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PubMed1989

Aeromonas species in aquaria: a reservoir of gastrointestinal infections?

To assess the role of aquaria in the epidemiology of aeromonas associated gastroenteritis, the prevalence and antibiotic susceptibility of aeromonads in ornamental aquaria were determined and compared to that of isolates obtained from patients with gastroenteritis. Thirty-eight (76%) of 50 aquaria, including those located in our hospital, yielded 61 isolates: 24 (39.3%) Aeromonas sorbria, 18 (29.0%) A. hydrophila, 15 (24.6%) A. caviae, and four (6.5%) which could not be speciated. In comparison, 41 (65%) of 63 faecal isolates were A. caviae. The aquarium isolates, in contrast to enteric isolates, were generally resistant to chloramphenicol, tetracycline, and trimethoprim/sulphamethoxazole. These findings indicate aquaria are unlikely sources of aeromonas-associated gastroenteritis, but their role as possible reservoirs for non-enteric infections with aeromonads needs to be defined.

Aeromonas↗
PubMed1983

Enterotoxigenicity, hemagglutination and cell-surface hydrophobicity in Aeromonas hydrophila, A. sobria and A. salmonicida.

Thirty-one Aeromonas hydrophila, 13 A. sobria and two A. salmonicida strains of diverse sources were tested for enterotoxigenicity, hemagglutination and cell surface hydrophobicity. Although 93% of the culture supernatant fluids of the Aeromonas strains exhibited cytotoxic effects on Y1 adrenal and Chinese hamster ovary (CHO) cells, typical rounding of Y1 adrenal cells was reproducibly observed before cytotoxicity for 80% of the isolates within 1 h of exposure. Twenty-eight strains were positive for delayed permeability factor (DPF) activity in rabbit skin. Culture filtrates of 16 of 20 strains that were positive both in the Y1 adrenal cell test and for DPF activity elicited fluid accumulation in rabbit ileal loops. The DPF and ileal loop activities were neutralizable by cholera antitoxin. All, except two strains each of A. sobria and A. hydrophila, produced a heat-stable, rapid permeability factor (RPF) detected in rabbit skin. Heat-treated culture supernatant fluids of two A. hydrophila and one A. sobria isolate gave positive responses in the infant mouse assay. Nine other strains gave borderline reactions. When A. hydrophila and A. sobria isolates were grown in broth, approximately 90% agglutinated bovine, chicken, human group A and guinea-pig erythrocytes in the presence of mannose at 4 degrees C and/or 20 degrees C. The two A. salmonicida isolates produced mannose resistant hemagglutination (MRHA) of these four blood types. Hydrophobic interaction chromatography indicated adhesive potential in 61% A. hydrophila and 100% A. sobria strains expressing weak to strong hydrophobic cell surface properties. The results of these investigations strongly imply that the Aeromonas strains produce a cytotonic enterotoxin immunologically related to cholera toxin. Adhesive characteristics were commonly found in both clinical and routine isolates.

Aeromonas↗
PubMedDate not supplied

Elastolytic activity among Aeromonas spp. Using a modified bilayer plate assay.

A total of 166 isolates of Aeromonas, representing diverse geographical regions and originating from various sources, were evaluated for the ability to produce elastase by using a bilayer elastin agar medium (BEAM) plate assay. The degree of elastase activity of individual strains was roughly assessed by measuring the clear area beneath or peripheral to the colony and recorded as 1+, 2+, or 3+. Of the 166 aeromonads tested, 53 (32%) were found to produce elastase, of which 26 (49%) were 3+, 21 (40%) were 2+, and 6 (11%) were 1+. All but one A. hydrophila (n = 45) were observed to produce elastase (98%). One of three A. schubertii strains as well as one isolate of Aeromonas group 501 were elastase positive. All 3+ elastolytic activity was associated with A. hydrophila only. Elastase activity was not detected even after prolonged incubation with A. veronii biogroup sobria (n = 26), A. caviae (n = 57), A. veronii biogroup veronii (n = 4), A. media (n = 1), and A. eucrenophila (n = 1). In addition to its value as a reliable indicator of elastase production for eventual use in virulence assays, we have found that the detection of elastase using the BEAM plate serves as a very useful phenotypic marker for the major, clinically important Aeromonas spp.

