Distribution and characterization of integrons in various serogroups of Vibrio cholerae strains isolated from diarrhoeal patients between 1992 and 2000 in Kolkata, India.

A total of 133 clinical strains of Vibrio cholerae comprising 44 strains of O1, 45 strains of O139 and 44 strains of non-O1, non-O139 serogroups isolated from hospitalized patients in Kolkata, India, from 1992 to 2000 was examined for the presence of class 1, 2 and 4 integrons. By PCR and DNA sequencing, seven strains of O1, one strain of O139 and six strains of non-O1, non-O139 serogroups were found to contain class 1 integron-harbouring genes aadA1, aadA2 (encoding resistance to streptomycin and spectinomycin), blaP1 (resistance to beta-lactams), aar-3 (resistance to rifampicin), aacA4 (resistance to kanamycin and gentamicin), and dfrA1 and dfrA15 (resistance to trimethoprim). Most strains produced one or two bands using primers specific for the amplification of the variable region where the antibiotic-resistance genes are located, and their sizes ranged from 700 to 1250 bp.

Genomic sequence and receptor for the Vibrio cholerae phage KSF-1phi: evolutionary divergence among filamentous vibriophages mediating lateral gene transfer.

KSF-1phi, a novel filamentous phage of Vibrio cholerae, supports morphogenesis of the RS1 satellite phage by heterologous DNA packaging and facilitates horizontal gene transfer. We analyzed the genomic sequence, morphology, and receptor for KSF-1phi infection, as well as its phylogenetic relationships with other filamentous vibriophages. While strains carrying the mshA gene encoding mannose-sensitive hemagglutinin (MSHA) type IV pilus were susceptible to KSF-1phi infection, naturally occurring MSHA-negative strains and an mshA deletion mutant were resistant.