[The pattern of the sensitivity of Aeromonas spp. that produce extraintestinal infections]

We studied the sensibility to several antimicrobics of aeromonas strains isolated in extraintestinal infections during a period of five years, in order to establish which could be the best empirical therapy in these processes. Twenty-two strains of A. hydrophila were evaluated, was isolated (8 from hemocultures, 6 from wound exudate, 2 from abscess aspirate, 2 from peritoneal fluid and 1 from urine, pleural fluid, bile and catheter). The identification was made using the GNI card System (Vitek System) and other tests. The sensibility was assessed using the GNS-BH and GNS-BI card System (Vitek), which allows to know the clinical category and CMI value in microgram/ml. All the strains presented some resistance to antibiotics. 77.8% of the strains were resistant to more than one antibiotic and 64.9%, to more than two antibiotics. We detected 21.7% strains resistant to 4 drugs. The most frequent resistance association was ampicillin, cephoxitine, cephazoline, cephalotine, with or without amoxicillin and clavulanic acid. All the strains were sensible to cephamandol, cephuroxime, cephtriaxone, cephtazidime, cephotaxime, thicarciline, aztreonam, azlociline, mezlociline, piperaciline, gentamycin, amikacine, chloranphenicol and ciprofloxacine. All the strains were resistant to ampicillin; 60.9% of the strains were sensible to the association amoxicillin and clavulonic acid. In conclusion, the treatment of extraintestinal infections does not differs basically from the treatment of the infections caused by Gram-negative bacillus. There are a broad range of effective antibiotics: aminoglycosides (gentamycin, tobramycin, amikacine), piperacyline, cephalosporines (cephuroxime, cephotaxime, cephtazidime and cephtriaxone), chloranphenicol, penemas, monobactanes of fluorquinolone.

Detection of Aeromonas hydrophila in food with an enzyme-linked immunosorbent assay

A microtitration plate, antibody capture, enzyme-linked immunosorbent assay was developed for the detection of Aeromonas hydrophila serotype O: 11 (highly virulent strains). The assay utilizes a detector antibody which shows no cross-reactions with Aeromonas strains other than serotype O: 11 or non-Aeromonas competing organisms. The detector antibody is mixed with the sample and incubated for 1 h, microcentrifuged and the supernatant fluid (unadsorbed antibody) titred in a microtitre plate coated with A. hydrophila cells from serotype O: 11. All the A. hydrophila strains from serotype O: 11 tested reacted strongly with the detector antibody. Also by culturing and performing the immunoassay with the detector antibody we established and quantified the presence of A. hydrophila O: 11 in different foods.

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.

Studies on the hemagglutinant activity of some Aeromonas strains

216 strains to Aeromonas genus (158 A. hydrophila, 33 A. salmonicida, 23 A. sobria, 1 A. caviae and 1 A. veronii strains) of different sources of isolation were studied concerning their hemagglutinating behaviour to 5 different erythrocyte species (human, bovine, chicken, African green monkey and guinea pig) in the presence/absence of mannose/fucose. The study aimed to establish the spectrum of their hemagglutinating activity and any possible correlation between the source of isolation, biochemical phenotype LDC VP and HA type/subtype. Different aspects of HA type/subtype and phenotype LDC VP of Aeromonas strains are discussed. Four Aeromonas hydrophila strains isolated from pig enteritis exhibited constantly FRHA to bovine erythrocytes suggesting a possible correlation between virulence and HA type of the respective strains.

Incidence of Aeromonas species in diarrhoeic stool in University College Hospital Ibadan, Nigeria

Between February and July 1989, stool samples from 100 diarrhoeic patients were screened for Aeromonas species. For isolation, alkaline peptone water was used for enrichment and xylose desoxycholate citrate agar as differential and selective medium. Only one sample (1%) yielded Aeromonas hydrophila having come from a 2-month old baby. No other enteric pathogens were isolated from the positive stool sample, a strong indication that A. hydrophila was responsible for the diarrhoea in the baby. Of nine antimicrobial agents used the lone A. hydrophila isolate was resistant only to ampicillin.

[Purification and characterization of hec toxin produced by Aeromonas hydrophila]

An extracellular toxin produced by Aeromonas hydrophila from cultured crucian carp with septicemia was detected. The toxin was purified by ammonium sulfate precipitation, DEAE-cellulose chromatography and Sephadex G-100 gel filtration. The factor was a single polypeptide with a molecular weight of 52.5kd determined by SDS-PAGE. The heat-stable toxin possesses hemolytic, enterotoxic and cytolytic activities. The hemolytic activity on human erythrocytes was 3.81 x 10(3) HU/mg, CD50 for Vero cell was 0.26 microgram. The LD50 for crucian carp and mice was 4.44 micrograms and 3.58 micrograms respectively. The toxin was neutralized py homologous antibodies. The toxin shows unique characteristics as compared with other known bacterial toxins therefore the authors propose to name the toxin "hec" toxin.

