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 271 records · Page 15Linked to original sources
PubMed1994

Assessment of some selective media for the recovery of Aeromonas hydrophila from surface waters.

A comparison was made of three different growing media already proposed by some authors for the recovery of Aeromonas hydrophila in environmental water samples of various origins. The media tested were Rippey and Cabelli m Aeromonas agar, Rimler-Shotts agar and the Ryan Aeromonas Base Medium with the addition of ampicillin. The efficiency of the three media was evaluated on the basis of the following reference criteria: accuracy, selectivity and specificity. The results obtained, analyzed by calculating the Kendall concordance coefficients, demonstrated that m Aeromonas agar is the most suitable media for quantitative recovery of Aeromonas hydrophila from surface water samples even if a reduction in the total heterotrophic load of 3-logs was never obtained with this medium.

Aeromonas hydrophila↗
PubMed1995

[Soft-tissue infection caused by Aeromonas hydrophila].

BACKGROUND: Two cases of soft tissue infection by Aeromonas hydrophila are presented with review of the literature. PATIENTS AND METHODS: Two cases of soft tissue infection by Aeromonas hydrophila diagnosed from 1992-1993 are reported. RESULTS: Most soft tissue infection produced by Aeromonas organisms are caused by Aeromonas hydrophila. These infections predominantly affect the lower limbs of middle-aged males with previous history of injury favoring infection. The most common clinical presentation is cellulitis with a good prognosis if bacteremia is not produced. Antibiotics, such as mainly third generation cephalosporins, imipenem, aztreonam, cotrimoxazole, tetracycline, chloramphenicol, quinolones and aminoglucosides (except streptomycin) are usually very active in vitro against these organisms. Surgery is often necessary to cure the process. CONCLUSIONS: Cellulitis by Aeromonas hydrophila is a very infrequent entity in Spain and is usually associated to previous injury and probable contamination by environmental bacteria.

Adult↗
PubMed1997

Pril-ampicillin-dextrin-ethanol agar for the isolation and quantification of Aeromonas spp. from polluted environmental waters.

Several selective media were evaluated for their suitability for the isolation and quantification of mesophilic Aeromonas species from naturally polluted samples. Satisfactory recoveries were obtained with most of them but only when densities of background microflora were low. When analysed samples were from highly polluted waters, results were inconsistent because they did not give quantitative recovery of mesophilic aeromonads or they did not permit ready differentiation of Aeromonas species from the competitive bacteria. A new medium was developed on the basis of the combination of some positive aspects of several published media, pril-ampicillin-dextrin-ethanol (PADE) agar. The medium employs dextrin (Merck 3006) as a fermentable carbohydrate and pril, ampicillin and ethanol as inhibitory substances. Recovery on PADE agar from suspensions of 15 tested strains of Aeromonas prepared from pure cultures was excellent. The confirmation rate of typical colonies designated Aeromonas spp. isolated from polluted samples exceeded 90%. Recoveries of stressed aeromonad strains on both PADE agar and a non-selective medium (TSA) did not show any significant difference (P > 0.05). PADE agar was more reliable for quantitative recovery of mesophilic aeromonads than the other selective media because of its characteristics: (i) inhibition of the swarming of Proteus, (ii) good reduction of the background, (iii) inhibition of the over growth of Klebsiella spp., (iv) absence of NaCl makes it unfavourable for the growth of halophilic vibrios, (v) combination of two pH indicators permitted a very easy differentiation between Aeromonas colonies and the competitive microflora. The medium can also be used for isolation of aeromonads from various sources by membrane filtration.

Aeromonas↗
PubMed1998

Incidence & enteropathogenicity of Aeromonas spp in children suffering from acute diarrhoea in Chennai.

