Cervico-vaginopathogenic Escherichia coli in Iran: Serogroup distributions, virulence factors and antimicrobial resistance properties

Abstract

Escherichia coli (E. coli) play an important role in urogenital infection in pregnant and non-pregnant women. They are classified based on various types of O antigen, virulence properties, phylogenetic background and antimicrobial susceptibility pattern. E. coli strains that cause genitourinary infections possess several genes encoding urogenito-virulent factors. The aim of the present study was to determine the prevalence of eight known urovirulence factors and its association with serotypes, phylogenetic background and antimicrobial susceptibility pattern. One hundred thirty two cervico-vaginal E. coli (CVEC) isolates from pregnant and non-pregnant women (18-55 years old) were surveyed for adhesins (fimH, iha), haemolysins (hlyA), outer membrane protease (ompT) and siderophore receptors (irp2, iroN and iucD), cytotoxic necrotizing factor 1 (cnf1), and 12 selected O serotypes by multiplex-PCR. E. coli isolates were classified into intraspecies phylogenetic groups by PCR amplifications of phylogenetic markers. Antimicrobial susceptibility was determined by Kirby-Bauer's disc diffusion method. The most frequently found virulence factor-encoding gene, in descending order were: fimH (71%), irp2 (63%), followed by ompT (45%), iucD (37%), and iroN (31%) genes. The most prevalent serogroups for all E. coli isolates were O25, O15 and O6. There was an acceptable correlation between serotype and genotype in CVEC. The most isolated strains belonged to the phylogenetic group B2, harboring all tested virulence genes. Resistance to ampicillin was most frequently observed, followed by resistance to amikacin and cefazolin. The results suggest that E. coli isolates from different infection origins may have different characteristics. A better understanding of these differences may lead to further development of evidence-based clinical guidelines for the management of cervico-vaginal infection.

Keywords: Cervico-vaginal infection; Escherichia coli; O Serotype; Phylogenetic analysis.