Detection of Escherichia coli O157 and non-O157 Serogroups in Cattle Faeces, Dairy Products and Water Samples in Northeast Nigeria

Abstract

Cattle have remained an important primary reservoir of both Escherichia coli O157 and non-O157 serotypes implicated in many diarrhoeal disease outbreaks in animals and humans worldwide. The prevalence of these diarrhoeagenic agents in cattle and environmental sources has not been ascertained in Northeast Nigeria. A total of 380 specimens comprising bovine rectal swabs, dairy products (raw cow milk, fermented cow milk, local cheese milk) and water from various sources in Borno and Adamawa States, Nigeria were collected and examined using standard bacteriological procedures. Of the 21 (5.5%) diarrhoeagenic Escherichia coli strains recovered E. coli O157 accounted for 5 (1.3%), 6 (1.6%) and 9 (2.4%) respectively. The rate of isolation of E. coli O157 in cattle faeces and raw cow milk was 1.5% each while, water was 6.3%. The frequency of isolation of E. coli O118, O111 and O26 serotypes from cattle faeces was 0.5%, 2.5% and 1.0% respectively, while raw cow milk accounted for 1.5% and 10.8% of E. coli O111 and 026 serogroups respectively. Fermented cow milk and cheese butter yielded none of these serogroups, in spite of the evidence of contamination rates of these products of 38.3% and 24.4% respectively by E. coli strains. E. coli bacteria contamination was highest in raw cow milk (53.8%). The detection rate of non-)157 in cattle faeces irrespective of health status was borderline significant (P=0.05). The relative risk (RR) associating cattle aged >24months with E. coli O157 shedding (3.33, 95% Cl 0.31 – 36.14) and non-O157 shedding (2.95, 95% Cl 0.19 – 44.86) was higher than the risk I calves aged <12 months. The result of this study underlies the need to drastically reduce the level of E. coli O157 and non-O157 in live cattle on the farm to further reduce the rate of cross contamination on carcasses and dairy products during processing and by ground water that come in contact with cattle faeces.

Keywords: Cattle, faeces, dairy products, water, E. coli O157, non-O157