Use of conventional and molecular techniques to Determine the prey alence of shigella and Enteroinv asive escherichia coli strains from Diarrhoea patients in selected health facilities in Rural western Kenya

Abstract

Diarrhoea is a major cause of infant morbidity and mortality worldwide. It accounts for 1.6- 2.5 million deaths annually and each child in the developing world experiences an average of three episodes of diarrhoea per year. Shigella spp and enteroinvassive Escherichia coli (EIEC) are common etiologic agents of bacillary dysentery. Currently, conventional culture techniques for identifying Shigella spp from stool has low sensitivity since the diagnosis is often obscured due to the presence bf low number of causative organisms, competition from commensals and inappropriate sample collection. The aim of this study was to determine the prevalence of Shigella and EIEC using conventional culture method and molecular technique targeting the ipaH gene, common to both Shigella spp and EIEC. Stool specimens from 440 patients of all ages presenting to nine health facilities with diarrhoea.were investigated for Shigella species and EIEC by conventional culture and a subset of the specimens evaluated by molecular technique. Of the 440 specimens cultured, 48 (10.9%) yielded Shigella species; S. flexneri (56%), S. dysenteriae non-type 1 (25%), and S. boydii and S. sonnei (8.3% each). No EIEC strains were isolated. Of the 421 specimens evaluated by PCR, 78 (18.5%) tested positive for ipaH gene, 331 (78.6%) tested negative, and 12 (2.9%) were weakly positive. All the Shigella species (100%) isolated by culture and an additional 33 (7.8 %) cases not identified by culture, were detected by ipaH PCR. Bloody specimens were more likely to yield a Shigella by culture (56%) and PCR (35%) than other types of diarrhoea (P<0.05). The findings of this study demonstrate that the magnitude of shigellosis in rural western Kenya is much higher than previously thought. Information from this study will help in evaluating the need to strengthen the basic preventing measures and other control measures against these pathogens.