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Long‐term survival of Escherichia coli O157:H7 and Salmonella Typhimurium in cowpats on pasture
- Nyberg, K.A., Andersson, G.M., Elving, J.
- Journal of applied microbiology 2019 v.126 no.2 pp. 651-660
- Escherichia coli O157, Salmonella Typhimurium, cattle, climate, cow manure, farms, grazing, herds, pathogens, risk, tandem repeat sequences, winter
- AIM: To investigate the survival of Escherichia coli O157:H7 and Salmonella Typhimurium in cowpats on pasture in a temperate Nordic climate. METHODS AND RESULTS: The study consists of two parts, the first part using artificially created cowpats inoculated with E. coli O157:H7 and S. Typhimurium and the second part using cowpats from empty pastures on which cattle herds positive for E. coli O157:H7 had grazed 6 month previously. Artificial cowpats were created, placed in an outdoor field station in June, August and October, and sampled over 1 year. Escherichia coli O157:H7 and S. Typhimurium were analysed by standard culture methods. The results showed viable E. coli O157:H7 and S. Typhimurium in the sampled cowpats throughout the 365‐day sample period for the June trial, 250 days for the August trial and 40–70 days for the October trial. In addition, 200 natural cowpats were sampled from eight pastures that had previously held E. coli O157:H7 positive cattle herds. Five positive E. coli O157:H7 isolates were obtained, all with the same multi‐locus variable number tandem repeat analysis pattern as had been found on the pasture the previous grazing season. CONCLUSIONS: Escherichia coli O157:H7 and S. Typhimurium can survive in cowpats up to a year and persist throughout a winter season. Therefore, there is a possibility that cowpats can act as a reservoir and be a source of re‐infection of Salmonella or E. coli O157:H7 in cattle between grazing seasons. SIGNIFICANCE AND IMPACT OF THE STUDY: The obtained results can provide valuable information for managing the risk posed by zoonotic pathogens originating from farm environments.