<i>Aeromonas hydrophila</i>clinical and environmental ecotypes as revealed by genetic diversity and virulence genes

Aguilera‐Arreola, Ma. Guadalupe; Hernández-Rodríguez, César; Zúñiga, Gerardo; Figueras, María José; Castro-Escarpulli, Graciela

doi:10.1016/j.femsle.2004.11.011

Cited by 77 publications

(66 citation statements)

References 58 publications

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“…In the present study, irrespective of the Aeromonas species, we found that the T3SS genes were more prevalent in water isolates (for aexU, 68 of 146 isolates were positive; for ascV, 60 of 146 isolates were positive) than in clinical isolates (for aexU, 5 of 53 isolates were positive; for ascV, 5 of 53 isolates were positive), a finding in agreement with data obtained in another recent study (4). However, these genes were more prevalent in clinical isolates than in water isolates specifically for the A. hydrophila group (Table 6).…”

Section: Discussionsupporting

confidence: 93%

Distribution of Virulence Factors and Molecular Fingerprinting of Aeromonas Species Isolates from Water and Clinical Samples: Suggestive Evidence of Water-to-Human Transmission

Khajanchi

Fadl

Borchardt

et al. 2010

Appl Environ Microbiol

138

121

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A total of 227 isolates of Aeromonas obtained from different geographical locations in the United States and different parts of the world, including 28 reference strains, were analyzed to determine the presence of various virulence factors. These isolates were also fingerprinted using biochemical identification and pulse-field gel electrophoresis (PFGE). Of these 227 isolates, 199 that were collected from water and clinical samples belonged to three major groups or complexes, namely, the A. hydrophila group, the A. caviae-A. media group, and the A. veronii-A. sobria group, based on biochemical profiles, and they had various pulsotypes. When virulence factor activities were examined, Aeromonas isolates obtained from clinical sources had higher cytotoxic activities than isolates obtained from water sources for all three Aeromonas species groups. Likewise, the production of quorum-sensing signaling molecules, such as N-acyl homoserine lactone, was greater in clinical isolates than in isolates from water for the A. caviae-A. media and A. hydrophila groups. Based on colony blot DNA hybridization, the heat-labile cytotonic enterotoxin gene and the DNA adenosine methyltransferase gene were more prevalent in clinical isolates than in water isolates for all three Aeromonas groups. Using colony blot DNA hybridization and PFGE, we obtained three sets of water and clinical isolates that had the same virulence signature and had indistinguishable PFGE patterns. In addition, all of these isolates belonged to the A. caviae-A. media group. The findings of the present study provide the first suggestive evidence of successful colonization and infection by particular strains of certain Aeromonas species after transmission from water to humans.

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Section: Discussionsupporting

confidence: 93%

Distribution of Virulence Factors and Molecular Fingerprinting of Aeromonas Species Isolates from Water and Clinical Samples: Suggestive Evidence of Water-to-Human Transmission

Khajanchi

Fadl

Borchardt

et al. 2010

Appl Environ Microbiol

138

121

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“…A search of GenBank for the ast gene sequence using the BLAST N system showed a 96% homology with the ast gene in the complete genome of A. hydrophila (Tables 1 and 3). These results are in agreement with earlier studies (2,21,25) and may suggest or confirm that the ast gene might be specific for A. hydrophila HG1 and might represent a potential taxonomic tool for the identification of A. hydrophila HG1. The low prevalence (2%) of the ast gene in food-borne Aeromonas isolates in the present study is similar to that reported in earlier studies involving human cases of diarrhea in India (23) but contrasts with the reported high prevalence of the ast gene in waterborne isolates (30%) from the United States (22), in isolates from healthy (48%) and sick (71%) children and in environment isolates (66%) from Bangladesh (3), and in clinical human isolates (13%) from southern Taiwan (25).…”

Section: Salmonicidasupporting

confidence: 93%

“…Although this gene occurs widely in clinical (2,3,23) and in environmental isolates of Aeromonas spp. (2,21), the data on the presence of the ast gene in food-borne isolates of Aeromonas spp. are lacking.…”

