Academic literature on the topic 'Salmonella typhimurium LT 2'
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Journal articles on the topic "Salmonella typhimurium LT 2"
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Fernández-Briera, Almudena, and Amando Garrido-Pertierra. "A degradation pathway of propionate in Salmonella typhimurium LT-2." Biochimie 70, no. 6 (June 1988): 757–68. http://dx.doi.org/10.1016/0300-9084(88)90105-8.
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Šišák, F., H. Havlíčková, R. Karpíšková, and I. Rychlík. "Prevalence of Salmonellae and their resistance to antibiotics in slaughtered pigs in the Czech Republic." Czech Journal of Food Sciences 22, No. 6 (November 16, 2011): 230–36. http://dx.doi.org/10.17221/3428-cjfs.
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Salmonella prevalence was assessed in 816 pigs from fifteen herds which were slaughtered in ten slaughterhouses from June 2001 to December 2002. No Salmonellae were isolated in pigs from eight herds in four slaughterhouses. Salmonella prevalence in pigs originating from the other seven herds ranged from 2.0% to 12.0%. The most frequent site of Salmonella isolation was caecum (2.45%). This finding is statistically significant (P < 0.01) as compared to those obtained with mesenteric lymph nodes (0.73%) and carcass swabs (0.12%). Salmonellae were not found in samples from the environments (n = 197). A total of 27 Salmonella isolates were classified into serotypes S. infantis (n = 8), S. typhimurium (n = 5), S. agona (n = 4), S. kaapstad (n = 4), S. derby (n = 3), S. bredeney (n = 2), and S. london (n = 1). All five S. typhimurium DT 104 were resistant to the phenotype ACSSuT. Resistance genes bla<sub>PSE-1</sub>, floR, aadA2, sul1, and tetG were identified in all pentaresistant strains. One strain of S. derby was resistant to gentamicin, streptomycin and sulphonamides. The other Salmonella isolates were sensitive to all antibiotics tested.
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JUNG, YONG SOO, ROBIN C. ANDERSON, JAMES A. BYRD, THOMAS S. EDRINGTON, RANDLE W. MOORE, TODD R. CALLAWAY, JACK McREYNOLDS, and DAVID J. NISBET. "Reduction of Salmonella Typhimurium in Experimentally Challenged Broilers by Nitrate Adaptation and Chlorate Supplementation in Drinking Water†." Journal of Food Protection 66, no. 4 (April 1, 2003): 660–63. http://dx.doi.org/10.4315/0362-028x-66.4.660.
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The effects of two feed supplements on Salmonella Typhimurium in the ceca of market-age broilers were determined. Broilers orally challenged 6 days before slaughter with a novobiocin- and nalidixic acid–resistant strain of Salmonella Typhimurium were divided into one of four groups (20 birds each). The first group (the control group) received no treatment, the second group received sodium nitrate (SN) treatment (574 mg of NaNO3 per kg of feed), the third group received experimental chlorate product (ECP) treatment (15 mM NaClO3 equivalents), and the fourth group received ECP treatment in combination with SN treatment. The SN treatment was administered via feed for 5 days immediately before slaughter, and ECP was provided via ad libitum access to drinking water for the last 2 days before slaughter. Cecal contents were subjected to bacterial analysis. Significant (P < 0.05) Salmonella Typhimurium reductions (ca. 2 log units) relative to levels for untreated control broilers were observed for broilers receiving ECP in combination with SN. The ECP-only treatment resulted in significant (P < 0.05) reductions (ca. 0.8 log) of Salmonella Typhimurium in trial 2. We hypothesize that increasing Salmonella Typhimurium nitrate reductase activity resulted in increased enzymatic reduction of chlorate to chlorite, with a concomitant decrease in cecal Salmonella Typhimurium levels. On the basis of these results, preadaptation with SN followed by ECP supplementation immediately preharvest could be a potential strategy for the reduction of Salmonella Typhimurium in broilers.
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Barrell, R. A. E. "Isolations of salmonellas from humans and foods in the Manchester area: 1981–1985." Epidemiology and Infection 98, no. 3 (June 1987): 277–84. http://dx.doi.org/10.1017/s0950268800062038.
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SUMMARYIsolations of salmonellas from humans and food products are recorded for the period 1981–5 and an attempt has been made to investigate the relationship between serotypes isolated from humans and those from meat products.The predominant serotypes isolated from humans were Salmonella typhimuriunu S. enterilidis and S. virchow. S. typhimurium was commonly isolated from a range of meat products. S. derby was one of the most common serotypes isolated from tripe and sausages but was relatively uncommon in humans.Salmonellas were found in < 0·5% of most cooked meat products apart from tripe and udder (3·2%) and pet foods (12·4%). Isolations from raw meats ranged from 3 % for pork to 28% for poultry.Incidents of salmonella infection in humans in Manchester increased between 1981 and 1984 but decreased during 1985.
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Abdelhadi, Iman M. A., Ahmed R. Sofy, Ahmed A. Hmed, Ehab E. Refaey, Hany E. Soweha, and Mohamed A. Abbas. "Discovery of Polyvalent Myovirus (vB_STM-2) Phage as a Natural Antimicrobial System to Lysis and Biofilm Removal of Salmonella Typhimurium Isolates from Various Food Sources." Sustainability 13, no. 21 (October 20, 2021): 11602. http://dx.doi.org/10.3390/su132111602.
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New and natural antimicrobials as an alternative control system are now an urgent need to overcome stubborn bacterial infections. Salmonella Typhimurium has become the most frequent serovar responsible for salmonellosis in humans around the world. The high antimicrobial resistance and biofilm production make this pathogen more dangerous. We aimed to isolate a broad lytic phage to prevent Salmonella infection and reduce its biofilms. Using Salmonella Typhimurium (ST-4) as a host, seven phages were isolated, and only three phages showed clear lytic plaques, two members of the Siphoviridae family (vB_STS-1 and vB_STS-3) and one of the Myoviridae family (vB_STM-2). The vB_STM-2 phage was the most potent broad lytic phage, infecting 100% of tested Salmonella Typhimurium serovars and non-Salmonella strains. Additionally, the vB_STM-2 phage was thermostable at −20 to 55 °C up to 24 h, while at 65 and 75 °C, a significant (p < 0.05) titer reduction was observed after 7 days. Moreover, the phage seemed to be stable at different pHs (4–11) after one to twelve hours (hrs), while increasing the time made the phage more sensitive to the alkaline medium rather than the acidic medium. Interestingly, the vB_STM-2 phage had the capacity to diminish or eradicate the biofilms of tested Salmonella Typhimurium, e.g., ST-4, ST-19, ST-30, ST-37, ST-45 and ST-49 by 81.2%, 76.4%, 43.6%, 41%, 39.8% and 93.4%, respectively, at a titer concentration of 106 PFU/mL. Eventually, the vB_STM-2 phage showed significant (p < 0.05) efficacy in the elimination of Salmonella Typhimurium (ST-4) from contaminated chicken breasts at both storage periods with high titer stability. The Salmonella count showed a severe decline from 7.00 ± 0.63 log10 CFU/cm2 to 0.88 ± 0.17 log10 CFU/cm2 on the seventh day of the short-term storage, and from 5.13 ± 0.44 log10 CFU/cm2 to 1.10 ± 0.12 log10 CFU/cm2 on day 27 of the long-term assay. In both periods, the phage titers remained stable, with insignificant (p < 0.05) loss. Therefore, this phage is considered a prime candidate to combat multi-drug-resistant Salmonella Typhimurium and its biofilms.
