Aeromonas is a gram-negative, facultative anaerobic rod that morphologically resembles members of the family Enterobacteriaceae. Fourteen species of Aeromonas have been described, most of which have been associated with human diseases. The most important pathogens are A. hydrophila, A. caviae, and A. veronii biovar sobria. The organisms are ubiquitous in fresh and brackish water.
Two major diseases associated with Aeromonas are gastroenteritis and wound infections, with or without bacteremia. Gastroenteritis typically occurs after the ingestion of contaminated water or food, whereas wound infections result from exposure to contaminated water.
Although some potential virulence factors (e.g. endotoxins, hemolysins, enterotoxins, adherence factors) have been identified, their precise role is unknown. Aeromonas species cause: 1) opportunistic systemic disease in immunocompromised patients, 2) diarrheal disease in otherwise healthy individuals, and 3) wound infections.
Gastrointestinal disease in children is usually an acute, severe illness, whereas that in adults tends to be chronic diarrhea. Severe Aeromonas gastroenteritis resembles shigellosis, with blood and leukocytes in the stool. Acute diarrheal disease is self limited, and only supportive care is indicated in affected patients.
Is necessary for patients with chronic diarrheal disease or systemic infection. Aeromonas species are resistant to penicillins, most cephalosporins, and erythromycin. Ciprofloxacin is consistently active against their strains in the U.S. and Europe, but resistant cases has been reported in Asia.