Isolation and Identification of E. Coli O157:H7 Strains Among Diarrheal Sample in Relation with the Presence of Stx1, Stx2, Hlya and Eaea Genes

Abstract

Escherichia coli serotype O157:H7 is a human pathogen that has been linked to meat and meat products, dairy products, vegetables, and water all over the world. The current investigation sought to isolate and identify E. coli O157:H7 strains from diarrheal samples in relation to the presence of shiga toxin genes (stx1, stx2, hlyA and eaeA).A cross-sectional study was carried out in Kirkuk city from November 2021 to April 2022. The study included 327 children with diarrhoea who admitted to Paediatric wards in Paediatric Hospital and Gynaecological and Paediatric (Al-Nasr) Hospital in Kirkuk city. Samples were inoculated on the MacConkey agar media and subculture on Eosin Methylene blue then on sorbitol MacConkey agar to get the pure culture of the microorganisms. The bacteria growing were diagnosed on the basis of color, shape, size, edge and height of the growing colonies, ferment or non-ferment the sorbitol MacConkey agar and further secondary culture were done for isolated E. coli O157:H7 strains for antibiotic sensitivity tests as well as different virulence factors included biofilm formation as well as detection of the presence of shiga toxin genes (stx1, stx2, hlyA and eaeA) by PCR. From total of 327 samples used in this study, E. coli O157:H7 represented 1.83% (6 of 327) and E. coli represented 57.80% (189 of 327). The study showed that all E. coli O157:H7 strains isolated from diarrheal samples were biofilm producers. The study showed that all E. coli O157:H7 strains isolated from diarrheal samples have eaeA and hlyA genes. The study showed that 83.33% E. coli O157:H7 strains isolated from fecal samples have STX1 gene and 16.67% E. coli O157:H7 strains have STX2 gene. The study demonstrated that all E. coli O157:H7 isolated strains were sensitive to Imipenem, Meropenem and Amikacin (100%) and 83.33 sensitive to gentamycin while all isolates were completely resistant to ticarcillin, Aztreonam, Piperacillin and 91.7% of them were resistant to ceftazidime.