Distribution of genes encoding virulence factors and multilocus variable-number tandem-repeat analysis (MLVA) of entero-aggregative Escherichia coli (EAEC) isolated in Iran from patients with diarrhoea.

Abstract

Entero-aggregative Escherichia coli (EAEC) is one of the main causes of diarrhoea worldwide. Several virulence factors have been identified in EAEC. This study was conducted to investigate the distribution of virulence factor genes in EAEC strains isolated in Iran from children with diarrhoea, as well as the genetic similarity of these isolates. A total of 37 EAEC isolates were tested for the presence of 11 virulence genes by PCR, and the genetic relatedness of these strains was further determined by multilocus variable-number tandem-repeat analysis (MLVA). All EAEC isolates were typical EAEC. pic, set1A and set1B were the most prevalent genes, detected in 54.1 % of the isolates, followed by sat (43.2 %), astA (32.4 %), pet (24.3 %), agg4A (24.3 %), sepA (18.9 %), agg3A (13.5 %), sigA (8.1 %), aggA (8.1 %) and aafA (5.4 %). Using MLVA, the 37 isolates were divided into 32 types and classified into five clonal complexes. This study showed that EAEC is a heterogeneous group of E. coli possessing a broad range of virulence factors. There was no notable association between MLVA patterns and virulence profiles.