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SAWYER, J. E., S. T. GREINER, G. R. ACUFF, L. M. LUCIA, E. CABRERA-DIAZ, and D. S. HALE. "Effect of Xylitol on Adhesion of Salmonella Typhimurium and Escherichia coli O157:H7 to Beef Carcass Surfaces." Journal of Food Protection 71, no. 2 (February 1, 2008): 405–10. http://dx.doi.org/10.4315/0362-028x-71.2.405.
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Effects of 10% xylitol (a five-carbon sugar alcohol) on adhesion of Escherichia coli O157:H7 and Salmonella Typhimurium to meat surfaces were examined with three approaches. First, beef outside round was inoculated with rifampin-resistant E. coli O157:H7 and Salmonella Typhimurium dispersed in xylitol or peptone solution. Samples were rinsed with water or not rinsed in a 2 × 2 factorial arrangement. No interaction existed between inoculum and rinsing treatments (P > 0.84). Incubation in xylitol had minimal impact on pathogen adhesion (P > 0.76); however, rinsing reduced pathogen cell counts (P < 0.01). Second, meat samples were treated with water, xylitol, or no rinse; inoculated with pathogens dispersed in peptone solution (8.6 log CFU/ml for each pathogen); and then treated with water, xylitol, or no rinse in a 3 × 3 factorial arrangement. No interactions were observed (P > 0.50). Postinoculation rinsing reduced pathogen loads (P < 0.01) without difference between water and xylitol (P > 0.64). Third, carcass surfaces inoculated with pathogens (5.5 log CFU/cm2) were treated with 35°C water wash, 2.5% l-lactic acid spray, 10% xylitol spray, lactic acid plus xylitol, or hot water plus xylitol. Lactic acid treatments reduced Salmonella Typhimurium at0h(P < 0.01) and 24 h (P < 0.02). Hot water treatments tended to reduce Salmonella Typhimurium at0h(P < 0.07). Xylitol did not reduce pathogens (P > 0.62) or increase effectiveness of other treatments. Xylitol does not influence E. coli O157:H7 and Salmonella Typhimurium adhesion to meat surfaces.
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COCHRANE, ROGER A., ANNE R. HUSS, GREGORY C. ALDRICH, CHARLES R. STARK, and CASSANDRA K. JONES. "Evaluating Chemical Mitigation of Salmonella Typhimurium ATCC 14028 in Animal Feed Ingredients." Journal of Food Protection 79, no. 4 (April 1, 2016): 672–76. http://dx.doi.org/10.4315/0362-028x.jfp-15-320.
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ABSTRACT Salmonella Typhimurium is a potential feed safety hazard in animal feed ingredients. Thermal mitigation of Salmonella spp. during rendering is effective but does not eliminate the potential for cross-contamination. Therefore, the objective of this experiment was to evaluate the effectiveness of chemicals to mitigate postrendering Salmonella Typhimurium ATCC 14028 contamination in rendered proteins over time. Treatments were arranged in a 6 ×4 factorial with six chemical treatments and four rendered protein meals. The chemical treatments included (i) control without chemical treatment, (ii) 0.3% commercial formaldehyde product, (iii) 2% essential oil blend, (iv) 2% medium chain fatty acid blend, (v) 3% organic acid blend, and (vi) 1% sodium bisulfate. The four rendered protein meals included (i) feather meal, (ii) blood meal, (iii) meat and bone meal, and (iv) poultry by-product meal. After matrices were chemically treated, they were inoculated with Salmonella Typhimurium ATCC 14028, stored at room temperature, and enumerated via plate counts on days 0, 1, 3, 7, 14, 21, and 42 postinoculation. The Salmonella concentration in ingredients treated with medium chain fatty acid and commercial formaldehyde were similar to one another (P =0.23) but were 2 log lower than the control (P < 0.05). Ingredients treated with organic acids and essential oils also had lower Salmonella concentrations than the control (P < 0.05). Time also played a significant role in Salmonella mitigation, because all days except days 14 and 21 (P = 0.92) differed from one another. Rendered protein matrix also affected Salmonella stability, because concentrations in meat and bone meal and blood meal were similar to one another (P =0.36) but were greater than levels in feather meal and poultry by-product meal (P < 0.05). In summary, chemical treatment and time both mitigated Salmonella Typhimurium ATCC 14028, but their effectiveness was matrix dependent. Time and chemical treatment with medium chain fatty acids or a commercial formaldehyde product were most effective at mitigating Salmonella Typhimurium ATCC 14028 in rendered protein meals.
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JUNG, YONG SOO, ROBIN C. ANDERSON, THOMAS S. EDRINGTON, KENNETH J. GENOVESE, J. ALLEN BYRD, TODD R. CALLAWAY, and DAVID J. NISBET. "Experimental Use of 2-Nitropropanol for Reduction of Salmonella Typhimurium in the Ceca of Broiler Chicks†‡." Journal of Food Protection 67, no. 9 (September 1, 2004): 1945–47. http://dx.doi.org/10.4315/0362-028x-67.9.1945.
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The effect of 2-nitropropanol (2NPOH) administration on Salmonella enterica serovar Typhimurium in experimentally infected chicks was determined. Chicks orally challenged with 106 CFU/ml of a novobiocin- and naladixic acid–resistant Salmonella Typhimurium at 6 days of age were divided into three groups receiving 0 (control), 6.5, and 13 mg 2NPOH per bird (experiment 1) or four groups receiving 0 (control), 13, 65, and 130 mg 2NPOH per bird (experiment 2). Treatments were administered orally 1 day post–Salmonella challenge. Cecal contents collected at necropsy 24 and 48 h after treatment were subjected to bacterial and volatile fatty acid (VFA) analysis. In experiment 1, concentrations (mean ± SD log CFU per g) of Salmonella were reduced (P < 0.05) in the group administered 13 mg 2NPOH per bird at both the 24- and 48-h samplings compared with the controls (2.58 ± 2.10 versus 4.64 ± 1.79 and 2.88 ± 2.78 versus 5.03 ± 2.42 at 24 and 48 h, respectively). In experiment 2, mean ± SD populations of Salmonella were reduced (P < 0.05) in all groups receiving 2NPOH compared with untreated controls (3.65 ± 2.01, 3.39 ± 2.42, and 3.47 ± 1.55 at 13, 65, and 130 mg, respectively, versus 6.09 ± 1.02). Propionate concentrations were reduced (P < 0.05) by the 13-mg 2NPOH per bird treatment. Total VFA concentrations from the group treated with 13 mg 2NPOH per bird were lower (P < 0.05) by 48, but not 24, hours posttreatment than those from the group treated with 6.5 mg 2NPOH per bird. These results demonstrate the inhibitory activity of 2NPOH against Salmonella Typhimurium in vivo.
