AEROMONAS AND PLESIOMONAS
The genera Aeromonas and Plesiomonas have bacteriologic features similar to those of the Enterobacteriaceae, Vibrio, and Pseudomonas. They are aerobic and facultatively anaerobic, attack carbohydrates fermentatively, and demonstrate various other biochemi-cal reactions. Aeromonas colonies are typically β-hemolytic. The major taxonomic re-semblance to Pseudomonas is that both Aeromonas and Plesiomonas are oxidase positive with polar flagella. Their habitat is basically environmental (water and soil), but they can occasionally be found in the human intestinal tract.
Aeromonas is an uncommon but highly virulent cause of wound infections ac-quired in fresh or saltwater. The onset can be as rapid as 8 hours after the injury and the cellulitis progresses rapidly to fasciitis, myonecrosis, and bacteremia in less than a day. Aeromonas is also the leading cause of infections associated with the use of leeches, due to its regular presence in the leech foregut. In addition to opportunistic infection, some evidence suggests an occasional role for Aeromonas in gastroenteritis through production of toxins with enterotoxic and cytotoxic properties. Plesiomonas is also associated with an enterotoxic diarrhea. These associations are not yet strong enough to justify attempts to routinely isolate Aeromonas and Plesiomonas from diar-rheal stools. Resistance to penicillins and cephalosporins is common. Most strains show susceptibility to tetracycline, with variable susceptibility to aminoglycosides, in-cluding gentamicin.