Purpose: The purpose of this study is to compare the survival of Shiga toxigenic Escherichia coli (STEC), Salmonella, total aerobic count (APC), and generic E. coli in cattle and different wild animal feces from Florida.
Methods: Rifampicin resistant 5-strain cocktails of STEC and Salmonella were inoculated into domestic cattle and wild animal feces (105 to 106 CFU/g; deer, wild pig, raccoon, and waterfowl). Fecal samples were stored at room temperature. Populations were enumerated for up to 1 year by spread plating onto TSAR. If no colonies were detected samples were enriched. Control samples were enumerated on TSA and CHROMagar ECC to monitor APC and generic E. coli concentrations. Models for comparing STEC, Salmonella and generic E. coli populations were developed.
Results: Over the 364 day storage, STEC and Salmonella populations declined by 2.4 and 0.8 log CFU/g in the cattle feces, and 2.1 and 1.6 in the deer feces, respectively. STEC populations rapidly declined during the first 28 days in pig, waterfowl, and raccoon feces, to ≤1.7 log CFU/g. Similarly, Salmonella populations in pig, waterfowl, and raccoon feces, declined to ≤2.6 log CFU/g over the first 56 days. No subsequent significant population changes (P>0.05) occurred during the remaining storage of pig, waterfowl, and raccoon feces after day 84 for STEC and day 112 for Salmonella. The rate of generic E. coli decline corresponded to pathogen decline in all fecal types. The calculated predictive power (R2) of the models relating pathogen declines to generic E. coli in each fecal type ranged from 0.4362 to 0.9774.
Significance: Determining appropriate risk mitigation strategies following animal intrusion can improved with a better understanding of pathogen survival in animal feces.