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Santana, Eliete Souza, Maria Auxiliadora Andrade, Marcos Barcelos Café, José Henrique Stringhini, Tatiane Martins Rocha, and Valéria de Sá Jaime. "Efeitos da lactulose na saúde gastrointestinal de frangos de corte experimentalmente inoculados com Salmonella entérica sorovar Typhimurium." Ciência Animal Brasileira 15, no. 2 (June 2014): 187–94. http://dx.doi.org/10.1590/1809-6891v15i13604.
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Avaliaram-se os efeitos da lactulose na saúde gastrointestinal de frangos de corte pela aferição do pH e enumeração de unidades formadoras de colônias (UFCs) de Salmonella Typhimurium e Escherichia coli no inglúvio e ceco de aves inoculadas experimentalmente, via oral, na dose de 5,0 X 102 UFC /0,5mL com Salmonella Typhimurium. O delineamento adotado foi o inteiramente casualizado, utilizando-se 630 pintos, machos, os quais foram distribuídos em seis tratamentos, com sete repetições e 15 aves por unidade experimental. O tratamento 1: grupo controle (placebo); tratamento 2: grupo que recebeu somente a lactulose na água; tratamento 3: grupo que recebeu somente Salmonella Typhimurium; tratamento 4: grupo que recebeu a lactulose e Salmonella Typhimurium simultaneamente no primeiro dia de vida [L (1d) + ST (1d)]; tratamento 5: grupo que recebeu a lactulose 48 horas antes de serem inoculadas com Salmonella Typhimurium [L (1d) + ST (48h)] e tratamento 6: grupo que foi inoculado com Salmonella Typhimurium no primeiro dia e 48 horas depois receberam a lactulose [ST (1d) + L (48h)]. Aos dias sete, 14, 21 e 28 uma ave por parcela foi sacrificada e os conteúdos do inglúvio e do ceco foram coletados para a aferição do pH e contagem de Salmonella Typhimurium e Escherichia coli. Constatou-se que a lactulose determinou redução nos valores (P<0,05) de pH nos conteúdos do trato digestório aos sete dias de vida, e esta redução se manteve até 28 dias somente para o inglúvio nos tratamentos que receberam a lactulose, independente do período de inoculação do patógeno. Verificou-se, também, que a lactulose reduziu (P<0,05) as UFCs de Escherichia coli e de Salmonella Typhimurium no inglúvio aos 21 e 28 dias de vida nos tratamentos em que se administrou a lactulose antes do patógeno. Pode-se concluir que a lactulose altera os valores de pH do inglúvio e reduza colonização de Salmonella Typhimurium no ceco e as UFCs de Escherichia coli no inglúvio em todo o período experimental.
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Saw, Seow Hoon, J. L. Mak, M. H. Tan, S. T. Teo, T. Y. Tan, M. Y. K. Cheow, C. A. Ong, et al. "Detection and quantification of Salmonella in fresh vegetables in Perak, Malaysia." Food Research 4, no. 2 (October 27, 2019): 441–48. http://dx.doi.org/10.26656/fr.2017.4(2).316.
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The eating of fresh and minimally processed vegetables is getting popular among Malaysians. This trend poses an increased risk of food poisoning associated with the consumption of fresh produce contaminated with pathogenic bacteria. Salmonellosis is a foodborne disease caused by several non-typhoidal Salmonella enterica serovars, predominantly serovars Enteritidis and Typhimurium. The present study aimed to determine the prevalence of Salmonella spp., S. enterica serovar Enteritidis and S. enterica serovar Typhimurium in fresh leafy vegetables such as cabbages (n = 40), lettuces (n = 20), and fruit vegetables such as tomatoes (n = 40), carrots (n = 40) and cucumbers (n = 40), which were sold by three different hypermarkets and a wet market in Kampar, Perak, Malaysia. The study was performed over a period of 13 months (January 2018 to January 2019). A combination of most probable number-multiplex polymerase chain reaction (MPN-mPCR) method was used to quantify the concentrations of Salmonella spp., S. enterica serovar Enteritidis and S. enterica serovar Typhimurium in the examined samples. The results of this study demonstrated that of the vegetables tested, tomatoes, carrots and lettuces were not contaminated by Salmonella spp., S. enterica serovar Enteritidis and S. enterica serovar Typhimurium. However, the presence of Salmonella spp. was detected in 3.3% of cabbages from the hypermarket, with estimated microbial loads ranging from <3.0 MPN/g to 15.0 MPN/g. On the other hand, S. enterica serovar Typhimurium was detected in 10.0% of the cucumbers from hypermarkets and 20% of them from the wet market. Their microbial loads were ranging from <3.0 MPN/g to >1,100 MPN/g. This indicated that cabbages and cucumbers could be the potential sources of salmonellosis. Therefore, the monitoring of food safety and hygienic practices should be strictly enforced by relevant government agencies to avoid potential poisoning by foodborne pathogens.
Dissertations / Theses on the topic "Salmonella typhimurium LT 2"
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Simmons, James Walter. "O-Acetylserine Sulhydralase-A from Salmonella typhimurium LT-2: Thermodynamic Properties and SPectral Identification of Intermediates." Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc278042/.
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O-Acetylserine Sulfhydrylase (OASS) is a pyridoxal phosphate enzyme that catalyzes the reaction of O-acetyl-Lserine with sulfide to give L-cysteine. OASS is present as two isoforms, designated -A and -B. The kinetic mechanism of OASS-A is well known and there is also much known concerning the acid-base chemistry of the enzyme. However, little is known concerning the location of the rate determining steps, the sequencing of chemical steps that occur at the active site, or the nature of the rate determining transition states. The studies performed to help elucidate these aspects of the OASS-A mechanism included determination of the thermodynamics of both half reactions, along with studies utilizing substrate analogs of OAS halting the reaction at specific points along the reaction pathway allowing the identification of reaction intermediates. The free energy change of the first half reaction was shown to be -5.7 Kcal/mole while the second half reaction was shown to be, for all intents and purposes, irreversible. Intermediates along the reaction pathway that have been previously identified include the internal Schiff base and the a-aminoacrylate. The external Schiff base was identified using the analogs cysteine, alanine, and glycine while the geminal diamine was identified using the analog serine. Formation of the external aldimine was shown to be pH dependent with a pK of 8.1 ± 0.3 most likely representing a general base that accepts a proton from the a-amine of cysteine to facilitate a nucleophilic attack on C4r of the PLP imine. Formation of the geminal diamine was also shown to be pH dependent with two pK values having an average value of 8.1. One of the groups most likely represents the general base which accepts a proton from the a-amine of cysteine while the second group likely interacts with the amino acid side chain to orientate the amino acid into the correct configuration.
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Žindul, Adam. "Salmonella enterica Serovar Typhimurium inaktyvacijos fotosensibilizacija vertinimas ir poveikio modeliavimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2011~D_20140701_164247-99768.
