African rodents and insectivores and the first in mycobacterial ecology to estimate the prevalence of mycobacteria after stratified pool screening. The fact that small mammals in urban areas carry more mycobacteria than those in the fields and that potentially pathogenic mycobacteria were isolated identifies a risk for other animals and humans, especially HIV/AIDS patients, that have a weakened immune system.
8
Zavgorodniy, A. I., S. A. Pozmogova, and M. V. Kalashnyk. "Domestic parrots as a potential source of Mycobacteriosis." Journal for Veterinary Medicine, Biotechnology and Biosafety 6, no. 2 (February 28, 2020): 5–8. http://dx.doi.org/10.36016/jvmbbs-2020-6-2-1.
Full textAbstract:
The article presents the results of bacteriological examination of five samples of feces from grey parrots (Psittacus) (n = 3), cockatoo (Cacatua) (n = 1), yellow-crowned amazon (Amazona) (n = 1). Five cultures of mycobacteria were bacteriologically isolated from the five samples. According to biochemical and cultural-morphological characteristics, mycobacterial cultures are classified as Mycobacterium scrofulaceum (n = 1) and Mycobacterium genavense (n = 4). Isolated cultures of mycobacteria are important in human pathology. Infected exotic poultry pose a potential risk of mycobacterial infection in their owners, so it is necessary to conduct research on biological material
9
Chin, Kai Ling. "Molecular Characterization of Mycobacterium species Isolates from Patients with Pulmonary Tuberculosis in Sabah, Malaysia." Medicine & Health 17, no. 1 (June 29, 2022): 198–210. http://dx.doi.org/10.17576/mh.2022.1701.15.
Full textAbstract:
Tuberculosis (TB) is one of the deadliest diseases worldwide, caused by members of Mycobacterium tuberculosis complex (MTBC), commonly by Mycobacterium tuberculosis (Mtb) and Mycobacterium bovis. In Malaysia, Sabah is one of the states of public health concern with the highest TB cases. Clinical presentations of TB and non-tuberculous mycobacteria (NTM) lung disease are similar, and mycobacteria appear to be identical under standard diagnosis with sputum smear microscopy, causing difficulty to diagnose TB. Identification of Mycobacterium species is essential for effective management of mycobacterial diseases treatment and their control strategy. Thus, this study aimed to identify the Mycobacterium species from suspected TB patients in Sabah using molecular methods. Sputum samples (n=595) were screened with GeneXpert MTB/RIF (Xpert), and positive TB samples (n=67) were processed and cultured in BACTEC MGIT. Forty-five isolates were successfully recovered in MGIT and characterisation of the mycobacterial isolates using PCR and/or sequencing with rpoB, RD9, hsp65, and 16S rRNA genes confirmed the presence of Mtb in 41 samples, and four non-mycobacteria, i.e. Microbacterium laevaniformans, Streptomyces sp., Streptomyces misionensis and Gordonia sp. These non-mycobacteria isolates showed negative results when tested directly with Xpert. In conclusion, Mtb is the predominant species of MTBC circulating in Sabah. The presence of non-mycobacteria in this study was due to bacterial contamination in MGIT, not bacterial cross-reactivity in Xpert, implying the high sensitivity and specificity of Xpert for diagnosis of TB.
10
Le Dantec, Corinne, Jean-Pierre Duguet, Antoine Montiel, Nadine Dumoutier, Sylvie Dubrou, and Véronique Vincent. "Occurrence of Mycobacteria in Water Treatment Lines and in Water Distribution Systems." Applied and Environmental Microbiology 68, no. 11 (November 2002): 5318–25. http://dx.doi.org/10.1128/aem.68.11.5318-5325.2002.
Full textAbstract:
ABSTRACT The frequency of recovery of atypical mycobacteria was estimated in two treatment plants providing drinking water to Paris, France, at some intermediate stages of treatment. The two plants use two different filtration processes, rapid and slow sand filtration. Our results suggest that slow sand filtration is more efficient for removing mycobacteria than rapid sand filtration. In addition, our results show that mycobacteria can colonize and grow on granular activated carbon and are able to enter distribution systems. We also investigated the frequency of recovery of mycobacteria in the water distribution system of Paris (outside buildings). The mycobacterial species isolated from the Paris drinking water distribution system are different from those isolated from the water leaving the treatment plants. Saprophytic mycobacteria (present in 41.3% of positive samples), potentially pathogenic mycobacteria (16.3%), and unidentifiable mycobacteria (54.8%) were isolated from 12 sites within the Paris water distribution system. Mycobacterium gordonae was preferentially recovered from treated surface water, whereas Mycobacterium nonchromogenicum was preferentially recovered from groundwater. No significant correlations were found among the presence of mycobacteria, the origin of water, and water temperature.
11
Inoue, Hiroyuki, Naoki Washida, Kohkichi Morimoto, Keisuke Shinozuka, Takahiro Kasai, Kiyotaka Uchiyama, Hirobumi Tokuyama, Shu Wakino, and Hiroshi Itoh. "Non-Tuberculous Mycobacterial Infections Related to Peritoneal Dialysis." Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 38, no. 2 (March 1, 2017): 147–49. http://dx.doi.org/10.3747/pdi.2017.00172.
Full textAbstract:
Most infections related to peritoneal dialysis (PD) are caused by common bacteria, and non-tuberculous mycobacteria are rare. The clinical characteristics and prognosis of PD patients with non-tuberculous mycobacterial infections were investigated at our hospital. Non-tuberculous mycobacteria were detected in 11 patients (exit-site infection, tunnel infection, and peritonitis in 3, 5, and 3 patients, respectively). Mycobacterium fortuitum, Mycobacterium chelonae, and Mycobacterium abscessus were identified in 4, 2, and 2 patients, respectively. Most patients with peritonitis or tunnel infection required catheter removal. During the study period (2007 – 2017), peritonitis occurred in 44 patients, including 3 patients (6.8%) with non-tuberculous mycobacterial peritonitis. When non-tuberculous mycobacterial infection occurs, multi-agent antibiotic therapy, unroofing surgery, and/or catheter replacement should be performed to prevent peritonitis.
12
Armianinova, D. K., D. S. Karpov, M. S. Kotliarova, and A. V. Goncharenko. "Genetic Engineering in Mycobacteria." Molecular Biology 56, no. 6 (December 2022): 830–41. http://dx.doi.org/10.1134/s0026893322060036.
Full textAbstract:
Abstract Genetic tools for targeted modification of the mycobacterial genome contribute to the understanding of the physiology and virulence mechanisms of mycobacteria. Human and animal pathogens, such as the Mycobacterium tuberculosis complex, which causes tuberculosis, and M. leprae, which causes leprosy, are of particular importance. Genetic research opens up novel opportunities to identify and validate new targets for antibacterial drugs and to develop improved vaccines. Although mycobacteria are difficult to work with due to their slow growth rate and a limited possibility to transfer genetic information, significant progress has been made in developing genetic engineering methods for mycobacteria. The review considers the main approaches to changing the mycobacterial genome in a targeted manner, including homologous and site-specific recombination and use of the CRISPR/Cas system.
13
Falkinham, Joseph O., Cheryl D. Norton, and Mark W. LeChevallier. "Factors Influencing Numbers of Mycobacterium avium, Mycobacterium intracellulare, and Other Mycobacteria in Drinking Water Distribution Systems." Applied and Environmental Microbiology 67, no. 3 (March 1, 2001): 1225–31. http://dx.doi.org/10.1128/aem.67.3.1225-1231.2001.
Full textAbstract:
ABSTRACT Eight water distribution systems were sampled over an 18-month period (528 water and 55 biofilm samples) to measure the frequency of recovery and number of mycobacteria, particularly Mycobacterium avium and Mycobacterium intracellulare, in raw source waters before and after treatment and within the distribution system. The systems were chosen to assess the influence of source water, treatment, and assimilable organic carbon levels on mycobacterial numbers. Overall, mycobacterial recovery from the systems was low (15% of samples). Numbers of mycobacteria ranged from 10 to 700,000 CFU liter−1. The number of M. avium in raw waters was correlated with turbidity. Water treatment substantially reduced the number of mycobacteria in raw waters by 2 to 4 log units. Mycobacterial numbers were substantially higher in the distribution system samples (average, 25,000-fold) than in those collected immediately downstream from the treatment facilities, indicating that mycobacteria grow in the distribution system. The increase in mycobacterial numbers was correlated with assimilable organic carbon and biodegradable organic carbon levels (r 2 = 0.65, P = 0.03). Although M. intracellulare was seldom recovered from water samples, it was frequently recovered (six of eight systems) in high numbers from biofilms (average, 600 CFU/cm2). Evidently, the ecological niches of M. avium and M. intracellulare are distinct.
14
Orumwense, Pedro Osagie, Eila Torvinen, and Helvi Heinonen-Tanski. "The survival of mycobacteria in pure human urine." Water Science and Technology 67, no. 8 (April 1, 2013): 1773–77. http://dx.doi.org/10.2166/wst.2013.052.
