Vibrio cholerae O1 with Reduced Susceptibility to Ciprofloxacin and Azithromycin Isolated from a Rural Coastal Area of Bangladesh.

Shah M Rashed,Md Mozammel Hoq,Anwar Huq,R Bradley Sack,Munirul Alam,Abdus Sadique,Marzia Sultana,Rita R Colwell,Nur A Hasan

doi:10.3389/fmicb.2017.00252

Abstract

Cholera outbreaks occur each year in the remote coastal areas of Bangladesh and epidemiological surveillance and routine monitoring of cholera in these areas is challenging. In this study, a total of 97 Vibrio cholerae O1 isolates from Mathbaria, Bangladesh, collected during 2010 and 2014 were analyzed for phenotypic and genotypic traits, including antimicrobial susceptibility. Of the 97 isolates, 95 possessed CTX-phage mediated genes, ctxA, ace, and zot, and two lacked the cholera toxin gene, ctxA. Also both CTX+ and CTX− V. cholerae O1 isolated in this study carried rtxC, tcpAET, and hlyA. The classical cholera toxin gene, ctxB1, was detected in 87 isolates, while eight had ctxB7. Of 95 CTX+ V. cholerae O1, 90 contained rstRET and 5 had rstRCL. All isolates, except two, contained SXT related integrase intSXT. Resistance to penicillin, streptomycin, nalidixic acid, sulfamethoxazole-trimethoprim, erythromycin, and tetracycline varied between the years of study period. Most importantly, 93% of the V. cholerae O1 were multidrug resistant. Six different resistance profiles were observed, with resistance to streptomycin, nalidixic acid, tetracycline, and sulfamethoxazole-trimethoprim predominant every year. Ciprofloxacin and azithromycin MIC were 0.003–0.75 and 0.19–2.00 μg/ml, respectively, indicating reduced susceptibility to these antibiotics. Sixteen of the V. cholerae O1 isolates showed higher MIC for azithromycin (≥0.5 μg/ml) and were further examined for 10 macrolide resistance genes, erm(A), erm(B), erm(C), ere(A), ere(B), mph(A), mph(B), mph(D), mef(A), and msr(A) with none testing positive for the macrolide resistance genes.

Highlights

Vibrio cholerae, the causative agent of cholera, is autochthonous to the estuarine and marine environment worldwide
Multidrug resistant (MDR) V. cholerae has been on the rise, causing clinicians to face a serious challenge when deciding a drug of choice and regimen for treating cholera patients
A total of 97 V. cholerae O1 isolated from rectal swabs and surface water samples collected in the coastal villages of Mathbaria, Bangladesh, between June, 2010 and December, 2014, as a part of epidemiological surveillance conducted by the International Centre for Diarrheal Disease Research, Bangladesh (ICDDR,B) were analyzed for antibiotic susceptibility and genotypic traits

Summary

INTRODUCTION

The causative agent of cholera, is autochthonous to the estuarine and marine environment worldwide. Over the past two decades, variants of ET with only a few CL attributes (phage-encoded repressor rstRCL and B-subunit of cholera toxin ctxBCL) have emerged in Asia and Africa These variants are collectively known as atypical ET (Safa et al, 2010; Kim et al, 2015). Genes conferring resistance to CIP and AZ have been shown to be transferred to V. cholerae via plasmids, gene cassettes, and mobile genetic elements with horizontal gene transfer mechanisms in environmental reservoir implicated in transforming sensitive bacteria to resistant (Kitaoka et al, 2011) Considering these phenotypic and genetic modifications that are reported, a study of 97 V. cholerae O1 isolates was undertaken to determine the antibiotic resistance/susceptibility status of V. cholerae O1 isolated from environmental samples and cholera cases in cholera endemic Mathbaria, Bangladesh

MATERIALS AND METHODS

RESULTS

DISCUSSION