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Šiame tiriamajame darbe nagrinėjama bakterijos Salmonella enterica Serovar Typhimurium inkubacijos priklausomybė nuo inkubacinio periodo. Trumpai aptariami bakterijų inaktyvavimą aprašantys dažniausiai naudojami modeliai, skaitiškai išreiškiama lag fazė, randama jos ilgį aprašantį funkciją. Toliau vertinamos tiesinė ir liekamoji dalys bei išvedama inaktyvavimą aprašanti lygtis. Darbas baigiamas išvestinės formulės praktiniu panaudojimu ir rezultatų aptarimu.Evaluation of Salmonella enterica Serovar Typhimurium inactivation by photosensitization and impact modeling The aim goal of this research is to evaluate the influence of irradiation of UV light and incubation period on Salmonella enterica Serovar Typhimurium bacteria. Shortly discussed most commonly used mathematical models of bacterial inactivation, expressed lag phase and its function. Next step is evaluation of line part and tail of inactivation (mortality) curve. At the end of the research the inactivation formula is deduced and the results are discussed.
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Figueira, Ana Rita. "Analysis of effectors of the Salmonella Typhimurium SPI-2 type three secretion system." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/9287.
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Salmonella enterica serovar Typhimurium (S. Typhimurium), an intracellular pathogen, causes gastroenteritis in humans and a systemic disease in mice. The ability of Salmonella to replicate inside host cells requires translocation of effector proteins across the vacuolar membrane, mediated by the Salmonella pathogenicity island‐2 (SPI‐2) type three secretion system (T3SS). However, the repertoire of effectors involved in this process has not been defined. The first part of this PhD work focused on SrfJ, a putative effector of the SPI‐2 T3SS with similarity to human lysosomal glucosylceramidase. Expression of its gene was dependent on SsrA/B, a two‐component regulatory system required for expression of most SPI‐2 effector genes. Expression of srfJ was also shown to occur under SPI‐2 T3SS activation conditions. However, there was no detectable secretion or translocation of the protein, although a srfJ mutant strain had an intracellular replication defect in primary bone marrow‐derived macrophages. Using a dual‐fluorescence reporter system that allows direct measurement of intracellular replication, the contribution to replication of individual SPI‐2 T3SS effectors was investigated. The replication kinetics of S. Typhimurium deletion mutants for all known SPI‐2 effectors were measured and compared in mouse bone marrow‐derived macrophages. Several mutant strains with replication defects were identified, thereby revealing that intracellular replication is the result of the contribution of numerous effectors. Two S. Typhimurium polymutant strains were generated whose replication defects closely resemble that of a SPI‐2 T3SS null mutant and are severely attenuated in virulence in vivo. These strains retained an intact T3SS and delivered a CD8+ T cell epitope via the SPI‐2 T3SS into the cytoplasm of infected cells. Since an S. Typhi mutant strain lacking the SPI‐2 T3SS has been shown to be safe and immunogenic in humans, these polymutant strains could have applications in vaccine design, as carrier strains for the delivery of heterologous antigens.
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Krogan, Nevan John. "Utilization of dihydroorotate by S. typhimurium LT-2, characterization of the dhpA gene." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0007/MQ45331.pdf.
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Cea, Medina Pablo Antonio. "Caracterización bioquímica de la 4-amino-5-hidroximetil-2-metilpirimidina quinasa de Salmonella typhimurium y Thermus thermophilus." Tesis, Universidad de Chile, 2019. http://repositorio.uchile.cl/handle/2250/168116.
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Seminario de Título entregado a la Universidad de Chile en cumplimiento parcial de los requisitos para optar al Título de Ingeniero en Biotecnología Molecular.La 4-amino-5-hidroximetil-2-metilpirimidina quinasa (HMPK, EC 2.7.1.49) es una enzima perteneciente a la superfamilia riboquinasa y participa en la biosíntesis de tiamina (vitamina B1) en bacterias. Se ha descrito que esta enzima es capaz de catalizar dos fosforilaciones consecutivas dependientes de ATP altamente específicas sobre el sustrato hidroximetil pirimidina (HMP), generando como producto hidroximetil pirimidina pirofosfato. Esto contrasta notablemente con lo que se ha observado en las piridoxal quinasas de bacterias Gram positivas (HMPK/PLK, EC 2.7.1.35), un grupo de enzimas homólogas cercanas capaces de fosforilar hidroximetil pirimidina, piridoxal, piridoxina y piridoxamina, pero incapaces de catalizar dos fosforilaciones consecutivas, por lo que sólo producen hidroximetil pirimidina fosfato. Las HMPKs no han sido estudiadas tan exhaustivamente como las HMPK/PLKs y sólo hay dos caracterizaciones breves disponibles en la literatura; la de la HMPK de Escherichia coli y la de Bacillus subtilis. Por lo tanto, aún no se conoce si las propiedades observadas en las enzimas descritas son ubicuas para linajes bacterianos distintos, especialmente aquellos filogenéticamente distantes y que han sido sometido a presiones selectivas fuertes, como los extremófilos. Por esta razón, en este trabajo se realizó la caracterización bioquímica de la HMPK de la enterobacteria Salmonella typhimurium (StHMPK) y de la bacteria termófila Thermus thermophilus (TtHMPK). A través de experimentos de estequiometría de reacción y análisis de generación de productos, se demostró que ambas enzimas son capaces de catalizar dos fosforilaciones consecutivas. Experimentos de especificidad de sustrato revelaron que ambas enzimas son altamente específicas por hidroximetil pirimidina. Análisis filogenéticos mostraron que estas enzimas están estrechamente relacionadas con las HMPKs/PLK de organismos gram positivos, y estas últimas parecen ser descendientes directos de las HMPKs. Por lo tanto, para estudiar cómo estos grupos de enzimas han divergido en términos de sus actividades catalíticas, se realizaron simulaciones de dinámica molecular del complejo ternario (Mg·ATP - HMP) de StHMPK, para analizar el sitio de unión a sustrato y compararlo con el de la HMPK/PLK de Staphylococcus aureus (SaPLK). Los resultados mostraron que existe un alto grado de conservación entre ambos sitios, existiendo sólo unas pocas diferencias que podrían explicar la divergencia funcional observada, principalmente la presencia de una treonina adyacente a la base catalítica en StHMPK, que es reemplazada por una alanina en SaPLK, y la presencia de una glutamina en StHMPK que forma puentes de hidrógeno con el HMP. La caracterización cinética de StHMPK y TtHMPK mostró que ambas enzimas poseen una KM similar para HMP (cercana a 30μM) y que la Vmax para TtHMPK es un orden de magnitud menor que para StHMPK a 37 °C. Sin embargo, estos parámetros fueron obtenidos para las curvas de saturación de HMP, las cuales mostraban un comportamiento del tipo Michaelis-Menten, mientras que las curvas de saturación para ATP mostraron una clara desviación de este modelo y por lo tanto, no se pudieron determinar parámetros cinéticos. Finalmente, se realizó una caracterización estructural y biofísica para evaluar diferencias de estabilidad. Ambas enzimas parecen ser monómeros en las condiciones estudiadas, a diferencia de lo reportado para la enzima de E. coli que forma un tetrámero. Experimentos de desplegamiento por temperatura y agentes químicos mostraron que TtHMPK es significativamente más estable que StHMPK. Las bases estructurales de estas diferencias fueron analizadas mediante simulaciones de dinámica molecular, las que revelaron que la proteína termoestable es más rígida, tiene un menor contenido de residuos polares en el núcleo y tiene mayor cantidad de interacciones electrostáticas que su homólogo mesoestable.
