Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AEROMONAS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed2002

A DNA probe specific for Aeromonas colonies.

Members of the genus Aeromonas are important enteropathogens. Commercial identification systems are often unable to correctly identify Aeromonas strains and misidentification as Vibrio spp. is common. A digoxigenin-DNA probe based on a 237 bp of the glycerophospholipid-cholesterol acyltransferase gene has been tested in a colony hybridization assay. The probe hybridized with all Aeromonas species tested (n = 16) but not with strains of other enteropathogenic bacteria (n = 20). The probe allowed the unequivocal identification of Aeromonas in primary isolation media within 36 h.

Acyltransferases↗
PubMed2003

Studies of aerolysin promoters from different Aeromonas spp.

Aeromonas spp. have been related to food and waterborne diseases. The pore forming toxin aerolysin is regarded as the most important virulence factor in Aeromonas food poisoning. In this work the aerolysin promoters from several Aeromonas spp. strains have been sequenced, and divided into two sequence groups. Further analyses of the promoters were carried out in a reporter-plasmid, pSTINA-II. This plasmid was constructed as a hybrid of pUC4K, pACYC184 and pKK232-8. We could conclude that our constructed reporter-gene plasmid was functional and was used to compare different promoters in an aerolysin negative Aeromonas spp. This construct made it possible to study the expression of the reporter gene using different aerolysin promoters under several conditions. We were able to show that the two obtained sequence groups of aerolysin promoters gave different expression of the reporter gene, and that this expression was dependent of temperature and osmolarity. Reducing the size of one promoter sequence from 254 to 148 bp and 102 bp gave a gradual reduction of the reporter gene expression under all conditions. According to our assay there seems to be more than one functional promoter upstream of the aerolysin gene, although the RT-PCR indicated one transcription starting point, under all test conditions.

Aeromonas↗
PubMed1999

Enterotoxins in Aeromonas-associated gastroenteritis.

Aeromonas species produce an array of virulence factors, and the pathogenesis of Aeromonas infections is therefore complex and multifactorial. Aeromonas-associated gastroenteritis is especially a problem in young children. The potential involvement of enterotoxins in the pathogenesis of Aeromonas infections is discussed.

Aeromonas↗
PubMed1990

The incidence of virulence factors in mesophilic Aeromonas species isolated from farm animals and their environment.

Sixty-one isolates of Aeromonas spp. 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 of Aeromonas hydrophila were cytotoxic (96.4%) and were capable of producing cell elongation factor (75%) and haemagglutinins (67.9%). In contrast few of the Aeromonas caviae isolates produced these three markers (13.6%, 27.3% and 36.4% respectively). In general, Aeromonas sobria occupied 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.

Aeromonas↗
PubMed1998

Occurrence, diversity and pathogenicity of mesophilic Aeromonas in estuarine waters of the Italian coast of the Adriatic Sea.

A total of 208 strains of Aeromonas were isolated by monthly sampling from two estuaries (one provided with, and the other devoid of a waste-water treatment system) on the Italian coast of the Adriatic sea between September 1994 and August 1995. Biotyping at the species level allowed the identification of 96 strains (46%) as Aer. caviae, 46 (22%) as Aer. sobria, 33 (16%) as Aer. hydrophila and 25 (12%) as Aer. veronii. Eight strains (4%) were regarded as unnamed aeromonads. Aeromonas caviae was the most prevalent species in water with a high degree of pollution, while Aer. hydrophila strains were more commonly isolated from cleaner water. Aeromonas sobria and Aer. veronii were equally distributed in both estuaries. There was no correlation between temperature and numbers of aeromonads in either estuary. Using a biochemical fingerprinting method, strains were divided into similarity groups (PhP-types) based on their biochemical phenotypes. Several different PhP-types were found in each estuary, yielding a high diversity for these strains. However, some identical PhP-types were also found in both estuaries and at different times of the year, indicating that certain Aeromonas strains can survive more widely varying physico-chemical conditions. The production of toxins capable of causing cytoskeletal-dependent changes in the morphology of Chinese hamster ovary (CHO) cells was detected in 14 strains and appeared to be dependent on the season.

Aeromonas↗
PubMed2000

Prevalence and virulence properties of Vibrio cholerae non-O1, Aeromonas spp. and Plesiomonas shigelloides isolated from Cambé Stream (State of Paraná, Brazil).

