Occurrence of antibiotic resistance gene cassettes aac(6')-Ib, dfrA5, dfrA12, and ereA2 in class I integrons in non-O1, non-O139 Vibrio cholerae strains in India.
Molecular mechanisms of multidrug resistance in Vibrio cholerae belonging to non-O1, non-O139 serogroups isolated during 1997 to 1998 in Calcutta, India, were investigated. Out of the 94 strains examined, 22 strains were found to have class I integrons. The gene cassettes identified were dfrA1, dfrA15, dfrA5, and dfrA12 for trimethoprim; aac(6')-Ib for amikacin and tobramycin; aadA1 and aadA2 for streptomycin and spectinomycin; and ereA2 for erythromycin resistance. To our knowledge, this is the first report of the presence of dfrA5, dfrA12, aac(6')-Ib, and ereA2 cassettes in class I integrons of V. cholerae. Forty-three of 94 strains also had plasmids, and out of these, 14 contained both class I integrons and plasmids. Pulsed-field gel electrophoresis followed by Southern hybridization revealed that in the 14 plasmid-bearing strains, class I integrons resided either on chromosomes, on plasmids, or on both. Our results indicated that besides class I integrons and plasmids, a conjugative transposon element, SXT, possibly contributed to the multiple antibiotic resistance.
Thungapathra
M
M
Institute of Microbial Technology, Chandigarh, India.
Amita
Sinha
Kislay K
KK
Chaudhuri
Saumya Ray
SR
Garg
Pallavi
P
Ramamurthy
Thandavarayan
T
Nair
Gopinath Balakrish
GB
Ghosh
Amit
A
D015139:Blotting, Southern; D002874:Chromosome Mapping; D015342:DNA Probes; D004251:DNA Transposable Elements / Q000235:genetics; D004269:DNA, Bacterial / Q000096:biosynthesis / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics*; D007194:India; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D021521:Ribotyping; D014169:Transformation, Bacterial; D014734:Vibrio cholerae / Q000187:drug effects / Q000235:genetics*
D015342:DNA Probes; D004251:DNA Transposable Elements; D004269:DNA, Bacterial