Full textAbstract:
Mycobacterial pathogens can be excreted in human urine by some infected individuals. High numbers of pathogenic mycobacteria in the urine could represent a new transmission route for mycobacterial infections if the urine is used for crop fertilization. In this study, the survival of spiked Mycobacterium aurum and M. fortuitum as fast-growing mycobacteria and M. avium and M. bovis as slow-growing mycobacteria were tested in urine. The tests were conducted in fresh (<1 day old) and stored human urine (>6 months old) at temperatures of 15 and 30 °C. The results indicate that these mycobacterial strains survived less than 2 weeks in stored urine at 30 °C with a pH value of around 9.0. Mycobacteria had the longest survival time, up to 6 weeks, in fresh urine stored at 15 °C. There were negative correlations between the increase in pH and the number of spiked mycobacteria in urine. In conclusion, if human urine is to be used for fertilization, it is advisable to store it for more than 6 weeks at least at 15 °C in order to prevent survival and subsequent exposure to pathogenic mycobacteria.
15
De Groote, Mary Ann, Norman R. Pace, Kayte Fulton, and Joseph O. Falkinham. "Relationships between Mycobacterium Isolates from Patients with Pulmonary Mycobacterial Infection and Potting Soils." Applied and Environmental Microbiology 72, no. 12 (October 20, 2006): 7602–6. http://dx.doi.org/10.1128/aem.00930-06.
Full textAbstract:
ABSTRACT High numbers of mycobacteria, including known pathogenic species such as Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium chelonae, were recovered from aerosols produced by pouring commercial potting soil products and potting soil samples provided by patients with pulmonary mycobacterial infections. The dominant mycobacteria in the soil samples corresponded to the dominant species implicated clinically. Profiles of large restriction fragments obtained by pulsed-field gel electrophoresis demonstrated a closely related pair of M. avium isolates recovered from a patient and from that patient's own potting soil. Thus, potting soils are potential sources of infection by environmental mycobacteria. Use of dust-excluding masks should be considered during potting or other activities that generate aerosol with soil.
16
Aspatwar, Ashok, Jean-Yves Winum, Fabrizio Carta, Claudiu Supuran, Milka Hammaren, Mataleena Parikka, and Seppo Parkkila. "Carbonic Anhydrase Inhibitors as Novel Drugs against Mycobacterial β-Carbonic Anhydrases: An Update on In Vitro and In Vivo Studies." Molecules 23, no. 11 (November 8, 2018): 2911. http://dx.doi.org/10.3390/molecules23112911.
Full textAbstract:
Mycobacteria cause a variety of diseases, such as tuberculosis, leprosy, and opportunistic diseases in immunocompromised people. The treatment of these diseases is problematic, necessitating the development of novel treatment strategies. Recently, β-carbonic anhydrases (β-CAs) have emerged as potential drug targets in mycobacteria. The genomes of mycobacteria encode for three β-CAs that have been cloned and characterized from Mycobacterium tuberculosis (Mtb) and the crystal structures of two of the enzymes have been determined. Different classes of inhibitor molecules against Mtb β-CAs have subsequently been designed and have been shown to inhibit these mycobacterial enzymes in vitro. The inhibition of these centrally important mycobacterial enzymes leads to reduced growth of mycobacteria, lower virulence, and impaired biofilm formation. Thus, the inhibition of β-CAs could be a novel approach for developing drugs against the severe diseases caused by pathogenic mycobacteria. In the present article, we review the data related to in vitro and in vivo inhibition studies in the field.
17
Galassi, L., R. Donato, E. Tortoli, D. Burrini, D. Santianni, and R. Dei. "Nontuberculous mycobacteria in hospital water systems: application of HPLC for identification of environmental mycobacteria." Journal of Water and Health 1, no. 3 (September 1, 2003): 133–39. http://dx.doi.org/10.2166/wh.2003.0016.
Full textAbstract:
Nontuberculous mycobacteria (NTM), ubiquitous in water environments, are increasingly recognized as nosocomial pathogens. Our study reports a one-year survey of the water system of two hospitals, A and B, in a small town near Florence, Italy. NTM were found throughout the study period in both settings, but B showed a significantly higher mycobacterial load. Mycobacterium gordonae and Mycobacterium fortuitum were the most frequent species isolated. Identification was carried out by conventional techniques and by high performance liquid chromatography (HPLC) analysis of cell wall mycolic acids. HPLC profiling could be used as a first-choice method for identification of environmental mycobacteria.
18
Davis, William C., Gaber S. Abdellrazeq, Asmaa H. Mahmoud, Kun-Taek Park, Mahmoud M. Elnaggar, Gaetano Donofrio, Victoria Hulubei, and Lindsay M. Fry. "Advances in Understanding of the Immune Response to Mycobacterial Pathogens and Vaccines through Use of Cattle and Mycobacterium avium subsp. paratuberculosis as a Prototypic Mycobacterial Pathogen." Vaccines 9, no. 10 (September 26, 2021): 1085. http://dx.doi.org/10.3390/vaccines9101085.
Full textAbstract:
Lack of understanding of the immune response to mycobacterial pathogens has impeded progress in development of vaccines. Infection leads to development of an immune response that controls infection but is unable to eliminate the pathogen, resulting in a persistent infection. Although this puzzle remains to be solved, progress has been made using cattle as a model species to study the immune response to a prototypic mycobacterium, Mycobacterium a. paratuberculosis (Map). As chronicled in the review, incremental advances in characterizing the immune response to mycobacteria during the last 30 years with increases in information on the evolution of mycobacteria and relA, a gene regulating the stringent response, have brought us closer to an answer. We provide a brief overview of how mycobacterial pathogens were introduced into cattle during the transition of humankind to nomadic pastoralists who domesticated animals for food and farming. We summarize what is known about speciation of mycobacteria since the discovery of Mybacterium tuberculsis Mtb, M. bovis Mbv, and Map as zoonotic pathogens and discuss the challenges inherent in the development of vaccines to mycobacteria. We then describe how cattle were used to characterize the immune response to a prototypic mycobacterial pathogen and development of novel candidate vaccines.
19
Pagán-Ramos, E., J. Song, M. McFalone, M. H. Mudd, and V. Deretic. "Oxidative Stress Response and Characterization of theoxyR-ahpC and furA-katG Loci inMycobacterium marinum." Journal of Bacteriology 180, no. 18 (September 15, 1998): 4856–64. http://dx.doi.org/10.1128/jb.180.18.4856-4864.1998.
Full textAbstract:
ABSTRACT Oxidative stress response in pathogenic mycobacteria is believed to be of significance for host-pathogen interactions at various stages of infection. It also plays a role in determining the intrinsic susceptibility to isoniazid in mycobacterial species. In this work, we characterized the oxyR-ahpC and furA-katG loci in the nontuberculous pathogen Mycobacterium marinum. In contrast to Mycobacterium smegmatis and likeMycobacterium tuberculosis and Mycobacterium leprae, M. marinum was shown to possess a closely linked and divergently oriented equivalents of the regulator of peroxide stress response oxyR and its subordinate geneahpC, encoding a homolog of alkyl hydroperoxide reductase. Purified mycobacterial OxyR was found to bind to theoxyR-ahpC promoter region from M. marinum and additional mycobacterial species. Mobility shift DNA binding analyses using OxyR binding sites from several mycobacteria and a panel of in vitro-generated mutants validated the proposed consensus mycobacterial recognition sequence. M. marinum AhpC levels detected by immunoblotting, were increased upon treatment with H2O2, in keeping with the presence of a functional OxyR and its binding site within the promoter region ofahpC. In contrast, OxyR did not bind to the sequences upstream of the katG structural gene, and katGexpression did not follow the pattern seen with ahpC. Instead, a new open reading frame encoding a homolog of the ferric uptake regulator Fur was identified immediately upstream ofkatG in M. marinum. The furA-katGlinkage and arrangement are ubiquitous in mycobacteria, suggesting the presence of additional regulators of oxidative stress response and potentially explaining the observed differences in ahpC andkatG expression. Collectively, these findings broaden our understanding of oxidative stress response in mycobacteria. They also suggest that M. marinum will be useful as a model system for studying the role of oxidative stress response in mycobacterial physiology, intracellular survival, and other host-pathogen interactions associated with mycobacterial diseases.
20
Soini, Hanna, and James M. Musser. "Molecular Diagnosis of Mycobacteria." Clinical Chemistry 47, no. 5 (May 1, 2001): 809–14. http://dx.doi.org/10.1093/clinchem/47.5.809.
Full textAbstract:
Abstract Tuberculosis is one of the leading infectious diseases in the world and is responsible for more than 2 million deaths and 8 million new cases annually. Because of the slow growth rate of the causative agent Mycobacterium tuberculosis, isolation, identification, and drug susceptibility testing of this organism and other clinically important mycobacteria can take several weeks or longer. During the past several years, many molecular methods have been developed for direct detection, species identification, and drug susceptibility testing of mycobacteria. These methods can potentially reduce the diagnostic time from weeks to days. Currently, two nucleic acid amplification methods, the Enhanced Mycobacterium tuberculosis Direct Test (Gen-Probe) and the Amplicor Mycobacterium tuberculosis Test (Roche Diagnostic Systems), have been approved by the Food and Drug Administration for direct detection of M. tuberculosis from clinical specimens. PCR-based sequencing has become commonly used to identify many mycobacterial species. DNA probes have been widely used for species determination of the most commonly encountered mycobacteria. High-density oligonucleotide arrays (DNA microarrays) also have been applied to simultaneous species identification and detection of mutations that confer rifampin resistance in mycobacteria.
