Intermittent and persistent shedding of Escherichia coli O157 in cohorts of naturally infected calves

• Published in: Journal of applied microbiology 2004-01, Vol.97 (5), p.1045-1053
• Main Authors: Robinson, S.E., Wright, E.J., Hart, C.A., Bennett, M., French, N.P.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cattle; Cattle Diseases - microbiology; Cohort Studies; Colony Count, Microbial; E. coli O157; enumeration; epidemiology; Escherichia coli; Escherichia coli Infections - microbiology; Escherichia coli Infections - transmission; Escherichia coli Infections - veterinary; Escherichia coli O157 - isolation & purification; Feces - microbiology; Fundamental and applied biological sciences. Psychology; Male; Microbiology; persistency; shedding; Specimen Handling - methods
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/j.1365-2672.2004.02390.x

Aims:  We conducted two short‐term studies of cohorts of naturally infected calves to determine the prevalence and concentrations of Escherichia coli O157 shed in faeces. Methods and Results:  Two cohorts of calves were sampled; in the first study 14 calves were sampled up to five times a day for 5 days; in the second study a group of 16 separate calves were sampled once or twice a day for 15 days. All cattle within the two cohorts shed E. coli O157 at some point during the respective studies. In 18% of samples, E. coli O157 could only be isolated using immunomagnetic separation after an enrichment period, suggesting concentrations 103 CFU g−1) were evident in both studies but, in the majority of calves, the pathogen was isolated intermittently. Significance and Impact of the Study:  The variable patterns of shedding have important implications for the design of appropriate sampling protocols and for gaining meaningful estimates of parameters used in mathematical models of transmission.