Abstract
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.
Highlights
Milk is the fluid normally secreted by female mammals for the nourishment of their young ones
Escherichia coli is among many pathogenic microorganisms, can access to milk and some of dairy products which is considered as a reliable indicator of contamination by manure, soil and contaminated water
The findings obtained in this study revealed that raw cow’s milk were found to be highly contaminated with the E. coli isolates
Summary
Milk is the fluid normally secreted by female mammals for the nourishment of their young ones. Milk is considered a complete and nutritious food; for the new-born mammal and for the human beings, but it is considered as a good medium for many microorganisms [3,4]. It starts its journey in the udder of a mammal as a sterile substance, but as it passes out of the teat, it is inoculated by the animal’s normal flora [5]. The threat posed by diseases spread through contaminated milk is well known and the epidemiological impact of such diseases is considerable The presence of these pathogenic microorganisms in milk has emerged as a major public health concern especially for those individuals who still drink raw milk [9]
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