Journal articles: 'Environmental aeromonads'

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Huddleston, Jennifer R., John C. Zak, and Randall M. Jeter. "Sampling bias created by ampicillin in isolation media forAeromonas." Canadian Journal of Microbiology 53, no. 1 (January 1, 2007): 39–44. http://dx.doi.org/10.1139/w06-103.

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Members of the bacterial genus Aeromonas are widely isolated from aquatic environments and studied in part for their ability to act as opportunistic pathogens in a variety of animals. All aeromonads, with the exception of Aeromonas trota, are generally thought to be resistant to ampicillin, so the antibiotic is frequently added to isolation medium as a selective agent. In this study, 282 aeromonads from environmental sources were isolated on a medium without ampicillin and their resistance to ampicillin determined. Of the 104 of these isolates that were judged to be independent (nonredundant), 18 (17.3%) were susceptible to ampicillin. A chi-square analysis was performed to determine the impact of ampicillin use on enumerating Aeromonas species from environmental samples. Our results indicate that, when ampicillin is used as a selective agent, a significant portion of the aeromonad population in at least some environ ments can be omitted from isolation.Key words: Aeromonas, ampicillin, selective media.

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Ashbolt, N. J., A. Ball, M. Dorsch, C. Turner, P. Cox, A. Chapman, and S. M. Kirov. "The identification and human health significance of environmental aeromonads." Water Science and Technology 31, no. 5-6 (March 1, 1995): 263–69. http://dx.doi.org/10.2166/wst.1995.0621.

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Aeromonads readily grow in waters, particularly if nutrified, to concentrations in excess of total coliforms. Strains of aeromonads can cause gastroenteritis and tissue necrosis. Several suspected virulence factors, such as haemolysins, cytotoxins and enterotoxins may be involved in their pathogenesis. Amongst the thirteen recognised hybridisation groups of Aeromonas, only five species were identified by eight phenotypic characteristics from 339 strains isolated from marine, fresh river or storm waters or from tertiary and sewage/primary effluents. The majority of strains (50%) showed atypical phenotypes, and 24% of 208 randomly selected strains were not identified as aeromonads with a genus specific 16S rDNA-targeted PCR. Most discrepancies occurred with A. schubertii phenotypes, none of which were identified as aeromonads by PCR. Marine waters contained the largest proportion of atypical phenotypes (45/67) of which 60%, compared to <20% for other water sources, were not identified as aeromonads by PCR. A. hydrophila was generally the predominant species identified (93/339), although A. caviae was more prevalent in tertiary treated sewage effluents. Freshwaters contained the largest proportion of aeromonads with haemolysin and/or enterotoxin activity, whereas cytotoxin activity was more prevalent from stormwater isolates. Freshwater strains of A. veronii biotype sobria and A. hydrophila appeared to be the most toxigenic. Furthermore, river sites downstream of sewage effluent release contained more aeromonads than sites immediately upstream of the discharge. Hence, there was a clear positive correlation between freshwater eutrophication and the presence of potentially virulent aeromonads, the majority of which were A. hydrophila and A. veronii which can most rapidly and accurately be identified by PCR.

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Bomo, A. M., M. V. Storey, and N. J. Ashbolt. "Detection, integration and persistence of aeromonads in water distribution pipe biofilms." Journal of Water and Health 2, no. 2 (June 1, 2004): 83–96. http://dx.doi.org/10.2166/wh.2004.0008.

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The occurrence of Aeromonas spp. within biofilms formed on stainless steel (SS), unplasticized polyvinyl chloride (uPVC) and glass (GL) substrata was investigated in modified Robbins Devices (MRD) in potable (MRD-p) and recycled (MRD-r) water systems, a Biofilm Reactor™ (BR) and a laboratory-scale pipe loop (PL) receiving simulated recycled wastewater. No aeromonads were isolated from the MRD-p whereas 3–10% of SS and uPVC coupons (mean 3.85 CFU cm−2 and 12.8 CFU cm−2, respectively) were aeromonad-positive in the MRD-r. Aeromonads were isolated from six SS coupons (67%) (mean 63.4 CFU cm−2) and nine uPVC coupons (100%) (mean 6.50×102 CFU cm−2) in the BR™ fed with recycled water and from all coupons (100%) in the simulated recycled water system (PL). Mean numbers of aeromonads on GL and SS coupons were 5.83×102 CFU cm−2 and 8.73×102 CFU cm−2, respectively. No isolate was of known human health significance (i.e. Aeromonas caviae, A. hydrophila or A. veronii), though they were confirmed as Aeromonas spp. by PCR and fluorescence in situ hybridization (FISH). Challenging the PL biofilms with a slug dose of A. hydrophila (ATCC 14715) showed that biofilm in the PL accumulated in the order of 103–104A. hydrophila cm−2, the number of which decreased over time, though could not be explained in terms of conventional 1st order decay kinetics. A sub-population of FISH-positive A. hydrophila became established within the biofilm, thereby demonstrating their ability to incorporate and persist in biofilms formed within distribution pipe systems. A similar observation was not made for culturable aeromonads, though the exact human health significance of this remains unknown. These findings, however, further question the adequacy of culture-based techniques and their often anomalous discrepancy with direct techniques for the enumeration of bacterial pathogens in environmental samples.

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Egorov, Andrey I., Jennifer M. Birkenhauer Best, Christopher P. Frebis, and Michella S. Karapondo. "Occurrence of Aeromonas spp. in a random sample of drinking water distribution systems in the USA." Journal of Water and Health 9, no. 4 (June 20, 2011): 785–98. http://dx.doi.org/10.2166/wh.2011.169.

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Aeromonads are aquatic bacteria found in drinking water supplies worldwide. Some species, such as Aeromonas hydrophila, can cause disease in humans. For this survey, 293 United States public water systems were selected using random sampling, stratified by water source and system type. Water samples were collected during one year from three sites (six samples per site) in each system. Temperature, pH, turbidity, total and free chlorine were measured using standard methods. Aeromonads were detected in 130 of 5,042 valid samples (2.6%) from 42 (14.3%) systems using the ampicillin-dextrin agar with vancomycin culture method with oxidase, trehalose and indole confirmation tests. Concentrations of aeromonads in positive samples were 0.2 to 880 (median 1.6) colony-forming units (CFU) per 100 mL. Adjusted odds ratios of Aeromonas detection were 1.6 (95% confidence limits 1.0, 2.5) during the summer season, 3.3 (1.8, 6.2) for turbidity above 0.5 nephelometric units and 9.1 (3.5, 24) at 0 mg/L compared with 0.25 mg/L total chlorine. Geographic region, system size and type of water source were not significant predictors of Aeromonas detection in multivariate regression analysis. The results of this survey demonstrate the importance of maintaining adequate residual chlorine and low turbidity for preventing drinking water contamination with aeromonads.

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Khan, Izhar U. H., Alyssa Loughborough, and Thomas A. Edge. "DNA-based real-time detection and quantification of aeromonads from fresh water beaches on Lake Ontario." Journal of Water and Health 7, no. 2 (February 1, 2009): 312–23. http://dx.doi.org/10.2166/wh.2009.041.

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The present study was designed to develop a novel, rapid, direct DNA-based protocol to enumerate aeromonads in recreational waters. An Aeromonas genus-specific real-time quantitative polymerase chain reaction (Q-PCR) protocol was developed and optimized using newly designed genus-specific oligonucleotide primers derived from the gyrase B subunit (GyrB) gene. A standard curve was developed based on the PCR protocol with a minimum quantification limit of 10 cell equivalents ml−1 achieved using an autoclaved water sample from recreational water spiked with known quantities of an Aeromonas ATCC strain. The Q-PCR protocol was validated and applied to detect and quantify the total number of aeromonads in water samples collected from two fresh water beaches on Lake Ontario. The Q-PCR protocol revealed significantly higher numbers of aeromonads in all water samples than a culture-based assay at both beaches. Foreshore sand was found to serve as a reservoir of high concentrations of Aeromonas similar to this phenomenon noted for enteric bacteria like Eschershia coli. The new real-time Q-PCR protocol facilitated the rapid quantification of total numbers of Aeromonas cells present in recreational water samples in <3 hours without culturing.

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Albert, M. John, M. Ansaruzzaman, Kaisar A. Talukder, Ashok K. Chopra, Inger Kuhn, Motiur Rahman, A. S. G. Faruque, M. Sirajul Islam, R. Bradley Sack, and Roland Mollby. "Prevalence of Enterotoxin Genes in Aeromonas spp. Isolated From Children with Diarrhea, Healthy Controls, and the Environment." Journal of Clinical Microbiology 38, no. 10 (2000): 3785–90. http://dx.doi.org/10.1128/jcm.38.10.3785-3790.2000.