21
Bashyam, Murali D., and Anil K. Tyagi. "Identification and Analysis of “Extended −10” Promoters from Mycobacteria." Journal of Bacteriology 180, no. 9 (May 1, 1998): 2568–73. http://dx.doi.org/10.1128/jb.180.9.2568-2573.1998.
Full textAbstract:
ABSTRACT Earlier studies from our laboratory on randomly isolated transcriptional signals of mycobacteria had revealed that the −10 region of mycobacterial promoters and the corresponding binding domain in the major sigma factor are highly similar to their Escherichia coli counterparts. In contrast, the sequences in −35 regions of mycobacterial promoters and the corresponding binding domain in the major sigma factor are vastly different from their E. colicounterparts (M. D. Bashyam, D. Kaushal, S. K. Dasgupta, and A. K. Tyagi, J. Bacteriol. 178:4847–4853, 1996). We have now analyzed the role of the TGN motif present immediately upstream of the −10 region of mycobacterial promoters. Sequence analysis and site-specific mutagenesis of a Mycobacterium tuberculosispromoter and a Mycobacterium smegmatis promoter reveal that the TGN motif is an important determinant of transcriptional strength in mycobacteria. We show that mutation in the TGN motif can drastically reduce the transcriptional strength of a mycobacterial promoter. The influence of the TGN motif on transcriptional strength is also modulated by the sequences in the −35 region. Comparative assessment of these extended −10 promoters in mycobacteria and E. coli suggests that functioning of the TGN motif in promoters of these two species is similar.
22
Av-Gay, Yossef, and Rafat Sobouti. "Cholesterol is accumulated by mycobacteria but its degradation is limited to non-pathogenic fast-growing mycobacteria." Canadian Journal of Microbiology 46, no. 9 (September 1, 2000): 826–31. http://dx.doi.org/10.1139/w00-060.
Full textAbstract:
In this report we show that fast-growing non-pathogenic mycobacteria degrade cholesterol from liquid media, and are able to grow on cholesterol as a sole carbon source. In contrast, slow-growing mycobacteria, including pathogenic Mycobacterium tuberculosis and bacillus Calmette-Guérin (BCG), do not degrade and use cholesterol as a carbon source. Nevertheless, pathogenic mycobacteria are able to uptake, modify, and accumulate cholesterol from liquid growth media, and form a zone of clearance around a colony when plated on solid media containing cholesterol. These data suggest that cholesterol may have a role in mycobacterial infection other than its use as carbon source.Key words: mycobacteria, cholesterol, biodegradation.
23
Fineran, Paul, Emyr Lloyd-Evans, Nathan A. Lack, Nick Platt, Lianne C. Davis, Anthony J. Morgan, Doris Höglinger, et al. "Pathogenic mycobacteria achieve cellular persistence by inhibiting the Niemann-Pick Type C disease cellular pathway." Wellcome Open Research 1 (November 18, 2016): 18. http://dx.doi.org/10.12688/wellcomeopenres.10036.1.
Full textAbstract:
Background. Tuberculosis remains a major global health concern. The ability to prevent phagosome-lysosome fusion is a key mechanism by which intracellular mycobacteria, including Mycobacterium tuberculosis, achieve long-term persistence within host cells. The mechanisms underpinning this key intracellular pro-survival strategy remain incompletely understood. Host macrophages infected with persistent mycobacteria share phenotypic similarities with cells taken from patients suffering from Niemann-Pick Disease Type C (NPC), a rare lysosomal storage disease in which endocytic trafficking defects and lipid accumulation within the lysosome lead to cell dysfunction and cell death. We investigated whether these shared phenotypes reflected an underlying mechanistic connection between mycobacterial intracellular persistence and the host cell pathway dysfunctional in NPC. Methods. The induction of NPC phenotypes in macrophages from wild-type mice or obtained from healthy human donors was assessed via infection with mycobacteria and subsequent measurement of lipid levels and intracellular calcium homeostasis. The effect of NPC therapeutics on intracellular mycobacterial load was also assessed. Results. Macrophages infected with persistent intracellular mycobacteria phenocopied NPC cells, exhibiting accumulation of multiple lipid types, reduced lysosomal Ca2+ levels, and defects in intracellular trafficking. These NPC phenotypes could also be induced using only lipids/glycomycolates from the mycobacterial cell wall. These data suggest that persistent intracellular mycobacteria inhibit the NPC pathway, likely via inhibition of the NPC1 protein, and subsequently induce altered acidic store Ca2+ homeostasis. Reduced lysosomal calcium levels may provide a mechanistic explanation for the reduced levels of phagosome-lysosome fusion in mycobacterial infection. Treatments capable of correcting defects in NPC mutant cells via modulation of host cell calcium were of benefit in promoting clearance of mycobacteria from infected host cells. Conclusion. These findings provide a novel mechanistic explanation for mycobacterial intracellular persistence, and suggest that targeting interactions between the mycobacteria and host cell pathways may provide a novel avenue for development of anti-TB therapies.
24
Fineran, Paul, Emyr Lloyd-Evans, Nathan A. Lack, Nick Platt, Lianne C. Davis, Anthony J. Morgan, Doris Höglinger, et al. "Pathogenic mycobacteria achieve cellular persistence by inhibiting the Niemann-Pick Type C disease cellular pathway." Wellcome Open Research 1 (June 21, 2017): 18. http://dx.doi.org/10.12688/wellcomeopenres.10036.2.
Full textAbstract:
Background. Tuberculosis remains a major global health concern. The ability to prevent phagosome-lysosome fusion is a key mechanism by which intracellular mycobacteria, including Mycobacterium tuberculosis, achieve long-term persistence within host cells. The mechanisms underpinning this key intracellular pro-survival strategy remain incompletely understood. Host macrophages infected with intracellular mycobacteria share phenotypic similarities with cells taken from patients suffering from Niemann-Pick Disease Type C (NPC), a rare lysosomal storage disease in which endocytic trafficking defects and lipid accumulation within the lysosome lead to cell dysfunction and cell death. We investigated whether these shared phenotypes reflected an underlying mechanistic connection between mycobacterial intracellular persistence and the host cell pathway dysfunctional in NPC. Methods. The induction of NPC phenotypes in macrophages from wild-type mice or obtained from healthy human donors was assessed via infection with mycobacteria and subsequent measurement of lipid levels and intracellular calcium homeostasis. The effect of NPC therapeutics on intracellular mycobacterial load was also assessed. Results. Macrophages infected with intracellular mycobacteria phenocopied NPC cells, exhibiting accumulation of multiple lipid types, reduced lysosomal Ca 2+ levels, and defects in intracellular trafficking. These NPC phenotypes could also be induced using only lipids/glycomycolates from the mycobacterial cell wall. These data suggest that intracellular mycobacteria inhibit the NPC pathway, likely via inhibition of the NPC1 protein, and subsequently induce altered acidic store Ca 2+ homeostasis. Reduced lysosomal calcium levels may provide a mechanistic explanation for the reduced levels of phagosome-lysosome fusion in mycobacterial infection. Treatments capable of correcting defects in NPC mutant cells via modulation of host cell calcium were of benefit in promoting clearance of mycobacteria from infected host cells. Conclusion. These findings provide a novel mechanistic explanation for mycobacterial intracellular persistence, and suggest that targeting interactions between the mycobacteria and host cell pathways may provide a novel avenue for development of anti-TB therapies.
25
Caire-Brändli, Irène, Alexia Papadopoulos, Wladimir Malaga, David Marais, Stéphane Canaan, Lutz Thilo, and Chantal de Chastellier. "Reversible Lipid Accumulation and Associated Division Arrest of Mycobacterium avium in Lipoprotein-Induced Foamy Macrophages May Resemble Key Events during Latency and Reactivation of Tuberculosis." Infection and Immunity 82, no. 2 (November 25, 2013): 476–90. http://dx.doi.org/10.1128/iai.01196-13.
Full textAbstract:
ABSTRACTDuring the dormant phase of tuberculosis,Mycobacterium tuberculosispersists in lung granulomas by residing in foamy macrophages (FM) that contain abundant lipid bodies (LB) in their cytoplasm, allowing bacilli to accumulate lipids as intracytoplasmic lipid inclusions (ILI). An experimental model of FM is presented where bone marrow-derived mouse macrophages are infected withM. aviumand exposed to very-low-density lipoprotein (VLDL) as a lipid source. Quantitative analysis of detailed electron microscope observations showed the following results. (i) Macrophages became foamy, and mycobacteria formed ILI, for which host triacylglycerides, rather than cholesterol, was essential. (ii) Lipid transfer occurred via mycobacterium-induced fusion between LB and phagosomes. (iii) Mycobacteria showed a thinned cell wall and became elongated but did not divide. (iv) Upon removal of VLDL, LB and ILI declined within hours, and simultaneous resumption of mycobacterial division restored the number of mycobacteria to the same level as that found in untreated control macrophages. This showed that the presence of ILI resulted in a reversible block of division without causing a change in the mycobacterial replication rate. Fluctuation between ILI either partially or fully extending throughout the mycobacterial cytoplasm was suggestive of bacterial cell cycle events. We propose that VLDL-driven FM constitute a well-defined cellular system in which to study changed metabolic states of intracellular mycobacteria that may relate to persistence and reactivation of tuberculosis.
