members of the Enterobacteriaceae family, such as Escherichia coli or Serratia species, it is important to alert
the laboratory to the clinical setting.
Initial therapy of a severe soft tissue infection related to Aeromonas should include aggressive wound
debridement to mitigate the potentially invasive nature of the organism. In one case of severe cellulitis
unresponsive to debridement, fasciotomy, and antibiotic therapy, treatment with hyperbaric oxygen was felt to
contribute to successful infection control.
Curiously, medicinal leeches can harbor Aeromonas in their gut flora; soft tissue infections related to
this phenomenon have been reported. The genus Plesiomonas also belongs to the family Vibrionaceae; it has
been definitively linked with aquarium-associated infection complicated by watery diarrhea and fever.
A General Approach to Antibiotic Therapy for Fresh Water Infections
Management of fresh water-acquired infections should include therapy against Aeromonas species.
First-generation cephalosporins provide inadequate coverage against growth of freshwater bacteria. Third-
generation cephalosporins provide excellent coverage, while second-generation products are less effective.
Ceftriaxone may not be efficacious against Aeromonas species. Ciprofloxacin, imipenem, ceftazidime,
gentamicin, and trimethoprim-sulfamethoxazole are superb antibiotics against gram-negative microorganisms.
Trimethoprim alone may be inefficacious, as is ampicillin.
Whether to begin antimicrobial therapy before establishment of a wound infection is controversial.
Pending a prospective evaluation of prophylactic antibiotics in fresh water acquired wounds, the following
recommendations are based on the potentially serious nature of soft tissue infections caused by Aeromonas
species:
1. Minor abrasions or lacerations do not require the administration of prophylactic antibiotics in the normal
host. Persons who have chronic illness, immunologic impairment, or serious liver disease, particularly those
with elevated serum iron levels, should be placed immediately on a regimen of oral ciprofloxacin or
norfloxacin (first choice), trimethoprim-sulfamethoxazole (second choice), or doxycycline/tetracycline (third
choice use only in the setting of allergy to the first two choices, as resistance to Aeromonas species has been
observed) because these persons appear to have an increased risk of serious wound infection and bacteremia.
Penicillin, ampicillin, erythromycin, and trimethoprim do not appear to be acceptable alternatives. The
appearance of an infection indicates the need for prompt debridement and antibiotic therapy. If an infection
develops, antibiotic coverage that will be efficacious against Staphylococcus and Streptococcus should be
chosen, since these are still probably the most common perpetrators of infection.
2. If the victim requires surgery and hospitalization for wound management, recommended antibiotics include
ciprofloxacin, gentamicin, or trimethoprim-sulfamethoxazole. Imipenem-cilastatin is an extremely powerful
antibiotic that should be used in a circumstance of sepsis or treatment failure. If the victim is to be managed as
an outpatient, the oral drug of choice is trimethoprim-sulfamethoxazole, or tetracycline or doxycycline. It is a
clinical decision whether oral therapy should be preceded by a single intravenous or intramuscular loading
dose of a similar or different antibiotic, commonly an aminoglycoside.
3. Infected wounds should be cultured. Pending culture and sensitivity results, the patient should be managed
with antibiotics as outlined previously. If fever or rapidly progressive cellulitis characterized by bullae and
large areas of necrosis develops, Aeromonas hydrophila infection should be suspected. Less rapidly
progressive Aeromonas infections may have the appearance of streptococcal cellulitis.
Sharks
Myth and folklore surround sharks, the most highly feared of all sea creatures. These occasionally
savage animals are the subject of many behavioral investigations, but until more reproducible data are
available, a degree of mystery will remain. Shark attacks on humans have always held enormous fascination
for scientists, adventurers, and clinicians. H. David Baldridge prepared a special technical report, Shark
Attack Against Man, for the U.S. Navy Bureau of Medicine and Surgery in 1973. The International Shark
Attack File, initiated by Perry W. Gilbert and Leonard P. Schultz in 1958 for the American Institute of
Biological Sciences and the Office of Naval Research and formerly maintained at the Mote Marine
Laboratory in Sarasota, Florida, is now housed at the University of Florida at Gainesville, where it is
maintained by the International Elasmobranch Society and the Florida Museum of Natural History. It remains
an authoritative collection of analyzed data, containing a series of approximately 3000 individual
investigations from the mid 1500s to the present. Mote Marine Laboratory (www.mote.org) is an independent,
