Haitian-like genetic traits with creeping MIC of Azithromycin in Vibrio cholerae O1 isolates from Puducherry, India.

ABSTRACT

Introduction. The emergence of novel strains of Vibrio cholerae O1 El Tor biotype has gained attention due to causing several epidemics around the world. Variant strains have evolved as a result of the acquisition of genes that confer extended virulence and pathogenicity.Aim. This study aimed to determine the presence of the most recently emerging Haitian-like genetic traits among the isolates from Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, Southern India. We also wanted to detect the prevalence of the sulfamethoxazole and trimethoprim (SXT) element, which is an integrating conjugative element (ICE) and the antimicrobial resistance genes present in our isolates.Methodology. Identification of Haitian-specific alleles was done by mismatched amplification mutation assay PCR (MAMA-PCR). The presence of SXT elements was carried out by PCR by detecting int, eex, att-prfC and setR genes. Detection of antibiotic resistance determinant, sul(1,2,3); dfr(A1,18,5) for trimethoprim resistance, tet(A,B,C,D,E,Y,G,M), tet34 for tetracycline resistance and erm(A,B,C), mph(A,B), ere(A,B), msr(A,D) for azithromycin resistance were targeted by PCR. The MIC of tetracycline, ciprofloxacin and azithromycin was determined by the E-test method.Results. Of the 95 isolates, 60 % of the isolates were found to carry Haitian-specific alleles of ctxB, tcpA and rtxA gene, 100 % of the isolates were found to carry SXT elements. All the isolates harboured the four conserved genes of the SXT element, except one which had only eex, att-prfC, setR genes. About 99 % harboured sul2 and dfrA1 genes. No tet and macrolide genes were detected. We observed a progressive increase in the MIC of azithromycin ranging from 0.75 µg ml-1 to 2 µg ml-1.Conclusion. None of the isolates were the prototype El Tor biotype. All the isolates were a Haitian variant. The presence of SXT elements across all our isolates and their creeping MIC of azithromycin is a matter of concern. Further testing for other genetic determinants of resistance will be carried out in our future studies.