Isolation of faecal coliform bacteria from the American alligator (Alligator mississippiensis).

AIMS: To determine whether American alligators (Alligator mississippiensis) are an unrecognized poikilothermic source of faecal coliform and/or potential pathogenic bacteria in South Carolina's coastal waters. METHODS AND RESULTS: Bacteria from the cloaca of American alligators, as well as bacteria from surface water samples from their aquatic habitat, were isolated and identified. The predominant enteric bacteria identified from alligator samples using biochemical tests included Aeromonas hydrophila, Citrobacter braakii, Edwardsiella tarda, Escherichia coli, Enterobacter cloacae, Plesiomonas shigelloides and putative Salmonella, and these were similar to bacteria isolated from the surface waters in which the alligators inhabited. Based on most-probable-number enumeration estimates from captive alligator faeces, faecal coliform bacteria numbered 8.0x10(9) g(-1) (wet weight) of alligator faecal material, a much higher concentration than many other documented endothermic animal sources. CONCLUSIONS: A prevalence of enteric bacteria, both faecal coliforms and potential pathogens, was observed in American alligators. The high faecal coliform bacterial density of alligator faeces may suggest that alligators are a potential source of bacterial contamination in South Carolina coastal waters. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings help to increase our understanding of faecal coliform and potential pathogenic bacteria from poikilothermic reptilian sources, as there is the potential for these sources to raise bacterial water quality levels above regulatory thresholds.

Relative distribution of polychlorinated biphenyls among tissues of neonatal American alligators (Alligator mississippiensis).

Recent papers have investigated the utility of chemical analysis of the chorioallantoic membrane (CAM) as a nonlethal indicator of avian and reptilian exposure to persistent environmental contaminants. This study was undertaken to evaluate the chemical distribution among fat, CAM, and residual yolk tissues of live neonatal American alligators (Alligator mississippiensis) to investigate the potential utility of CAM use as a nonlethal indicator of exposure to polychlorinated biphenyls (PCBs). CAMs were collected from neonatal alligators at hatch, whereas yolk sacs and fat tissues were taken from each animal at euthanization (3 weeks posthatch). All collected tissue samples were separately Soxhlet extracted and analyzed by GC/ECD for PCBs. Log normalized, individual PCB congener concentrations in CAMs were significantly correlated with concentrations in fat (r(2) = 0.62) and yolk (r(2) = 0.56) tissues. Coefficients of determination from comparisons of homologue group concentrations varied from 0.13 to 0.90. Residue levels in neonatal oviparous organism tissues may be qualitatively assessed through chemical analyses of CAM tissues removed from discarded eggshells.