A total of 200 stool samples from children below 10 yr suffering from diarrhoea were screened for enteric pathogens with special interest on Aeromonas. Aeromonas spp were isolated from 6.5 per cent of the patients, comprising 4 per cent A. hydrophila, 2 per cent A. sobria and 0.5 per cent A. caviae. Among the 13 isolates obtained, 10 isolates produced enterotoxin in ligated rabbit ileal loops, and 11 produced cytotoxin in HEp 2 cells. Many of the Aeromonas isolates exhibited resistance to commonly used antibiotics such as trimethoprim, sulphdiazine, chloramphenicol and tetracycline. None of the stool samples obtained from 52 age matched control children yielded Aeromonas species. Four isolates of Salmonella typhi, 7 of S. paratyphi A, 6 of Shigella flexneri, 4 of Sh. dysenteriae and 3 isolates of Vibrio cholerae (Ogawa) were also recovered during the study. Among the samples analyzed, one from a 7 yr old female patient, had A. hydrophila with S. paratyphi A. The results of this study indicate that drug resistant enteropathogenic Aeromonas is also an important etiological agent of childhood diarrhoea in Chennai.

Acute Disease↗
PubMed1998

The risk to public health of aeromonas in ready-to-eat salad products.

Mesophilic Aeromonas spp. are isolated regularly from cases of gastrointestinal infection and have markers indicative of enteropathogenicity. Is aeromonas, which is present in a large proportion of ready-to-eat salads, actually a gastrointestinal pathogen? Isolates of mesophilic aeromonas from salads were characterised in terms of their ability to grow at refrigeration temperatures over the given shelf life and by the presence of markers of potential virulence. The major phenospecies present in salads, A.caviae, showed little enteropathogenic potential. Thirty-five per cent of aeromonas salad isolates are A.hydrophila or A.sobria, however, and all isolates tested had at least one marker of enteropathogenicity, including cytotoxin and haemolysin production, adherence to epithelial cells, and resistance to certain antibiotics Despite the presence of markers of enteropathogencity, the lack of epidemiological evidence of a link between infectious intestinal disease and the consumption of salads suggests that their contamination with aeromonas does not pose a significant risk to health in immunocompetent adults.

Aeromonas↗
PubMed1999

Survival ability of cytotoxic strains of motile Aeromonas spp. in different types of water.

The ability of motile Aeromonas spp. to survive in drinking water (mineral and tap water) and in sea water was experimentally tested. Clinically isolated cytotoxic strains of A. hydrophila, A. caviae and A. sobria were selected for this study. After contamination of water samples, the survival of Aeromonas strains was studied for at least three months using viable counts. The results obtained show that the survival of the Aeromonas spp. varies considerably depending on species and water type. For all three species, the survival time was longest in mineral water, where viable bacteria of each strain were still detected after 100 d. Moreover, A hydrophila and A. caviae also re-grew on the first day. In tap water all strains showed marked survival, although to a lesser extent than in mineral water. Aeromonas cells showed a rapid decline in sea water (90% reduction in viable cells after about two d) and thus seem to be more sensitive to saline/marine stress than chlorination.

Aeromonas↗
PubMed1991

Distribution of Aeromonas species in waters with different levels of pollution.

Strains of Aeromonas spp. (883) were isolated from 10 stations in the north-west of Spain. Biotyping of the strains gave: 55% Aeromonas caviae, 34% A. hydrophila, 6% A. sobria and 5% Aeromonas spp. Phenotypic characters that have been claimed to be related to virulence such as haemolysis and the Voges-Proskauer reaction were detected mostly in A. hydrophila and A. sobria. The distribution of the species was significantly related to levels of faecal pollution in waters. Aeromonas caviae predominated in sewage and waters with a high degree of faecal pollution. In less polluted waters, either fresh or marine, A. caviae and A. hydrophila were almost equally distributed. In waters with low or no faecal pollution, the proportion of A. sobria to other species increased considerably.

Aeromonas↗
PubMed1993

Aeromonas spp. can secrete Escherichia coli alkaline phosphatase into the culture supernatant, and its release requires a functional general secretion pathway.

