Prevalence of EHEC 0157:H7 from human and environmental samples from Lagos and Zaria

ABSTRACT

Prevalence, antibiotic patterns and plasmid profiles of Enterohaemorrhagic Escherichia coli [EHEC] 0157H7 from humans and environmental sources were studied at various seasons of the year in Nigeria. Stool and environmental samples were obtained from Lagos and Zaria and characterized as EHEC 0157H7 using the method of Cowan and serotyping. The isolates were further characterized using antibiotic susceptibility testing and plasmid profile. Out of 132 stool samples, 42 [31.8%] of EHEC 0157H7 were isolated between April to December 2004. These samples were from Lagos [Western Nigeria] and Zaria [Northern Nigeria]. Thirty-three isolates were from Lagos while 9 were from Zaria. Out of 90 environmental samples, 11 [12.2%] were positive for EHEC 0157H7. The highest number of isolates [13] was obtained during the month of December, the dry, harmattan and festive season. Most of the isolates from Zaria were resistant to ampicillin, nitrofurantoin and tetracycline, while those from Lagos were resistant to ampicillin, cotrimoxazole, nitrofurantoin and tetracycline. Nine out of 53 [17%] isolates harboured detectable plasmids. The presence of multi-drug resistance amongst these isolates is of concern and so antibiotic therapy should not be recommended as it complicates the disease while misuse in our environment has led to emergence of resistance strains