Genetic relatedness of Escherichia coli O157:H7 strains from Lettuce and flies collected from irrigation farms in Kano metropolis

Abstract

The genotypic characteristics of 17 E. coli 0157:H7 strains from lettuce and 11 flies around lettuce farms were investigated. Relatedness was determined by plasmid DNA analyses and chromosomal DNA restriction digest with Sma 1. Plasmid analyses revealed 3 different plasmids profiles that contained plasmids ranged from 1 – 4 (0.523 kilobase (kb) to 11.495 kb) in some strain. Most strains (76.5%) had only one plasmid (11.495 kb) mainly strains from flies. While restriction digests analyses revealed 9 clusters, strains in cluster one had up to 70% similarity. Similarly, most strains from flies (FS1, 2, 7, 8, 9, 19, 22 and 26) were closely related (> 50%) than that from lettuce. Nevertheless, a strain from lettuce was observed to be similar at more than 56% with a strain from flies (LS96 and FS 1). Other observed to be similar were FS30/LS72, FS11/LS96 and FS8/LS69 at 39%, 48% and 49% respectively. The result showed a considerable level of relatedness, this indicates they were probably transmitted from same source. The ubiquitous nature of flies made this relationship of public health importance, and therefore further researches are needed to identify the original source of the organism for proper mitigation.