Aeromonas↗
PubMedDate not supplied

Wound infection due to fresh water contamination by Aeromonas hydrophila.

We report the case of a 24-year-old man who sustained a scalp laceration in a diving accident. His wound became infected, and he was treated with an oral cephalosporin, with subsequent progression of the infection. Cultures subsequently grew Aeromonas hydrophila. Many strains of Aeromonas are not sensitive to the antibiotics commonly used for wound infections. Aeromonas must be suspected as a pathogen in all wounds occurring in fresh water if proper treatment is to be initiated.

Adult↗
PubMed2004

Engineered Aeromonas hydrophila for enhanced production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) with alterable monomers composition.

Aeromonas hydrophila 4AK4 produces poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) containing 3-hydroxybutyrate (3HB) and about 15 mol% 3-hydroxyhexanoate (3HHx) from dodecanoate. To study the factors affecting the monomer composition and PHBHHx content, genes encoding phasin (phaP), PHA synthase (phaC) and (R)-specific enoyl-CoA hydratase (phaJ) from Aeromonas punctata (formerly named Aeromonas caviae) were introduced individually or jointly into A. hydrophila 4AK4. The phaC gene increased 3HHx fraction more significantly than phaP, while phaJ had little effect. Expression of phaC alone increased the 3HHx fraction from 14 to 22 mol%. When phaC was co-expressed with phaP and phaJ, the 3HHx fraction increased from 14 to 34 mol%. Expression of phaP or phaC alone or with another gene enhanced PHBHHx content up to 64%, cell dry weight (CDW) as much as 4.4 gL(-1) and PHBHHx concentration to 2.7 gL(-1) after 48 h in shake flask culture. The results suggest that a higher PHA synthase activity could lead to a higher 3HHx fraction and PHBHHx content. Co-expression of phaJ with phaC or phaP would favor PHA accumulation, although over-expression of phaJ did not affect PHA synthesis much. In addition, inhibition of beta-oxidation by acrylate in A. hydrophila 4AK4 enhanced PHBHHx content. However, no monomers longer than 3HHx were detected. The results show that genetic modification of A. hydrophila 4AK4 enhanced PHBHHx production and altered monomer composition of the polymer.

3-Hydroxybutyric Acid↗
PubMed2005

Occurrence and characterization of Aeromonas spp. in mussels from the Adriatic Sea.

Samples of mussels (Mytilus galloprovincialis) were collected from natural beds on the Adriatic Sea in front of Ancona Province (Marches, Central Italy) officially recognized for human consumption. The mussels were analyzed to evaluate the prevalence of Aeromonas spp. pathogenic strains. Out of 144 samples, 32 Aeromonas strains were isolated and 12 showed virulence and enterophatogenicity on mice. Isolates were also examined to check their sensitivity to different antimicrobial agents. All isolates were sensitive to imepenem, neomycin, ciprofloxacin, tetracycline, oxytetracycline, doxycicline, chloramphenicol, polymyxin B, and colistin sulfate, but resistant to penicillin, carbenicillin, cephalotin, sulfamethoxazole, lincomycin, novobiocin, and rifampicin. Multiple resistance to antimicrobial agents with different mechanism of action was observed. Owing to the high occurrence of pathogenic Aeromonas strains, the risk of developing human infections by eating raw or undercooked mussels is envisaged.

Aeromonas↗
PubMed2005

Immunoreactive antigens of the outer membrane protein of Aeromonas hydrophila, isolated from goldfish, Carassius auratus (Linn.).