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Aeromonads are causative agents of a number of human infections. Even though aeromonads have been isolated from patients suffering from diarrhea, their etiological role in gastroenteritis is unclear. In spite of a number of virulence factors produced byAeromonas species, their association with diarrhea has not been clearly linked. Recently, we have characterized a heat-labile cytotonic enterotoxin (Alt), a heat-stable cytotonic enterotoxin (Ast), and a cytotoxic enterotoxin (Act) from a diarrheal isolate ofAeromonas hydrophila. Alt and Ast are novel enterotoxins which are not related to cholera toxin; Act is aerolysin related and has hemolytic, cytotoxic, and enterotoxic activities. We studied the distribution of the alt, ast, andact enterotoxin genes in 115 of 125 aeromonads isolated from 1,735 children with diarrhea, in all 27 aeromonads isolated from 830 control children (P = 7 × 10−4for comparison of rates of isolation of aeromonads from cases versus those from controls), and in 120 randomly selected aeromonads from different components of surface water in Bangladesh.Aeromonas isolates which were positive only for the presence of the alt gene had similar distributions in the three sources; the number of isolates positive only for the presence of the ast gene was significantly higher for the environmental samples than for samples from diarrheal children; and isolates positive only for the presence of the act gene were not found in any of the three sources. Importantly, the number of isolates positive for both the alt and ast genes was significantly higher for diarrheal children than for control children and the environment. Thus, this is the first study to indicate that the products of both the alt and ast genes may synergistically act to induce severe diarrhea. In 26 patients,Aeromonas spp. were isolated as the sole enteropathogen. Analysis of clinical data from 11 of these patients suggested that isolates positive for both the alt and astgenes were associated with watery diarrhea but that isolates positive only for the alt gene were associated with loose stools. Most of the isolates from the three sources could be classified into seven phenospecies and eight hybridization groups. For the first time,Aeromonas eucrenophila was isolated from two children, one with diarrhea and another without diarrhea.

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Tokajian, Sima, and Fuad Hashwa. "Phenotypic and genotypic identification of Aeromonas spp. isolated from a chlorinated intermittent water distribution system in Lebanon." Journal of Water and Health 2, no. 2 (June 1, 2004): 115–22. http://dx.doi.org/10.2166/wh.2004.0011.

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Aeromonas spp. were detected in samples collected from both untreated groundwater and treated drinking water in Lebanon. Aeromonas spp. levels ranged between 2 and 1,100 colonies per 100 ml in the intake underground well and between 3 and 43 colonies per 100 ml in samples from the distribution system. Samples positive for Aeromonas spp. from the network had a free chlorine level ranging between 0 and 0.4 mg l −1. Multiple antibiotic-resistance was common among the isolated aeromonads; all were resistant to amoxycillin while 92% showed resistance to cephalexin. Haemolysis on blood agar was detected in 52% of the isolates recovered from the distribution network and 81% of isolates from the untreated underground source. The Biolog microbial identification system assigned identities to all of the isolated presumptive aeromonads (at least at the genus level), which was not the case with the API 20NE strips. Differences at the species level were observed when results from the Biolog system were compared with identification based on the MicroSeq 500 16S rDNA sequence analysis. The presence of Aeromonas spp. in drinking water can be an important threat to public health, thus greater awareness of Aeromonas strains as potential enteropathogens is warranted.

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Lamy, Brigitte, Fréderic Laurent, and Angeli Kodjo. "Validation of a partialrpoBgene sequence as a tool for phylogenetic identification of aeromonads isolated from environmental sources." Canadian Journal of Microbiology 56, no. 3 (March 2010): 217–28. http://dx.doi.org/10.1139/w10-006.

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A collection of 50 aeromonads isolated from environmental sources were studied, together with all known Aeromonas nomenspecies, by phenotypic, amplified 16S rDNA restriction analysis (16S rDNA RFLP) and by partial sequence alignment of both 16S rDNA and rpoB genes. Although most of the type strain showed a unique phenotypic pattern, a database constructed on type strain phenotype allowed the identification of only 24% of the isolates. Analysis of 16S rDNA RFLP and the rpoB sequence were almost concordant in identifying environmental isolates at the species level, except for strains belonging to Aeromonas caviae spp., which were not differentiated from Aeromonas aquariorum , nor Aeromonas hydrophila susbsp. dhakensis by 16S rDNA RFLP. In addition, rpoB gene analysis clustered separately a group of isolates found in snails within the A. hydrophila species. In contrast to 16S rDNA RFLP and rpoB, the partial 16S rDNA sequence analysis was weak in resolving species identity. Part of these results, phenotypic and phylogenetic data, showed that Aeromonas molluscorum and Aeromonas sharmana are distant from all other Aeromonas species and that the type species of A. hydrophila subsp. anaerogenes is similar to A. caviae and should be considered synonymous.

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Ashbolt, N. J., G. S. Grohmann, and C. S. W. Kueh. "Significance of Specific Bacterial Pathogens in the Assessment of Polluted Receiving Waters of Sydney, Australia." Water Science and Technology 27, no. 3-4 (February 1, 1993): 449–52. http://dx.doi.org/10.2166/wst.1993.0390.

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The impact of primary sewage released from Sydney's ocean outfalls and chlorinated tertiary treated sewage effluent discharged into Sydney's main river system (Hawkesbury-Nepean) have been studied for faecal microorganisms over two years. Faecal indicator bacteria and a range of potential bacterial pathogens (Aeromonas spp., Campylobacters, Pseudomonas aeruginosa, Staphylococcus aureus and salmonellae) were also cultured. Diverting primary-treated sewage from cliff edge release to deepwater (80m) ocean release some 3 km offshore resulted in significant reductions in all bacterial groups examined, with spores of Clostridium perfringens (C.p) being the most sensitive indicator of water quality improvement. In contrast, contamination of inshore sediments has not markedly declined. Campylobacters were not isolated from effluents or seawater, and numbers of S. aureus and P. aeruginosa were very low if detected. Inland river waters were dominated by motile aeromonads, and along with C.p were the most resistant organisms to chlorination following tertiary sewage treatment. However, aeromonads appeared to grow throughout the river system. Campylobacters were associated with areas of agricultural input whereas salmonellae appeared to be associated with significant urban sewage input. Of the indicator bacteria, C.p correlated best with salmonellae, while viruses correlated poorly with the bacterial groups examined. Further work is required to identify possible sources of virulent aeromonads, Campylobacters and salmonellae.

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Imziln, Boujamaa. "Occurrence and Antibiotic Resistance of Mesophilic Aeromonas in Three Riverine Freshwaters of Marrakech, Morocco." Scientific World JOURNAL 1 (2001): 796–807. http://dx.doi.org/10.1100/tsw.2001.284.

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I n order to evaluate the impact of pollution and sewage on the occurrence and antibiotic resistance of mesophilic aeromonads in riverine freshwaters of Marrakech, samples were collected from three rivers (Oukaimeden, Ourika, and Tensift) upstream and downstream from the principal bordering villages. During a 2-year study, indicators of pollution increased dramatically in the downstream waters. Bacterial indicators (faecal coliforms and faecal streptococci) correlated with mesophilic aeromonads only in heavily polluted waters. In low and moderately polluted sources, densities of mesophilic aeromonads were independent of water quality indicators and did not correlate statistically with faecal indicators. Average counts of Aeromonas in low and heavily polluted waters were 2.5 × 103 and 2.1 × 106 colony forming units per 100 ml, respectively. The biochemical identification of 841 isolates indicated a predominance of A. caviae in heavily and moderately polluted water and sediment. A. hydrophila was dominant only in low polluted waters and when the temperature was below 12°C. High densities of A. sobria were found in low, moderately polluted, or cleaned waters and when the water temperature was above 18°C. All selected isolates (total = 841) were tested for antibiotic susceptibility against 21 antibiotics. Antibiotic resistance frequencies recorded were: ampicillin and amoxicillin, 100%; novobiocin, 96%; cefalotin, 81%; colistin, 72%; sulfamethoxazole, 40%; cefamandole, 37%; polymyxin B, 23%; trimethoprim, 17%; erythromycin, 15%; streptomycin, 8%; amoxicillin-clavulanate, 5%. Resistance to cefotaxime, kanamycin, gentamycin, chloramphenicol, tetracycline, oxytetracycline, nalidixic acid, rifampicin, or trimethoprim-sulfamethoxazole was found to be <5%. Antibiotic resistance rates did vary according to the source of a strain’s isolation, and high numbers of antibiotic resistant strains were recorded in polluted samples. Since no correlation between mesophilic aeromonads and conventional faecal pollution indicators was observed in low or moderately polluted waters, and since these freshwaters are used for domestic supply, we propose the use of mesophilic aeromonads as complementary water pollution indicators to ensure the safety of water.