26
Torvinen, Eila, Sini Suomalainen, Markku J. Lehtola, Ilkka T. Miettinen, Outi Zacheus, Lars Paulin, Marja-Leena Katila, and Pertti J. Martikainen. "Mycobacteria in Water and Loose Deposits of Drinking Water Distribution Systems in Finland." Applied and Environmental Microbiology 70, no. 4 (April 2004): 1973–81. http://dx.doi.org/10.1128/aem.70.4.1973-1981.2004.
Full textAbstract:
ABSTRACT Drinking water distribution systems were analyzed for viable counts of mycobacteria by sampling water from waterworks and in different parts of the systems. In addition, loose deposits collected during mechanical cleaning of the main pipelines were similarly analyzed. The study covered 16 systems at eight localities in Finland. In an experimental study, mycobacterial colonization of biofilms on polyvinyl chloride tubes in a system was studied. The isolation frequency of mycobacteria increased from 35% at the waterworks to 80% in the system, and the number of mycobacteria in the positive samples increased from 15 to 140 CFU/liter, respectively. Mycobacteria were isolated from all 11 deposits with an accumulation time of tens of years and from all 4 deposits which had accumulated during a 1-year follow-up time. The numbers of mycobacteria were high in both old and young deposits (medians, 1.8 × 105 and 3.9 × 105 CFU/g [dry weight], respectively). Both water and deposit samples yielded the highest numbers of mycobacteria in the systems using surface water and applying ozonation as an intermediate treatment or posttreatment. The number and growth of mycobacteria in system waters correlated strongly with the concentration of assimilable organic carbon in the water leaving the waterworks. The densities of mycobacteria in the developing biofilms were highest at the distal sites of the systems. Over 90% of the mycobacteria isolated from water and deposits belonged to Mycobacterium lentiflavum, M. tusciae, M. gordonae, and a previously unclassified group of mycobacteria. Our results indicate that drinking water systems may be a source for recently discovered new mycobacterial species.
27
Hosseiniporgham, Sepideh, and Leonardo A. Sechi. "A Review on Mycobacteriophages: From Classification to Applications." Pathogens 11, no. 7 (July 7, 2022): 777. http://dx.doi.org/10.3390/pathogens11070777.
Full textAbstract:
Mycobacterial infections are a group of life-threatening conditions triggered by fast- or slow-growing mycobacteria. Some mycobacteria, such as Mycobacterium tuberculosis, promote the deaths of millions of lives throughout the world annually. The control of mycobacterial infections is influenced by the challenges faced in the diagnosis of these bacteria and the capability of these pathogens to develop resistance against common antibiotics. Detection of mycobacterial infections is always demanding due to the intracellular nature of these pathogens that, along with the lipid-enriched structure of the cell wall, complicates the access to the internal contents of mycobacterial cells. Moreover, recent studies depicted that more than 20% of M. tuberculosis (Mtb) infections are multi-drug resistant (MDR), and only 50% of positive MDR-Mtb cases are responsive to standard treatments. Similarly, the susceptibility of nontuberculosis mycobacteria (NTM) to first-line tuberculosis antibiotics has also declined in recent years. Exploiting mycobacteriophages as viruses that infect mycobacteria has significantly accelerated the diagnosis and treatment of mycobacterial infections. This is because mycobacteriophages, regardless of their cycle type (temperate/lytic), can tackle barriers in the mycobacterial cell wall and make the infected bacteria replicate phage DNA along with their DNA. Although the infectivity of the majority of discovered mycobacteriophages has been evaluated in non-pathogenic M. smegmatis, more research is still ongoing to find mycobacteriophages specific to pathogenic mycobacteria, such as phage DS6A, which has been shown to be able to infect members of the M. tuberculosis complex. Accordingly, this review aimed to introduce some potential mycobacteriophages in the research, specifically those that are infective to the three troublesome mycobacteria, M. tuberculosis, M. avium subsp. paratuberculosis (MAP), and M. abscessus, highlighting their theranostic applications in medicine.
28
Pavlik, Ivo, Vit Ulmann, Dana Hubelova, and Ross Tim Weston. "Nontuberculous Mycobacteria as Sapronoses: A Review." Microorganisms 10, no. 7 (July 3, 2022): 1345. http://dx.doi.org/10.3390/microorganisms10071345.
Full textAbstract:
Mycobacteria are a unique group of microorganisms. They are characterised by exceptional adaptability and durability. They are capable of colonisation and survival even in very unfavourable conditions. In addition to the well-known obligate human pathogens, Mycobacterium tuberculosis and M. leprae, more than 200 other species have been described. Most of them form a natural part of the microflora of the external environment and thrive in aquatic and soil environments especially. For many of the mycobacterial species associated with human disease, their natural source has not yet been identified. From an ecological point of view, mycobacteria are saprophytes, and their application in human and animal diseases is opportunistic. Most cases of human disease from saprophytic mycobacteria occur in immunocompromised individuals. This adaptability and resilience to environmental pressures makes treatment of mycobacterial diseases (most often sapronoses and less often zoonoses) and permanent eradication of mycobacteria from the environment very difficult. Saprophytic mycobacterial diseases (sapronoses) are chronic and recurrent due to the fact of repeated endogenous or exogenous re-exposure. Therefore, knowledge regarding their occurrence in soil and dust would aid in the prevention of saprophytic mycobacterioses. In conjunction, their presence and ecological significance in the environment can be revealed.
29
Miller, Nancimae, Susanna Infante, and Tim Cleary. "Evaluation of the LiPA MYCOBACTERIA Assay for Identification of Mycobacterial Species from BACTEC 12B Bottles." Journal of Clinical Microbiology 38, no. 5 (2000): 1915–19. http://dx.doi.org/10.1128/jcm.38.5.1915-1919.2000.
Full textAbstract:
The LiPA MYCOBACTERIA (Innogenetics NV, Ghent, Belgium) assay was used to identify mycobacterial isolates using culture fluid from positive BACTEC 12B bottles. The LiPA method involves reverse hybridization of a biotinylated mycobacterial PCR fragment, a 16 to 23S rRNA spacer region, to oligonucleotide probes arranged in lines on a membrane strip, with detection via biotin-streptavidin coupling by a colorimetric system. This system identifies Mycobacteriumspecies and differentiates M. tuberculosis complex,M. avium-M. intracellulare complex, and the following mycobacterial species: M. avium, M. intracellulare, M. kansasii, M. chelonaegroup, M. gordonae, M. xenopi, and M. scrofulaceum. The mycobacteria were identified in the laboratory by a series of tests, including the Roche AMPLICOR Mycobacterium tuberculosis (MTB) test, the Gen-Probe ACCUPROBE, and a PCR-restriction fragment length polymorphism (PCR-RFLP) analysis of the 65-kDa heat shock protein gene. The LiPA MYCOBACTERIA assay detected 60 mycobacterium isolates from 59 patients. There was complete agreement between LiPA and the laboratory identification tests for 26 M. tuberculosis complex, 9 M. avium, 3 M. intracellulare complex, 3 M. kansasii, 4 M. gordonae, and 5 M. chelonae group (all were M. abscessus) isolates. Three patient samples were LiPA positive forM. avium-M. intracellulare complex, and all were identified as M. intracellulare by the PCR-RFLP analysis. Seven additional mycobacterial species were LiPA positive forMycobacterium spp. (six were M. fortuitum, and one was M. szulgai). The LiPA MYCOBACTERIA assay was easy to perform, and the interpretation of the positive bands was clear-cut. Following PCR amplification and gel electrophoresis, the LiPA assay was completed within 3 h.
30
Sriruan, Chanjuti, Watchara Kasinrerk, Sorasak Intorasoot, Bordin Butr-Indr, Nathiprada Netirat, Jiaranai Khantipongse, and Ponrut Phunpae. "Identification and monitoring of Mycobacterium tuberculosis growth in liquid culture by Antigen 85 detection." Journal of Associated Medical Sciences 55, no. 3 (September 2, 2022): 96–104. http://dx.doi.org/10.12982/jams.2022.030.
Full textAbstract:
Background: Mycobacterium tuberculosis is the most common causative agent of tuberculosis. It releases secretory proteins, especially the Ag85 complex, from actively growing mycobacteria, which can be detected in mycobacterial liquid culture. Ag85B is the most abundant in the Ag85 complex and is an interesting target for the detection of tuberculosis. In addition, measuring Ag85 level is beneficial for comparing growing and non-growing mycobacteria in liquid culture. Objectives: To detect Ag85B protein from active growing M. tuberculosis in liquid culture for the diagnosis of tuberculosis and compare the level of Ag85B between growing and non-growing mycobacteria. Materials and methods: A sandwich ELISA assay using anti-Ag85B monoclonal antibody was performed to detect Ag85B protein. Drug-susceptible mycobacteria, M. tuberculosis H37Ra and M. tuberculosis H37Rv, as well as 12 other M. tuberculosis complex strains isolated from clinical specimens were cultured in liquid media. In addition, mycobacterial culture was separated into two conditions: untreated and treated with streptomycin. Then the liquid media were collected, filtered for sterility, and used for the detection of Ag85B. The levels of Ag85B between treated and untreated conditions were analyzed. Results: In untreated mycobacterial culture, Ag85B protein was detected and continuously increased each day. However, Ag85B in treated mycobacterial culture increased slightly in the early days and then stabilized. These results demonstrate that the growth of mycobacteria was inhibited after culturing with streptomycin. Thus, the increase of Ag85B was not observed because this protein cannot be secreted by dead mycobacteria. On the other hand, living mycobacteria can secrete the Ag85B protein continuously. Moreover, Ag85B accumulated and increased with each passing day. Conclusion: M. tuberculosis can produce and release Ag85B protein. In this study, detection of Ag85B in liquid culture by a sandwich ELISA assay was used to identify M. tuberculosis. When M. tuberculosis was suppressed or killed by anti-TB medications, it stopped growing and the increase in Ag85B proteins disappeared. As a result, the levels of Ag85B could be used to detect living mycobacteria. Furthermore, this knowledge can be further applied to monitor mycobacterial growth affected by testing mycobacteria with anti-TB drugs.
