Development and application of a spiral plating method for the enumeration of Escherichia coli O157 in bovine faeces

• Published in: Journal of applied microbiology Vol. 97; no. 3; pp. 581 - 589
• Main Authors: Robinson, S.E., Wright, E.J., Williams, N.J., Hart, C.A., French, N.P.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.01.2004; Blackwell Science; Oxford University Press
• Subjects: Animals; Biological and medical sciences; Cattle; Colony Count, Microbial - methods; enumeration; epidemiology; Escherichia coli; Escherichia coli O157; Escherichia coli O157 - growth & development; Escherichia coli O157 - isolation & purification; Feces - microbiology; Fundamental and applied biological sciences. Psychology; Microbiology; Reproducibility of Results; survival; Enumeration; Bovine; Applied microbiology; Escherichia coli; Method; Enumeration(counting); Vertebrata; Mammalia; Bacteria; Artiodactyla; Feces; Application; Ungulata; Enterobacteriaceae
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/j.1365-2672.2004.02339.x

Aim:  To develop and validate a direct plating method applicable to epidemiological studies for enumerating Escherichia coli O157 in cattle faeces. Methods and Results:  The spiral plate count method was used to enumerate E. coli O157 in faecal samples. The accuracy and variation of counts was then assessed using faecal samples inoculated with E. coli O157. There was good agreement between inoculated levels of E. coli O157 and those recovered from faeces, particularly when counts were >102 CFU g−1 of faeces. The method was applied to a small study assessing short‐term survival of E. coli O157 in naturally infected cattle faeces. E. coli O157 was found to survive in faeces for over 10 days at concentrations above 103 CFU g−1 of faeces. Populations of E. coli O157 were also found to increase 100‐fold in the first few hours after defecation. Conclusions:  The enumeration method is easy to implement and enables a quick throughput of large numbers of samples. The method is accurate and reliable and enables the inherent variation in count data to be explored but needs to be used in combination with a more sensitive method for samples containing <102 CFU g−1 of faeces. Significance and Impact of the Study:  The method described is appropriate for enumeration of E. coli O157 in cattle faeces in large‐scale epidemiological studies.