4-amino-5-hydroxymethyl-2-methylpyrimidine kinase (HMPK, EC 2.7.1.49) is a bacterial enzyme that belongs to the ribokinase superfamily and participates in the thiamine (vitamine B1) biosynthetic pathway. It has been described that this enzyme is capable to catalyze two consecutive highly specific ATP dependent phosphorylations on the substrate hydroxymethyl pyrimidine, yielding hydroxymethyl pyrimidine pyrophosphate. This contrast notoriously with what has been observed for the closely related homologous enzymes pyridoxal kinases from Gram positive bacteria (HMPK/PLK, EC 2.7.1.35), which can phosphorylate hydroxymethyl pyrimidine, pyridoxal, pyridoxine and pyridoxamine, but are unable to catalyze two consecutive phosphorylations, thus only produce hydroxymethyl pyrimidine phosphate. HMPKs have not been as extensively studied as HMPKs/PLK, and only two brief biochemical characterizations are available on the literature; the characterization of the HMPK from Escherichia coli and from Bacillus subtilis. Therefore, it is still unknown whether the properties observed in the described enzymes are ubiquitous among different bacterial lineages, especially those that come from a very distinct phylogenetic background and have been subject to strong selective pressures, as the enzymes from extremophilic organisms. For this reason, in this work we address the biochemical characterization of the HMPK from the enterobacteria Salmonella typhimurium (StHMPK) and the thermophilic bacteria Thermus thermophilus (TtHMPK). Through stoichiometric experiments and product generation analysis, it was established that both enzymes are able to perform two consecutive phosphorylations. Substrate specificity experiments revealed that both enzymes are highly specific for hydroxymethyl pyrimidine. Phylogenetic analysis of these enzymes showed that are closely related to HMPKs/PLK from Gram positive organisms, being the later a direct descendant from HMPKs. Therefore, to study how these two groups of enzymes have diverged so much in terms of their catalytic activities, we analysed the substrate binding site of StHMPK by molecular dynamics simulations of the ternary complex (Mg·ATP - HMP) and compared it to the binding site of the PLK from Staphylococcus aureus (SaPLK). The results showed that there is an overall great conservation among the active sites, with just a few differences that could be responsible for the functional divergences observed, mainly the presence of a threonine residue adjacent to the catalytic base in StHMPK which is replaced by an alanine in SaPLK, and the presence of a glutamine that forms hydrogen bonds with the HMP in StHMPK. Kinetic characterization of StHMPK and TtHMPK showed that both enzymes have a similar KM for HMP (around 30 μM) while the Vmax for TtHMPK is one order of magnitude lower than the Vmax for StHMPK. However, these parameters were obtained only for HMP saturation curves, which showed a Michaelis-Menten behaviour, whereas ATP saturation curves displayed a clear deviation from a Michaelis-Menten model and therefore, no kinetic parameters could be deduced from these experiments. Finally, a biophysical and structural characterization to assess stability differences was performed. Both enzymes seem to be in monomeric state under the conditions assayed, in contrast with what was reported for the enzyme from E. coli, which forms a tetramer. Thermal and chemical unfolding experiments showed that TtHMPK is significantly more stable than StHMPK. The structural basis for these differences were investigated through molecular dynamics simulations, which revealed that the thermostable protein is more rigid, has a reduced content of polar amino acids in its core, and has more electrostatic interactions than its mesostable homologous.
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Barreto, Arce Liz Judith. "Efecto de la lactoferrina bovina en la invasión de Salmonella typhimurium cepa SL 1344 a células HEp-2." Master's thesis, Universidad Nacional Mayor de San Marcos, 2017. https://hdl.handle.net/20.500.12672/6131.
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Analiza el efecto de la lactoferrina en la cinética de crecimiento de Salmonella typhimurium cepa SL 1344 ΔhilA, evalúa el efecto citotóxico del tratamiento con gentamicina a células HEp-2, determina el efecto in vitro de la lactoferrina sobre la adhesión de Salmonella typhimurium SL 1344 ΔhilA y especifica el tratamiento y concentración de lactoferrina que permita mayor disminución de la adherencia e invasión a las células HEp-2.Tesis
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Havemann, Gregory Dale. "Polyhedral Organelles involved in the B12-dependent metabolism of 1, 2-propanediol in Salmonella enterica serovar typhimurium LT2." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000697.
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Marjoshi, Delphine. "Investigating the effects of three herbicides - Kamba, 2,4-D and Roundup on Salmonella enteric serovar Typhimurium growth and antibiotic tolerance phenotypes." Thesis, University of Canterbury. School of Biological Sciences, 2014. http://hdl.handle.net/10092/10284.
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Herbicides are a common tool in weed control. With the introduction of genetically modified herbicide-tolerant crops, there has been a dramatic increase in the use of particular herbicides. Herbicides contaminate the environment and food and feed and can come into contact with non-target organisms, especially bacteria. Salmonella enteric serovar Typhimurium, which is a human and animal pathogen, was chosen to investigate if the commercial formulations of three herbicides – Kamba, 2,4-D and Roundup are toxic to bacteria and whether sub-lethal concentrations cause a response to antibiotics. In addition, earlier work demonstrating an effect of salicylic acid on antibiotic response was reconfirmed in this study.
The herbicides were toxic to S. typhimurium at concentrations above the manufacturers recommended application rates. A key finding of this study was that when S. typhimurium was grown in sub-lethal concentrations of the herbicides, it demonstrated a change in its susceptibility to various antibiotics. Kamba and 2,4-D caused increased tolerance of chloramphenicol, tetracycline, ampicillin and ciprofloxacin and increased sensitivity to kanamycin. Exposure to Roundup caused increased sensitivity to chloramphenicol and tetracycline and increased tolerance towards kanamycin and ciprofloxacin. Roundup had no measureable affect on ampicillin susceptibility.
The minimum concentrations of herbicides that induced an antibiotic response were within the recommended application rates. Furthermore, the minimum 2,4-D concentration that induced tetracycline, chloramphenicol and ampicillin tolerance was at or below the maximum residue limits set for food and feed commodities. Simultaneous exposure to an herbicide and an antibiotic was necessary for the induction of antibiotic tolerance. In addition, the effect of the herbicide on the antibiotic response was faster than the lethal effect of the antibiotics. Kamba induced chloramphenicol, tetracycline, ampicillin and ciprofloxacin tolerance was maintained in the absence of Kamba once tolerance was induced by simultaneous exposure to Kamba and antibiotic.