31
Gan, Wei Chong, Hien Fuh Ng, and Yun Fong Ngeow. "Mechanisms of Linezolid Resistance in Mycobacteria." Pharmaceuticals 16, no. 6 (May 24, 2023): 784. http://dx.doi.org/10.3390/ph16060784.
Full textAbstract:
Mycobacteria form some of the most notorious and difficult-to-treat bacterial pathogens. As a group, they are intrinsically resistant to many commonly used antibiotics, such as tetracyclines and beta-lactams. In addition to intrinsic resistances, acquired multidrug resistance has also been observed and documented in Mycobacterium tuberculosis (MTB), Mycobacterium leprae and non-tuberculous mycobacteria (NTM). To combat multidrug resistant infections by these pathogens, innovative antimicrobials and treatment regimens are required. In this regard, linezolid, an oxazolidinone introduced for clinical use just two decades ago, was added to the therapeutic armamentarium for drug-resistant mycobacteria. It exhibits antibacterial activity by binding to the 50S ribosomal subunit and inhibiting protein synthesis. Unfortunately, linezolid resistance has now been documented in MTB and NTM, in many parts of the world. Most linezolid-resistant mycobacterial strains show mutations in the ribosome or related genes, such as in the rplC, rrl and tsnR genes. Non-ribosomal mechanisms appear to be rare. One such mechanism was associated with a mutation in fadD32, which encodes a protein that plays an important role in mycolic acid synthesis. Mycobacterial efflux proteins have also been implicated in linezolid resistance. This review summarises current knowledge of genetic determinants of linezolid resistance in mycobacteria, with the aim of contributing information that could facilitate the discovery of new therapeutic approaches to overcome, delay or avoid further developments of drug resistance among these important pathogens.
32
Qadri, S. M. Hussain, and Kevin K. Smith. "Nonspecificity of the Anda A60-tb ELISA test for serodiagnosis of mycobacterial disease." Canadian Journal of Microbiology 38, no. 8 (August 1, 1992): 804–6. http://dx.doi.org/10.1139/m92-131.
Full textAbstract:
The conventional methods for the laboratory diagnosis of tuberculosis and other mycobacterial diseases are time consuming and beyond the scope of most of the small and medium-sized hospital facilities. Therefore, there has been considerable interest in the development of a serological method for the detection of antibodies against mycobacteria. We recently evaluated a commercially available ELISA test (Anda Biologicals, Strasbourg, France) that measures antibody levels to A60 antigen, a membrane glycoprotein that is found in most mycobacteria. Of the 123 patients with positive pulmonary cultures for Mycobacterium tuberculosis, 82% had detectable antibodies against the kit antigen. Of the 68 patients with extrapulmonary tuberculosis, 59% yielded positive results. Specimens from 2 of the 12 patients that grew Mycobacterium avium–intracellulare complex, and one each with Mycobacterium fortuitum and Mycobacterium chelonei, were considered significant on the basis of medical history and repeated isolation of the bacterium from clinical specimens, and these patients yielded positive serology. Of the healthy, normal PPD positive and PPD negative controls, 24% gave false positive results. Key words: Anda A60-tb ELISA, serodiagnosis of mycobacteria, mycobacterium.
33
Torkko, Pirjo, Marja-Leena Katila, and Merja Kontro. "Gas-chromatographic lipid profiles in identification of currently known slowly growing environmental mycobacteria." Journal of Medical Microbiology 52, no. 4 (April 1, 2003): 315–23. http://dx.doi.org/10.1099/jmm.0.05113-0.
Full textAbstract:
Cellular fatty acid analysis by GLC is widely used in the species identification of mycobacteria. Combining mycolic acid cleavage products with shorter cellular fatty acids increases the informative value of the analysis. A key has been created to aid in the identification of all currently known slowly growing environmental species. In this scheme, the species are classified into six categories, each characterized by a combination of fatty markers shared by those species. Within each category, individual species may be distinguished by the presence or absence of specific marker substances, such as methyl-branched fatty acids or secondary alcohols. This study also describes earlier unpublished GLC profiles of 14 rare, slowly growing, environmental mycobacteria, Mycobacterium asiaticum, Mycobacterium botniense, Mycobacterium branderi, Mycobacterium conspicuum, Mycobacterium cookii, Mycobacterium doricum, Mycobacterium heckeshornense, Mycobacterium heidelbergense, Mycobacterium hiberniae, Mycobacterium kubicae, Mycobacterium lentiflavum, Mycobacterium scrofulaceum, Mycobacterium triplex and Mycobacterium tusciae. Though no single identification technique alone, even sequencing of an entire single gene such as 16S rRNA, can identify all mycobacterial species accurately, GLC has proven to be both reliable and reproducible in the identification of slowly growing mycobacteria. In cases of earlier unknown species, it generates useful information that allows their further classification and may lead to the description of novel species.
34
Seagar, A. Louise, Carmel Prendergast, F. Xavier Emmanuel, Alan Rayner, Susan Thomson, and Ian F. Laurenson. "Evaluation of the GenoType Mycobacteria Direct assay for the simultaneous detection of the Mycobacterium tuberculosis complex and four atypical mycobacterial species in smear-positive respiratory specimens." Journal of Medical Microbiology 57, no. 5 (May 1, 2008): 605–11. http://dx.doi.org/10.1099/jmm.0.47484-0.
Full textAbstract:
A novel, commercially available reverse hybridization assay [GenoType Mycobacteria Direct (GTMD), version 2.0; Hain Lifescience] was evaluated for the direct detection of five clinically relevant mycobacterial species [Mycobacterium tuberculosis complex (MTBC), Mycobacterium avium, Mycobacterium malmoense, Mycobacterium kansasii and Mycobacterium intracellulare] from 54 smear-positive respiratory specimens and the findings were compared with culture results. Three approaches were used for specimen preparation using either whole or ‘split’ sample volumes and N-acetyl-l-cysteine/3 % NaOH or 4 % NaOH as decontamination chemicals. Forty-three out of 52 samples in which RNA amplification was successful gave GTMD results that concurred with the identification of the cultured isolate. All cases of MTBC were detected. Twenty-two samples contained M. tuberculosis complex, seven had M. kansasii, four had M. malmoense, seven contained atypical mycobacteria other than those detectable using the GTMD assay and three specimens contained no viable mycobacteria. The assay is easy to use and can be completed in one working day. Results interpretation is facilitated by the inclusion of an internal amplification control with each sample to allow identification of specimens containing amplification inhibitors. A positive GTMD result will quickly identify patients with MTBC infection or provide specific identification of four other atypical mycobacteria from the same specimen. This allows more rapid drug susceptibility testing, treatment, and public health and infection control decisions.
35
Menendez, M. C., M. J. Garcia, M. C. Navarro, J. A. Gonzalez-y-Merchand, S. Rivera-Gutierrez, L. Garcia-Sanchez, and R. A. Cox. "Characterization of an rRNA Operon (rrnB) of Mycobacterium fortuitum and Other Mycobacterial Species: Implications for the Classification of Mycobacteria." Journal of Bacteriology 184, no. 4 (February 15, 2002): 1078–88. http://dx.doi.org/10.1128/jb.184.4.1078-1088.2002.
Full textAbstract:
ABSTRACT Mycobacteria are thought to have either one or two rRNA operons per genome. All mycobacteria investigated to date have an operon, designated rrnA, located downstream from the murA gene. We report that Mycobacteriun fortuitum has a second rrn operon, designated rrnB, which is located downstream from the tyrS gene; tyrS is very close to the 3" end of a gene (3-mag) coding for 3-methylpurine-DNA-glycosylase. The second rrn operon of Mycobacterium smegmatis was shown to have a similar organization, namely, 5" 3-mag-tyrS-rrnB 3". The rrnB operon of M. fortuitum was found to have a single dedicated promoter. During exponential growth in a rich medium, the rrnB and rrnA operons were the major and minor contributors, respectively, to pre-rRNA synthesis. Genomic DNA was isolated from eight other fast-growing mycobacterial species. Samples were investigated by Southern blot analysis using probes for murA, tyrS, and 16S rRNA sequences. The results revealed that both rrnA and rrnB operons were present in each species. The results form the basis for a proposed new scheme for the classification of mycobacteria. The approach, which is phylogenetic in concept, is based on particular properties of the rrn operons of a cell, namely, the number per genome and a feature of 16S rRNA gene sequences.
36
Rindi, Laura, Vincenzo Puglisi, Iacopo Franconi, Roberta Fais, and Antonella Lupetti. "Rapid and Accurate Identification of Nontuberculous Mycobacteria Directly from Positive Primary MGIT Cultures by MALDI-TOF MS." Microorganisms 10, no. 7 (July 18, 2022): 1447. http://dx.doi.org/10.3390/microorganisms10071447.
