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PubMed1997

Toxicity of crude extracellular products of Aeromonas hydrophila in tilapia, Tilapia nilotica.

Extracellular products (ECP) secreted from Aeromonas hydrophila with haemolytic and proteolytic activity were studied with respect to temperature and time of incubation as well as the lethal toxicity on tilapia, Tilapia nilotica. The highest production of the haemolysin product was achieved when Aer. hydrophila was grown at 35 degrees C for 30 h. Tilapia erythrocyte was found to be more susceptible than sheep erythrocyte for determining the haemolytic activity. The haemolytic activity against tilapia erythrocyte was completely inactivated after heating the ECP at 60 degrees C for 10 min or 55 degrees C for 15 min. The proteolytic activity was maximized when the bacterium was grown at 30 degrees C for 36 h. Complete inactivation of the protease enzyme was performed after heating the ECP at 80 degrees C for 10 min or 70 degrees C for 15 min. Aeromonas hydrophila was found to produce haemolytic and proteolytic exotoxin lethal to tilapia (LD50 2.1 x 10(4) cell/fish), as well as heat stable unknown virulent factors that were responsible for 20% mortality. The lethality of ECP was decreased by heating and completely inactivated by boiling at 100 degrees C for 10 min.

Aeromonas hydrophila↗
PubMed1999

A comparison of different culture media for the membrane filter quantification of Aeromonas in water.

A comparative assessment of culture media for the membrane filter enumeration of Aeromonas spp. in water was performed, testing the effects of different incubation conditions (aerobic and anaerobic), temperatures (30 and 37 degrees C) and times (24 and 48 h). Different water samples seeded with test suspensions of Aeromonas spp., fecal material or raw sewage were examined. Results indicate clearly that plates should be incubated aerobically at 30 degrees C for 24 h. If the bacterial contamination is likely to be low, the use of most sensitive culture media, such as SAA, mA, ADA or PADE Agar, is recommended. By contrast, samples with an expected high level of background microbial flora should be analysed through more selective media, such as MIX Agar. However, the low selectivity of all media tested and the high likelihood of false negatives based upon the macroscopic examination of colonies means that further research directed to the development of more efficient media is needed.

Aerobiosis↗
PubMed2006

[Postoperative infection of an epigastric hematoma caused by Aeromonas veronii biovar sobria].

HISTORY: A 52-year-old man with a gastric signet-ring cell carcinoma but without acute symptoms was admitted for reconstructive surgery of the gastrointestinal tract. INVESTIGATIONS: Before the present surgery all functional and radiological tests merely confirmed the previously known disease. Except for mild anemia and abnormal electrolytes all laboratory tests were within normal limits. COURSE, DIAGNOSIS AND TREATMENT: The patient underwent reconstructive surgery of the gastrointestinal tract, namely an ascending sigmoidostomy and resection of an enterocutaneous fistula. For a few days the postoperative development was as expected and the drain, placed during surgery, was removed at the expected time. 9 days postoperatively the patient developed signs of an infection (fever up to 38.8 degrees C, increased WBC and raised C-reactive protein levels). Computed tomography (CT) of the abdomen revealed an epigastric tumor measuring 6 x 5 cm. CT-guided needle aspiration of this lesion showed macroscopic signs of an infected hematoma. A pigtail catheter was successfully implanted for continuous drainage. Both the fluids obtained from CT-guided aspiration and the pigtail drain grew Aeromonas veronii biovar sobria when cultured on standard blood agar. Administration of both cefotaxim and metronidazole for 10 days produced a decrease in the inflammatory parameters. The abdominal CT at that time showed a noticeable regression of the epigastric mass so that the patient was discharged from hospital 3 weeks after surgery. CONCLUSION: This case emphasizes the importance of adequately dosed antibiotic therapy, also for unusual bacteria such as species of Aeromonas.

Aeromonas↗
PubMedDate not supplied

Necrotizing fasciitis caused by Aeromonas hydrophila.

Aeromonas Hydrophila is a gram-negative bacillus commonly found in soil, sewage, and fresh or brackish water in many parts of the United States. In healthy people, the most common clinical manifestations attributed to Aeromonas are diarrhea and soft tissue infections. In people with suppressed immune systems or liver disease, A hydrophila can cause meningitis, endocarditis, peritonitis, hemolytic-uremic syndrome, or septicemia. We present the first known case of fulminant necrotizing fasciitis from A hydrophila that is not associated with trauma, liver disease, or immunosuppression.

Aeromonas hydrophila↗
PubMed2004

Polyphasic taxonomic study of "Aeromonas eucrenophila-like" isolates from clinical and environmental sources.