The emergence of antibiotic tolerance is an important health issue that may compromise treatment of serious bacterial infections. The widespread use of herbicides in agricultural, urban and domestic settings increases the number of bacteria that are exposed to herbicides. The tolerance induced by the herbicides may increase the frequency of antibiotic tolerant strains, increase the chance of co-exposure to antibiotics, and increase the potential for failure to treat bacterial infections as a result.
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Raux, Evelyne Christine. "Biosynthesis of cobalamin (vitamin Bâ†1â†2) in Salmonella typhimurium and Bacillus megaterium de Bary : characterisation of the anaerobic pathway." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313359.
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Deschenes, Marianne. "Régulation de la réponse immunitaire in vivo et in vitro au cours de l'infection chronique par Salmonella typhimurium." Paris 11, 1989. http://www.theses.fr/1989PA114803.
Full textBooks on the topic "Salmonella typhimurium LT 2"
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(Editor), Frederick C. Neidhardt, and Roy Curtiss (Editor), eds. Escherichia Coli and Salmonella (2 Volume Set: Cellular and Molecular Biology. 2nd ed. ASM Press, 1996.
Find full textBook chapters on the topic "Salmonella typhimurium LT 2"
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Isaacson, R. E., C. Argyilan, L. Kwan, S. Patterson, and K. Yoshinaga. "Phase Variable Switching of in Vivo and Environmental Phenotypes of Salmonella Typhimurium." In Mechanisms in the Pathogenesis of Enteric Diseases 2, 281–89. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-4143-1_30.
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Mehta, Alka, Surjit Singh, and Nirmal Kumar Ganguly. "Effect of Salmonella typhimurium enterotoxin (S-LT) on lipid peroxidation and cell viability levels of isolated rat enterocytes." In Stress Adaptation, Prophylaxis and Treatment, 175–81. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-5097-6_22.
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Sternberg, Nat L., and Russell Maurer. "[2] Bacteriophage-mediated generalized transduction in Escherichia coli and Salmonella typhimurium." In Methods in Enzymology, 18–43. Elsevier, 1991. http://dx.doi.org/10.1016/0076-6879(91)04004-8.
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Tsuruda, Carina Terumi, Patrícia Canteri De Souza, Erick Kenji Nishio, Ricardo Sérgio Couto de Almeida, Luciano Aparecido Panagio, Ana Angelita Sampaio Baptista, Sandra Garcia, Renata Katsuko Takayama Kobayashi, and Gerson Nakazato. "AVALIAÇÃO DO EFEITO PROBIÓTICO DE Lactobacillus rhamnosus V5 CONTRA SALMONELLA ENTERICA sorovariedade Typhimurium." In Análise Crítica das Ciências Biológicas e da Natureza 2, 231–40. Atena Editora, 2019. http://dx.doi.org/10.22533/at.ed.58319270521.
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Zamri, Amir Izzwan, Nor Hazwani Mohd Hasali, Muhammad Hariz Mohd Hasali, Tuan Zainazor Tuan Chilek, Fisal Ahmad, and Mohd Khairi Mohamed Zainol. "Microbiological Diversity and Properties of Stingless Bee Honey." In Advances in Environmental Engineering and Green Technologies, 141–52. IGI Global, 2023. http://dx.doi.org/10.4018/978-1-6684-6265-2.ch008.
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The study was to compare and evaluate the performance of stingless bee honey (Heterotrigona itama spp.) with ordinary honey in terms of proximate composition as a comparison. Both honeys have shown diverse application and importance either traditionally and scientifically. However, due to the heightened interest on stingless bee honey, antimicrobial tests were also performed to determine the inhibition activity of stingless bee honey against food-borne pathogens using agar well diffusion assay. All three honey samples showed very good inhibitory activities (measured by inhibition zone) against Salmonella typhimurium (25-33 mm), Escherichia coli (17-33 mm), Pseudomonas aeruginosa (15-25 mm), and Staphylococcus aureus (25-29 mm). As for resistance to bile salts, pH tolerance was done and indicated the Lactic acid bacteria was able to survive the human digestive system. The haemolytic study shows that the LAB used was not virulent when introduced to red blood cells, which is important for any bacterium to be classified as safe.
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Medeiros, A. R. S., M. V. S. Couto, T. Z. Rodrigues, J. G. Santos, E. F. Garcia, and P. P. F. Vieira. "APLICAÇÃO DE CRISTALIZAÇÃO EM FRUTAS EM DIFERENTES ESTAGIOS DE MATURAÇÃO E SUA QUALIDADE." In Ciência e Tecnologia de Alimentos: Pesquisas e Avanços. Agron Food Academy, 2022. http://dx.doi.org/10.53934/9786599539664-41.
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O processamento de frutas e hortaliças resultam em uma quantidade substancial de resíduos na forma de cascas, sementes e bagaço, Este trabalho teve por objetivo desenvolver e analisar as características microbiológicas e físico-químicas de frutas desidratadas osmoticamente (cristalizadas) em diferentes estágios de maturação. Foram realizadas análises físico-químicas de atividade de água, acidez titulável, pH, umidade, sólidos solúveis e análises microbiológicas de bolores e leveduras, Escherichia coli e Salmonella spp. Os resultados das análises físico-químicas para as frutas elaboradas indicaram que o aumento do pH e a diminuição da acidez estão diretamente interligados, isto ocorre devido ao estágio de maturação e é durante o amadurecimento que os sólidos solúveis obtiveram maiores valores. Quanto às análises microbiológicas os resultados estavam dentro dos padrões exigidos pela legislação vigente: ausência de Salmonella spp. em 100% das amostras analisadas, quanto às contagens de E. coli e bolores e leveduras as amostras não apresentaram crescimento superiores a < 2 UFC/g e < 4 UFC/g, respectivamente. Com base nos resultados obtidos podemos concluir que a desidratação osmótica seguida de secagem, no protocolo proposto foi eficaz para a conservação das frutas testadas e para a manutenção de sua estabilidade microbiológica.
Conference papers on the topic "Salmonella typhimurium LT 2"
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Wen, Tao, Ronghui Wang, America F. Sotero, and Yanbin Li. "A Portable Impedance Immunosensing System for Rapid Detection of <i>Salmonella</i> Typhimurium." In 2017 Spokane, Washington July 16 - July 19, 2017. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2017. http://dx.doi.org/10.13031/aim.201700368.
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Sotero, America F., Ronghui Wang, Wen Tao, Benhua Zhang, and Yanbin Li. "<i>A Portable Impedance Aptasensing System for Rapid Detection of Salmonella Typhimurium in Poultry Products</i>." In 2018 Detroit, Michigan July 29 - August 1, 2018. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2018. http://dx.doi.org/10.13031/aim.201801147.
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Haesebrouck, Freddy, F. Boyen, J. Volf, N. Botteldoorn, C. Adriaensen, J. P. Hernalsteens, R. Ducatelle, F. van Immerseel, M. Heyndrickx, and F. Pasmans. "SPI-2 of Salmonella Typhimurium is not necessary for long term colonization of pigs." In Seventh International Symposium on the Epidemiology and Control of Foodborne Pathogens in Pork. Iowa State University, Digital Press, 2007. http://dx.doi.org/10.31274/safepork-180809-112.