Aeromonas hydrophila conjunctivitis in a pet parrot (Amazona versicolor)

A bilateral conjunctivitis in a pet parrot (Amazona versicolor) is reported. Aeromonas hydrophila was isolated in pure culture from both eyes and considered of diagnostic significance. Biochemical characteristics and antimicrobial susceptibility of the strain were studied, as were the factors that could have contributed to the clinical conjunctivitis and the role of A. hydrophila as an opportunistic pathogen.

The use of medicinal leeches in the salvage of flaps with venous congestion

The use of medicinal leeches (Hirudo medicinalis) for the salvage of tissues with venous congestion has been intermittent over the last two centuries. During the last decade, interest in leech therapy has undergone a resurgence. Hirudo's tricuspid bite injects a highly potent anticoagulant. The site usually bleeds for 1 to 2 hours and under special circumstances may bleed for up to 24 hours. This collective series presents four patients in whom immediate postoperative venous congestion threatened the survival of three tissue replants and one latissimus dorsi flap. Two of the replants were completely salvaged; the other two failed due to infection. Hirudo medicinalis is an important adjunct in preventing flap or replant failure secondary to venous congestion, but its use is associated with significant risks.

Aeromonas hydrophila infections following use of medicinal leeches in replantation and flap surgery

Aeromonas hydrophila infections are a recognized complication of postoperative leech application, and can occur with measurable frequency in populations of patients treated with leeches. We review 11 previously reported leech-related Aeromonas infections and analyze seven unreported cases. These infections range from minor wound complications to extensive tissue loss and sepsis. Often, these infections followed leech application to tissue with questionable arterial perfusion. Onset of clinical infection in these patients ranged from within 24 hours of leech application to 10 days or more after leech application. Late infections may represent bacterial invasion from colonized necrotic tissue. Based on these observations, we recommend that leech applications be restricted to tissue with arterial perfusion to minimize contamination of necrotic tissue. We also recommend that patients treated with leeches receive antibiotics effective against Aeromonas hydrophila before leech application. Patients treated with leeches and discharged with eschars or open wounds might benefit from oral antibiotic therapy until wound closure. These precautions may minimize or eliminate this complication of leech use.

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.

Comparative study of virulence and virulence factors of Aeromonas hydrophila strains isolated from water and sediments of a river

Seventy-four strains of Aeromonas hydrophila isolated from water and sediments of the River Porma (León, N.W. Spain) were characterized biochemically and biologically. Fifty-seven strains (77.02%) were virulent for rainbow trout (Salmo gairdneri) by intramuscular challenge but showed differing degree of pathogenicity which could not be associated with the source. A lack of correlation between caseinase, haemolytic and cytotoxic activities of the strains and their isolation source was also observed. Only two surface characters, acriflavine 0.2% agglutination and non-agglutinating SP-/PAB-phenotypes, were significantly associated with water and sediment strains, respectively.

Prevalence of bacterial agents of diarrhoeal disease at the National University Hospital, Singapore and their resistance to antimicrobial agents

Over a 50-month period, 4,508 stool specimens from patients with diarrhoea were bacteriologically examined at the National University Hospital, Singapore. Salmonella serotypes other than the typhoid and paratyphoid bacilli were the most common finding, being isolated in 10.8% of cases. Campylobacter jejuni was unexpectedly infrequent (1.9%); Aeromonas hydrophila was found in 1.8%. No other aerobic pathogen occurred in more than 1% of cases. Clostridium difficile was sought only when requested, and was isolated from 9.6% of cases tested. Testing for enteropathogenic Escherichia coli was limited to children under 1 year old. Gentamicin was active against the greatest number of aerobic isolates, followed by chloramphenicol and cotrimoxazole. The C. difficile isolates were all sensitive to metronidazole.

Aeromonas hydrophila fulminant pneumonia in a fit young man

A previously healthy 24 year old athletic man became ill suddenly with pneumonia the day after swimming in the sea. Despite intensive support measures in the intensive care unit he died three hours after admission and 21 hours after his first symptom. Necropsy showed bilateral haemorrhagic necrotising pneumonia. Aeromonas hydrophila was isolated from a blood culture taken at admission and from the lungs at necropsy. The infection may have come from contaminated sea water.

