Determining the prevalence of Escherichia coli, Salmonella, and shiga toxin-producing Escherichia coli in manure of dairy lagoons.

ABSTRACT

AIM: The aim of this study was to determine the prevalence of microbial pathogens in manure of dairy lagoons in California. METHODS AND RESULTS: To determine pathogens in dairy manure stored in anaerobic lagoons of dairy farm, an extensive field study was conducted across California to sample manure from 20 dairy farms. Samples were analyzed to determine the prevalence of indicator Escherichia coli, Shiga toxin producing E. coli (STEC), Salmonella, and E. coli O157 H7. To test the E. coli, STEC, and Salmonella, we used agar culture-based method followed by polymerase chain reaction (PCR) method. In addition, a real- time PCR based method was used to determine the presence of E coli O157 H7. Study demonstrated that the prevalence of Salmonella in manure sample is lower than E. coli. The presence of Salmonella was found in 2.26% of the samples, and both the culture-based and PCR methods yielded comparable outcomes in detecting Salmonella. Moreover, ∼11.30% of the total samples out of the 177 were identified as positive for STEC by qPCR. CONCLUSION: These findings demonstrate that indicator E. coli are abundantly present in anaerobic lagoons. However, the presence of STEC, and Salmonella is substantially low.