Prevalence and Antibiotic Susceptibility of Gram-negative Aerobic Bacteria Cultured from the Intestine and Hepatopancreas of Blue Land Crab (Cardisoma guanhumi) in Grenada, West Indies

Aim: To evaluate the prevalence of aerobic bacteria associated with the intestine and hepatopancreas of blue land crab and the susceptibility of the bacteria to a panel of antimicrobials that included some drugs used for the treatment of bacterial infections in the human and veterinary clinics in Grenada.
Study Design: The tested crabs were collected during a three month period from November 2011 to February 2012 from six parishes of Grenada and analyzed in the bacteriology lab in the Pathobiology Department, School of Veterinary medicine, St. George’s University, Grenada, West Indies.
Methodology: A total of 65 blue land crabs were examined for the presence of Gram-negative aerobic bacteria in their intestines and hepatopancreas by culture. The isolated bacterial species were tested against 12 antibiotics using the disc diffusion method.
Results: Eighty-nine percent of crabs were culture positive. Klebsiella pneumoniae was the most common species (60%), followed by Citrobacter freundii (28%), Enterobacter cloacae (17%), Salmonella spp. (17%), and Escherichia coli (12%). Vibrio isolates included V. alginolyticus (8%), V. parahaemolyticus (5%), and V. fluvialis (3%). Antimicrobial susceptibility tests against 12 drugs showed susceptibility of all K. pneumoniae, C. freundii, Enterobacter cloacae, and Escherichia coli isolates to enrofloxacin, gentamicin, and imipenem. Resistance to ciprofloxacin, chloramphenicol, and trimethoprim-sulfamethoxazole was ≤ 7%. All K. pneumoniae isolates were resistant to ampicillin, and all C. freundii isolates were resistant to cephalothin. Resistance to tetracycline was highest (33%) in E. cloacae, and ≤ 13% in the other three major species. Susceptibility of Salmonella serotypes has been published, and no resistance was seen among any of the isolates.
Conclusion: This study showed that the blue land crabs of Grenada, commonly used as food, can serve as reservoirs of potential human pathogens, and may carry bacteria resistant to antimicrobial drugs used for treatment in human medicine.