بررسي ژن هاي بيماري زاي stx1، stx2، eae A و hly با روش Multiplex PCR در سويه هاي E.coli O157:H7 جداسازي شده از كودكان مبتلا به گاستروانتريت حاد در شهرستان مرودشت

Prevalence of Virulence Genes stxx, stx2, hly and eaeA with Multiplex PCR from E.coli 0157:H7 Strains Among Children with Acute Gastroenteritis in Marvdasht

Background and objective : Enterohemorrhagic Escherichia coli (EHEC) strains are the most common enteric pathogens with cause of the hemorrhagic colitis , hemolytic-uremic syndrome and especially renal failure in children. The purpose of this study is to survey the prevalence sever diarrhea arising from this bacteria in children under 5 years old in Marvdasht. Materials and methods: In this study stool samples of children from four original areas in Marvdasht are collected and after enrichment in two culture media ECB , TSB in temperature and evaluation sorbitol fermentation on CT-SMAC , sorbitol negative bacteria with the use of specific biochemical tests for identification as E.coli. In the next step their p-glucoronidase activity has been tested on specific chromogenic media. Then with the use of specific antisera the isolation of bacteria has been confirmed. Finally with multiplex PCR method presence of virulence genes stx1, stX2, eaeA, hly has been tested. Results : Out of 615 children (278 females, 337 males), of 7 children E.coli 0157:H7 isolated (1.14%).The significant different was seen between isolation of bacteria from age group 18-23 month and other age groups (P=0.004) and only 1 case had the stx1 and eaeA genes (0.16%) and none of them had stx2 and hly genes. Conclusion : For severity of E.coli 0157:H7 pathogenesis, low infectious dose and lack of routin assay for detection of this bacteria in clinical laboratory, further and completed studies on diagnosis and genotyping of this E.coli 0157:H7 strain has been recommended.