Aeromonas: Human Healh Criteria Document

PATHOGENICITY: Associated with gastroenteritis, wound infections (cellulitis), septicemia, ocular
and respiratory tract infections, pneumonia and urinary tract infections; frequent pathogens for
cold-blooded marine and freshwater amphibians and reptiles (red leg disease in frogs); also in birds

EPIDEMIOLOGY: Worldwide; especially near freshwater sources; incidence of serious human
disease is increasing and many isolates are probably misdiagnosed as coliforms

HOST RANGE: Humans, amphibians, fish, reptiles, birds


MODE OF TRANSMISSION: Fecal-oral transmission; contact with contaminated water, food, soil,
faeces; ingestion of contaminated fish or reptiles

INCUBATION PERIOD: Not clearly identified

COMMUNICABILITY: Not usually transmitted from person to person


H2S gas and necrotizing fasciitis and myonecrosis

The 10 EPA approve coliform test systems suppress the growth of non-target organisms,
specifically, they suppress Aeromonas spp.,

The Disease (in Humans)

Bacteraemia (bacteria in the blood) is the most common pathogenic manifestation of Aeromonas in
humans. Mild symptoms include fever and chills, but patients who become septic (overwhelming
bacterial infection) with Aeromonas often exhibit abdominal pain, nausea, vomiting, and diarrhea.

Reports of Aeromonas wound infections have appeared increasingly in the literature. Unlike
gastroenteritis, these infections can have fatal or serious debilitating outcomes, such as
amputations. Aeromonas wounds fall into three categories, listed in order of increasing severity of
damage caused: cellulitis, myonecrosis, and ecthyma gangrenosum.

Cellulitis, the most frequently encountered Aeromonas wound infection, is an acute inflammation of
subcutaneous tissue characterized by redness and induration that may arise from injury or
secondary to sepsis (Musher, 1980). Myonecrosis and ecthyma, the two less commonly seen types
of Aeromonas infections, are typically found in patients that are immunocompromised. Myonecrosis,
or bullous lesions, is characterized by the liquefaction of muscles with blackening of the tissue which
may be gangrenous with gas formation. These patients require agressive antimicrobial therapy and
debridement; those individuals that fail to respond to these measures may require amputation
(Haburchak, 1996). The third type, ecthyma gangrenosum, is a
cutaneous necrotic or
gangrenous pustule
that occurs secondary to sepsis. Lesions have an erythematous border
surrounding a vesicle which can progress to necrosis of the soft tissue within 24 h. This type of
infection is usually fatal (Musher, 1980).

Outcomes such as these serve as a sobering reminder to properly attend to wounds with clean water
and antiseptics. Never wash a wound with lake or river water!

A. hydrophila infections require prompt attention at the first sign of onset. Most infections are treated
with fluoroquinolones. Alternative agents include aztreonam, trimethoprim-sulfamethoxazole,
third-generation cephalosporins, and/or aminoglycosides (Mani et al., 1995
A. hydrophila infection
(cellulitis of forearm)
following puncture with
fishing hook  (photo
courtesy of Dr.
Forearm showing bullous
lesions as a result of A.
hydrophila infection (photo
courtesy of Dr. Haburchak)
Leg showing Ecthyma
gangrenosum (photo
courtesy of Medscape)