Variation in growth kinetics and phenotype of Aeromonas spp. from clinical, meat processing and fleshfood sources

Sixty-four strains of motile aeromonads (A. hydrophila, A. sobria and A. caviae), isolated from clinical meat processing and ready-to-eat fleshfood sources, and the A. hydrophila type strain were tested with respect to their growth kinetics at 4 degrees C and 37 degrees C, and the reported indicators of pathogenicity: autoagglutination and haemolysis (tested using a CAMP reaction). Between the species, A. caviae grew the fastest at 37 degrees C and had the highest percentage of strains not able to grow at 4 degrees C (after 200 h incubation). Within the species, food-derived strains of A. hydrophila were better adapted to growth at lower temperatures than those from clinical or meat processing sources. Clinical strains of A. hydrophila autoagglutinated more frequently than those from other sources, but not differences in CAMP reactions were noted. Aeromonas caviae and A. sobria isolates appeared to be homogeneous with respect to growth kinetics at the temperatures tested. A comparison of the growth kinetics of the A. hydrophila type strain and a food-derived A. hydrophila strain clearly reflected the latter's enhanced ability to grow at low temperatures.

Enterotoxicity of clinical and environmental isolates of Aeromonas spp

Of 147 isolates of three species of Aeromonas, 54 were from clinical and 93 from environmental sources. When tested for enterotoxin production, most of the isolates (56%) caused accumulation of fluid in rabbit ileal loops (RILs). Although large proportions of clinical and environmental isolates of A. caviae (55% and 65%, respectively) elicited such a response in RILs, isolates of A. hydrophila and A. sobria produced significantly more fluid (p less than 0.05). Furthermore, the environmental strains of A. hydrophila and A. sobria produced more fluid than the clinical isolates (p less than 0.05). The strains of Aeromonas spp. that caused little or no fluid accumulation in the initial experiments became enterotoxin producers after 1-3 passages through RILs, regardless of their source, and showed gradual enhancement of fluid outpouring after each passage. The present study suggests that all strains of these species of Aeromonas are potentially enterotoxigenic, whether from clinical or environmental sources.

Plasmid associated virulence properties of environmental isolates of Aeromonas hydrophila

The plasmid profiles, and their association with antimicrobial resistance, of 60 strains of Aeromonas hydrophila isolated from fish, shellfish and water were investigated. Only two strains were susceptible to all the antimicrobial agents tested; the highest incidences of resistance were to tetracycline (96.7%), prystanamycin (93.3%), ampicillin (91.7%) and cephalothin (91.7%). Forty strains harboured one or more plasmids and the plasmid profile most frequently detected (15%) was the association of three small plasmids of 4.2, 3.2 and 2.8 Mda. Curing experiments indicated that the plasmid-free derivative strains simultaneously lost their resistance determinants to tobramycin, neomycin, gentamicin and kanamycin. More than 90% of the strains tested produced siderophores and displayed haemolytic activity. However, the relationship between these virulence characters and the presence of plasmids was different; in 74.5% of the strains there was siderophore production and plasmids were detectable, whereas only 60% of the strains simultaneously possessed plasmids and haemolytic activity.

Parapharyngeal soft-tissue infection with Aeromonas hydrophila

Parapharyngeal soft tissue infections may be rapidly progressive and life-threatening. Prompt institution of appropriate antimicrobial therapy is of paramount importance. This report highlights the potential virulence of Aeromonas hydrophila in infection of the head and neck and the need to consider this organism in selected patients.

Can isolation of Aeromonas hydrophila from human feces have any clinical significance?

A total of 27,480 stool specimens from 15,548 patients with gastroenteritis were analyzed for bacterial enteropathogens during a 4-year period between 1986-89 at a major referral center in Saudi Arabia. Bacterial pathogens were isolated from 1,152 patients, Salmonella being the most frequent, followed by Campylobacter, Shigella, and Aeromonas hydrophila. The latter bacterium was found in 58 patients; seven of them were associated with other enteric pathogens, but A. hydrophila was the only organism in 51 patients. All had gastrointestinal symptoms, the most common being diarrhea (92%), followed by abdominal pain (68%), fever (37%), and vomiting (27%). Stool specimens from 1,368 control patients were negative for A. hydrophila.

[Aeromonas spp. and Plesiomonas shigelloides in bivalves, mud, and water from the Gulf of Nicoya, Costa Rica]

Bivalves, mud, and surface water were collected at three different sites of the Gulf of Nicoya, Costa Rica, in search of Aeromonas spp. and Plesiomonas shigelloides. For their isolation, these bacteria were enriched in alkaline peptone water and streaked on MacConkey agar and on brilliant green bile inositol agar. This was followed by the biochemical tests necessary for their identification. Thirty-five strains of A. hydrophila, 58 of A. caviae, 43 of A. sobria, and 7 of P. shigelloides were isolated. None of these predominated nor was there any indication of a seasonal distribution along the 15 month's duration of the study. Seven strains of A. hydrophila and two of A. sobria showed the biochemical characteristics associated with toxin production (positive Voges-Proskauer and lysine decarboxylase tests). These species are widely distributed in the gulf and there is risk of contracting an infection while bathing or when eating raw bivalves from this area.