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Horikawa, Shin, Kiril A. Vaglenov, Dana M. Gerken, Yating Chai, Mi-Kyung Park, Suiqiong Li, Valery A. Petrenko, and Bryan A. Chin. "Rapid, enhanced detection of <i>Salmonella Typhimurium</i> on fresh spinach leaves using micron-scale, phage-coated magnetoelastic biosensors." In SPIE Defense, Security, and Sensing. SPIE, 2012. http://dx.doi.org/10.1117/12.920456.
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Cappuyns, Astrid M., Kristel Bernaerts, Sigrid C. De Keersmaecker, and Jan F. Van Impe. "A simple structured model for growth and AI-2 mediated cell-cell communication of Salmonella Typhimurium." In Automation (MED 2008). IEEE, 2008. http://dx.doi.org/10.1109/med.2008.4602087.
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Augustine, Shancy, Pan Gu, Xiangjun Zheng, Toshikazu Nishida, and Z. Hugh Fan. "Development of All-Plastic Microvalve Array for Multiplexed Immunoassay." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38154.
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There is a need for low-cost immunoassays that measure the presence and concentration of multiple harmful agents in one device. Currently, comparable immunoassays employ a one-analyte-per-test format that is time consuming and not cost effective for the requirement of detecting multiple analytes in a single sample. For instance, if a spectrum of harmful agents, including E. coli O157, cholera toxin, and Salmonella typhimurium, should be simultaneously monitored in foods and drinking water, then a one-analyte-per-test would be inefficient. This work demonstrates a platform capable of simultaneous detection of multiple analytes in a single, low-cost, microvalve array-enabled multiplexed immunoassay. This multiplexed immunoassay platform is demonstrated in a prototype COC (cyclic olefin copolymer) device with a 2×3 array in which 6 analytes can be detected simultaneously. In order to contain and regulate the flow of reagents in the multichannel device, an array of microfluidic valves actuated by a thermally expandable material and microfabricated resistors have been developed to direct the flow to the necessary assay sites. The microvalve-based immunoassay is shown to be reliable, easy to operate, and compatible with large-scale integration. The all-plastic microvalves use paraffin wax as the thermally sensitive material which drastically reduces power consumption by latching upon closing so that pulsed power is required only to close and latch the microvalve until it is necessary to re-open the valve. The multiplexed detection scheme has been demonstrated by using three proteins, C reactive protein (CRP) and transferrin, both of which are biomarkers associated with traumatic brain injury (TBI) as well as bovine serum albumin (BSA) as the negative control. Since there are no external bulky pneumatic accessories required to operate/latch the microvalves in the device, this compact, thermally actuated and latching microvalve-enabled multiplexed immunoassay has the potential to realize a portable, low power, battery operated microfluidic device for biological assays.
Reports on the topic "Salmonella typhimurium LT 2"
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Irudayaraj, Joseph, Ze'ev Schmilovitch, Amos Mizrach, Giora Kritzman, and Chitrita DebRoy. Rapid detection of food borne pathogens and non-pathogens in fresh produce using FT-IRS and raman spectroscopy. United States Department of Agriculture, October 2004. http://dx.doi.org/10.32747/2004.7587221.bard.
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Rapid detection of pathogens and hazardous elements in fresh fruits and vegetables after harvest requires the use of advanced sensor technology at each step in the farm-to-consumer or farm-to-processing sequence. Fourier-transform infrared (FTIR) spectroscopy and the complementary Raman spectroscopy, an advanced optical technique based on light scattering will be investigated for rapid and on-site assessment of produce safety. Paving the way toward the development of this innovative methodology, specific original objectives were to (1) identify and distinguish different serotypes of Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, and Bacillus cereus by FTIR and Raman spectroscopy, (2) develop spectroscopic fingerprint patterns and detection methodology for fungi such as Aspergillus, Rhizopus, Fusarium, and Penicillium (3) to validate a universal spectroscopic procedure to detect foodborne pathogens and non-pathogens in food systems. The original objectives proposed were very ambitious hence modifications were necessary to fit with the funding. Elaborate experiments were conducted for sensitivity, additionally, testing a wide range of pathogens (more than selected list proposed) was also necessary to demonstrate the robustness of the instruments, most crucially, algorithms for differentiating a specific organism of interest in mixed cultures was conceptualized and validated, and finally neural network and chemometric models were tested on a variety of applications. Food systems tested were apple juice and buffer systems. Pathogens tested include Enterococcus faecium, Salmonella enteritidis, Salmonella typhimurium, Bacillus cereus, Yersinia enterocolitis, Shigella boydii, Staphylococus aureus, Serratiamarcescens, Pseudomonas vulgaris, Vibrio cholerae, Hafniaalvei, Enterobacter cloacae, Enterobacter aerogenes, E. coli (O103, O55, O121, O30 and O26), Aspergillus niger (NRRL 326) and Fusarium verticilliodes (NRRL 13586), Saccharomyces cerevisiae (ATCC 24859), Lactobacillus casei (ATCC 11443), Erwinia carotovora pv. carotovora and Clavibacter michiganense. Sensitivity of the FTIR detection was 103CFU/ml and a clear differentiation was obtained between the different organisms both at the species as well as at the strain level for the tested pathogens. A very crucial step in the direction of analyzing mixed cultures was taken. The vector based algorithm was able to identify a target pathogen of interest in a mixture of up to three organisms. Efforts will be made to extend this to 10-12 key pathogens. The experience gained was very helpful in laying the foundations for extracting the true fingerprint of a specific pathogen irrespective of the background substrate. This is very crucial especially when experimenting with solid samples as well as complex food matrices. Spectroscopic techniques, especially FTIR and Raman methods are being pursued by agencies such as DARPA and Department of Defense to combat homeland security. Through the BARD US-3296-02 feasibility grant, the foundations for detection, sample handling, and the needed algorithms and models were developed. Successive efforts will be made in transferring the methodology to fruit surfaces and to other complex food matrices which can be accomplished with creative sampling methods and experimentation. Even a marginal success in this direction will result in a very significant breakthrough because FTIR and Raman methods, in spite of their limitations are still one of most rapid and nondestructive methods available. Continued interest and efforts in improving the components as well as the refinement of the procedures is bound to result in a significant breakthrough in sensor technology for food safety and biosecurity.
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Schat, Karel Antoni, Irit Davidson, and Dan Heller. Chicken infectious anemia virus: immunosuppression, transmission and impact on other diseases. United States Department of Agriculture, 2008. http://dx.doi.org/10.32747/2008.7695591.bard.
