Incidence of Shiga toxin-producing Escherichia coli in bloody diarrheal cases in Baghdad city

Shiga toxin-producing Escherichia coli (STEC) affects the human colon and causes bloody diarrhoea due to the secretion of two types of Shiga toxins. This study aimed to screen for STEC among enterohemorrhagic Escherichia coli (EHEC), especially E. coli O157:H7, in patients with bloody diarrhoea. EHEC isolates were isolated from human bloody diarrhea cases on selective media and identified as E. coli using the VITEK 2system. The isolated bacteria were tested for antibiogram profiles using the disc diffusion test. The occurrence of Shiga toxin genes (stx1 and stx2) and serotyping of STEC isolates were tested using polymerase chain reaction (PCR)-specific primers. Only 5.5% of the samples were STEC-positive. Almost all isolated STEC were isolated from the stools of infants and children. The stx1 gene was more predominant than the stx2 gene among the STEC isolates, and most of the STEC belonged to E. coli O157:H. The other hemorrhagic colitis cases were due to non-O157: non-H7 E. coli, and only one O157:H7 E. coli was isolated from the stool. In conclusion, STEC is a low-incidence cause of hemorrhagic colitis that affects infants and children under four years old. The STEC serotypes E. coli O157 and E. coli non-O157 were the causative agents of hemorrhagic colitis, and O157:H7 is low among STEC-caused hemorrhagic colitis, which provides an idea of the serotype of this bacterium currently present in Iraq, especially those causing bloody diarrhoea and HUS.