Ciência e Tecnologia Veterinária

Isolation, Identification and Antimicrobial Susceptibility Testing of Escherichia coli Isolated from Selected Dairy Farms in and Around Mekelle, Tigray, Ethiopia

Abstract

Gebremedhin Yohannes

A cross sectional study was conducted from November 2014 to April 2015 in selected dairy farms in and around Mekelle, Tigray, Ethiopia with the objective of isolating and identifying Escherichia coli from raw cow’s milk and determining its antimicrobial susceptibility pattern. From a total of 300 raw milk samples collected, 75 (25%) were found to be positive for E. coli organisms by culture method. Among the potential risk factors, stage of lactations (x2=149.677; P=0.000), age groups (x2=6.010; P=0.04) and parity numbers (x2=11.594; P=0.009) were found significantly associated with occurrence of E. coli. The highest percentage of E. coli isolates were found from cows’ milk with early stage of lactation 53 (84.1%) and from cows with four and above parity number 43 (32.8%). On the other hand, the association between different farms were not statistically significant (x2=5.712; P=0.222.) with the occurrence of E. coli organisms. The antimicrobial susceptibility pattern revealed that all the isolates were found to be 100% susceptible to gentamicin followed by kanamycin (92%), sulphamethoxazole- trimethoprim (76%); were found to be 100% resistant to penicillin G followed by amoxicillin (84%) and tetracycline (60%). Therefore, gentamicin, kanamycin and sulphamethoxazole-trimethoprim were found to be the most effective drugs against E. coli. To safeguard the quality of raw milk, people engaged in milk and dairy production chain should be trained for hygienic practices.