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Schubert, R. "Ecology of aeromonads and isolation from environmental samples." Experientia 43, no. 4 (April 1987): 351–54. http://dx.doi.org/10.1007/bf01940399.

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Huddleston, Jennifer R., John C. Zak, and Randall M. Jeter. "Antimicrobial Susceptibilities of Aeromonas spp. Isolated from Environmental Sources." Applied and Environmental Microbiology 72, no. 11 (September 1, 2006): 7036–42. http://dx.doi.org/10.1128/aem.00774-06.

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ABSTRACT Aeromonas spp. are ubiquitous aquatic bacteria that cause serious infections in both poikilothermic and endothermic animals, including humans. Clinical isolates have shown an increasing incidence of antibiotic and antimicrobial drug resistance since the widespread use of antibiotics began. A total of 282 Aeromonas pure cultures were isolated from both urban and rural playa lakes in the vicinity of Lubbock, Texas, and several rivers in West Texas and New Mexico. Of these, at least 104 were subsequently confirmed to be independent isolates. The 104 isolates were identified by Biolog and belonged to 11 different species. The MICs of six metals, one metalloid, five antibiotics, and two antimicrobial drugs were determined. All aeromonads were sensitive to chromate, cobalt, copper, nickel, zinc, cefuroxime, kanamycin, nalidixic acid, ofloxacin, tetracycline, and sulfamethoxazole. Low incidences of trimethoprim resistance, mercury resistance, and arsenite resistance were found. Dual resistances were found in 5 of the 104 Aeromonas isolates. Greater numbers of resistant isolates were obtained from samples taken in March versus July 2002 and from sediment versus water. Plasmids were isolated from selected strains of the arsenite- and mercury-resistant organisms and were transformed into Escherichia coli XL1-Blue MRF′. Acquisition of the resistance phenotypes by the new host showed that these resistance genes were carried on the plasmids. Mercury resistance was found to be encoded on a conjugative plasmid. Despite the low incidence of resistant isolates, the six playa lakes and three rivers that were sampled in this study can be considered a reservoir for antimicrobial resistance genes.

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Mendes-Marques, Carina Lucena, Larissa Mélo do Nascimento, Grace Nazareth Diogo Theophilo, Ernesto Hofer, Osvaldo Pompílio de Melo Neto, and Nilma Cintra Leal. "Molecular characterization of Aeromonas spp. and Vibrio cholerae O1 isolated during a diarrhea outbreak." Revista do Instituto de Medicina Tropical de São Paulo 54, no. 6 (December 2012): 299–304. http://dx.doi.org/10.1590/s0036-46652012000600001.

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This work aimed to assess pathogenic potential and clonal relatedness of Aeromonas sp. and Vibrio cholerae isolates recovered during a diarrhea outbreak in Brazil. Clinical and environmental isolates were investigated for the presence of known pathogenic genes and clonal relatedness was assessed by intergenic spacer region (ISR) 16S-23S amplification. Four Aeromonas genes (lip, exu, gcat, flaA/B) were found at high overall frequency in both clinical and environmental isolates although the lip gene was specifically absent from selected species. A fifth gene, aerA, was rarely found in A. caviae, the most abundant species. The ISR profile revealed high heterogeneity among the Aeromonas isolates and no correlation with species identification. In contrast, in all the V. cholerae isolates the four genes investigated (ctxA, tcpA, zot and ace) were amplified and revealed homogeneous ISR and RAPD profiles. Although Aeromonas isolates were the major enteric pathogen recovered, their ISR profiles are not compatible with a unique cause for the diarrhea events, while the clonal relationship clearly implicates V. cholerae in those cases from which it was isolated. These results reinforce the need for a better definition of the role of aeromonads in diarrhea and whether they benefit from co-infection with V. cholerae.

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Gray, S. J., D. J. Stickler, and T. N. Bryant. "The incidence of virulence factors in mesophilicAeromonasspecies isolated from farm animals and their environment." Epidemiology and Infection 105, no. 2 (October 1990): 277–94. http://dx.doi.org/10.1017/s0950268800047889.

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SUMMARYSixty-one isolates ofAeromonasspp. from the faeces of pigs, cows and a variety of associated environmental sources were examined for the characteristics that are reputed to have roles in pathogenicity. Most isolates ofAeromonas hydrophilawere cytotoxic (96·4%) and were capable of producing cell elongation factor (75%) and haemagglutinins (67·9%). In contrast few of theAeromonas caviaeisolates produced these three markers (13·6 %, 27·3% and 36·4% respectively). In general,Aeromonas sobriaoccupied an intermediate position (36·4%, 27·3% and 54·5%), but they did produce the highest mean invasion index for HEp-2 cells. Statistical analysis revealed significant associations between the carriage of these factors and it was clear that many isolates of aeromonads from water and animals possessed the full battery of putative virulence factors.

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Razzolini, Maria Tereza Pepe, Marisa Di Bari, Petra Sanchez Sanchez, and Maria Inês Zanoli Sato. "Aeromonas detection and their toxins from drinking water from reservoirs and drinking fountains." Journal of Water and Health 6, no. 1 (November 1, 2007): 117–23. http://dx.doi.org/10.2166/wh.2007.018.

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Aeromonads are inhabitants of aquatic ecosystems and are described as being involved in intestinal disturbances and other infections. A total of 200 drinking water samples from domestic and public reservoirs and drinking fountains located in São Paulo (Brazil), were analyzed for the presence of Aeromonas. Samples were concentrated by membrane filtration and enriched in APW. ADA medium was used for Aeromonas isolation and colonies were confirmed by biochemical characterization. Strains isolated were tested for hemolysin and toxin production. Aeromonas was detected in 12 samples (6.0%). Aeromonas strains (96) were isolated and identified as: A. caviae (41.7%), A.hydrophila (15.7%), A.allosacharophila (10.4%), A. schubertii (1.0%) and Aeromonas spp. (31.2%).The results revealed that 70% of A. caviae, 66.7% of A. hydrophila, 80% of A. allosacharophila and 46.6% of Aeromonas spp. were hemolytic. The assay for checking production of toxins showed that 17.5% of A. caviae, 73.3% of A. hydrophila, 60% of A. allosacharophila, 100% of A. schubertii, and 33.3% of Aeromonas spp. were able to produce toxins. The results demonstrated the pathogenic potential of Aeromonas, indicating that the presence of this emerging pathogen in water systems is a public health concern.

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Janda, J. Michael, and Sharon L. Abbott. "The Genus Aeromonas: Taxonomy, Pathogenicity, and Infection." Clinical Microbiology Reviews 23, no. 1 (January 2010): 35–73. http://dx.doi.org/10.1128/cmr.00039-09.

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SUMMARY Over the past decade, the genus Aeromonas has undergone a number of significant changes of practical importance to clinical microbiologists and scientists alike. In parallel with the molecular revolution in microbiology, several new species have been identified on a phylogenetic basis, and the genome of the type species, A. hydrophila ATCC 7966, has been sequenced. In addition to established disease associations, Aeromonas has been shown to be a significant cause of infections associated with natural disasters (hurricanes, tsunamis, and earthquakes) and has been linked to emerging or new illnesses, including near-drowning events, prostatitis, and hemolytic-uremic syndrome. Despite these achievements, issues still remain regarding the role that Aeromonas plays in bacterial gastroenteritis, the extent to which species identification should be attempted in the clinical laboratory, and laboratory reporting of test results from contaminated body sites containing aeromonads. This article provides an extensive review of these topics, in addition to others, such as taxonomic issues, microbial pathogenicity, and antimicrobial resistance markers.

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Schmidt, Anja S., Morten S. Bruun, Inger Dalsgaard, Karl Pedersen, and Jens L. Larsen. "Occurrence of Antimicrobial Resistance in Fish-Pathogenic and Environmental Bacteria Associated with Four Danish Rainbow Trout Farms." Applied and Environmental Microbiology 66, no. 11 (November 1, 2000): 4908–15. http://dx.doi.org/10.1128/aem.66.11.4908-4915.2000.