The incidence of Vibrio cholerae, Aeromonas spp. and Plesiomonas shigelloides was determined in water samples from Cambé Stream. The samples were collected from seven different sites. The serogroups, virulence markers and drug resistance profiles were also evaluated. Twelve Aer. hydrophila, 12Aer. caviae, eight Aer. sobria, seven Ple. shigelloides and two V. cholerae non-O1 were isolated. They belonged to different serogroups and all produced haemolysis in different assays. Five of the Aeromonas strains and one of V cholerae non-O1 were positive for enterotoxin activity. Haemagglutination and its inhibition, using erythrocytes of different origins, was variable for Aeromonas spp. and V. cholerae, while none of the Ple. shigelloides haemagglutinated in association with any type of erythrocyte. All isolates exhibited multiple drug resistance. These results indicate that the occurrence of V. cholerae non-O1, Aeromonas spp. and Ple. shigelloides, in water used for vegetable irrigation, human recreation and animal consumption, among others, represents a potential risk for humans.

Aeromonas↗
PubMed2001

Characterization of Aeromonas and Vibrio species isolated from a drinking water reservoir.

AIMS: To study the phenotypic and chemotaxonomic (i.e. phospholipid and cellular fatty acid composition) characteristics of environmental Aeromonas spp. and Vibrio spp. isolated from a drinking water reservoir near Vladivostok City, and the application of some chemotaxonomic markers for discrimination of the two genera and species. METHODS AND RESULTS: Presumptive Aeromonas species were dominant in surface water samples (up to 25% of the total number of bacteria recovered). These strains were consistent with respect to the cultural and biochemical properties used to define the species Aeromonas sobria (seven strains) and Aer. popoffii (three strains). Vibrio mimicus (two strains) and Vibrio metschnikovii (one strain) were identified according to phenotypic features and cellular fatty acid composition. CONCLUSION: Environmental Aer. sobria isolates were atypical in their ability to grow at 42 degrees C, and were haemolytic, proteolytic and cytotoxic. Although it was present in a high proportion in the water samples, atypical Aer. sobria is not an indicator of polluted water. SIGNIFICANCE AND IMPACT OF THE STUDY: The incidence of Aeromonas in the drinking water reservoirs in the Far East of Russia is reported for the first time.

Aeromonas↗
PubMed2003

Solar inactivation of mesophilic Aeromonas by exogenous photooxidation in high-rate algal pond treating waste water.

AIMS: Investigations were carried out to observe the effect of sunlight on the survival of mesophilic Aeromonas (A. caviae, A. hydrophila and A. sobria) in high-rate algal pond. METHODS AND RESULTS: Light damage was estimated by loss of bacterial culturability, using simple beaker experiments. Survival of the strains studied under illuminated conditions was highly affected by the physico-chemical conditions within the microcosms. The inactivation of Aeromonas increased strongly as dissolved oxygen was increased, and was dependent on exogenous sensitizers. This process was enhanced by the high pH of water. Die-off of bacteria was prevented by adding catalase and pyruvate (H2O2 scavengers) into the microcosms. CONCLUSIONS: The damage of Aeromonas was mainly due to exogenous photooxidation. Hydrogen peroxide at least was involved in light-induced damage of bacteria. Aeromonas sobria appeared to be slightly less sensitive to photooxidation than A. hydrophila and A. caviae. SIGNIFICANCE AND IMPACT OF STUDY: The present study could explain the relative resistance of A. sobria to treatment in wastewater stabilization ponds.

Aeromonas↗
PubMed2003

Molecular characterization and distribution of virulence-associated genes amongst Aeromonas isolates from Libya.

AIMS: The aim of the study was to type 52 Aeromonas spp. isolates from chicken carcasses, children with diarrhoea and a hospital environment in Libya, and to determine the distribution of putative virulence genes amongst them. METHODS AND RESULTS: Macrorestriction analysis using pulsed-field gel electrophoresis (PFGE) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of 16S rRNA and aroA genes were used to type the isolates. Whereas 30 of 32 chicken isolates were identified as Aeromonas veronii, eight of 12 environmental isolates were Aer. caviae. Three species were identified amongst the eight isolates from children. Aeromonas veronii and Aer. caviae isolates could be divided into eight and five PFGE types, respectively. All species could be further subtyped into one of 21 aroA PCR-RFLP groups. Aerolysin-like haemolysin or enterotoxin gene sequences were detected in all the isolates. Overall carriage rates for hlyA and alt were 77 and 75%, respectively. CONCLUSIONS: Seven of eight isolates from children were of different subtypes, indicating a lack of any common source of acquisition. Isolates of common molecular type did not share identical distributions of putative virulence genes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates the effectiveness of using molecular typing to identify and study genetic variation amongst Aeromonas isolates.

Aeromonas↗
PubMed1998

False-positive coliform reaction mediated by Aeromonas in the Colilert defined substrate technology system.

