Characterization of Extended-spectrum Beta-lactamase (Esbl) - Producing Escherichia Coli Isolated From Raw Dairy Cattle Milk in Peri-urban Farms in Nairobi, Kenya

Abstract

Antimicrobial resistance has become a global health concern as many pathogens are becoming resistant to more than one antibiotic, and new, last-resort antibiotics are expensive and often out of reach for those who need them from low income countries. Beta-lactams (penicillins and cephalosporins) are one of the most commonly used classes of antibiotics in the treatment of infections caused by multidrug-resistant gram-negative bacteria particularly Escherichia coli and Klebsiella species both in human and animals. Emergence of extended spectrum beta lactamase (ESBL) producing strains of bacteria represent one of the biggest threats to global health. There have been reports worldwide on food animals and foods of animal origin being potential sources of ESBL-producing strains raising serious food safety questions regarding the prevalence of these strains in foods of animal origin. This study was carried out to characterize extended-spectrum beta-lactamase (ESBL) producing Escherichia coli isolated from raw dairy cattle milk in peri-urban farms in Nairobi Kenya. The study was carried on 351 raw dairy milk samples collected between November 2016 to October 2017 from five dairy farms, namely: - University of Nairobi Veterinary Farm at Kanyariri (n=103), Department of Veterinary services farm at Ngong (n=52), Dominic Farm (n=106), Kabogo Farm (n=50) and Karuga Farm (n=40) all around Nairobi. Pooled milk samples of a volume of 10 ml from four teats of an individual cow were collected directly from the udder by hand milking into a sterile bijou bottle. Samples of dairy milk were then placed in cool boxes and transported to University of Nairobi, department of public health, pharmacology and toxicology laboratories. Isolation of Escherichia coli was by employing enrichment in buffered peptone water followed by inoculation in tryptone soy agar and then cultured in EMB Agar selective medium. Identification of Escherichia coli was done through morphological characteristics, biochemical reactions and final confirmation by polymerase.........................................................................................