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ABSTRACT Surveillance of bacterial susceptibility to five antimicrobial agents was performed during a 1-year period in and around four freshwater fish farms situated along a stream in western Denmark. Besides assessing the levels of antibiotic resistance among the culturable fraction of microorganisms in fish, water, and sediment samples, two major fish pathogens (88Flavobacterium psychrophilum isolates and 134Yersinia ruckeri isolates) and 313 motileAeromonas isolates, representing a group of ubiquitous aquatic bacteria, were isolated from the same samples. MICs were obtained applying a standardized agar dilution method. A markedly decreased susceptibility of F. psychrophilum isolates to most antimicrobial agents presently available for use in Danish aquaculture was detected, while the collected Y. ruckeriisolates remained largely sensitive to all therapeutic substances. Comparing the inlet and outlet samples, the increase of the antibiotic-resistant proportions observed among the culturable microflora was more pronounced and statistically significant among the motile aeromonads. High levels of individual and multiple antimicrobial resistances were demonstrated within the collected flavobacteria and aeromonads, thus indicating a substantial impact of fish farming on several groups of bacteria associated with aquacultural environments.

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Obukhova, Olga V., and L. V. Lartseva. "HALOTOLERANCE AEROMONADS ISOLATED FROM WATER AND PERCH (SANDER LUCIOPERCA) IN THE DELTA OF THE VOLGA RIVER." Hygiene and sanitation 96, no. 3 (March 27, 2019): 240–42. http://dx.doi.org/10.18821/0016-9900-2017-96-3-240-242.

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The article presents the results of a study of halotolerance in aeromonads isolated from 447 specimens of perch (Sander lucioperca) and 375 water samples in areas of its habitat in the delta of the Volga River. They were subdominant in the microbial landscape of these biotopes. There were no significant differences inoculation aeromonads found in various parts of the delta. Their halotolerance was studied by means of inoculation of daily pure cultures of meat--peptone broth with 3, 7 and 10% of sodium chloride content and incubation at 37◦C. All the studied microflora of this spieces was established to have significant indices of halotolerance with a predominance in water isolates. Whereby in cases of 3.0 and 7.0% NaCl concentrations were 2.2 times more and in the 10.0% NaCl solution with water and fish strains had similar indices, showing them to be of “marine origin”. Among isolated aeromonads, shattering the water and fish most halophilic strains of A. hydrophila and A. sobria, and halophobic strains were presented by A. caviae. As a rule, water strains had stability indices above in the average of 1.3 times higher than fish ones. Epidemiologically important strains of A. sobria were isolated from water more frequently than from fish, whereas A. hydrophila was isolated as in water as in fish at the same level. Halotolerance of isolated aeromonads in hydroecosystems of the delta of the Volga River had seasonal specificity and dynamics. The gain in halotolerance in aquatic strains of aeromonads in spring and autumn was caused by natural and climatic processes and the elevation in the salinity of delta waters. Enhanced halophilic strains of fish in these seasons is determined by their migration with fish, because in seasons pike migrates from the sea to the river ecosystem.

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Moyer, N. P., G. M. Luccini, L. A. Holcomb, N. H. Hall, and M. Altwegg. "Application of ribotyping for differentiating aeromonads isolated from clinical and environmental sources." Applied and Environmental Microbiology 58, no. 6 (1992): 1940–44. http://dx.doi.org/10.1128/aem.58.6.1940-1944.1992.

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Schmidt, Anja S., Morten S. Bruun, Inger Dalsgaard, and Jens L. Larsen. "Incidence, Distribution, and Spread of Tetracycline Resistance Determinants and Integron-Associated Antibiotic Resistance Genes among Motile Aeromonads from a Fish Farming Environment." Applied and Environmental Microbiology 67, no. 12 (December 1, 2001): 5675–82. http://dx.doi.org/10.1128/aem.67.12.5675-5682.2001.

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ABSTRACT A collection of 313 motile aeromonads isolated at Danish rainbow trout farms was analyzed to identify some of the genes involved in high levels of antimicrobial resistance found in a previous field trial (A. S. Schmidt, M. S. Bruun, I. Dalsgaard, K. Pedersen, and J. L. Larsen, Appl. Environ. Microbiol. 66:4908–4915, 2000), the predominant resistance phenotype (37%) being a combined oxytetracycline (OTC) and sulphadiazine/trimethoprim resistance. Combined sulphonamide/trimethoprim resistance (135 isolates) appeared closely related to the presence of a class 1 integron (141 strains). Among the isolates containing integrons, four different combinations of integrated resistance gene cassettes occurred, in all cases including a dihydrofolate reductase gene and a downstream aminoglycoside resistance insert (87 isolates) and occasionally an additional chloramphenicol resistance gene cassette (31 isolates). In addition, 23 isolates had “empty” integrons without inserted gene cassettes. As far as OTC resistance was concerned, only 66 (30%) out of 216 resistant aeromonads could be assigned to resistance determinant class A (19 isolates), D (n = 6), or E (n = 39); three isolates contained two tetracycline resistance determinants (AD, AE, and DE). Forty OTC-resistant isolates containing large plasmids were selected as donors in a conjugation assay, 27 of which also contained a class 1 integron. Out of 17 successful R-plasmid transfers to Escherichia coli recipients, the respective integrons were cotransferred along with the tetracycline resistance determinants in 15 matings. Transconjugants were predominantly tetApositive (10 of 17) and contained class 1 integrons with two or more inserted antibiotic resistance genes. While there appeared to be a positive correlation between conjugative R-plasmids andtetA among the OTC-resistant aeromonads, tetEand the unclassified OTC resistance genes as well as class 1 integrons were equally distributed among isolates with and without plasmids. These findings indicate the implication of other mechanisms of gene transfer besides plasmid transfer in the dissemination of antibiotic resistance among environmental motile aeromonads.

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Gomes, Sónia, Conceição Fernandes, Sandra Monteiro, Edna Cabecinha, Amílcar Teixeira, Simone Varandas, and Maria Saavedra. "The Role of Aquatic Ecosystems (River Tua, Portugal) as Reservoirs of Multidrug-Resistant Aeromonas spp." Water 13, no. 5 (March 5, 2021): 698. http://dx.doi.org/10.3390/w13050698.

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The inappropriate use of antibiotics, one of the causes of the high incidence of antimicrobial-resistant bacteria isolated from aquatic ecosystems, represents a risk for aquatic organisms and the welfare of humans. This study aimed to determine the antimicrobial resistance rates among riverine Aeromonas spp., taken as representative of the autochthonous microbiota, to evaluate the level of antibacterial resistance in the Tua River (Douro basin). The prevalence and degree of antibiotic resistance was examined using motile aeromonads as a potential indicator of antimicrobial susceptibility for the aquatic environment. Water samples were collected from the middle sector of the river, which is most impacted area by several anthropogenic pressures. Water samples were plated on an Aeromonas-selective agar, with and without antibiotics. The activity of 19 antibiotics was studied against 30 isolates of Aeromonas spp. using the standard agar dilution susceptibility test. Antibiotic resistance rates were fosfomycin (FOS) 83.33%, nalidixic acid (NA) 60%, cefotaxime (CTX) 40%, gentamicin (CN) 26.67%, tobramycin (TOB) 26.67%, cotrimoxazole (SXT) 26.67%, chloramphenicol (C) 16.67%, and tetracycline (TE) 13.33%. Some of the nalidixic acid-resistant strains were susceptible to fluoroquinolones. Multiple resistance was also observed (83.33%). The environmental ubiquity, the natural susceptibility to antimicrobials and the zoonotic potential of Aeromonas spp. make them optimal candidates for studying antimicrobial resistance (AMR) in aquatic ecosystems. Aquatic environments may provide an ideal setting for the acquisition and dissemination of antibiotic resistance because anthropogenic activities frequently impact them. The potential risk of multi- and pan-resistant bacteria transmission between animals and humans should be considered in a “One Health—One World” concept.

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YUCEL, NIHAL, and SEDA ERDOGAN. "Virulence Properties and Characterization of Aeromonads Isolated from Foods of Animal Origin and Environmental Sources." Journal of Food Protection 73, no. 5 (May 1, 2010): 855–60. http://dx.doi.org/10.4315/0362-028x-73.5.855.