The Colilert defined substrate technology system allows specific, one-step detection of both coliforms and Escherichia coli while claiming to suppress the influence of non-coliform heterotrophs. The Colilert assay was examined in order to determine whether organisms from the genus Aeromonas could interfere and cause production of a false-positive coliform result as aquatic Aeromonas are known to constitute a fraction of the heterotrophic population found in drinking water. Results obtained clearly demonstrate that Aeromonas sp. can elicit a positive coliform type reaction at very low densities. Cell suspensions as low as 1 x 10(1) cells 10 ml-1 were observed to yield a positive reaction using Colilert reagent 4 weeks short of shelf-life expiry. Use of aged Colilert for monitoring water quality could lead to overestimation of coliforms as Aeromonas have been identified in many treated drinking water supplies.

Aeromonas↗
PubMed2003

Misidentification of Aeromonas veronii biovar sobria as Vibrio alginolyticus by the Vitek system.

AIMS: To find the cause of misidentification of aeromonads when using the Vitek system. METHODS AND RESULTS: Two Aeromonas veronii biovar sobria isolates were misidentified as Vibrio alginolyticus by the Vitek system. Both strains' identification was confirmed by biochemical testing, API 20E/20NE kits and/or 16S RFLP analysis. Thirty-one known Aeromonas species were tested by the Vitek system using 0.45 and 0.85% saline in the suspension medium. It was not clear whether low salinity causes misidentification of Aeromonas species more frequently. CONCLUSIONS: The specified reaction time may be inappropriately short for some critical biochemical tests of some strains. An ingenious reading strategy regarding incubation time is necessary to improve identification of Aeromonas species by the Vitek system. SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first report of misidentification of A. veronii biovar sobria as V. alginolyticus in the Vitek system.

Aeromonas↗
PubMed2003

Phylogenetic affiliation of Aeromonas culicicola MTCC 3249(T) based on gyrB gene sequence and PCR-amplicon sequence analysis of cytolytic enterotoxin gene.

We determined the gyrB gene sequences of all 17 hybridizations groups of Aeromonas. Phylogenetic trees showing the evolutionary relatedness of gyrB and 16S rRNA genes in the type strains of Aeromonas were compared. Using this approach, we determined the phylogenetic position of Aeromonas culicicola MTCC 3249(T), isolated from midgut of Culex quinquefasciatus. In the gyrB based-analysis A. culicicola MTCC 3249(T) grouped with A. veronii whereas, it grouped with A. jandaei in the 16S rRNA based tree. The number of nucleotide differences in 16S rRNA sequences was less than found with the gyrB sequence data. Most of the observed nucleotide differences in the gyrB gene were synonymous. The Cophenetic Correlation Coefficient (CCC) for gyrB sequences was 0.87 indicating this gene to be a better molecular chronometer compared to 16S rRNA for delineation of Aeromonas species. This strain was found to be positive for the cytolytic enterotoxin gene. PCR-Amplicon Sequence Analysis (PCR-ASA) of this gene showed that the isolate is affiliated to type I and is potentially pathogenic. These PCR-ASA results agreed in part with the gyrB sequence results.

Aeromonas↗
PubMed2003

Aeromonas infection of the hepatobiliary system: report of 15 cases and review of the literature.

Aeromonas species cause both intestinal and extraintestinal disease. We reviewed hospital laboratory and medical records to identify patients with Aeromonas infection of the hepatobiliary or pancreatic system. Analysis of data from our hospital, as well as a review of the published literature, yielded a total of 41 episodes in 39 patients, and the features of these episodes are described. The most common manifestation of Aeromonas hepatobiliary infection among all reported cases was cholangitis (29 of 41 episodes). The majority of infections in our hospital occurred in patients with underlying immunosuppression or malignancy (13 of 15 patients), including 4 liver transplant recipients, and nosocomial infection was not infrequent (8 of 17 episodes). Infection occurred most commonly in patients with obstruction of the biliary tract due to stones, tumor, or stricture and was associated with a relatively high mortality rate (11.8%). Antibiotic susceptibility testing revealed that gentamicin, imipenem, and ciprofloxacin had the highest activity against the Aeromonas species isolated.

Adolescent↗
PubMed1975

Recurrent Aeromonas sepsis in a patient with leukemia.

A case of recurrent sepsis due to Aeromonas hydrophila in a patient with acute myelogenous leukemia is reported. The patient's first infection leading to bacteremia followed contamination of a mosquito bite by stagnant water. After recovery from the first bacteremia, the patient again became septic with a second strain of Aeromonas hydrophila, which again responded to antimicrobial therapy. It is hypothesized that contamination of the local water supply may have led to the establishment of a gastrointestinal carrier state that produced the second bout of Aeromonas sepsis when the patient was markedly leukopenic. The importance of the oxidase test to differentiate Aeromonas species from members of the family Enterobacteriaceae is re-emphasized.

