Identification, differentiation and phylogenetic typing of diarrheagenic Escherichia coli in Iraqi infants and children

Abstract

Several traditional identification and typing methods were available depending on the phenotype of diarrheagenic Escherichia coli (DEC). Multiplex-PCR was rapid for the identification of specific genes that encoded to specific virulence factors and as a consequence the identification of the pathotypes of DEC. The aim of this study to the identification of DEC by the virulence factors genes and genotyping of clinical isolates of DEC isolated from the diarrheal stool of infants and children. Forty-eight DEC isolates had been collected from different hospitals in Baghdad city and identified by Vitek 2 system. An antibiotic sensitivity test was carried out by the VITEK-2 System method for all DEC isolates. The virulence genes amplification was used to identify DEC pathotypes and DEC was typed by Enterobacterial Repetitive Intergenic Consensus (ERIC-PCR) methods. The occurrence of virulence genes is varied according to the pathotypes. Statistically, the eae and cadA genes are significantly found in all pathotypes of DEC (P = 0.001), whereas ipaH, elt, estA1, and stx2 genes are absent in all DEC pathotypes. The most predominant of the pathotypes are belonged to enteropathogenic Escherichia coli (EPEC) especially aEPEC followed by diffusely adherent E. coli (DAEC), enterotoxigenic E. coli (ETEC), and enterohaemorrhagic E. coli (EHEC), respectively. Moreover, The DEC isolates were multidrug-resistant to most of the antimicrobials. Ticarcillin was the less effective one while Gentamicin was the more effective one and the DEC pathotypes are differ in their antibiotic resistance pattern. The ERIC typing of E. coli pathotypes showed that almost all of the isolates are located on the same cluster, the same is noticed in EPEC isolates, The DEC pathotypes are dissimilar (Simson index = 1.0) except for EPEC isolates that showed some similarity among some of them (Simson index < 1.0). This study may be the first in using ERIC typing in typing of the E. coli pathotypes. In conclusion, amplification of virulence genes is a useful tool for the identification of DEC pathotypes. The highest percentage of DEC pathotypes was aEPEC followed by DAEC, tEPEC, ETEC and the less one was EHEC, while there was no exit to enteroinvasive E. coli and enteroaggregative E. coli. Most of the DEC clinical isolates are multidrug-resistant and are different in their antibiotic resistance pattern. The most common gene of local DEC isolates was cadA and eae genes followed by daaD and bfp, whereas ipaH, elt, estA1, and stx2 are not detected in all local isolates of DEC. Most of the DEC clinical isolates have a high level of dissimilarity among DEC pathotypes clinical isolates.