In the current study, a group of 17 "Aeromonas eucrenophila-like" isolates from clinical and environmental origins was subjected to a polyphasic taxonomic characterization including ribotyping, 16S rDNA sequencing, FAFLP fingerprinting, and biochemical testing. Genotypic, phylogenetic, and phenotypic results were consistent with the conclusion that this group of 17 isolates may represent a currently undescribed Aeromonas taxon most closely related to A. eucrenophila HG6. In addition, comparison of newly obtained 16S rDNA sequencing data with published sequences demonstrated a high phylogenetic heterogeneity among isolates currently classified in the species A. encheleia.

Aeromonas↗
PubMed2004

Restriction fragment length polymorphism of 16S-23S rDNA intergenic spacer of Aeromonas spp.

We analyzed restriction fragment length polymorphism (RFLP) of 16S-23S rDNA intergenic spacer region (ISR) of Aeromonas species. A total of 69 isolates belonging to 18 DNA hybridization groups (HG; equivalent of genomic species) were used in this study. ISRs were amplified by PCR and the products were digested with four restriction endonucleases: Hin6I, Csp6I, TaqI, and TasI. The RFLP patterns obtained after digesting by particular enzymes revealed ISR polymorphism of isolates allocated to individual genomic species. The combined Hin6I, Csp6I, TaqI, and TasI restriction profiles were examined by Dice coefficient (SD) and unweighted pair group method of clustering (UPGMA). The isolates were allocated into 15 groups, three strains were unclustered. The strains belonging to the following genomic species: A. hydrophila, A. bestiarum, A. salmonicida, A. caviae, A. media, A. schubertii, A. allosaccharophila, A. popoffii, and A. culicicola formed distinct clusters. Strains belonging to HG 6, HG 7, HG 11, and HG 16 revealed similar combined RFLP patterns and constituted one group. Similarly, the strains of A. jandaei (HG 9) and the type strain of A. trota were allocated into one cluster. Two isolates of HG 14 formed distinct cluster. We noticed a genetic diversity among A. veronii isolates, the strains were clustered in two groups. Our study showed that combined ISR-RFLP analysis may be used for identification of some species of Aeromonas.

Aeromonas↗
PubMed2001

Formation of viable but non-culturable state (VBNC) of Aeromonas hydrophila and its virulence in goldfish, Carassius auratus.

In this study we investigated the viable but non-culturable (VBNC) state of Aeromonas hydrophila and its virulence in goldfish. Aeromonas hydrophila cultured in a 0.35% NaCl solution at pH 7.5 and at 25 degrees C for 50 days showed the VBNC state. In the VBNC state we were unable to detect viable bacteria by the plate count method but we did find 10(4) cells/ml by the direct viable count microscopical method after staining with fluorescein diacetate and ethidium bromide. The virulence comparison in goldfish showed that bacteria cultured at 25 degrees C for 1 day in a 0.35% NaCl solution were more virulent than bacteria cultured for 28 days. VBNC bacteria showed lower virulence in goldfish compared to 28-day-cultured bacteria by intraperitoneal injection. The results from the study suggest that A. hydrophila can remain in the aquatic environment for prolonged periods in the VBNC state but those cells are not pathogenic to goldfish.

Aeromonas hydrophila↗
PubMed2001

Three cases of bacteraemia caused by Aeromonas veronii biovar sobria.

Septicaemia caused by Aeromonas species is a life-threatening condition, arising primarily in immunocompromised patients, which has rarely been reported in Scandinavia. Herein we describe 3 cases of Aeromonas sobria bacteraemia from Denmark. All the patients were male and all 3 cases occurred during the summer. Two patients had acute leukaemia and HIV infection, respectively, while the third patient had colorectal cancer diagnosed several years later. The clinical presentation in all patients was chest and/or abdominal pain with fever developing into sepsis without any known infectious focus. All patients responded well to antibiotic therapy.

Adult↗
PubMed2006

Fatal case of myonecrosis and septicaemia caused by Aeromonas hydrophila in Finland.

A 48-y-old female developed cellulitis, myonecrosis and sepsis after a prick wound in her hand while boning freshwater fish. Cultures revealed Aeromonas hydrophila, a Gram-negative bacillus. Despite prompt care the patient died 4 d after the incident. Our case shows that the occurrence of severe Aeromonas infections is not limited to tropical and subtropical areas of the world.

Aeromonas hydrophila↗
PubMed2003

Detection of erythrocytes deficient in glycosylphosphatidyl-inositol anchored membrane proteins in patients with paroxysmal nocturnal hemoglobinuria by the toxin HEC secreted by Aeromonas hydrophila J-1.

