Aeromonas

Aeromonas is a genus of Gram-negative, facultative anaerobic, rod-shaped bacteria that morphologically resemble members of the family Enterobacteriaceae. Most of the 14 described species 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. They group with the gamma subclass of the Proteobacteria. 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. In its most severe form, Aeromonas spp. can cause necrotizing fasciitis, which is life-threatening, usually requiring treatment with antibiotics and even amputation. Although some potential virulence factors (e.g. endotoxins, hemolysins, enterotoxins, adherence factors) have been identified, their precise roles are unknown. Aeromonas species cause: Diarrheal disease in otherwise healthy individuals Wound infections Opportunistic systemic disease in immunocompromised patients If automated machines are not using the most updated database, Elizabethkingia meningoseptica may be mistaken for A. salmonicida. Literature exists on this subject, but many papers have not adequately studied the causal role of the Aeromonas strain(s) that were isolated from the cases that were studied. The presence of an Aeromonas strain in a fecal specimen does not prove or even imply that the strain was causing the diarrhea. 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. Wound infections are the second-most common type of human infection associated with Aeromonas.