Isolation, Identification and Antimicrobial Susceptibility Testing of Escherichia Coli from Intensive Dairy Farms in Modjo and Adama, Central Ethiopia

Abstract

A cross-sectional study was conducted from February2019 to June2019in intensive dairy farms located in Modjo and Adama, central Ethiopia with the objective of isolating and identifying Escherichia coli from raw cow’s milk sample, bulk milk sample, hand swap sample, floor sample and faces and determine its antimicrobial susceptibility pattern. Of the total 166 samples E. coli was isolated from 21/166 (12.65%). Of the 21 E. coli isolates, 14/56 (25%) lactating cow’s milk, 0 (0%) bulk milk, 0 (0%) hand swap, 1/8 (12.5%) floor sample and 6/84(7.1%) faces were found to be positive for E. coli organisms by culture methods. Samples were propagated on nutrient broth and nutrient agar media followed by culture on selective media–Eosin Methylene Blue Agar, MacConkey agar. All the isolates were found to have the specific morphological, cultural characteristics and were selected for biochemical test and microscopic examination after staining. Biochemical properties of the isolates were studied and reaction in TSI agar slant was also observed. Antimicrobial susceptibility tests were also performed. Accordingly, all E. coli isolates were susceptible to gentamicin 100%, followed by cefoxitin (87.7%), ciprofloxacin (76.2%), nitrofurantoin (71.4%), nalidixic acid (62%), cefuroxime (61.9%) and streptomycin (52.4%). Furthermore, resistance of 76.2%, 66.7%, and 57.1% was recorded to tetracycline, methicillin, and erythromycin respectively. In conclusion, E. coli was isolated from the dairy farms where the majority of isolates showed resistance to one or more antimicrobials tested. Hence, improving the hygienic practices at the farm level is very important to safeguard the community from infections with antimicrobial resistant foodborne bacterial that could pose public health and therapeutic problems to consumers.