Aerolysin is a channel-forming protein secreted by Aeromonas hydrophila. To determine if regions of aerolysin could direct the secretion of another protein, portions of aerA were fused to phoA, the Escherichia coli alkaline phosphatase gene and cloned into E. coli, Aeromonas salmonicida, and A. hydrophila. We were surprised to find that secretion of the enzyme by both Aeromonas spp. was independent of the aerolysin segments fused to it. The smallest fusion product contained only the signal sequence and two amino acids of aerolysin. The largest had more than 90% of the aerolysin molecule. The fusion proteins were found in the periplasms of E. coli and A. salmonicida grown in LB medium containing glucose, as well as in the shocked cells. Aerolysin itself was secreted by A. salmonicida under these conditions. In contrast, when A. salmonicida containing any of the fused genes was grown in LB medium without glucose, most of the alkaline phosphatase activity was extracellular, whereas beta-lactamase remained in its normal periplasmic location. Similar results were obtained with A. hydrophila. The change in location of the enzyme in A. salmonicida appeared to be related to the pH of the growth medium. A. salmonicida and A. hydrophila also secreted native E. coli alkaline phosphatase, but A. hydrophila strains with mutations in the general secretion pathway were unable to release the enzyme. We conclude that the Aeromonas secretion system can recognize the E. coli enzyme as an extracellular protein and direct it outside the cell.

Aeromonas↗
PubMed2003

Molecular typing of Aeromonas isolates in natural mineral waters.

A total of 103 isolates of Aeromonas spp. were obtained over a 3-year period from a natural mineral water and from surface streams located within the boundaries of the watershed of the natural mineral water wells and were typed by macrorestriction analysis of genomic DNA with XbaI and by pulsed-field gel electrophoresis. All Aeromonas caviae isolates from the natural mineral water belonged to the same clone, and an analogous clonal identity was found among Aeromonas hydrophila isolates. These two clones expressed no hemolytic or cytotoxic activities. Aeromonas isolates from surface waters showed high molecular heterogeneity and were not related to the clones found in the natural mineral water. The presence of aeromonads chronically found in the natural mineral water was a likely consequence of a localized development of a biofilm, with no exogenous contamination of the aquifer. Molecular fingerprinting of drinking water isolates is a useful tool in explaining possible reasons for bacterial occurrences.

Aeromonas↗
PubMed2004

Complete type III secretion system of a mesophilic Aeromonas hydrophila strain.

We have investigated the existence and genetic organization of a functional type III secretion system (TTSS) in a mesophilic Aeromonas strain by initially using the Aeromonas hydrophila strain AH-3. We report for the first time the complete TTSS DNA sequence of an Aeromonas strain that comprises 35 genes organized in a similar disposition as that in Pseudomonas aeruginosa. Using several gene probes, we also determined the presence of a TTSS in clinical or environmental strains of different Aeromonas species: A. hydrophila, A. veronii, and A. caviae. By using one of the TTSS genes (ascV), we were able to obtain a defined insertion mutant in strain AH-3 (AH-3AscV), which showed reduced toxicity and virulence in comparison with the wild-type strain. Complementation of the mutant strain with a plasmid vector carrying ascV was fully able to restore the wild-type toxicity and virulence.

Aeromonas↗
PubMed1997

[Prevalence of Aeromonas spp. in surface water].

Some Aeromonas strains are well recognized enteropathogens according to microbiological, clinical, immunological and epidemiological evidence. The main source of infection seems to be untreated water, these microorganisms can be found in virtually all aquatic environments. Additionally, some Aeromonas, which include enterotoxigenic strains, are capable of rapid growth at 5 degrees C and even of producing toxins. Vegetable products irrigated with contaminated water may reach critical Aeromonas levels after being kept under refrigeration, this could represent a public health risk when they are consumed as uncooked salads. This study was pursued to evaluate such risk. Surface water samples were streaked on starch ampicillin and inositol-brilliant green-bile salts agar dishes. In addition, 100 ml of each sample were filtered through a 0.45 micron Millipore membrane filter. The filters were incubated on alkaline peptone water as enrichment media during 24 h at 35 degrees C. Enrichment broth was then streaked on the selective agars above mentioned. Isolates from both tests were identified using the API 20 E System. The prevalence of Aeromonas strains in the analyzed samples was 17.8%. A higher isolation rate was observed after the enrichment technique. Starch ampicillin agar showed a higher recuperation rate. A Veronii biotype sobria (formerly A. sobria) was isolated with higher frequency. Since this species has been associated with the greatest virulence, the use of contaminated water to irrigate vegetable products that are to be kept under refrigeration and consumed without ulterior cooking may represent a risk to the public health.