Full textAbstract:
Over the last years, nontuberculous mycobacteria (NTM) have emerged as important human pathogens. Accurate and rapid mycobacterial species identification is needed to successfully diagnose, treat, and manage infections caused by NTM. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, MALDI-TOF MS, was demonstrated to effectively identify mycobacteria isolates subcultured from solid or liquid media rather than new positive cultures. The present study aims to develop a new extraction protocol to yield rapid and accurate identification of NTM from primary MGIT cultures by MALDI-TOF MS. A total of 60 positive MGIT broths were examined by the Bruker Biotyper system with Mycobacteria Library v. 2.0 (Bruker Daltonics GmbH & Co. KG., Bremen, Germany). The results were compared with those obtained by the molecular method, line probe assay GenoType Mycobacterium CM/AS/NTM-DR. All samples were concordantly identified by MALDI-TOF MS and the molecular test for all the tested mycobacteria. Fifty-seven (95%) MGIT positive cultures for NTM from clinical samples had a MALDI-TOF MS analysis score S ≥ 1.8. Although a small number of strains and a limited diversity of mycobacterial species were analysed, our results suggest that MALDI-TOF MS could represent a promising routine diagnostic tool for identifying mycobacterial species directly from primary liquid culture.
37
Ufimtseva, Elena. "Differences betweenMycobacterium-Host Cell Relationships in Latent Tuberculous Infection of MiceEx Vivoand Mycobacterial Infection of Mouse CellsIn Vitro." Journal of Immunology Research 2016 (2016): 1–21. http://dx.doi.org/10.1155/2016/4325646.
Full textAbstract:
The search for factors that account for the reproduction and survival of mycobacteria, including vaccine strains, in host cells is the priority for studies on tuberculosis. A comparison of BCG-mycobacterial loads in granuloma cells obtained from bone marrow and spleens of mice with latent tuberculous infection and cells from mouse bone marrow and peritoneal macrophage cultures infected with the BCG vaccinein vitrohas demonstrated that granuloma macrophages each normally contained a single BCG-Mycobacterium, while those acutely infectedin vitrohad increased mycobacterial loads and death rates. Mouse granuloma cells were observed to produce the IFNγ, IL-1α, GM-CSF, CD1d, CD25, CD31, СD35, and S100 proteins. None of these activation markers were found in mouse cell cultures infectedin vitroor in intact macrophages. Lack of colocalization of lipoarabinomannan-labeled BCG-mycobacteria with the lysosomotropic LysoTracker dye in activated granuloma macrophages suggests that these macrophages were unable to destroy BCG-mycobacteria. However, activated mouse granuloma macrophages could control mycobacterial reproduction in cells bothin vivoand inex vivoculture. By contrast, a considerable increase in the number of BCG-mycobacteria was observed in mouse bone marrow and peritoneal macrophages after BCG infectionin vitro, when no expression of the activation-related molecules was detected in these cells.
38
Banducci-Karp, Adrianna, Jiajun Xie, Sem A. G. Engels, Christos Sarantaris, Patrick van Hage, Monica Varela, Annemarie H. Meijer, and Michiel van der Vaart. "DRAM1 Promotes Lysosomal Delivery of Mycobacterium marinum in Macrophages." Cells 12, no. 6 (March 7, 2023): 828. http://dx.doi.org/10.3390/cells12060828.
Full textAbstract:
Damage-Regulated Autophagy Modulator 1 (DRAM1) is an infection-inducible membrane protein, whose function in the immune response is incompletely understood. Based on previous results in a zebrafish infection model, we have proposed that DRAM1 is a host resistance factor against intracellular mycobacterial infection. To gain insight into the cellular processes underlying DRAM1-mediated host defence, here we studied the interaction of DRAM1 with Mycobacterium marinum in murine RAW264.7 macrophages. We found that, shortly after phagocytosis, DRAM1 localised in a punctate pattern to mycobacteria, which gradually progressed to full DRAM1 envelopment of the bacteria. Within the same time frame, DRAM1-positive mycobacteria colocalised with the LC3 marker for autophagosomes and LysoTracker and LAMP1 markers for (endo)lysosomes. Knockdown analysis revealed that DRAM1 is required for the recruitment of LC3 and for the acidification of mycobacteria-containing vesicles. A reduction in the presence of LAMP1 further suggested reduced fusion of lysosomes with mycobacteria-containing vesicles. Finally, we show that DRAM1 knockdown impairs the ability of macrophages to defend against mycobacterial infection. Together, these results support that DRAM1 promotes the trafficking of mycobacteria through the degradative (auto)phagolysosomal pathway. Considering its prominent effect on host resistance to intracellular infection, DRAM1 is a promising target for therapeutic modulation of the microbicidal capacity of macrophages.
39
Sethiya, Jigar P., Melanie A. Sowards, Mary Jackson, and Elton Jeffrey North. "MmpL3 Inhibition: A New Approach to Treat Nontuberculous Mycobacterial Infections." International Journal of Molecular Sciences 21, no. 17 (August 27, 2020): 6202. http://dx.doi.org/10.3390/ijms21176202.
Full textAbstract:
Outside of Mycobacterium tuberculosis and Mycobacterium leprae, nontuberculous mycobacteria (NTM) are environmental mycobacteria (>190 species) and are classified as slow- or rapid-growing mycobacteria. Infections caused by NTM show an increased incidence in immunocompromised patients and patients with underlying structural lung disease. The true global prevalence of NTM infections remains unknown because many countries do not require mandatory reporting of the infection. This is coupled with a challenging diagnosis and identification of the species. Current therapies for treatment of NTM infections require multidrug regimens for a minimum of 18 months and are associated with serious adverse reactions, infection relapse, and high reinfection rates, necessitating discovery of novel antimycobacterial agents. Robust drug discovery processes have discovered inhibitors targeting mycobacterial membrane protein large 3 (MmpL3), a protein responsible for translocating mycolic acids from the inner membrane to periplasm in the biosynthesis of the mycobacterial cell membrane. This review focuses on promising new chemical scaffolds that inhibit MmpL3 function and represent interesting and promising putative drug candidates for the treatment of NTM infections. Additionally, agents (FS-1, SMARt-420, C10) that promote reversion of drug resistance are also reviewed.
40
Vieira, Otilia V., Rene E. Harrison, Cameron C. Scott, Harald Stenmark, David Alexander, Jun Liu, Jean Gruenberg, Alan D. Schreiber, and Sergio Grinstein. "Acquisition of Hrs, an Essential Component of Phagosomal Maturation, Is Impaired by Mycobacteria." Molecular and Cellular Biology 24, no. 10 (May 15, 2004): 4593–604. http://dx.doi.org/10.1128/mcb.24.10.4593-4604.2004.
Full textAbstract:
ABSTRACT Pathogenic mycobacteria survive within macrophages by precluding the fusion of phagosomes with late endosomes or lysosomes. Because the molecular determinants of normal phagolysosome formation are poorly understood, the sites targeted by mycobacteria remain unidentified. We found that Hrs, an adaptor molecule involved in protein sorting, associates with phagosomes prior to their fusion with late endosomes or lysosomes. Recruitment of Hrs required the interaction of its FYVE domain with phagosomal phosphatidylinositol 3-phosphate, but two other attachment sites were additionally involved. Depletion of Hrs by use of small interfering RNA impaired phagosomal maturation, preventing the acquisition of lysobisphosphatidic acid and reducing luminal acidification. As a result, the maturation of phagosomes formed in Hrs-depleted cells was arrested at an early stage, characterized by the acquisition and retention of sorting endosomal markers. This phenotype is strikingly similar to that reported to occur in phagosomes of cells infected by mycobacteria. We therefore tested whether Hrs is recruited to phagosomes containing mycobacteria. Hrs associated readily with phagosomes containing inert particles but poorly with mycobacterial phagosomes. Moreover, Hrs was found more frequently in phagosomes containing avirulent Mycobacterium smegmatis than in phagosomes with the more virulent Mycobacterium marinum. These findings suggest that the inability to recruit Hrs contributes to the arrest of phagosomal maturation induced by pathogenic mycobacteria.
41
Pandey, N., K. Singh, F. Ahmad, and R. Sharma. "Characterization of biofilm formation by Mycobacterium smegmatis during different environmental stress conditions: An in-vitro study." Journal of Environmental Biology 43, no. 6 (November 15, 2022): 771–78. http://dx.doi.org/10.22438/jeb/43/6/mrn-4081.
