one shark (presumed bronze whaler) attack victim in Australia grew both Vibrio parahaemolyticus and
Aeromonas caviae from his wounds, while another grew Vibrio alginolyticus and Aeromonas hydrophila from
his wound.
For practical purposes, most marine isolates are heterotrophic (require exogenous carbon and nitrogen-
containing organic supplements) and motile gram-negative rods. Previous opinions that enteric pathogens
(associated with the intestines of warm-blooded animals) deposited into marine environments ultimately
succumbed to sedimentation, predation, parasitism, sunlight, temperature, osmotic stress, toxic chemicals, or
high salt concentration may be untrue. Pathogens may accumulate in surface water in association with lipoidal
particulates, from which they are rapidly dispersed toward shore by wave and wind activity.
Wound Infections Due to Vibrio Species
Vibrio organisms can cause gastroenteric disease and soft tissue infections, particularly in
immunocompromised hosts. Extraintestinal infections may be associated with bacteremia and death. Vibrio
species are the most potentially virulent halophilic organisms that flourish in the marine environment. The
teeth of a great white shark have been swabbed and yielded V. alginolyticus, V. fluvialis, and V.
parahaemolyticus. Mako shark tooth culture has yielded V. damsela, V. furnisii, and V. splendidus I. V.
parahaemolyticus has also been identified in freshwater habitats. Water that is brackish (salinity of 15 to 25
parts per thousand) allows the growth of Vibrio species if appropriate nutrients are present; V. vulnificus
infection has been documented after exposure to waters with salinities of 2 and 4 ppt. The optimal season for
disease appears to be summer, when water temperatures encourage bacterial proliferation. In most studies
reported, infections seem to cluster during the summer months; this may be related to increased numbers of
people at the seashore. This has been corroborated to some degree by the observation that V.
parahaemolyticus cultured from marine mammals was recovered only in the warmer months of the year in the
Northeast or in animals from subtropical regions.
Vibrio species are halophilic, gram-negative rods that are facultative anaerobes capable of using D-
glucose as their sole or principal source of carbon and energy.
They are part of the normal flora of coastal waters
not only in the United States, but also in many exotic locations frequented by recreational and industrial divers
and seafarers. Vibrios are mesophilic organisms and grow best at temperatures of 24
° to 40° C, with essentially
no growth below 8
° to 10° C. Other marine bacteria are facultative psychrophiles, barophiles, or both. Vibrio
species seem to require less sodium for maximal growth than do other more fastidious marine organisms, a
factor that allows explosive reproduction in the 0.9% saline environment of the human body. At least 11 of the
34 recognized Vibrio species have been associated with human disease.
Wound infections have been
documented to yield V. cholerae 0 group 1 and non-01, V. parahaemolyticus, V. vulnificus, V. alginolyticus, and
V. damsela. Septicemia, with or without an obvious source, has been attributed to infections with V. cholerae
non-01, V. parahaemolyticus, V. alginolyticus, V. vulnificus, and V. metschnikoviii.
Antibiotic Therapy
The objectives for the management of infections from marine microorganisms are to recognize the
clinical condition, culture the organism, and provide antimicrobial therapy. Management of marine-acquired
infections should include therapy against Vibrio species. Third-generation cephalosporins (cefoperazone,
cefotaxime, or ceftazidime) provide variable coverage in vitro; first- and second-generation products
(cefazolin, cephalothin, cephapirin, cefamandole, cefonicid, ceforanide, or cefoxitin) appear to be less
effective in vitro. The organism has been reported in some cases to be resistant in vitro to third generation
cephalosporins, mezlocillin, aztreonam, and piperacillin. A combination of cefotaxime and minocycline seems
to be synergistic and extremely effective against V. vulnificus in vitro.
Oral cultures taken from two captive
moray eels at the Chicago Shedd Aquarium demonstrated V. fluvialis, V. damsela, V. vulnificus, and
Pseudomonas putrefaciens sensitive to cefuroxime, ciprofloxacin, tetracycline, and trimethoprim-
sulfamethoxazole. Imipenem-cilastatin is efficacious against gram-negative marine bacteria, as are
trimethoprim-sulfamethoxazole, tetracycline. Gentamicin, tobramycin, and chloramphenicol have tested
favorably against P. putrefaciens and Vibrio strains. Nonfermentative bacteria (such as Alteromonas,
Pseudomonas, and Deleya species) appear to be sensitive to most antibiotics. In a mouse model, combination
therapy with minocyline and cefotaxime was more effective than either drug alone.
Quantitative wound culture has no advantage before the appearance of a wound infection. Pending a
prospective evaluation of prophylactic antibiotics in the management of marine wounds, the following