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Aeromonas species are increasingly recognized as enteric pathogens, and they possess several virulence factors that may contribute to illness. In this work, the biochemical, enzymatic, and some virulence properties of 73 potentially pathogenic strains of Aeromonas spp. isolated from food and environmental sources were investigated to compare strains from different sources and establish the possible relationships between some phenotypic characters and pathogenicity. Virulence factors (hemolysin and siderophores), biochemical properties (Voges-Proskauer and lysine decarboxylase reactions), and enzymatic properties (lipase, phospholipase, protease, and DNase activities) were examined in these strains. Results indicated that 57% of the strains from environmental sources produced siderophores and hemolysin, whereas 39.0% of strains from food produced siderophores and 60.5% produced hemolysin. Protease, lipase, DNase, and phospholipase activities in strains isolated from food and environmental sources were 69.5 to 94.3, 73.6 to 68.5, 52.6 to 68.6, and 71.0 to 68.4%, respectively. A higher percentage of strains of environmental origin (94.3%) had protease activity, and higher lipase activity (73.6%) was observed in food isolates. For all antimicrobials tested, all strains had the least resistance to meropenem, and high levels of resistance were found to amoxicillin–clavulanic acid and cephalothin. These findings demonstrate the presence of potentially pathogenic and multidrug-resistant Aeromonas spp. in environmental and food sources, thereby indicating a significant risk to public health.

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van der Kooij, D., H. S. Vrouwenvelder, and H. R. Veenendaal. "Kinetic aspects of biofilm formation on surfaces exposed to drinking water." Water Science and Technology 32, no. 8 (October 1, 1995): 61–65. http://dx.doi.org/10.2166/wst.1995.0264.

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Biofilm formation in drinking water distribution systems should be limited to prevent the multiplication of undesirable bacteria and other organisms. Certain types of drinking water with an AOC concentration below 10 μg of acetate-C eq/l can support the growth of Aeromonas. Therefore, the effect of acetate at a concentration of 10 μg of C/l on the biofilm formation rate (BFR) of drinking water with a low AOC concentration (3.2 μg C/l) was determined. Drinking water without acetate had a BFR of 3.9 pg ATP/cm2.day, whereas a BFR value of 362 pg ATP/cm2.day was found with acetate added. These data indicate that a low acetate concentration strongly affects biofilm formation, and that only a small fraction of AOC is available for biofilm formation. Aeromonads did not multiply in the biofilm despite their ability to grow at a concentration of 10 μg of acetate-C/l. Further investigations are needed to elucidate the relationship between substrate concentration and biofilm formation in drinking water distribution systems and the growth of undesirable bacteria in these biofilms.

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Sharma, Anjana, Nidhi Dubey, and Bandana Sharan. "Characterization of aeromonads isolated from the river Narmada, India." International Journal of Hygiene and Environmental Health 208, no. 5 (September 2005): 425–33. http://dx.doi.org/10.1016/j.ijheh.2005.03.007.

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HOLMES, P., and L. M. NICOLLS. "Aeromonads in Drinking-Water Supplies: Their Occurrence and Significance." Water and Environment Journal 9, no. 5 (October 1995): 464–69. http://dx.doi.org/10.1111/j.1747-6593.1995.tb01484.x.

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Miranda, C. D., and G. Castillo. "Resistance to antibiotic and heavy metals of motile aeromonads from Chilean freshwater." Science of The Total Environment 224, no. 1-3 (December 1998): 167–76. http://dx.doi.org/10.1016/s0048-9697(98)00354-4.

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Doi, Yohei, Naohiro Shibata, Keigo Shibayama, Kazunari Kamachi, Hiroshi Kurokawa, Keiko Yokoyama, Tetsuya Yagi, and Yoshichika Arakawa. "Characterization of a Novel Plasmid-Mediated Cephalosporinase (CMY-9) and Its Genetic Environment in an Escherichia coli Clinical Isolate." Antimicrobial Agents and Chemotherapy 46, no. 8 (August 2002): 2427–34. http://dx.doi.org/10.1128/aac.46.8.2427-2434.2002.

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ABSTRACT An Escherichia coli strain, HKYM68, which showed resistance to broad-spectrum cephalosporins was isolated from a sputum specimen in Japan. The high-level resistance of the strain to ceftazidime, cefpirome, and moxalactam was carried by a self-transferable plasmid. The β-lactamase gene responsible for the resistance was cloned and sequenced. The deduced amino acid sequence of this gene product, CMY-9, had a single amino acid substitution (E85D), the residue reported to be part of the recognition site for the R1 side chain of β-lactams, compared with the amino acid sequence of CMY-8 and also had 78% identity with the amino acid sequence of CepH, a chromosomal cephalosporinase of Aeromonas hydrophila. A sul1-type class 1 integron containing an aacA1-orfG gene cassette was identified upstream of bla CMY-9 and ended with a truncated 3′ conserved segment. The following 2.1 kb was almost identical to the common region of integrons In6 and In7 and the integron of pSAL-1, except that orf513 encoding a putative transposase was identified instead of orf341 due to addition of a single nucleotide. bla CMY-9 was closely located downstream of the end of the common region. These observations are indicative of the exogenous derivation of bla CMY-9 from some environmental microorganisms such as aeromonads.

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Araujo, Rosa M., Rosa M. Arribas, Francisco Lucena, and Ramon Pares. "Distribution of Mesophilic Aeromonads in Temperate Aquatic Habitats–Relationship with Faecal Indicators." Water Science and Technology 21, no. 3 (March 1, 1989): 247–50. http://dx.doi.org/10.2166/wst.1989.0110.

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de Melo Rodrigues Sobral, Mariana, Camila Barreto, Kayo Bianco, Samara Sant'Anna de Oliveira, and Maysa Mandetta Clementino. "Virulence determinants in genetically heterogeneous populations of Aeromonads recovered from an urban lagoon." Journal of Water and Health 17, no. 3 (March 13, 2019): 380–92. http://dx.doi.org/10.2166/wh.2019.288.

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Abstract The diversity and distribution of Aeromonas spp. associated with virulence profiles from the Rodrigo de Freitas Lagoon were investigated using phylogenetic analysis of gyrB/rpoB gene sequences for speciation. The concatenated gyrB/rpoB gene sequences clustered into five species: Aeromonas punctata/caviae (n = 37), A. hydrophila (n = 10), A. dhakensis (n = 16), A. jandaei (n = 1) and A. enteropelogenes/trota (n = 3). The virulence genes (atc/aerA/hlyA/asp/amp) resulted in 19 virulence profiles, distributed heterogeneously among the five Aeromonas species. Out of the 67 isolates, 16% presented five distinct profiles carrying four virulence genes and 7% showed all genes investigated. The hemolytic genes were detected as follows: act 54% (37/67), aerA 36% (24/67), hlyA 26% (18/67) and proteolytic genes such as asp 36% (24/57) and amp in 85% (57/67) were widely distributed in lagoon sampling stations. Meanwhile, 88% (59/67) and 92% (62/67) of the isolates showed hemolytic and proteolytic activity, respectively. Our results demonstrated that concatenated sequences of the gyrB and rpoB genes showed to be an adequate approach for the Aeromonas speciation and prevalence. The high heterogeneity of virulence genes among the species resulted in several virulence profiles, as well as high percentages of hemolytic and proteolytic activity, demonstrating the necessity of further epidemiological surveys of Aeromonas species pathogenicity in an aquatic recreational lagoon.

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Andrew Hudson, J., and Sandra J. Mott. "Presence of Listeria monocytogenes, motile aeromonads and Yersinia enterocolitica in environmental samples taken from a supermarket delicatessen." International Journal of Food Microbiology 18, no. 4 (June 1993): 333–37. http://dx.doi.org/10.1016/0168-1605(93)90155-a.

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Roges, Emily Moraes, Salvatore Siciliano, Camilla Domit, Paulo Henrique Ott, Lucia Helena Berto, Maria Helena Cosendey de Aquino, and Dalia dos Prazeres Rodrigues. "Detection of putative virulence traits in Aeromonas spp. from brazilian food chain through phenotypic tests and polymerase chain reaction." Research, Society and Development 11, no. 16 (December 9, 2022): e315111635897. http://dx.doi.org/10.33448/rsd-v11i16.35897.