Aeromonas↗
PubMed1991

Aeromonas hydrophila: variability in biochemical characteristics of environmental isolates.

A total of 161 strains, including 144 aeromonads, of which 100 had been isolated from water and sediment samples from the Chesapeake Bay, five clinical and 33 Anacostia River isolates of Aeromonas hydrophila, six Aeromonas sobria, and ten reference cultures were examined in a numerical taxonomy study in which each of the strains were examined for 56 unit characters. Similarity between strains was computed using the simple matching (SSM) and Jaccard (SJ) coefficients. The strains were clustered by unweighted average linkage and single linkage algorithms. Results of all analyses yielded similar clusterings of strains. Of the 161 strains included in the study, 148 were recovered in seven major clusters. A large cluster of Aeromonas hydrophila yielded two sub-clusters. From the results of the taxonomic analysis it is concluded that several biovars of Aeromonas hydrophila can be isolated from the aquatic environment, but geographical or site specific distribution of the biovars could not be detected.

Aeromonas hydrophila↗
PubMed1996

Molecular and biochemical characterization of a heat-labile cytotonic enterotoxin from Aeromonas hydrophila.

We report herein the DNA sequence analysis of the heat-labile cytotonic enterotoxin gene (alt) from Aeromonas hydrophila and the biological function of the purified hyperproduced toxin (Alt). One large open-reading frame (ORF), comprised of 1104 bp, was detected at positions 804 to 1907 bp on a 4.0-kb Sa/l DNA fragment from Aeromonas. This ORF encodes for a protein having 368 amino acids (aa) with a computed molecular weight of 38 kDa. The aa sequence of the first 15 NH2-terminal residues of the mature native Alt from A. hydrophila matched with the DNA-derived aa sequence of the alt gene expressed in E. coli starting at position 19, which was leucine. The first 18aa residues of the Alt represented a putative signal sequence with alanine at its carboxy terminus. A BLAST search of the entire database showed 45-51% identity of the Alt, starting at position 158 with the carboxy half of the phospholipase C (PLC) and lipase from A. hydrophila; however, the purified Alt had no lipase/PLC activity. The alt gene was hyperexpressed using gene fusion expression vector systems, and the recombinant Alt exhibited a size of 35-40 kDa. The pure recombinant Alt elongated Chinese hamster ovary cells and elicited fluid secretion in rats ligated intestinal loops, indicating its enterotoxicity. Immunization of mice with recombinant Alt resulted in a reduced fluid secretory response when challenged with Aeromonas. The biological activity of the recombinant Alt in E. coli was about 10-fold less, compared to native Alt from Aeromonas, indicating differential processing of the toxin. The antibodies to native Alt neutralized the biological activity of the recombinant toxin, and these antibodies reacted with the same specificity to the native and recombinant Alt in immunoblots. The role of cyclic adenosine monophosphate and prostaglandins in causing a fluid secretory response by Alt also was demonstrated.

Aeromonas hydrophila↗
PubMed1997

Aeromonas spp. possess at least two distinct type IV pilus families.

