The Frequency of Enteroaggregative Escherichia Coli and Important Virulence Genes Isolated from Children with Diarrhea

Enteroaggregative Escherichia coli (EAEC) has recently been identified as the cause of epidemic and endemic chronic watery diarrhea worldwide, especially in developing countries. The aim of this study was to determine the frequency of this strain and its important virulence genes in diarrhea samples.

This study was performed on 80 Escherichia coli isolates from children with diarrhea referred to Imam Hossein hospital, Isfahan, Iran. The bacteria were confirmed using biochemical tests and multiplex polymerase chain reaction (multiplex PCR) was performed to detect aggR, aap, aatA genes in EAEC strains.

The frequency of EAEC was 21 (26.6%). According to multiplex PCR results, the aggR, aap, and aatA genes were detected in 21 (100%), 7 (33%), and 3 (14.3%) of strains, respectively. Moreover, 7 strains (33.3%) harbored two aggR and aap genes, 3 (14.3%) carried the aatA and aggR genes, and aatA and aap genes were presented in 2 strains (9.5%). None of the strains had 3 genes simultaneously.

This study provides the first report of a relatively high frequency of typical EAEC strains in children under 5 years of age with symptoms of diarrheal disease in Isfahan. Moreover, we found that the EAEC strains not only exhibited high frequency, but also showed a high frequency of carrying virulence genes especially aggR that indicated the importance of identifying this strain in patients showing the symptoms of acute and chronic diarrhea, especially in our country, as the diagnosis of this strain is not done routinely.