Full textAbstract:
Aim: In-vitro characterisation of biofilm produced by Mycobacterium smegmatis (M. smegmatis), a surrogate model for biofilm production by Mycobacteria, and to evaluate the impact of different environmental stress on mycobacterial growth and biofilm formation. Methodology: M. smegmatis biofilms were studied using tissue culture plate and tube adherence methods. Confocal Laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were used to study the 3D structure and surface morphology, respectively. Additionally, the effect of different environmental stress, such as the absence of essential ions, exposure to harsh environmental conditions, such as acidic environment or oxidative stress, on mycobacterial biofilm formation and mycobacterial growth was assessed. Results: All the exposures, except for carbon supplemented media had a detrimental effect on the number of viable counts and on biofilm formation by mycobacteria (p<0.001). Growth in low pH and oxidative stress was found to be maximum showing reduction by 98% when compared with control. Interpretation: Our findings present various environmental conditions that profoundly affect biofilm formation and thus, may find practical implications in future as effective mycobacterial control strategies having attributes of mycobacterial growth as well as biofilm inhibition. Key words: Biofilm, Environmental stress, Multi-drug resistance, Mycobacterium
42
Bartos, M., J. O Falkinham, III, and I. Pavlik. "Mycobacterial catalases, peroxidases, and superoxide dismutases and their effects on virulence and isoniazid-susceptibility in mycobacteria – a review." Veterinární Medicína 49, No. 5 (March 29, 2012): 161–70. http://dx.doi.org/10.17221/5691-vetmed.
Full textAbstract:
Mycobacteria are intracellular bacterial parasites which survive and proliferate inside of macrophages for long periods of time. Because mycobacterial survival in macrophages is required for virulence, a great deal of effort has been focused on identifying the genetic and physiologic determinants of intracellular survival and growth. A number of factors, among them catalases, peroxidases, and superoxide dismutase have been suggested as agents permitting mycobacteria to overcome the intracellular defences of macrophages. The characteristic features of mycobacterial catalase/peroxidases and superoxide dismutase, their distribution within the genus Mycobacterium, and their mutual interactions in the inactivation of toxic oxygen products are reviewed. Focus is placed on evidence of the role of mycobacterial catalase-peroxidase and superoxide dismutase in virulence and on the role of catalase-peroxidase in susceptibility to isonicotinic acid hydrazide.
43
Roach, Shannon K., and Jeffrey S. Schorey. "Differential Regulation of the Mitogen-Activated Protein Kinases by Pathogenic and Nonpathogenic Mycobacteria." Infection and Immunity 70, no. 6 (June 2002): 3040–52. http://dx.doi.org/10.1128/iai.70.6.3040-3052.2002.
Full textAbstract:
ABSTRACT Mycobacteria are the etiologic agents of numerous diseases which account for significant morbidity and mortality in humans and other animal species. Many mycobacteria are intramacrophage pathogens and therefore the macrophage response to infection, which includes synthesis of cytokines such as tumor necrosis factor alpha (TNF-α) and production of nitric oxide, has important consequences for host immunity. However, very little is known about the macrophage cell signaling pathways initiated upon infection or how pathogenic mycobacteria may modulate the macrophage responses. Using primary murine bone marrow macrophages, we established that p38 and extracellular signal-regulated kinases 1 and 2 of the mitogen-activated protein kinase (MAPK) pathways are activated upon infection with different species of mycobacteria. However, we observed decreased MAPK activity over time in macrophages infected with pathogenic Mycobacterium avium strains relative to infections with nonpathogenic mycobacteria. Furthermore, macrophages infected with M. avium produced lower levels of TNF-α, interleukin 1β, and inducible nitric oxide synthase 2 than macrophages infected with nonpathogenic species. Inhibitor studies indicate that the MAPKs are required for the Mycobacterium-mediated induction of these effector proteins. Our data indicate that MAPKs are activated in macrophages upon invasion by mycobacteria and that this activation is diminished in macrophages infected with pathogenic strains of M. avium, resulting in decreased production of important immune effector proteins. The decreased MAPK activation associated with M. avium infections suggests a novel point of immune intervention by this mycobacterial species.
44
Falkinham, Joseph O. "The Changing Pattern of Nontuberculous Mycobacterial Disease." Canadian Journal of Infectious Diseases 14, no. 5 (2003): 281–86. http://dx.doi.org/10.1155/2003/323058.
Full textAbstract:
Nontuberculous mycobacteria are human opportunistic pathogens whose source of infection is the environment. These include both slow-growing (eg,Mycobacterium kansasii and Mycobacterium avium) and rapid-growing (eg,Mycobacterium abscessusandMycobacterium fortuitum) species. Transmission is through ingestion or inhalation of water, particulate matter or aerosols, or through trauma. The historic presentation of pulmonary disease in older individuals with predisposing lung conditions and in children has been changing. Pulmonary disease in elderly individuals who lack the classic predisposing lung conditions is increasing. Pulmonary disease and hypersensitivity pneumonitis have been linked with occupational or home exposures to nontuberculous mycobacteria. There has been a shift fromMycobacterium scrofulaceumtoM aviumin children with cervical lymphadenitis. Further, individuals who are immunosuppressed due to therapy or HIV-infection are at a greatly increased risk for nontuberculous mycobacterial infection. The changing pattern of nontuberculous mycobacterial disease is due in part to the ability of these pathogens to survive and proliferate in habitats that they share with humans, such as drinking water. The advent of an aging population and an increase in the proportion of immunosuppressed individuals suggest that the prevalence of nontuberculous mycobacterial disease will increase.
45
Liu, Cui Hua, Jie Li, Bingxi Li, and Jing Wang. "M. tuberculosis Mce3C promotes mycobacterial mammalian cell entrance and enhances mycobactrial intracellular survival." Journal of Immunology 196, no. 1_Supplement (May 1, 2016): 65.7. http://dx.doi.org/10.4049/jimmunol.196.supp.65.7.
Full textAbstract:
Abstract It has been suggested that the mammalian cell entry (Mce) proteins are involved in the macrophage cell entry process and the subsequent intracellular survival of Mycobacterium tuberculosis during infection. However, relatively little is known about the specific roles of Mce3C in modulation of phagocytosis and host innate immune defenses. Here we demonstrate that Mce3C can promote the entry of mycobacteria into macrophage cells in a RGD motif-dependent manner. During our attempt to screen for potential Mce3C-interacting host proteins utilizing yeast two-hybrid assay, we found that Mce3C interacts with integrin β2 subunit, which renders it very likely that Mce3C binds β2 family of leukocyte integrins including αLβ2,αMβ2 and αXβ2 through its RGD motif, thus enhancing phagocytosis of mycobacteria by macrophage cells. Furthermore, Mce3C blocks the activation of ERK1/2 signaling pathway, leading to the suppression of Tnf and Il-1β expression, and the promotion of mycobacterial survival within macrophages. Finally, we discover that Mce3C undermines apoptosis of macrophage cells during the course of mycobacterial infection, which further facilitates the intracellular survival of mycobacteria. Thus, these results indicate that M. tuberculosis Mce3C not only strengthens the internalization of macrophage cells by mycobacteria via RGD-mediated interaction with β2 family of leukocyte integrins, but also enhances the intracellular survival of mycobacteria through inhibition of ERK1/2 signaling pathway and apoptosis in macrophage cells.
46
Harth, Günter, and Marcus A. Horwitz. "An Inhibitor of Exported Mycobacterium tuberculosis Glutamine Synthetase Selectively Blocks the Growth of Pathogenic Mycobacteria in Axenic Culture and in Human Monocytes: Extracellular Proteins as Potential Novel Drug Targets." Journal of Experimental Medicine 189, no. 9 (May 3, 1999): 1425–36. http://dx.doi.org/10.1084/jem.189.9.1425.
Full textAbstract:
Mycobacterium tuberculosis and other pathogenic mycobacteria export abundant quantities of proteins into their extracellular milieu when growing either axenically or within phagosomes of host cells. One major extracellular protein, the enzyme glutamine synthetase, is of particular interest because of its link to pathogenicity. Pathogenic mycobacteria, but not nonpathogenic mycobacteria, export large amounts of this protein. Interestingly, export of the enzyme is associated with the presence of a poly-l-glutamate/glutamine structure in the mycobacterial cell wall. In this study, we investigated the influence of glutamine synthetase inhibitors on the growth of pathogenic and nonpathogenic mycobacteria and on the poly-l-glutamate/glutamine cell wall structure. The inhibitor l-methionine-S-sulfoximine rapidly inactivated purified M. tuberculosis glutamine synthetase, which was 100-fold more sensitive to this inhibitor than a representative mammalian glutamine synthetase. Added to cultures of pathogenic mycobacteria, l-methionine- S-sulfoximine rapidly inhibited extracellular glutamine synthetase in a concentration-dependent manner but had only a minimal effect on cellular glutamine synthetase, a finding consistent with failure of the drug to cross the mycobacterial cell wall. Remarkably, the inhibitor selectively blocked the growth of pathogenic mycobacteria, all of which release glutamine synthetase extracellularly, but had no effect on nonpathogenic mycobacteria or nonmycobacterial microorganisms, none of which release glutamine synthetase extracellularly. The inhibitor was also bacteriostatic for M. tuberculosis in human mononuclear phagocytes (THP-1 cells), the pathogen's primary host cells. Paralleling and perhaps underlying its bacteriostatic effect, the inhibitor markedly reduced the amount of poly-l-glutamate/glutamine cell wall structure in M. tuberculosis. Although it is possible that glutamine synthetase inhibitors interact with additional extracellular proteins or structures, our findings support the concept that extracellular proteins of M. tuberculosis and other pathogenic mycobacteria are worthy targets for new antibiotics. Such proteins constitute readily accessible targets of these relatively impermeable organisms, which are rapidly developing resistance to conventional antibiotics.