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Aeromonads are natural inhabitants of aquatic environments and may be associated with numerous infections in humans and animals. The human disease may range from self-limiting diarrhea to a more severe form. The pathogenesis of infections are multifactorial, because of their wide variety of virulence factors. This study aimed to evaluate virulence markers in Aeromonas isolates and determinate their virulence profiles. There were analyzed 120 strains of A. caviae (n = 57) and A. hydrophila (n = 63) from human, animal and environmental sources between 2008 and 2012. All isolates were examined to detect extracellular virulence enzymes by phenotypic activity and the presence of virulence genes hlyA, aerA, lip, gcat, ser, act, alt and exu by PCR. We observed more than 90% of positivity for at least one phenotypic virulence factors and all of them had at least two of the virulence genes measured. Among the virulence enzymes detected, the DNase was present in 93.33% of the isolates and hemolytic activity was detected in 62.5%. Collagenase and elastase were found in 13.33% and 10.83% of the strains, respectively. We found exu and gcat in 100% of the isolates, lip in 40.83%, aerA in 40.83%, hlyA in 40%, alt in 19.16%, act in 17.5% and ser in 11.66%. It was possible to observe different combinations of virulence factors between the isolates showing the multifactorial virulence among the isolates. The diversity of virulence profiles found in this study hint heterogeneity in clones circulating in our environment.

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Schubert, Ralph H. W., and R. H. W. Schubert. "Intestinal cell adhesion and maximum growth temperature of psychrotrophic aeromonads from surface water." International Journal of Hygiene and Environmental Health 203, no. 1 (January 2000): 83–85. http://dx.doi.org/10.1078/s1438-4639(04)70012-7.

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Bruun, Morten S., Anja S. Schmidt, Inger Dalsgaard, and Jens L. Larsen. "Conjugal Transfer of Large Plasmids Conferring Oxytetracycline (OTC) Resistance: Transfer between Environmental Aeromonads, Fish-Pathogenic Bacteria, andEscherichia coli." Journal of Aquatic Animal Health 15, no. 1 (March 2003): 69–79. http://dx.doi.org/10.1577/1548-8667(2003)015<0069:ctolpc>2.0.co;2.

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Fewtrell, L., D. Kay, M. Wyer, A. Godfree, and G. O'Neill. "Microbiological quality of bottled water." Water Science and Technology 35, no. 11-12 (June 1, 1997): 47–53. http://dx.doi.org/10.2166/wst.1997.0708.

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Bottled water is now the biggest selling soft drink in Europe (van Musschenbroek, 1995) with sales topping 700 million litres in 1994 in the UK alone (Natural Mineral Water Association, pers comm). As part of a wide ranging UK Department of the Environment Programme to assess possible risks from the consumption of drinking water from all sources, a survey of the microbiological quality of still bottled water, at the point of sale, was conducted. A total of 17 different brands of still water (both natural mineral and other bottled water) in a variety of different containers (plastic and glass, clear and coloured) were tested for total colony counts at 22°C and 37°C, total coliforms, Escherichia coli, Pseudomonas aeruginosa, aeromonads, faecal streptococci and sulphite-reducing clostridia. Bottles were purchased from various suppliers in order to obtain a range of different sell by dates.

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Schade, M., and H. Lemmer. "Counting Bacteria of Selected Metabolic Groups in Activated Sludge – An Assessment of Methods." Water Science and Technology 29, no. 7 (April 1, 1994): 75–79. http://dx.doi.org/10.2166/wst.1994.0312.

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For counting bacteria of selected metabolic groups in activated sludge several methods such as the MPN-method, the pour plate method, the surface plate method, and the membrane filter technique are available. Population densities of heterotrophic saprophytes were assessed with the MPN-method, the pour plate and the surface plate method. The surface plate method yielded higher bacterial counts compared to the pour plate method. The MPN-method is not suitable because of the ambiguity of results leading to large statistical errors. The membrane filter technique yielded significantly higher counts of ammonifying bacteria compared to the MPN-method. The population density of nitrate reducing bacteria was estimated by the MPN-method and the membrane filter technique. Higher counts were found with the MPN-method. However, both methods are not satisfactory for determining nitrate reducers. Methodological problems are discussed. For counting coliform bacteria the MPN-method has to be preferred over plate count methods for MacConkey agar-medium selects aeromonads instead of enterobacteria.

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Roy, Dola, Subharthi Pal, Sriparna Datta Ray, and Sumit Homechaudhuri. "Evaluating Oxidative Stress in Labeo rohita, Infected Asypmtomatically with Native and Invasive Aeromonads Using Biochemical Indices." Proceedings of the National Academy of Sciences, India Section B: Biological Sciences 89, no. 3 (July 25, 2018): 973–78. http://dx.doi.org/10.1007/s40011-018-1012-y.

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Topic Popovic, Natalija, Snjezana P. Kazazic, Ivancica Strunjak-Perovic, Josip Barisic, Roberta Sauerborn Klobucar, Slavko Kepec, and Rozelinda Coz-Rakovac. "Detection and diversity of aeromonads from treated wastewater and fish inhabiting effluent and downstream waters." Ecotoxicology and Environmental Safety 120 (October 2015): 235–42. http://dx.doi.org/10.1016/j.ecoenv.2015.06.011.

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Wu, Chi-Jung, Yin-Ching Chuang, Mei-Feng Lee, Chin-Chi Lee, Hsin-Chun Lee, Nan-Yao Lee, Chia-Ming Chang, et al. "Bacteremia Due to Extended-Spectrum-β-Lactamase-Producing Aeromonas spp. at a Medical Center in Southern Taiwan." Antimicrobial Agents and Chemotherapy 55, no. 12 (October 3, 2011): 5813–18. http://dx.doi.org/10.1128/aac.00634-11.

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ABSTRACTAlthough extended-spectrum-β-lactamase (ESBL)-producing aeromonads have been increasingly reported in recent years, most of them were isolates from case reports or environmental isolates. To investigate the prevalence of ESBL producers amongAeromonasblood isolates and the genes encoding ESBLs, consecutive nonduplicateAeromonasblood isolates collected at a medical center in southern Taiwan from March 2004 to December 2008 were studied. The ESBL phenotypes were examined by clavulanate combination disk test and the cefepime-clavulanate ESBL Etest. The presence of ESBL-encoding genes, includingblaTEM,blaPER,blaCTX-M, andblaSHVgenes, was evaluated by PCR and sequence analysis. The results showed that 4 (2.6%) of 156Aeromonasblood isolates, 1Aeromonas hydrophilaisolate and 3Aeromonas caviaeisolates, expressed an ESBL-producing phenotype. The ESBL gene in twoA. caviaeisolates wasblaPER-3, which was located in both chromosomes and plasmids, as demonstrated by Southern hybridization. Of four patients with ESBL-producingAeromonasbacteremia, two presented with catheter-related phlebitis and the other two with primary bacteremia. Three patients had been treated with initial noncarbapenem β-lactams for 5 to 10 days, and all survived. In conclusion, ESBL producers exist amongAeromonasblood isolates, and clinical suspicion of ESBL production should be raised in treating infections due to cefotaxime-resistantAeromonasisolates.

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Kozińska, Alicja, and Agnieszka Pękala. "Characteristics of Disease Spectrum in relation to Species, Serogroups, and Adhesion Ability of Motile Aeromonads in Fish." Scientific World Journal 2012 (2012): 1–9. http://dx.doi.org/10.1100/2012/949358.

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An attempt was made to delineate the relationship between ofAeromonasspecies and/or serogroups and specific disease symptoms in common carpCyprinus carpioL. and rainbow troutOncorhynchus mykissWalbaum. The adhesion ofAeromonasstrains to various tissues in relation to disease spectrum was also tested. All strains ofA. hydrophilacaused skin ulcers as well as septicaemia in both carp and trout while the other strains were able to cause only skin ulcers or some specific internal lesions with or without septicaemia depending on which species and/or serogroup they represented. Disease symptoms depended also on fish species. It was found that adhesion intensity ofAeromonasstrains tested was significantly higher to tissues, which were susceptible to infection with these strains. The results indicate that adhesion to various cells of the fish organism is principal marker to detect virulentAeromonasstrains. The findings presented in this study may be helpful in the appraisal of aeromonads disease risk and kind of the infection in particular fish farms by epizootiological studies or/and during routine fish examinations. They will also be useful to improve and facilitate diagnosis of bacterial fish disease.

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Långmark, J., M. V. Storey, N. J. Ashbolt, and T. A. Stenström. "Biofilms in an urban water distribution system: measurement of biofilm biomass, pathogens and pathogen persistence within the Greater Stockholm area, Sweden." Water Science and Technology 52, no. 8 (October 1, 2005): 181–89. http://dx.doi.org/10.2166/wst.2005.0259.