Type IV pili have been purified from strains of most of the Aeromonas species associated with gastroenteritis (A. veronii biovar sobria, A. hydrophila, A. trota and A. caviae). They appear to be a related family (molecular mass of pilin 19 to 23 kDa) with a tendency to bundle-formation. Hence, we have designated them 'bundle-forming pili' (Bfp). A type IV pilus biogenesis gene cluster (tapABCD) recently cloned from a strain of A. hydrophila, however, encoded a 17 kDa pilin which differed significantly in its N-terminal amino acid sequence from the Bfp pilins. This paper describes the cloning of part (tapA and approximately 20% of tapB) of a homologous pilin gene cluster from a Bfp-positive strain of A. veronii biovar sobria, and presents evidence that the entire pilin gene cluster (tapABCD) is present in this strain. The predicted N-terminal amino acid sequence of the pilin encoded by the A. veronii biovar sobria tapA differed markedly from the corresponding sequence of its Bfp pilin, and those of the Bfp purified from other Aeromonas strains and species. Probing with tapA and tapD genes showed that these Bfp-positive Aeromonas strains also possessed the Tap gene cluster. TapA proteins of A. veronii biovar sobria and A. hydrophila shared 53% identity and 63% homology. We conclude that Aeromonas species are potentially able to express at least two distinct families of type IV pili (Bfp and Tap).

Aeromonas↗
PubMed1991

Comparison of different media for the identification and quantification of Aeromonas spp. in water.

In order to assess the suitability of the Starch glutamate ampicillin penicillin-10C agar for the isolation of Aeromonas spp. from waters it was necessary to compare the properties of this medium with those of three others, Starch ampicillin agar, Ampicillin dextrin agar and m-Aeromonas medium, and to monitor different kinds of waters. A selection of forty eight samples were taken from moderately polluted river water, highly polluted river water, polluted sea water (littoral) and treatment & distribution water and monitored using these media. The results were similar with Ampicillin dextrin agar, m-Aeromonas medium and Starch glutamate ampicillin penicillin-10C, but the simplicity of composition and use and its selectivity recommends the last medium as the most adequate for the isolation of Aeromonas spp.

Aeromonas↗
PubMedDate not supplied

Aeromonas caviae: an enteric pathogen?

Of the Aeromonas spp. isolated routinely in our laboratory from human feces, about two thirds represent Aeromonas caviae. In contrast to Aeromonas hydrophila and Aeromonas sobria, this species has been considered to be of little enteropathogenic significance due to the absence of known virulence factors. The clinical data presented here suggest a clinical significance of A. caviae, at least in some cases. As yet nothing is known about the pathogenic mechanisms involved.

Adolescent↗
PubMed1988

Wound infection with aerogenic Aeromonas strains: a review of twenty-seven cases.

Aeromonas spp. have been implicated in a wide spectrum of human disease including wound infection. A review is made of local experience of 27 wound infections from which aerogenic strains of Aeromonas were recovered; of these, Aeromonas was isolated in pure culture from five infections. Twenty-five infections were related to trauma and were community acquired, while two were probably nosocomial. Of the 25 community acquired infections, 16 were associated with contamination by soil and one with water. Twenty-six cases were surgically debrided or a limb or digit amputated, but in only one case was amputation performed because of uncontrolled infection. Fifteen patients received antibiotics inappropriate for the infection, yet the outcome was uniformly good. This series is discussed with a review of the English language literature. Aeromonas is most likely to be isolated when there is contamination of a wound by soil or water; adequate surgical debridement is probably of primary importance.

Adult↗
PubMed1994

Virulence factors in clinical and food isolates of Aeromonas species.

Virulence factors were compared in 15 Aeromonas spp. isolated from faeces of patients with Aeromonas-associated gastroenteritis and in 81 strains isolated from food. Strains from food did not show differences in the distribution of virulence factors when compared with strains isolated from faeces. However, 88.8% of Aeromonas strains isolated from food were capable of producing possible virulence factors. Characterization of 28 autoagglutinating (AA+) Aeromonas spp. indicated that the human strains differed from the food strains in hemagglutinating and hemolytic capacities. These results suggest that autoagglutination associated with hemagglutinating and hemolytic capacities in food strains may be a helpful indicator of potential pathogenicity.

Acriflavine↗