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1. Original Objectives. The original broad objectives of the grant were to determine A) the impact of CAV on the generation of cytotoxic T lymphocytes (CTL) to reticuloendotheliosis virus (REV) (CU), B). the interactions between chicken anemia virus (CAV) and Marek’s disease virus (MDV) with an emphasis on horizontal spread of CAV through feathers (KVI), and C) the impact of CAV infection on Salmonella typhimurium (STM) (HUJI). During the third year and the one year no cost extension the CU group included some work on the development of an antigen-antibody complex vaccine for CAV, which was partially funded by the US Poultry and Egg Association. 2. Background to the topic. CAV is a major pathogen causing clinical disease if maternal antibody-free chickens are infected vertically or horizontally between 1 and 14 days of age. Infection after 3 weeks of age when maternal antibodies are not longer present can cause severe subclinical immunosuppression affecting CTL and cytokine expression. The subclinical immunosuppression can aggravate many diseases including Marek’s disease (MD) and several bacterial infections. 3. Major conclusions and achievements. The overall project contributed in the following ways to the knowledge about CAV infection in poultry. As expected CAV infections occur frequently in Israel causing problems to the industry. To control subclinical infections vaccination may be needed and our work indicates that the development of an antigen-antibody complex vaccine is feasible. It was previously known that CAV can spread vertically and horizontally, but the exact routes of the latter had not been confirmed. Our results clearly show that CAV can be shed into the environment through feathers. A potential interaction between CAV and MD virus (MDV) in the feathers was noted which may interfere with MDV replication. It was also learned that inoculation of 7-day-old embryos causes growth retardation and lesions. The potential of CAV to cause immunosuppression was further examined using CTL responses to REV. CTL were obtained from chickens between 36 and 44 days of age with REV and CAV given at different time points. In contrast to our earlier studies, in these experiments we were unable to detect a direct impact of CAV on REV-specific CTL, perhaps because the CTL were obtained from older birds. Inoculation of CAV at one day of age decreased the IgG antibody responses to inactivated STM administered at 10 days of age. 4. Scientific and Agricultural Implications The impact of the research was especially important for the poultry industry in Israel. The producers have been educated on the importance of the disease through the many presentations. It is now well known to the stakeholders that CAV can aggravate other diseases, decrease productivity and profitability. As a consequence they monitor the antibody status of the breeders so that the maternal antibody status of the broilers is known. Also vaccination of breeder flock that remain antibody negative may become feasible further reducing the negative impact of CAV infection. Vaccination may become more important because improved biosecurity of the breeder flocks to prevent avian influenza and Salmonella may delay the onset of seroconversion for CAV by natural exposure resulting in CAV susceptible broilers lacking maternal antibodies. Scientifically, the research added important information on the horizontal spread of CAV through feathers, the interactions with Salmonella typhimurium and the demonstration that antigen-antibody complex vaccines may provide protective immunity.
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Willis, C., F. Jorgensen, S. A. Cawthraw, H. Aird, S. Lai, M. Chattaway, I. Lock, E. Quill, and G. Raykova. A survey of Salmonella, Escherichia coli (E. coli) and antimicrobial resistance in frozen, part-cooked, breaded or battered poultry products on retail sale in the United Kingdom. Food Standards Agency, May 2022. http://dx.doi.org/10.46756/sci.fsa.xvu389.
Full textAbstract:
Frozen, breaded, ready-to-cook chicken products have been implicated in outbreaks of salmonellosis. Some of these outbreaks can be large. For example, one outbreak of Salmonella Enteritidis involved 193 people in nine countries between 2018 and 2020, of which 122 cases were in the UK. These ready-to-cook products have a browned, cooked external appearance, which may be perceived as ready-to-eat, leading to mishandling or undercooking by consumers. Continuing concerns about these products led FSA to initiate a short-term (four month), cross-sectional surveillance study undertaken in 2021 to determine the prevalence of Salmonella spp., Escherichia coli and antimicrobial resistance (AMR) in frozen, breaded or battered chicken products on retail sale in the UK. This study sought to obtain data on AMR levels in Salmonella and E. coli in these products, in line with a number of other FSA instigated studies of the incidence and nature of AMR in the UK food chain, for example, the systematic review (2016). Between the beginning of April and the end of July 2021, 310 samples of frozen, breaded or battered chicken products containing either raw or partly cooked chicken, were collected using representative sampling of retailers in England, Wales, Scotland and Northern Ireland based on market share data. Samples included domestically produced and imported chicken products and were tested for E. coli (including extended-spectrum beta-lactamase (ESBL)-producing, colistin-resistant and carbapenem-resistant E. coli) and Salmonella spp. One isolate of each bacterial type from each contaminated sample was randomly selected for additional AMR testing to determine the minimum inhibitory concentration (MIC) for a range of antimicrobials. More detailed analysis based on Whole Genome Sequencing (WGS) data was used to further characterise Salmonella spp. isolates and allow the identification of potential links with human isolates. Salmonella spp. were detected in 5 (1.6%) of the 310 samples and identified as Salmonella Infantis (in three samples) and S. Java (in two samples). One of the S. Infantis isolates fell into the same genetic cluster as S. Infantis isolates from three recent human cases of infection; the second fell into another cluster containing two recent cases of infection. Countries of origin recorded on the packaging of the five Salmonella contaminated samples were Hungary (n=1), Ireland (n=2) and the UK (n=2). One S. Infantis isolate was multi-drug resistant (i.e. resistant to three different classes of antimicrobials), while the other Salmonella isolates were each resistant to at least one of the classes of antimicrobials tested. E. coli was detected in 113 samples (36.4%), with counts ranging from <3 to >1100 MPN (Most Probable Number)/g. Almost half of the E. coli isolates (44.5%) were susceptible to all antimicrobials tested. Multi-drug resistance was detected in 20.0% of E. coli isolates. E. coli isolates demonstrating the ESBL (but not AmpC) phenotype were detected in 15 of the 310 samples (4.8%) and the AmpC phenotype alone was detected in two of the 310 samples (0.6%) of chicken samples. Polymerase Chain Reaction (PCR) testing showed that five of the 15 (33.3%) ESBL-producing E. coli carried blaCTX-M genes (CTX-M-1, CTX-M-55 or CTX-M-15), which confer resistance to third generation cephalosporin antimicrobials. One E. coli isolate demonstrated resistance to colistin and was found to possess the mcr-1 gene. The five Salmonella-positive samples recovered from this study, and 20 similar Salmonella-positive samples from a previous UKHSA (2020/2021) study (which had been stored frozen), were subjected to the cooking procedures described on the sample product packaging for fan assisted ovens. No Salmonella were detected in any of these 25 samples after cooking. The current survey provides evidence of the presence of Salmonella in frozen, breaded and battered chicken products in the UK food chain, although at a considerably lower incidence than reported in an earlier (2020/2021) study carried out by PHE/UKHSA as part of an outbreak investigation where Salmonella prevalence was found to be 8.8%. The current survey also provides data on the prevalence of specified AMR bacteria found in the tested chicken products on retail sale in the UK. It will contribute to monitoring trends in AMR prevalence over time within the UK, support comparisons with data from other countries, and provide a baseline against which to monitor the impact of future interventions. While AMR activity was observed in some of the E. coli and Salmonella spp. examined in this study, the risk of acquiring AMR bacteria from consumption of these processed chicken products is low if the products are cooked thoroughly and handled hygienically.