47
Roth, Andreas, Udo Reischl, Anna Streubel, Ludmila Naumann, Reiner M. Kroppenstedt, Marion Habicht, Marga Fischer, and Harald Mauch. "Novel Diagnostic Algorithm for Identification of Mycobacteria Using Genus-Specific Amplification of the 16S-23S rRNA Gene Spacer and Restriction Endonucleases." Journal of Clinical Microbiology 38, no. 3 (2000): 1094–104. http://dx.doi.org/10.1128/jcm.38.3.1094-1104.2000.
Full textAbstract:
A novel genus-specific PCR for mycobacteria with simple identification to the species level by restriction fragment length polymorphism (RFLP) was established using the 16S-23S ribosomal RNA gene (rDNA) spacer as a target. Panspecificity of primers was demonstrated on the genus level by testing 811 bacterial strains (122 species in 37 genera from 286 reference strains and 525 clinical isolates). All mycobacterial isolates (678 strains among 48 defined species and 5 indeterminate taxons) were amplified by the new primers. Among nonmycobacterial isolates, only Gordonia terrae was amplified. The RFLP scheme devised involves estimation of variable PCR product sizes together with HaeIII and CfoI restriction analysis. It yielded 58 HaeIII patterns, of which 49 (84%) were unique on the species level. Hence,HaeIII digestion together with CfoI results was sufficient for correct identification of 39 of 54 mycobacterial taxons and one of three or four of seven RFLP genotypes found inMycobacterium intracellulare and Mycobacterium kansasii, respectively. Following a clearly laid out diagnostic algorithm, the remaining unidentified organisms fell into five clusters of closely related species (i.e., the Mycobacterium aviumcomplex or Mycobacterium chelonae-Mycobacterium abscessus) that were successfully separated using additional enzymes (TaqI, MspI, DdeI, orAvaII). Thus, next to slowly growing mycobacteria, all rapidly growing species studied, including M. abscessus,M. chelonae, Mycobacterium farcinogenes,Mycobacterium fortuitum, Mycobacterium peregrinum, and Mycobacterium senegalense (with a very high 16S rDNA sequence similarity) were correctly identified. A high intraspecies sequence stability and the good discriminative power of patterns indicate that this method is very suitable for rapid and cost-effective identification of a wide variety of mycobacterial species without the need for sequencing. Phylogenetically, spacer sequence data stand in good agreement with 16S rDNA sequencing results, as was shown by including strains with unsettled taxonomy. Since this approach recognized significant subspecific genotypes while identification of a broad spectrum of mycobacteria rested on identification of one specific RFLP pattern within a species, this method can be used by both reference (or research) and routine laboratories.
48
Aboagye, Samuel Yaw, Emelia Danso, Kobina Assan Ampah, Zuliehatu Nakobu, Prince Asare, Isaac Darko Otchere, Katharina Röltgen, Dzidzo Yirenya-Tawiah, and Dorothy Yeboah-Manu. "Isolation of Nontuberculous Mycobacteria from the Environment of Ghanian Communities Where Buruli Ulcer Is Endemic." Applied and Environmental Microbiology 82, no. 14 (May 6, 2016): 4320–29. http://dx.doi.org/10.1128/aem.01002-16.
Full textAbstract:
ABSTRACTThis study aimed to isolate nontuberculous mycobacterial species from environmental samples obtained from some selected communities in Ghana. To optimize decontamination, spiked environmental samples were used to evaluate four decontamination solutions and supplemented media, after which the best decontamination solution and media were used for the actual analysis. The isolates obtained were identified on the basis of specific genetic sequences, including heat shock protein 65, IS2404, IS2606,rpoB, and the ketoreductase gene, as needed. Among the methods evaluated, decontamination with 1 M NaOH followed by 5% oxalic acid gave the highest rate of recovery of mycobacteria (50.0%) and the lowest rate of contamination (15.6%). The cultivation medium that supported the highest rate of recovery of mycobacteria was polymyxin B-amphotericin B-nalidixic acid-trimethoprim-azlocillin–supplemented medium (34.4%), followed by isoniazid-supplemented medium (28.1%). Among the 139 samples cultivated in the main analysis, 58 (41.7%) yielded mycobacterial growth, 70 (50.4%) had no growth, and 11 (7.9%) had all inoculated tubes contaminated. A total of 25 different mycobacterial species were identified. Fifteen species (60%) were slowly growing (e.g.,Mycobacterium ulcerans,Mycobacterium avium,Mycobacterium mantenii, andMycobacterium malmoense), and 10 (40%) were rapidly growing (e.g.,Mycobacterium chelonae,Mycobacterium fortuitum, andMycobacterium abscessus). The occurrence of mycobacterial species in the various environmental samples analyzed was as follows: soil, 16 species (43.2%); vegetation, 14 species (38.0%); water, 3 species (8.0%); moss, 2 species (5.4%); snail, 1 species (2.7%); fungi, 1 species (2.7%). This study is the first to report on the isolation ofM. ulceransand other medically relevant nontuberculous mycobacteria from different environmental sources in Ghana.IMPORTANCEDiseases caused by mycobacterial species other than those that cause tuberculosis and leprosy are increasing. Control is difficult because the current understanding of how the organisms are spread and where they live in the environment is limited, although this information is needed to design preventive measures. Growing these organisms from the environment is also difficult, because the culture medium becomes overgrown with other bacteria that also live in the environment, such as in soil and water. We aimed to improve the methods for growing these organisms from environmental sources, such as soil and water samples, for better understanding of important mycobacterial ecology.
49
Menozzi, F. D., J. H. Rouse, M. Alavi, M. Laude-Sharp, J. Muller, R. Bischoff, M. J. Brennan, and C. Locht. "Identification of a heparin-binding hemagglutinin present in mycobacteria." Journal of Experimental Medicine 184, no. 3 (September 1, 1996): 993–1001. http://dx.doi.org/10.1084/jem.184.3.993.
Full textAbstract:
Adherence to mammalian host tissues is an important virulence trait in microbial pathogenesis, yet little is known about the adherence mechanisms of mycobacteria. Here, we show that binding of mycobacteria to epithelial cells but not to macrophages can be specifically inhibited by sulfated carbohydrates. Using heparin-Sepharose chromatography, a 28-kD heparin-binding protein was purified from culture supernatants and cell extracts of Mycobacterium bovis and Mycobacterium tuberculosis. This protein, designated heparin-binding hemagglutinin (HBHA), promotes the agglutination of rabbit erythrocytes, which is specifically inhibited by sulfated carbohydrates. HBHA also induce mycobacterial aggregation, suggesting that it can mediate bacteria-bacteria interactions as well. Hemagglutination, mycobacterial aggregation, as well as attachment to epithelial cells are specifically inhibited in the presence of anti-HBHA antibodies. Immunoelectron microscopy using anti-HBHA monoclonal antibodies revealed that the protein is surface exposed, consistent with a role in adherence. Immunoblot analyses using antigen-specific antibodies indicated that HBHA is different from the fibronectin-binding proteins of the antigen 85 complex and p55, and comparison of the NH2-terminal amino acid sequence of purified HBHA with the protein sequence data bases did not reveal any significant similarity with other known proteins. Sera from tuberculosis patients but not from healthy individuals were found to recognize HBHA, indicating its immunogenicity in humans during mycobacterial infections. Identification of putative mycobacterial adhesins, such as the one described in this report, may provide the basis for the development of new therapeutic and prophylactic strategies against mycobacterial diseases.
50
Park, Sae W., Eun H. Hwang, Hyuck Park, Jeong A. Kim, Jinho Heo, Key H. Lee, Taeksun Song, et al. "Growth of Mycobacteria on Carbon Monoxide and Methanol." Journal of Bacteriology 185, no. 1 (January 1, 2003): 142–47. http://dx.doi.org/10.1128/jb.185.1.142-147.2003.
Full textAbstract:
ABSTRACT Several mycobacterial strains, such as Mycobacterium flavescens, Mycobacterium gastri, Mycobacterium neoaurum, Mycobacterium parafortuitum, Mycobacterium peregrinum, Mycobacterium phlei, Mycobacterium smegmatis, Mycobacterium tuberculosis, and Mycobacterium vaccae, were found to grow on carbon monoxide (CO) as the sole source of carbon and energy. These bacteria, except for M. tuberculosis, also utilized methanol as the sole carbon and energy source. A CO dehydrogenase (CO-DH) assay, staining by activity of CO-DH, and Western blot analysis using an antibody raised against CO-DH of Mycobacterium sp. strain JC1 (formerly Acinetobacter sp. strain JC1 [J. W. Cho, H. S. Yim, and Y. M. Kim, Kor. J. Microbiol. 23:1-8, 1985]) revealed that CO-DH is present in extracts of the bacteria prepared from cells grown on CO. Ribulose bisphosphate carboxylase/oxygenase (RubisCO) activity was also detected in extracts prepared from all cells, except M. tuberculosis, grown on CO. The mycobacteria grown on methanol, except for M. gastri, which showed hexulose phosphate synthase activity, did not exhibit activities of classic methanol dehydrogenase, hydroxypyruvate reductase, or hexulose phosphate synthase but exhibited N,N-dimethyl-4-nitrosoaniline-dependent methanol dehydrogenase and RuBisCO activities. Cells grown on methanol were also found to have dihydroxyacetone synthase. Double immunodiffusion revealed that the antigenic sites of CO-DHs, RuBisCOs, and dihydroxyacetone synthases in all mycobacteria tested are identical with those of the Mycobacterium sp. strain JC1 enzymes.