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Distribution pipe biofilms can provide sites for the concentration of a wide range of microbial pathogens, thereby acting as a potential source of continual microbial exposure and furthermore can affect the aesthetic quality of water. In a joint project between Stockholm Water, the MISTRA “Sustainable Urban Water” program, the Swedish Institute for Infectious Disease Control and the Royal Technical University, Stockholm, the aim of the current study was to investigate biofilms formed in an urban water distribution system, and quantify the impact of such biofilms on potential pathogen accumulation and persistence within the Greater Stockholm Area, Sweden. When used for primary disinfection, ultra-violet (UV) treatment had no measurable influence on biofilm formation within the distribution system when compared to conventional chlorination. Biofilms produced within a model pilot-plant were found to be representative to those that had formed within the larger municipal water distribution system, demonstrating the applicability of the novel pilot-plant for future studies. Polystyrene microspheres (1.0μm) and Salmonella bacteriophages demonstrated their ability to accumulate and persist within the model pilot-plant system, where the means of primary disinfection (UV-treatment, chlorination) had no influence on such phenomena. With the exception of aeromonads, potential pathogens and faecal indicators could not be detected within biofilms from the Stockholm water distribution system. Results from this investigation may provide information for water treatment and distribution management strategies, and fill key data gaps that presently hinder the refinement of microbial risk models.

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Sousa, Oscarina V., Norma S. Evangelista-Barreto, Karla M. Catter, Antonio A. Fonteles-Filho, Andrew Macrae, and Regine Helena S. Fernandes Vieira. "Specificity of a defined substrate method used to monitor balneability of tropical coastal waters impacted by polluted stormwater." Journal of Water and Health 8, no. 3 (March 9, 2010): 543–49. http://dx.doi.org/10.2166/wh.2010.132.

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Defined substrate (DS) is an alternative technique to monitoring the water quality based on species-specific enzyme activity. Although more sensitive and more specific than traditional media, there is some controversy over use in the warmer waters of tropical and subtropical environments, rich in organic matter and microorganism groups capable of interfering with results. The aim of this study was to test the specificity of DS method (Colilert, IDEXX) for detection of coliforms and Escherichia coli in stormwater seawater samples from a coastal city (Fortaleza, Brazil) compared to findings obtained with the multiple tube fermentation (MTF) method. The samples were collected from stormsewers and adjacent seashore locations. The most probable number (MPN) of total coliforms (TC), thermotolerant coliforms (TtC) and E. coli was determined and the selectivity of the enzymatic substrate medium in the seawater samples was tested. The MTF method showed samples from sampling points 1, 2 and 3 to be 13.3, 13.3 and 46.7%, respectively, above the legal cut-off value for coastal balneability. With the DS method, the corresponding figures were 60, 53.3 and 80% for E. coli. Overall, coliform levels were higher with the DS medium. Vibrios and aeromonads were isolated from E. coli-positive DS tubes.

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McBain, Andrew J., Robert G. Bartolo, Carl E. Catrenich, Duane Charbonneau, Ruth G. Ledder, Bradford B. Price, and Peter Gilbert. "Exposure of Sink Drain Microcosms to Triclosan: Population Dynamics and Antimicrobial Susceptibility." Applied and Environmental Microbiology 69, no. 9 (September 2003): 5433–42. http://dx.doi.org/10.1128/aem.69.9.5433-5442.2003.

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ABSTRACT Recent concern that the increased use of triclosan (TCS) in consumer products may contribute to the emergence of antibiotic resistance has led us to examine the effects of TCS dosing on domestic-drain biofilm microcosms. TCS-containing domestic detergent (TCSD) markedly lowered biofouling at 50% (wt/vol) but was poorly effective at use levels. Long-term microcosms were established and stabilized for 6 months before one was subjected to successive 3-month exposures to TCSD at sublethal concentrations (0.2 and 0.4% [wt/vol]). Culturable bacteria were identified by 16S rDNA sequence analysis, and their susceptibilities to four biocides and six antibiotics were determined. Microcosms harbored ca. 10 log10 CFU/g of biofilm, representing at least 27 species, mainly gamma proteobacteria, and maintained dynamic stability. Viable cell counts were largely unaffected by TCSD exposure, but species diversity was decreased, as corroborated by denaturing gradient gel electrophoresis analysis. TCS susceptibilities ranged widely within bacterial groups, and TCS-tolerant strains (including aeromonads, pseudomonads, stenotrophomonads, and Alcaligenes spp.) were isolated before and after TCSD exposure. Several TCS-tolerant bacteria related to Achromobacter xylosoxidans became clonally expanded during dosing. TCSD addition did not significantly affect the community profiles of susceptibility to the test biocides or antibiotics. Several microcosm isolates, as well as reference bacteria, caused clearing of particulate TCS in solid media. Incubations of consortia and isolates with particulate TCS in liquid led to putative TCS degradation by the consortia and TCS solubilization by the reference strains. Our results support the view that low-level exposure of environmental microcosms to TCS does not affect antimicrobial susceptibility and that TCS is degradable by common domestic biofilms.

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Borrell, N., M. J. Figueras, and J. Guarro. "Phenotypic identification ofAeromonasgenomospecies from clinical and environmental sources." Canadian Journal of Microbiology 44, no. 2 (February 1, 1998): 103–8. http://dx.doi.org/10.1139/w97-135.

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A collection of 983 Aeromonas isolates from environmental and clinical sources have been identified to the genomospecies level. A phenotypic method identified 93% of the strains. The use of citrate and the production of acid from sorbitol enabled the members of the Aeromonas hydrophila complex to be separated. The most common genomospecies from intestinal sources were Aeromonas veronii biotype sobria and Aeromonas caviae. The former, together with A. hydrophila,was the most frequently isolated species of extraintestinal origin. Most pathogenic species were very prevalent in environmental samples, with A. veronii biotype sobria being the most common in lakes and reservoirs (41.5%) and in treated drinking water (25.0%), and A. caviae was the most common in sea water (26.0%) and milk products (35.5%). Aeromonas hydrophila (18.1%) was the second most prevalent species isolated in untreated drinking water. Since Aeromonas infections are generally regarded as a water- and food-borne diseases, the high environmental prevalence of these pathogenic genomospecies should be regarded as an important threat to public health.Key words: Aeromonas, food, water, clinical, Spain.

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Tai-Lee, Hu. "Removal of reactive dyes from aqueous solution by different bacterial genera." Water Science and Technology 34, no. 10 (November 1, 1996): 89–95. http://dx.doi.org/10.2166/wst.1996.0243.

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The use of biomass for the removal of reactive dyes from an aqueous solution with different bacterial genera has been investigated. Three Gram-negative bacteria: Aeromonas sp., P. luteola and E. coli, and two Gram-positive bacteria: B. subtilis and S. aureus and a mixed biomass of activated sludge are the tested biosorbents. Dead cells of Gram-negative bacteria have a higher specific adsorption capacity than the living cells. The dye removal is in the order of Aeromonoas sp. > P. luteola > E. coli. The adsorption equilibrium can be reached within one hour. Due to the positively charged cells at acidic pH, the removal of reactive dyes increases with decreasing pH. Evaluating the adsorption parameters, bacterial biomass exhibits stable adsorption characteristics, which makes it a suitable adsorbent for different dye compounds.

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Yousif, Samira Y., and Rasha Abid Ali Al-Khalidi. "Isolation and identification of motile Aeromonas spp.from different sources." Journal of Biotechnology Research Center 5, no. 3 (December 18, 2011): 56–65. http://dx.doi.org/10.24126/jobrc.2011.5.3.185.

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Total of 507 samples (clinical, environmental, food) were collected from different hospitals in Baghdad, water, soil, and different food stuffs. Biochemical and morphological characterization tests showed that seventeen isolates were identified as Aeromonas spp.These were farther characterized as Aeromonas hydrophila 10 isolates, Aeromonas sobria 2 isolates, Aeromonas eucrenophila 3 isolates, one isolate belongs to Aeromonas caviae and another one belongs to Aeromonas schubertii. Antibiotic susceptibility tests of all the isolates towards fifteen antibiotics agents were carried out and results showed that all isolates 100% were resistant to penicillin, ampicillin, ampiclox, 99% were resistant to lincomycin, 76.7% to cephalothin, 52.9% to cefotaxime. All isolates except one isolate of Aeromonas eucrenophila were sensitive to meropenem.

