Necrotizing Fasciitis and Myonecrosis Due to Aeromonas hydrophila

Discussion

Aeromonas hydrophila is a heterotrophic, gram-negative bacterium, mainly found in areas where the climate is very warm. This bacterium can also be found in fresh, salt, marine, estuarine, chlorinated, and unchlorinated water. Aeromonas hydrophila is resistant to chlorine, refrigeration, or cold temperatures (Aeromonas hydrophila has been known to survive in temperatures as low as 4DEC).^[7,8]Aeromonas hydrophila contains a gene called Aerolysin Cytotoxic Enterotoxin (ACT) that releases a toxin that can cause tissue damage. The aerolysin toxin is produced by some strains of Aeromonas hydrophila. It is an extracellular, soluble, hydrophilic protein that exhibits both hemolytic and cytolytic properties. Aerolysin binds to specific glycoprotein receptors on the surface of eucaryotic cells before inserting into the lipid bilayer and forms holes.^[9,10]

In the presented case (the first reported in Bulgaria), Aeromonas hydrophila was cultured from the necrotic tissue and from hemoculture. Only single reports of this rare infection are available in the medical literature.^[3]In all reported cases, the contamination occurred in an aquatic environment mostly upon biting.^[3,6]Aeromonas hydrophila releases aerolysin and was presumed to be the cause of the necrotizing fasciitis and myonecrosis. The other bacteria cultured from biopsy tissue (Enterococcus sp, S aureus, Klebsiella oxytoca, Morganella morganii, and E coli) may have been a result of the wound contamination. Most likely these bacteria act synergistically with Aeromonas hydrophila although they have not been characterized in the literature as independent agents of necrotizing fasciitis and myonecrosis. This particular interaction has been confirmed by other reports.^[3]

Gastroenteritis is a disease associated with Aeromonas hydrophila. This disease can infect anyone, but it occurs mostly among young children and individuals who have compromised immune systems and growth problems.^[8,11]Immunocompromised hosts can develop Aeromonas pneumonia, sepsis or meningitis, and both immunocompetent and immunocompromised hosts can suffer from Aeromonas-infected wounds.^[12–15]

The 3 types of wound infections that can stem from Aeromonas hydrophila in humans are cellulitis, myonecrosis with necrotizing fasciitis, and ecthyma gangrenosum. Cellulitis is the most common infection associated with Aeromonas hydrophila.^[8]Myonecrosis with necrotizing fasciitis and ecthyma gangrenosum are less common, but have more damaging results.^[3]Cellulitis, with the proper medication, will pass with minimal damage, while the others can result in amputation and sometimes death.^[16,17]

This microbe is resistant to penicillin, ampicillin, carbenicillin, and ticarcillin, but is susceptible to broad-spectrum cephalosporins, aminoglycosides, carbapenems, chloramphenicol, tetracycline, trimethoprim-sulfamethoxazole, and quinolones.^[18]

Necrotizing fasciitis must be promptly recognized and aggressively treated since the resulting rates of morbidity and mortality are high if treatment is delayed. Treatment of necrotizing fasciitis is first and foremost surgical intervention that includes antibiotic therapy and supportive care.^[3,16,17]

Wounds. 2007;19(8):223-226. © 2007  Health Management Publications, Inc.

Copyright © 1999 by HMP Communications, LLC All rights reserved.

Cite this: Necrotizing Fasciitis and Myonecrosis Due to Aeromonas hydrophila - Medscape - Aug 01, 2007.