Detection of virulence genes in ESBL producing, quinolone resistant commensal Escherichia coli from rural Indian children

Abstract

Introduction: Extended-spectrum β-lactamase producing commensal Escherichia coli are considered as a reservoir of antibiotic resistance genes that may be transmitted in the community. This study aimed to determine the genes coding for ESBLs, plasmid mediated quinolone resistance and virulence markers in commensal E. coli isolated from healthy school children.

Methodology: ESBL producing E. coli isolates (n = 47) were obtained from 529 fecal samples of healthy school children from a rural area in central India. Multiplex PCR was used to detect the genes coding for cephalosporin and quinolone resistance, for virulence fluA, fluB, stx_1, stx_2, eae, bfp, lt, stII, virF, ipaH, daaE, aafII and phylogenetic groups.

Results: Of the 47 ESBL producing E. coli, 41 were positive for CTXM-15, 23 for TEM-1_, 8 for OXA-1and a single for SHV-12_. For plasmid-mediated quinolone resistance, all the 47 isolates carried the aac(6’)-ib-cr gene, and amongst them18 were qnrS positive. Virulence gene, fluA was detected in 32,whereas eae in 14, daaE in 7 and fluB in 1. In 10 isolates, fluA and eae and in 7, fluA and daaE co-existed. Of the 47 E. coli isolates, 18 were grouped into the phylogenetic group B2, 17 in D and 12 in A. The proportion of isolates positive for fluA gene in the phylogenetic group B2 (18/18), was significantly higher than in group A (7/12) and D (6/17).

Conclusion: Commensal E. coli in healthy children in rural India may serve as reservoirs of resistance towards cephalosporins and fluoroquinolones and virulence coding genes for urinary tract and diarrheal infections.