Rapid spread of the new clone of Vibrio cholerae O1 biotype El Tor in cholera endemic areas in India

Abstract

Using molecular techniques, we investigated whether the clone of Vibrio cholerae O1 biotype El Tor which appeared in Calcutta, India, in 1994 has spread to other cholera endemic areas in the country. The ribotype of 31 of the 33 strains isolated from different parts of India during 1996 and 1997 was identical to the ribotype displayed by the new clone of V. cholerae O1 which emerged in Calcutta in 1994. Likewise, 12 of the 15 strains examined by pulsed-field gel electrophoresis (PFGE) showed identical profile to that exhibited by the new clone of O1. The restriction fragment length polymorphism (RFLP) of CTX genetic element of these strains also matched with the new clone of O1 which emerged after the outbreak of V. cholerae 0139 in Calcutta. However, two strains (AH042 and AH046) isolated from an outbreak in Ahmedabad (western India) showed different CTX RFLP but had the same ribotype and PFGE profile as the new clone, whereas one strain from Goa (G2) showed distinct ribotype and PFGE profile and the CTX RFLP was identical to the O1 strains which prevailed before the genesis of 0139 in Calcutta. The drug resistance pattern of most of the O1 strains examined in this study, except strain G2, was similar to that of the new clone of V. cholerae O1. None of the strains in this study carried plasmids. Molecular studies clearly show that the new expanded drug resistant clone of V. cholerae O1 has spread to all cholera endemic areas in India and also provide evidence for the evolution of new clones of the O1 serogroup.

Distribution and Content of Class 1 Integrons in Different Vibrio cholerae O-Serotype Strains Isolated in Thailand

“…However, reports of V. cholerae strains resistant to commonly used antibiotics are appearing with increasing frequency and susceptibility testing is now recommended for monitoring of resistance among toxigenic V. cholerae O1 and O139, the two serotypes which cause cholera (4,20,23,29,54).…”

Cholera in Lao P. D. R.: Past and Present

“…Amongst these strains, antibiotic resistance was limited to Ampicillins. However, the characteristics of the cholera bacteria changed in the strains collected in 1996 and afterwards as reported in India, Vietnam and Thailand (Bag et al, 1998;Dalsgaard et al, 1999;Dalsgaard et al, 2000). The genomic analyses revealed that these strains were introduced with a SXT constin gene that regulates for multidrug resistancy (Iwanaga et al, 2004).…”

“…The causative vibrios collected by the active surveillance in 1993-1995 were all identified as Vibrio cholerae O1 serotype Ogawa and biotype El Tor at the National Institute of Hygiene and Epidemiology (NIHE) (Nakamura et al 1998), and the strains contributed for further publications (Toma et al, 1997). Amongst these strains, antibiotic resistance was limited to Ampicillins.…”

Antibiotic Resistance Mechanisms Focusing on Quinolones Resistance in Vibrio CHOLERAE

“…The frequency of plasmid carriage in clinical strains of V. cholerae O1 was less (2%) compared with clinical non-O1 strains (25%) as reported elsewhere. Most of the clinical strains of V. cholerae O1 isolated from different geographical regions lacked the plasmids (48,49), and when present, the size and functions of plasmids were not uniform. A study reported some of the naturally occurring conjugative and non-conjugative plasmids harboring drug resistance determinants in environmental and clinical isolates of V. cholerae encoding genes inducing various antibiotics resistance.…”