Emergence of Tetracycline ResistantVibrio choleraeO1 Biotype El Tor Serotype Ogawa with ClassicalctxBGene from a Cholera Outbreak in Odisha, Eastern India

Abstract

In September 2010, a cholera outbreak was reported from Odisha, Eastern India.V. choleraeisolated from the clinical samples were biochemically and serologically confirmed as serogroup O1, biotype El Tor, and serotype Ogawa. Multiplex PCR screening revealed the presence of various genes, namely,ompW,ctxB,zot,rfbO1,tcp,ace,hlyA,ompU,rtx,andtoxR,in all of the isolates. The isolates were resistant to co-trimoxazole, nalidixic acid, polymyxin B, spectinomycin, streptomycin, sulfamethoxazole, tetracycline, trimethoprim, and vibriostatic agent 2,4-diamino-6,7-diisopropylpteridine (O/129). Minimum inhibitory concentration of tetracycline decreased in the presence of carbonyl cyanidem-chlorophenylhydrazone (CCCP), suggesting the involvement of efflux pumps. PCR analysis confirmed the presence of class I integrons as well as SXT elements harbouring antibiotic resistance genes in all isolates. Sequencing revealed the presence ofctxBgene of classical biotype in all the isolates. The isolates harboured an RS1-CTX prophage array with El Tor typerstRand classicalctxBon the large chromosome. The study indicated that theV. choleraeEl Tor variants are evolving in the area with better antibiotic resistance and virulence potential.