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Dhanapala, Pavithra M., Ruwani S. Kalupahana, Anil W. Kalupahana, D. P. H. Wijesekera, Sanda A. Kottawatta, Niromi K. Jayasekera, Ayona Silva-Fletcher, and S. S. S. de S. Jagoda. "Characterization and Antimicrobial Resistance of Environmental and Clinical Aeromonas Species Isolated from Fresh Water Ornamental Fish and Associated Farming Environment in Sri Lanka." Microorganisms 9, no. 10 (October 6, 2021): 2106. http://dx.doi.org/10.3390/microorganisms9102106.

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The aims of this study were to characterize and investigate antimicrobial susceptibility and presence of integrons in 161 Aeromonas spp. isolated from ornamental freshwater fish farming environment, apparently healthy and diseased fish. Phylogenetic analyses of the gyrB gene sequences identified Aeromonas veronii as the most abundant species (75.8%) followed by Aeromonashydrophila (9.3%), Aeromonas caviae (5%), Aeromonas jandaei (4.3%), Aeromonas dhakensis (3.7%), Aeromonas sobria (0.6%), Aeromonas media (0.6%), and Aeromonas popoffii (0.6%). Susceptibility to thirteen antimicrobials was determined and antimicrobial resistance frequencies were: amoxicillin (92.5%), enrofloxacin (67.1%), nalidixic acid (63.4%), erythromycin (26.1%), tetracycline (23.6%), imipenem (18%), trimethoprim-sulfamethoxazole (16.8%), and gentamicin (16.8%). Multi-drug resistance (MDR) was widespread among the isolates (51.6%, 83/161) with 51.6% (63/122) A. veronii isolates being MDR. In addition, 68.3% of isolates had multiple antibiotic resistance (MAR) indexes higher than 0.2, suggesting that they originated from a high-risk source of contamination where antimicrobials are often used. In all, 21.7% isolates carried class 1 integrons, with 97.1% having gene cassettes, while there were 12 isolates carrying class 2 integron gene cassettes. Our findings highlight that the aquatic environment and ornamental fish act as reservoirs of multidrug resistant Aeromonas spp. and underline the need for a judicious use of antimicrobials and timely surveillance of antimicrobial resistance (AMR) in aquaculture.

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OSMAN, KAMELIA M., ZEINAB M. S. AMIN, MAGDY A. K. ALY, HANY HASSAN, and WALEED S. SOLIMAN. "SDS-PAGE Heat-Shock Protein Profiles of Environmental Aeromonas Strains." Polish Journal of Microbiology 60, no. 2 (2011): 149–54. http://dx.doi.org/10.33073/pjm-2011-021.

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Aeromonas microorganisms normally grow at temperatures between 5 degrees C and 45 degrees C and therefore should have high thermotolerance. Thus it was of interest to find out whether A. hydrophila, A. caviae and A. veronii biovar sobria serovars respond to abrupt temperature changes with a heat shock-like response. To this end the present study was undertaken to determine whether Aeromonas species exhibits a heat shock response to different temperatures and time factors. The response of Aeromonas serovars to 24 h and 48 h of thermal stress at 25 degrees C, 42 degrees C and 50 degrees C involved the synthesis of 12-18 heat shock proteins (HSPs) bands with molecular weights ranging between 83.5-103.9 kDa in the high HSP molecular mass and 14.5-12.0 as low molecular mass HSP. Electrophoretic analysis of the HSPs showed that the serovars do not cluster very tightly and also that they are distinct from each other.

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Ünver, B., and M. Z. Bakıcı. "Motile aeromonad septicemia (MAS) at Cyprinus carpio L., 1758 (Actinopterygii:Cyprinidae) in Lake Tödürge (Sivas/Turkey)." Arquivo Brasileiro de Medicina Veterinária e Zootecnia 73, no. 2 (March 2021): 320–26. http://dx.doi.org/10.1590/1678-4162-11989.

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ABSTRACT In this study, fish’s morphologic and anatomic lesions caused by motile aeromonad septicemia (MAS) depending on environmental stress in carp, Cyprinus carpio population living in Lake Tödürge were identified. Various morphological and anatomical deformations and lesions were observed in the body of approximately 17% (252 fish specimens) of a total of 1488 carp samples. Bacteria are grown from all wipe samples. Bacterial colonies have a gray-white appearance with round, convex and smooth edges. 15-20 cfu colonies were observed in each aerop culture. As a result of analysis of wet wipe samples from infected fish’s skin, gill, kidney and liver, it is determined that the bacteria which causes septicemia is Aeromonas sobria from the Aeromonadaceae family (with 99.2% confidence value). No bacteria were grown in cultures except A. sobria. Some symptoms of the infection are inflammation on different parts of the fish bodies, eruption on skin and scales, dermal necrosis, degeneration at soft rays of the fins, exophthalmos, and purulent liquid accumulation in the abdominal cavity, etc. Infected fish were most commonly encountered in July and August (water temperature above 20ºC), the lowest in October and November (water temperature below 10ºC).

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Castelo-Branco, Débora de Souza Collares Maia, Glaucia Morgana de Melo Guedes, Raimunda Sâmia Nogueira Brilhante, Marcos Fábio Gadelha Rocha, José Júlio Costa Sidrim, José Luciano Bezerra Moreira, Rossana de Aguiar Cordeiro, et al. "Virulence and antimicrobial susceptibility of clinical and environmental strains of Aeromonas spp. from northeastern Brazil." Canadian Journal of Microbiology 61, no. 8 (August 2015): 597–601. http://dx.doi.org/10.1139/cjm-2015-0107.

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The aims of the present study were to isolate and identify clinical and environmental strains of Aeromonas spp. by means of biochemical tests and the automated method VITEK 2 and to investigate the presence of the virulence genes cytotoxic enterotoxin (act), hemolysin (asa-1), and type III secretion system (ascV), and also the in vitro antimicrobial susceptibility of the strains. From the clinical isolates, 19 Aeromonas hydrophila, 3 Aeromonas veronii bv. sobria, and 1 Aeromonas caviae were identified, while from the environmental strains, 11 A. hydrophila, 22 A. veronii bv. sobria, 1 A. veronii bv. veronii, and 1 A. caviae were recovered. The gene act was detected in 69.5% of clinical isolates, asa-1 in 8.6%, and ascV in 34.7%. In the environmental strains, the detection rates were 51.4%, 45.7%, and 54.2% for the genes act, asa-1, and ascV, respectively. Resistance to amoxicillin–clavulanate and piperacillin–tazobactam was observed in 15 and 3 clinical strains, respectively, and resistance to ceftazidime, meropenem, imipenem, ciprofloxacin, and trimethoprim–sulfamethoxazole was observed in 1 strain for each drug. Resistance to amoxicillin–clavulanate and piperacillin–tazobactam was detected in 17 and 1 environmental strain, respectively. Higher resistance percentages were observed in clinical strains, but environmental strains also showed this phenomenon and presented a higher detection rate of virulence genes. Thus, it is important to monitor the antimicrobial susceptibility and pathogenic potential of the environmental isolates.

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Balsalobre, L. C., M. Dropa, G. R. Matté, and M. H. Matté. "Molecular detection of enterotoxins in environmental strains of Aeromonas hydrophila and Aeromonas jandaei." Journal of Water and Health 7, no. 4 (July 1, 2009): 685–91. http://dx.doi.org/10.2166/wh.2009.082.

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Aeromonas species are widely distributed in aquatic environments and recent studies include the genus in the emergent pathogens group because of its frequent association with local and systemic infections in immunocompetent humans. Aiming to search for virulence genes in environmental strains of Aeromonas hydrophila and Aeromonas jandaei, we designed specific primers to detect act/hly A/aer complex and alt genes. Primers described elsewhere were used to detect ast. Eighty-seven strains previously identified using phenotypic and genotypic tests as A. hydrophila (41) and A. jandaei (46) were analysed for the presence of the virulence genes using PCR. DNA fragments of expected size were purified and directly sequenced. Among the 41 strains of A. hydrophila 70.7% (29), 97.6% (40) and 26.8% (11) possessed act/hly A/aer complex, ast and alt genes, respectively. Among the 46 strains of A. jandaei, 4.4% (2), 0% (0) and 32.6% (15) were positive for act/hly A/aer complex, ast and alt genes, respectively. Sequencing allowed for the confirmation of amplified products using BLAST. The present work proposes a specific and rapid diagnostic method to detect the main virulence determinants of Aeromonas, a genus potentially pathogenic to humans.

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Journal articles on the topic 'Environmental aeromonads'

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