Abstract:
A cross sectional study was conducted from November 2018 to July 2019, to assess the hygienic practice in dairy farms, and prevalence of milk and milk product contamination by E. coli and S. aureus along dairy supply chain in selected town of central Ethiopia. A total of 330 raw milks, processed milk products and others surface swabs samples were collected and processed using standard microbiological techniques to isolate E. coli and S. aureus. Raw milks, bulky and processed milk products samples were also tested for total bacterial count in order to assess microbial load in dairy supply chain. In addition, 85 individuals’ workers in dairy farm and milk processing plant owners were interviewed using a semi-structured questionnaire regarding milk handling and hygienic practices. From the total 330 samples done for laboratory analysis 125(37.88%) and 179(54.24%) samples were positive for E. coli and S. aureus respectively. Similarly out of 300 different samples taken from ten intensive dairy farms which were sent to be cultured, 114(38%) and 162(54%) of E. coli and S. aureus were isolated respectively. Even though different prevalence of milk contamination by E. coli and S. aureus recorded in all dairy farms, there was statistically significant difference in the occurrence of these microorganisms as source of milk contaminant within and in between samples from dairy farms (P<0.05). All positive isolates of E. coli and S. aureus were anti-microbial susceptibility tested against different antimicrobial discs. E. coli isolates were highly susceptible and more resistant against Nidixic acid (96%) and Streptomycin (70.4%) respectively. On the other hand, isolates of S. aureus were resistant against Penicillin G (96.6%) and Methicillin (45.8%). Out of 170 samples tested for total bacterial count, the overall average count at Mean± Standard deviation for all samples from all study sites was 7.24±0.34 CFU/ml which was above acceptable bacterial load limit. There was statically significant difference in mean bacterial count within different samples sources across milk supply chain (P<0.05). The present study revealed that the higher prevalence of milk contamination by E. coli and S. aureus was due to minimum attention on implementation of proper milking procedure, poor personal and farm hygienic practices by most farm owners and milk producers. Therefore, awareness should be created how to control and minimize the risk factors associated with milk contamination and repeated use of antimicrobials.
