Relative sensitivity of Escherichia coli O157 detection from bovine feces and rectoanal mucosal swabs.
The need to quantify the potential human health risk posed by the bovine reservoir of Escherichia coli O157 has led to a wealth of prevalence studies and improvements in detection methods over the last two decades. Rectoanal mucosal swabs have been used for the detection of E. coli O157 fecal shedding, colonized animals, and those predisposed to super shedding. We conducted a longitudinal study to compare the detection of E. coli O157 from feces and rectoanal mucosal swabs (RAMS) from a cohort of dairy heifers. We collected 820 samples that were tested by immunomagnetic separation of both feces and RAMS. Of these, 132 were detected as positive for E. coli O157 from both samples, 66 were detected as positive from RAMS only, and 117 were detected as positive from feces only. The difference in results between the two sample types was statistically significant (P < 0.001). The relative sensitivities of detection by immunomagnetic separation were 53% (confidence interval, 46.6 to 59.3) from RAMS and 67% (confidence interval, 59.6 to 73.1) from fecal samples. No association between long-term shedding (P = 0.685) or super shedding (P = 0.526) and detection by RAMS only was observed.
Faculty of Veterinary Science, University of Sydney, Camden, New South Wales 2570, Australia. karen.williams@sydney.edu.au.
K J
KJ
Williams
Faculty of Veterinary Science, University of Sydney, Camden, New South Wales 2570, Australia.
M P
MP
Ward
Faculty of Veterinary Science, University of Sydney, Camden, New South Wales 2570, Australia.
O
O
Dhungyel
Faculty of Veterinary Science, University of Sydney, Camden, New South Wales 2570, Australia.
L
L
Van Breda
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D015331:Cohort Studies; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000254:growth & development / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology*; D005260:Female; D008137:Longitudinal Studies; D009092:Mucous Membrane / Q000382:microbiology*; D012007:Rectum / Q000382:microbiology*; D012680:Sensitivity and Specificity