ISOLATION AND ANTIMICROBIAL SUSCEPTIBILITY PATTERN OF ESCHERCHIA COLI O157:H7 ISOLATED FROM RAW MILK AND MILK PRODUCTS MARKETED IN HARAMAYA AND HARAR TOWNS, EASTERN ETHIOPIA

Abstract

Pathogenic strains of E. coli are among the major cause of diseases in both animal and human population. E. coli O157:H7 is a food-borne pathogen and it has been reported as a main cause of human outbreaks after consumption of contaminated foods like raw milk and milk products. A cross-sectional study was conducted from August 2021 to May 2022 to estimate the occurrence of E. coli O157:H7 in milk and milk products marketed in Harar and Haramaya towns, Eastern Ethiopia. This study also investigated the antimicrobial sensitivity pattern of the isolates using a disc diffusion method. Our study result showed, out of 165 milk and milk products samples examined, 27.88% (46/165) and 9.7 % (16/165) of the samples were positive for E. coli and E. coli O157:H7, respectively. Among the analyzed milk and milk products the highest prevalence of E coli O157:H7 was found in raw milk (18.2%) and followed by cheese (11.4%) and yogurts (6.8%). However, the E. coli O157:H7 was not isolated from pasteurized milk. On the other hand, occurrence of E. coli O157:H7 had no statistical differences (p> 0.05) between Harar and Haramaya towns and among the sample collection sites considered in the present study. E. coli O157:H7 isolates were also tested for their susceptibility profile and among the six antibiotics used, the isolates were found highly susceptible to Chloramphenicol (100%), Gentamycin (93.75%) and Nalidixic acid (81.25%). The isolates were resistant to Streptomycin (87.5%), Ampicillin (75%) and Cefoxitin (31.25%). This study observed that 37.5% of isolates were showed multi-drug resistance to two to three antibiotics. In general, the high prevalence E coli O157:H7 in milk and milk products and presence of multi drug resistance of the isolates revealed the importance of the pathogen as public health risks following consumption of raw milk and milk products at our study areas. Therefore, we recommend further studies with larger sample size and using molecular diagnostic methods that characterizes E coli O157:H7 isolates to the genetic level.