Abstract

In our laboratory, routine post-mortem examination of beach stranded Cetaceans includes aerobic and anaerobic bacterial culture of heart blood and intestine, among other sites, and any lesions that might be found. The purpose of this examination is to identify organisms potentially hazardous to handlers of dead animals and animals in rehabilitation, and to determine the contribution of infectious agents to stranding. In addition, it was intended to determine which organisms were responsible for the very rapid formation of gas in tissues occasionally seen. Similar cultures were collected from live beach-stranded animals in rehabilitation over a period of days to months. 66 different bacteria and 3 fungi were identified in 42 animals stranding along the beaches of the western Gulf of Mexico.

The most common organisms identified, apart from coliforms, were Clostridium (8 species, 21 isolates) Vibrio (8 species, 51 isolates), Citrobacter (2 species, 10 isolates) and Edwardsiella tarda (5 isolates). The majority of these species are known to be pathogenic or potentially pathogenic for man. The fungi identified included two species of Candida, and Mucor.

Heart blood cultures were frequently positive (25 of 30 cultures) most often with mixed organisms. Two animals in rehabilitation went from no growth to positive on sequential cultures, despite antibiotic therapy, while one went from positive to no growth.

Tissue examination often revealed colonies of organisms growing in vessels; some of these were associated with marked necrosis of adjacent tissues.

Organisms growing in tissues after death were seeded in life, probably during the course of a terminal bacteremia. Histologic evidence suggests invasion of ischemic intestinal mucosa as a site of entry into the circulation. Given the pathogenicity of many of the organisms identified, bacteremia associated with stranding may contribute to the high mortality of stranded animals. The presence of potential human pathogens in blood, intestinal contents and lesions indicates that handlers must be aware of the risk of infection, and take appropriate precautions when working with stranded animals.