OBJECTIVE: To study the feasibility of diagnosing paroxysmal nocturnal hemoglobinuria (PNH) with toxin HEC, the abbreviation of hemolytic, entreotoxigenicity and cytotoxity secreted by Aeromonas hydrophila J-1. METHODS: The crude toxin HEC was extracted from the culture medium of Aeromonas hydrophila J-1 by precipitating with saturated (NH(4))(2)SO(4) and then purified through DEAE52. Purified toxin HEC is different from Aerolysin in molecular weight and necessity of activation. Crude toxin is prepared possessed same effect as purified ones. This crude toxin was used to act on red blood cells (RBCs) from patients with PNH, non-PNH anemia, and normal persons. Absorbance at 630 nm was measured to quantitate the extent of hemolysis. Toxin HEC treated and untreated RBCs were both stained with anti-CD59 monoclonal antibody and FITC labeled goat-anti-mouse IgG. The percentage of CD59(+) cells was detected by flow cytometry (FCM). RESULTS: After toxin HEC treatment, RBCs from PNH patients showed resistance to the toxin hemolysis, which was negatively related to the percentage of CD59(+) cells, while RBCs from normal persons and non-PNH anemic patient were nearly totally lysed. CONCLUSION: Detection of RBCs resistance to toxin HEC can be used for the diagnosis of PNH.

Aeromonas hydrophila↗
PubMed1999

Site-directed mutagenesis of Asp313, Glu315, and Asp391 residues in chitinase of Aeromonas caviae.

Site-directed mutagenesis was used to explore the roles of amino acid residues involved in the activity of chitinase from Aeromonas caviae. Kinetic parameters for 4-methylumbelliferyl-N,N'-diacetyl-chitobiose or 4-methylumbelliferyl-N,N',N"-triacetylchitotriose hydrolysis were determined with wild-type and mutant chitinases. Chitinases with the mutations E315D (or Q) and D391E (or N) were severely impaired and had dramatically decreased kcat. However, the effect of the these mutations on the Km values were different. The function of the carboxyl group of Asp313 was partially replaced by the amide of Asn when the 4-methylumbelliferyl-N,N',N"-triacetylchitotriose substrate was used. Results indicated that Asp313, Glu315, and Asp391 might be the best candidates for the catalytic residues of chitinase A from Aeromonas caviae.

Aeromonas↗
PubMed2002

Nosocomial Infections with Aeromonas hydrophila from Leeches.

The manner in which leeches are maintained before they are used for therapy has not been studied as a factor contributing to nosocomial infections. A 5-year retrospective survey of Aeromonas hydrophila nosocomial infections at a hospital in Marseille, France, revealed infections in 5 (4.1%) of an estimated 122 patients treated with leeches in the Hand Surgery Unit and 2 (2.4%) of an estimated 85 patients treated with leeches in other hospital units. The retrospective survey showed that the Hand Surgery Unit was the only unit that had its own aquarium for maintaining leeches; this aquarium was filled with tap water contaminated with Aeromonas species and was not regularly disinfected or cleaned. Leeches used in other units were maintained in noncarbonated water in a transport device. Use of leeches kept in aquariums that are filled with tap water and not disinfected or cleaned regularly may be linked to A. hydrophila infections.

Aeromonas hydrophila↗
PubMed1998

Evolving concepts regarding the genus Aeromonas: an expanding Panorama of species, disease presentations, and unanswered questions.

It has been almost 10 years since a major review on the association of Aeromonas with human disease has been published. During that period the number of valid species in the genus has grown to 14, with a new family (Aeromonadaceae) established to house this genus. Despite this explosion in the number of new genomospecies, only five (Aeromonas hydrophila, A. caviae, A. veronii, A. jandaei, and A. schubertii) are currently recognized as human pathogens. New syndromes attributed to this genus include hemolytic uremic syndrome, burn-associated sepsis, and a variety of respiratory tract infections, including epiglottitis. Convincing evidence suggests that some aeromonads do cause gastroenteritis, but it is presently unclear whether many of the strains isolated from feces are involved in diarrheal disease. Many questions regarding this genus remain unanswered.

Aeromonas↗
PubMed1993

Failure of the Vitek AutoMicrobic system to detect beta-lactam resistance in Aeromonas species.