Aeromonas hydrophila causes disease under stress conditions or in concert with infection by other pathogens in goldfish. Sero-diagnostic and/or immunoprophylactic tools against Aeromonas infection in goldfish are not available so far. The present study was undertaken to fractionate and characterise the outer membrane proteins (OMP) of A. hydrophila and to identify suitable immunoreactive components. A total of 10 fractions were generated from crude OMP antigens upon gel permeation and subsequent ion-exchange chromatography. One of the fractionated antigens (GPID2), primarily a 57-kDa polypeptide, showed maximum sero-reactivity, even higher than the crude OMP. Suitability of GPID2 antigen for use in diagnostic preparations was assessed by dip-stick ELISA. In vitro goldfish lymphoproliferative ability of fractionated antigen, GPIID2 (primarily a 23-kDa polypeptide) was observed to be higher than all the fractionated antigens as well as crude OMP. It can be concluded that the 57 kDa and 23 kDa polypeptides of the OMP of A. hydrophila, possessing high immunoreactivity, should be given due attention while preparing immunodiagnostic and immunoprophylatic tools against Aeromonas infections in goldfish.

Aeromonas hydrophila↗
PubMed2002

The occurrence of cytotoxic Aeromonas hydrophila strains in Italian mineral and thermal waters.

Bacteria of the genus Aeromonas are ubiquitous in aquatic environments, including mineral drinking and thermal waters. Motile species are related to different diseases, mostly gastrointestinal disorders. Criteria for Aeromonas pathogenicity in humans and animals are still unclear and neither is the relationship between production virulence and pathogenicity factors. In the present study, strains of Aeromonas hydrophila, from 61 samples of bottled mineral waters and 23 thermal Italian sources have been isolated and identified by biochemical tests, for toxicity and detection of the aerolysin gene by the Polymerase Chain Reaction (PCR). Six strains were isolated from the mineral waters and were found to be cytotoxic and in possession of the aerolysin gene. For the twelve strains isolated from thermal waters, seven were cytotoxic and eleven contained the aerolysin gene.

Aeromonas hydrophila↗
PubMed1982

Aeromonas-associated gastroenteritis.

Enterotoxigenic Aeromonas spp. were isolated from 118 (10.2%) children with diarrhoea and 7 (0.6%) of those without diarrhoea in a prospective, year-long study of 1156 children with gastroenteritis and the same number of age and sex matched controls. In Perth, Western Australia, aeromonas-associated diarrhoea is distinctly seasonal with a sharp summer peak. The disease most commonly presents in children under two years of age as watery diarrhoea of short duration and mild fever which require no specific treatment. In more than one-third of patients diarrhoea lasted for over 2 weeks and in almost one-quarter there was a dysentery-like illness. In some patients with aeromonas-associated diarrhoea the clinical features could be regarded as suggestive of ulcerative colitis.

Aeromonas↗
PubMed1985

Pathogenicity of aeromonas.

The ability of 15 Aeromonas sobria and 9 Aeromonas hydrophila isolates to cause subcutaneous lesions was tested. An inoculum of 10(11) colony forming units/l was injected subcutaneously into mice. Surviving animals developed a subcutaneous abscess and/or localised skin sloughing and loss of hair (alopecia). An abscess was induced by all nine A. hydrophila isolates and by three of the 15 A. sobria isolates. The induction of local epidermal sloughing and loss of hair followed challenge with either A. hydrophila or A. sobria and correlated with the organisms' lethality for mice and their cytotoxicity in the Y-I adrenal cell assay. Local epidermal sloughing was not induced by the media used for growing the organisms or by sonicated cells of the isolates. The ability to cause epidermal sloughing was lost by incubating viable cells at 45 degrees C for 35 minutes. These yet unreported in vivo features of Aeromonas sp. may be useful in studies of the pathogenicity of the species as well as for rapid assay of toxicity of strains.

Abscess↗
PubMed2000

Selective enrichment broth for the isolation of Aeromonas sp. from chicken meat.

