Antibiotic resistance and virulence factors in Escherichia coli from broiler chicken slaughtered at Tigoni processing plant in Limuru, Kenya.

BACKGROUND: Antibiotics and disinfectant use in broiler farms is a common practice and an important risk factor for promoting the emergence, selection and spread of antimicrobial-resistant micro-organisms in environment, veterinary and human medicine.
OBJECTIVES: To investigate multi-drug resistance and presence of virulence related genes in Escherichia coli isolates from healthy broiler chicken at slaughter time.
DESIGN: Cross sectional and laboratory based study.
SETTING: Tigoni processing plant, Limuru, Kenya.
RESULTS: High resistance levels were detected for most commonly used drugs like tetracycline (75.9%) and cotrimoxazole (72.4%). Other antibiotics like ampicillin (39%), chloramphenicol (13.2%) and ciprofloxacin (19%) recorded resistance levels although they are rarely used in poultry farming. One hundred and seventeen isolates showed resistance to two and more antibiotics. Different farm treatments were a significant factor for multi-drug resistance (p < or = 0.001). The E. coli isolates showed twenty-one different multi-drug resistant patterns with tetracycline/cotrimoxazole being the most common. Sixty samples were analysed for virulence related genes using multiplex PCR. Seven virulence related genes were investigated but ten isolates were positive for verotoxin and three for intimin. Serotype 0111, 0126, 06 and 078 were positive for verotoxin, 0126 and 0111 were positive for intimin. There was no significant relationship between virulence and multi-drug resistance (p < or = 0.05).
CONCLUSION: The present study highlights the presence of multi-drug resistant and virulent E. coli among healthy broiler chicken in Kenya. The possible source of antibiotic resistance in the broilers is the use of recommended antibiotics which co-select resistance for other antibiotics. Surveillance for drug resistance pathogens in food products is recommended.