The ability of the Vitek AutoMicrobic system (AMS; Vitek, Inc., Hazelwood, MO) and disk-diffusion method to detect beta-lactam resistance was assessed with 25 strains from four species of Aeromonas. A very major error was indicated when a strain was shown to be susceptible by the AMS or disk-diffusion method but resistant by the agar dilution method. The rates for very major errors for disk diffusion and the AMS were 0% and 43%, respectively. The beta-lactam agents and numbers of very major errors for the AMS were as follows: ticarcillin, 17; mezlocillin, 3; piperacillin, 4; cephalothin, 9; cefazolin, 3; cefoxitin, 1; cefotetan, 2; and cefuroxime, 1. Thus, these data suggest that the AMS currently is not reliable for testing the resistance of Aeromonas to beta-lactam agents.

Aeromonas↗
PubMed1985

A case report: Aeromonas sobria gastroenteritis in an adult.

Aeromonas sobria, a member of the Aeromonas hydrophila group, recently has been recognized as a gastrointestinal pathogen in adults. There have been a few documented cases, and these have come from far eastern countries, namely India, Thailand, and Indonesia. The authors have isolated a strain of A. sobria from a 62-year-old male patient suffering from diarrheal disease. He had no history of travel outside of the United States for several decades. He presented with a severe diarrheal disease that closely mimicked cholera, producing large quantities of green "rice water" stool. He was severely dehydrated and was in electrolyte imbalance. No other enteric pathogen could be detected. The organism presumptively was identified as Vibrio cholera (81.5% probability) by the Micro Scan system, but later was identified definitively as A. sobria using the API 20E and ZYM systems. Cell-free extract of this strain contained hemolysins, proteolytic enzymes, and enterotoxin. The strain closely fits the description of Burke and associates (J Clin Microbiol 1982; 15:48-52) for their group A, type 1 (VP positive, arabinose negative, enterotoxin producer). The patient was treated with tetracycline and recovered.

Aeromonas↗
PubMed1993

Aeromonas hydrophila infections of skin and soft tissue: report of 11 cases and review.

We report the clinical and microbiological characteristics of 11 cases of Aeromonas hydrophila infection of skin and soft tissue, and we review the English-language literature on such infections. Of our 11 patients, seven (64%) presented to the hospital between the months of May and September (inclusive). Three patients (27%) had an underlying systemic illness, and two (18%) had nosocomially acquired infection. The nine patients with community-acquired infection had all experienced antecedent trauma, and seven (78%) of these nine reported recent exposure to freshwater. All patients had clinical evidence of soft-tissue inflammation, and nine (82%) had fever. Four wounds were characterized by a foul odor. The infection was polymicrobial in nine cases (82%). Treatment included the administration of antibiotics in nine instances, but empirical antimicrobial therapy provided coverage against Aeromonas in only two cases. Ten patients required surgical management of their wounds. Posttraumatic wound infections with a history of freshwater exposure should alert the clinician to the possible presence of A. hydrophila. Prompt surgical evaluation of wounds in combination with appropriate antibiotic therapy is recommended for the management of these infections.

Adolescent↗
PubMedDate not supplied

Bacteremia caused by Aeromonas species in hospitalized cancer patients.

Bacteremia caused by Aeromonas species occurred in 24 hospitalized patients in a cancer institute during a 13-year period. All but one of these patients had a malignancy (88% had leukemia), and most were receiving chemotherapy for cancer. There was a striking numerical predominance of male patients (82%). Unlike some previously described patients with infections due to this organism, none of these 24 patients had recently been exposed to fresh or salt water or to fish. The source of the infecting organism was thought to be endogenous--i.e., from patients' own gastrointestinal tracts. The clinical presentation of sepsis caused by this organism was nonspecific, except that ecthyma gangrenosum occurred in several patients. The overall mortality rate was 28%. The combination of an aminoglycoside and a cephalosporin is appropriate therapy for bacteremia caused by Aeromonas species.

Acute Disease↗
PubMed1983

In-vitro antagonism by N-formimidoyl thienamycin and cefoxitin of second and third generation cephalosporins in Aeromonas hydrophila and Serratia marcescens.

Antagonism of beta-lactam antibiotics by second and third generation cephalosporins was studied in 28 clinical strains of Serratia marcescens and Aeromonas hydrophila. Of the antibiotics tested, both cefoxitin and N-formimidoyl thienamycin (N-f-thienamycin) were capable of antagonism in Ser. marcescens (17 of 20) but in Aerom. hydrophila (7 of 8), only cefoxitin induced antagonism. Antagonism was observed to the greatest degree with cefotaxime and cefoperazone; intermediate with cefamandole and latamoxef (moxalactam) and essentially none with N-f-thienamycin. Inducible beta-lactamase was found in all strains of both genera which exhibited antagonism. The induced beta-lactamase showed enhanced inactivation for other antibiotics in only four strains with none occurring in Aeromonas.

Aeromonas↗