Six selective agents (ampicillin, novobiocin, cephalothin, bile salts, brilliant green and ethanol) were tested during the development of a selective enrichment broth for the isolation of Aeromonas sp. from food. Cephalothin at 10 mg/l was found to be the best selective agent owing to its greater selectivity and efficiency in recovering stressed and lower cell concentrations of Aeromonas sp. Higher concentrations (15-25 mg/l) of cephalothin were inhibitory to some strains of A. sobria. Cephalothin (10 mg/l) was incorporated in buffered dextrin broth (BCDB-10) and alkaline peptone water (CAPW-10) and employed for the isolation of Aeromonas sp. from chicken meat naturally and artificially inoculated (with 10(9) cells/ml of A. hydrophila). The highest isolation rate (22%) with naturally contaminated chicken was achieved with CAPW-10 in comparison to 16% with BCDB-10 and 8% with APW. Similarly, from artificially inoculated samples, 100% isolation was accomplished with CAPW-10, against 80% with BCDB-10 and 50% with APW.

Aeromonas↗
PubMed2003

Prevalence and resistance to antibiotics for Aeromonas species from retail fish in Malaysia.

A total of 87 market fish samples representing five types of fish were evaluated for the presence of Aeromonas spp. Of the samples examined, 69%, 55%, 11.5% and 2.3% harbored Aeromonas spp., A. veronii biovar sobria, A. hydrophila and A. caviae, respectively. The 60 isolated Aeromonas spp. strains were further examined for hemolytic activity, resistance to antimicrobial agents and presence of plasmids. Hemolytic activity varied widely among the isolated strains. Though all the isolates demonstrated resistance to three or more of the antibiotics tested, all were susceptible to ceptazidime. Thirty-four (56.7%) of the sixty isolates harbored plasmids, with sizes ranging from 2.3 to 15.7 kb. These results indicate that hemolytic, multiple antibiotic resistant and genetically diverse aeromonads are easily recovered from fish in this region.

Aeromonas↗
PubMed1999

An in-vitro evaluation of the activity of chlorine against environmental and nosocomial isolates of Aeromonas hydrophila.

A chlorine preparation was tested against 34 strains of Aeromonas hydrophila isolated from a hospital water facility and patients with nosocomial infections in a French medical school hospital. In-vitro bactericidal activity was determined by a macro- and micromethod, using specific interfering substances over a range of dilutions and temperatures, after 1 and 5 minute exposure times. A 10(5)-fold reduction in the challenge inoculum was taken as the criterion of efficacy. Results obtained by both methods agreed and indicated a median minimal bacterial concentration of chlorine of from 0.95 ppm without interfering substances to 297 ppm in the presence of interfering substances. These data indicate that Aeromonas hydrophila isolates are relatively resistant to chlorine, thus precluding the use of chlorine alone as a disinfectant for water supplies contaminated with Aeromonas spp.

Aeromonas hydrophila↗
PubMed2003

Bacteriocin-like substance (BLS) production in Aeromonas hydrophila water isolates.

30 Aeromonas hydrophila water isolates were tested for bacteriocin-like substance (BLS) production using a target panel of closely related microorganisms and other Gram-positive and Gram-negative bacteria, including food-borne pathogens. A. hydrophila showed antibacterial activity against one or more indicator microorganisms, but the activity emerged only with non-phylogenetically related genera or species. In particular all A. hydrophila showed antibacterial activity against one or more of the tested Staphylococcus strains, five against Listeria spp. (Listeria seeligeri, Listeria welshimeri and Listeria ivanovii), and eight presented a weak antagonistic activity towards Streptococcus agalactiae and Lactobacillus spp. Inhibitory activity was not observed against the other Gram-positive (Listeria monocytogenes, Listeria innocua and Enterococcus spp.) and Gram-negative tested strains, including Aeromonas sobria, Aeromonas caviae and the same A. hydrophila, when used as indicator. Anti-staphylococcal activity was observed with a gradual increase of the inhibition zone during incubation and seemed to be influenced by A. hydrophila hemolytic expression. Extrachromosomal analysis showed the presence, in 70% of the strains, of one to five plasmids with molecular masses ranging from 2.1 to 41.5 MDa, but it was not possible to relate this result with BLS production.