Section: Salmonicidamentioning

confidence: 99%

Multiplex PCR Method for Detection of Three Aeromonas Enterotoxin Genes

Kingombe¹,

D'aoust²,

Huys

et al. 2010

Appl Environ Microbiol

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A novel multiplex PCR method using three sets of specific primers was developed for the detection of the cytotoxic (act), heat-labile (alt), and heat-stable (ast) enterotoxin genes in Aeromonas spp. This assay was used to characterize 35 reference strains as well as 537 food-borne isolates. A total of seven gene pattern combinations were encountered, including act, alt, act/alt, act/alt/ast, act/alt/148-bp amplicon, alt/ast, and alt/148-bp amplicon. The alt gene was detected with 34 reference strains (97%) and occurred singly in 14% of these strains. The frequency of occurrence of the act/alt, act/alt/ast, and alt/ast gene patterns in reference strains was 14 (40%), 2 (6%), and 2 (6%), respectively. An unpredicted amplicon was detected in 11 reference strains (31%). Characterization of this amplicon showed that its size was 148 bp, as generated by the AHLF and AHLR primers, and that it uniquely aligned with the Aeromonas salmonicida A449 genome sequence (GenBank accession number CP000644). This amplicon was named Aeromonas salmonicida subsp. salmonicida hypothetical protein amplicon (AssHPA). In the 537 food-borne isolates, the act and alt genes were most dominant and were detected in 349 (65%) and 452 (84%) isolates, respectively, either alone or in combinations. The act and alt genes occurred singly in 30 (6%) and 128 (24%) of these strains, respectively. The act/alt gene pattern occurred in 315 isolates (59%), whereas the ast gene was always linked to strains exhibiting the act/alt/ast and alt/ast gene combinations in 4 (0.7%) and 5 (0.9%) isolates, respectively. The uniplex amplification of three enterotoxin genes separately confirms the specificity of the unique selected primers. This multiplex PCR is rapid and simple and can detect the presence of three Aeromonas enterotoxin genes in a single assay.Aeromonas spp. are widely distributed in aquatic environments and are isolated from a wide range of food of animal and plant origin (6). Aeromonas spp. can produce several putative virulence factors, including extracellular enzymes, siderophores, cytotoxic and cytotonic enterotoxins, Shiga-like toxins, endotoxins, invasins, and adhesins (18). Aeromonas spp. can grow and produce toxins in foods at refrigeration temperatures (17). The recent isolation of enterotoxigenic aeromonads from drinking water in the United States (21) reiterates the potential human health hazard of waterborne Aeromonas spp. The observation that strains harboring the alt and ast genes were more prevalent in children with diarrhea than in healthy controls underlines the importance of enterotoxins in the pathogenicity of aeromonads (3).Exotoxins are major virulence factors of Aeromonas spp. that include a cytotoxic heat-labile enterotoxin (Act), also known as aerolysin/hemolysin (8); a cytotonic heat-labile enterotoxin (Alt), also known as lipase, extracellular lipase, or phospholipase (4, 10, 24); and a cytotonic heat-stable enterotoxin (Ast) (9). These toxins are encoded by the genes act (GenBank accession number M84709), alt (GenBank acces...

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“…This diversity indicates the need for regular monitoring of Aeromonas strains for pathogenic characteristics and for the possibility of epidemic strains that could be circulating in the population. Studies of clinical and environmental ecotypes of Aeromonas in Mexico demonstrated the high intraspecific diversity within A. hydrophila and revealed a clear differentiation of strains according to their ecological origins (16). The same study also confirmed, based on the distribution of virulence-related genes, that A. hydrophila is a genetically-heterogeneous species that harbour ecotypes which have different pathogenic potentials to humans and other animals.…”

Section: Discussionsupporting

confidence: 52%

Random Amplified Polymorphic DNA Typing of Clinical and Environmental <i>Aeromonas hydrophila</i> Strains from Limpopo Province, South Africa

Ramalivhana

Lawrence

Samie

et al. 2010

J Health Popul Nutr

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The aim of the present study was to determine the genetic relatedness of strains isolated from diarrhoeal stool and water specimens collected from water-storage containers from different geographical areas in the Limpopo province. In total, 32 Aeromonas strains isolated from stool specimens collected from HIV/AIDS patients suffering from gastroenteritis and their household drinking-water stored in 20-L and 25-L containers were analyzed by random amplified polymorphic DNA PCR (RAPD). The RAPD fingerprints obtained proved reproducible when repeated on three different occasions using whole-cell DNA isolated from the Aeromonas strains. In total, 12 unique RAPD fingerprints were found. The results revealed a tendency of the isolates to cluster according to their origin of isolation (best-cut test 0.80 and bootstrap values >50%). However, a certain degree of similarity was also observed between isolates of water sources and clinical sources which indicated genetic relatedness. There were also genetic similarities between the clinical and the environmental strains of Aeromonas spp. isolated from different geographical areas. This study has demonstrated the genetic relatedness of Aeromonas hydrophila isolates from household drinking-water and clinical sources in South Africa, which may be due to cross-contamination from water to patients or vice-versa. This observation is of publichealth significance, particularly in the era of HIV/AIDS. This study points to the importance of monitoring and evaluating infection-control measures for improved hygiene and to prevent cross-contaminations.

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Aeromonas hydrophilaclinical and environmental ecotypes as revealed by genetic diversity and virulence genes

Cited by 77 publications

References 58 publications

Distribution of Virulence Factors and Molecular Fingerprinting of Aeromonas Species Isolates from Water and Clinical Samples: Suggestive Evidence of Water-to-Human Transmission

Distribution of Virulence Factors and Molecular Fingerprinting of Aeromonas Species Isolates from Water and Clinical Samples: Suggestive Evidence of Water-to-Human Transmission

Multiplex PCR Method for Detection of Three Aeromonas Enterotoxin Genes

Random Amplified Polymorphic DNA Typing of Clinical and Environmental <i>Aeromonas hydrophila</i> Strains from Limpopo Province, South Africa

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