Adult↗
PubMed1983

The microbiology of childhood gastroenteritis: Aeromonas species and other infective agents.

A prospective, 12-month study of 975 non-Aboriginal children with diarrhea and age- and sex-matched children without diarrhea, in Perth, Western Australia, was designed to investigate the significance of enterotoxigenic Aeromonas species as a cause of diarrhea. Enterotoxigenic Aeromonas species were found in the fecal specimens of 10.8% of the patients with diarrhea but in only 0.7% of those without diarrhea. Most Aeromonas species were isolated during the summer. Other important bacterial pathogens included Campylobacter, Salmonella, Shigella, and enterotoxigenic Escherichia coli; rotavirus infections appeared to be much less important in the Western Australian environment. Most of the patients were younger than two years of age and about one-quarter had mixed bacterial and/or viral intestinal infections. Enterotoxigenic Aeromonas species can be identified with 97% accuracy using a simple hemolysin assay which should be considered for use by routine diagnostic laboratories, particularly in children's hospitals.

Aeromonas↗
PubMed1991

Intestinal secretory immune response to infection with Aeromonas species and Plesiomonas shigelloides among students from the United States in Mexico.

Intestinal secretory IgA (sIgA) response or lack of response among adults in Mexico with diarrhea was used as an indicator of enteropathogenicity of Aeromonas species and Plesiomonas shigelloides. sIgA was extracted from stool specimens obtained at day of presentation and 5 days later. Total sIgA was standardized, and specific sIgA titer against the organism being shed by each patient was determined. Western blotting was used to determine which microbial antigens elicited an intestinal sIgA response. Of 12 subjects shedding Aeromonas sobria or Aeromonas hydrophila, 11 had a fourfold or greater sIgA titer rise against the infecting strain. Western blotting showed that somatic lipopolysaccharides were the immunodominant antigens. No sIgA titer rises were detected among two patients shedding Aeromonas caviae or in 14 shedding P. shigelloides. This study provides further evidence of the significance of A. sobria and A. hydrophila as pathogens in acute diarrhea but raises additional questions about the role of P. shigelloides, at least in US adults with travelers' diarrhea.

Adult↗
PubMed1996

The 'hidden' carbapenemase of Aeromonas hydrophila.

It has been presumed that there are just two beta-lactamases in the motile Aeromonas species, a carbapenemase and a cephalosporinase, based on the premise that all beta-lactamases can be detected by hydrolysis of the chromogenic cephalosporin, nitrocefin. However, when it was recently found that a non-motile species of Aeromonas that causes furunculosis in salmon, contained three beta-lactamases, one of which was a carbapenemase which could not be detected with nitrocefin, it was hypothesised that genetic exchange could occur between fish pathogens and human pathogens resulting in the transfer of the carbapenemase-encoding gene. This could have a potentially serious impact on intensive therapy units where carbapenems are employed. The purpose of this study was to determine whether the human pathogen Aeromonas hydrophila demonstrated the same beta-lactamase profile. After anion and cation exchange chromatography had been employed to separate the beta-lactamases of a clinical strain of A. hydrophila, three different beta-lactamases were found, one of which is a carbapenemase which does not hydrolyse nitrocefin. It is, therefore, probable that many strains of Aeromonas spp. contain a similar array of beta-lactamases which include a carbapenemase that cannot be detected with nitrocefin. Similar carbapenemases may well remain hidden in other species of bacteria unless appropriate techniques to detect the enzymes are employed.

Aeromonas hydrophila↗
PubMed1992

Postprandial Aeromonas hydrophila cultures and antibiotic levels of enteric aspirates from medicinal leeches applied to patients receiving antibiotics.

Increasing use of medicinal leeches has been accompanied by increasing numbers of reports of Aeromonas hydrophila infections after leech application on or near damaged tissue. We examined the enteric contents of postprandial leeches after their application to patients receiving antibiotics. We found measurable levels of antibiotic in the leech enteric contents, and in leeches applied to patients receiving an antibiotic effective against Aeromonas hydrophila, there was a significant decrease in positive Aeromonas enteric cultures. Suppression of leech enteric bacteria by antibiotic administration to the patient may be an effective strategy to prevent invasive infection by Aeromonas hydrophila as well as bacterial colonization of devitalized tissue that could be the source of late infection. Clinical studies will be required to clarify whether suppression of leech enteric flora results in a decrease in infections associated with leech use.

Aeromonas hydrophila↗