Microbiology
Gram-negative rod; includes A. caviae, A. hydrophilia, A. salmonicida, A. sobria. A. veronii, and many others depending on the source.
Epidemiologic Risks
Freshwater exposure. It is found in warmer climates, including cases in the Caribbean. It causes bacteremia in patients with underlying medical problems.
A. hydrophila has been isolated from meat, meat products, milk, dairy products, and vegetables.
Chicken and fish may be a source, in part as it can grow at refrigeration temperatures (Pubmed). "SomeAeromonas spp. can grow relatively uninhibited in food during refrigeration under a broad range of pH and NaCl concentrations, and in various packaging atmospheres (Pubmed)."
A. veronii is part of the normal flora of leeches, so infections are associated with medicinal leeches (used in reattachment of fingers and the like). Even though antibiotics are given with leech therapy, occasionally a resistant organism sneaks in (PubMed). It is spread by Leech-exuded mucus (Pubmed).
Syndromes
Colitis, often in the immunocompromised and with a summer-autumn predominance, sometimes mimicking acute ulcerative colitis.
Necrotizing soft tissue infection after freshwater trauma.
Cellulitis often with bacteremia (PubMed).
The usual hodgepodge of focal infections.
In Korea and Taiwan, it is a major cause of SBP in cirrhotics (PubMed).
In drowning patients (well, those who survive drowning) it is the most common cause of pneumonia (PubMed).
Case of recurrent infection traced to well, or not so well, water. If you ask you will be surprised at the various sources from which people get their water, even in urban areas. Here in the great Pacific NW, a remarkable number of people are on well water.
Treatment
Third-generation cephalosporins, carbapenems, or quinolones anything BUT ampicillin or ticarcillin. Note the BUT. BUT BUT BUT.
For diarrhea ciprofloxacin, 750 mg once a day; or azithromycin, 500 mg once a day, both for 3 days (PubMed).
Notes
I once had a patient who had severe colitis from Aeromonas and the source was Holy Water she brought back from a Catholic shrine in S. America. True story. From this, I deduce that Louis Pasteur went to Hell. As an aside, it is possible to get a variety of infections from Holy Water. The water in shrines often has flora similar to stool.
Curious Cases
Relevant links to my Medscape blog
Last update: 12/19/19