Aeromonas hydrophila↗
PubMed1999

Polymerase chain reaction (PCR)-based typing analysis of atypical isolates of the fish pathogen Aeromonas salmonicida.

Two hundred and five isolates of atypical Aeromonas salmonicida, recovered from a wide range of hosts and countries were characterized by polymerase chain reaction (PCR) targeting four genes. The chosen genes were those encoding the extracellular A-layer protein (AP), the serine protease (Sprot), the glycerophospholipid:cholestrol acetyltransferase protein (GCAT), and the 16S rRNA (16S rDNA). All the atypical A. salmonicida isolates could be assigned to 4 PCR groups. Group 1 comprised 45 strains which tested positive for PCR amplification, using the 16S rDNA, GCAT2, Sprot2, and AP primer-sets. Group 2 comprised 88 strains with produced PCR products using the 16S rDNA, GCAT2 and AP primer-sets. Group 3 comprised 21 strains which produced PCR products using 16S rDNA, GCAT2 and Sprot2 primer-sets, and group 4 comprised 51 strains which produced PCR products using the 16S rDNA and GCAT2 primer-sets only. A. salmonicida subsp. salmonicida isolates tested, belonged to group 1. The PCR primer-sets separated A. salmonicida from other reference strains of Aeromonas species and related bacteria with the exception of Aeromonas hydrophila. The results indicated that PCR typing is a useful framework for characterization of the increasing number of isolations of atypical A. salmonicida.

Acyltransferases↗
PubMed2000

Spontaneous bacterial empyema caused by Aeromonas veronii biotype sobria.

Spontaneous bacterial empyema is a complication of hepatic hydrothorax in cirrhotic patients. The pathogen, clinical course and treatment strategy are different to the empyema secondary to pneumonia. A 54-year-old man, who was a cirrhotic patient with hepatic hydrothorax, was admitted to National Taiwan University Hospital for fever, dyspnea and right side pleuritic pain. The image study revealed massive right pleural effusion and no evidence of pneumonia. The culture of pleural effusion yielded Aeromonas veronii biotype sobria. The diagnosis of spontaneous bacterial empyema caused by Aeromonas veronii biotype sobria was established. To our best knowledge, Aeromonas veronii biotype sobria had never been reported in English literature as the causative pathogen of spontaneous bacterial empyema.

Aeromonas↗
PubMed2001

Rapid iodometric detection of Aeromonas amylase and its diagnostic significance.

Twenty-five Aeromonas hydrophila isolates from different sources (Food, 13; Clinical, 6 and Environmental, 6) were studied for the mode of production of Amylase and rapid iodometric detection of the enzyme in vitro. All twenty-five of the isolates produced the enzyme constitutively at 37 degrees C. Amylase producing ability was not dependent on the source of isolation of Aeromonas (F = 0.1069; p > 0.05). Using iodometric technique, in a microtitration tray, the enzyme was fully demonstrated in 10(40%) of the isolates within 30 min, in 22(88%) within 60 min and in all (25 or 100%) within 90 min. The rapid detection of Aeromonas amylase will, no doubt, be of great value in routine diagnostic microbiology.

Aeromonas hydrophila↗
PubMedDate not supplied

Near-drowning-associated Aeromonas pneumonia.

Aeromonas is increasingly recognized as a human pathogen that causes a variety of different infections. Aeromonas has rarely been reported as a cause of respiratory infection, and it has been described in near-drowning-associated pneumonia. This article reviews a case of Aeromonas sobria pneumonia associated with a near drowning and considers the clinical and epidemiological characteristics of 10 previously reported cases. Nearly all of the cases involved young healthy men, a rapid development of pneumonia and sepsis after a brief stable period postimmersion, and bilateral infiltrates on chest radiography. A very high rate of positive blood cultures and mortality was also noted. The epidemiological and clinical data in this review may be helpful to the clinician caring for near-drowning victims. Although prophylactic antibiotics are not recommended for near-drowning victims, broad-spectrum antibiotics should be rapidly instituted with any evidence of infection.

Adolescent↗