vibrio cholerae o1 are classified into two biotypes, classical and el tor based on susceptibility to bacteriophages and some biochemical properties, each encoding a biotype-specific genetic determinants. before 1961, most epidemics had been caused by the classical biotype. however, with the passage of time, the classical biotype missed from the scenario and the el tor emerged as the major bioty...

The emergence and spread of Vibrio cholerae O1 El Tor variant strains causing severe diarrhea has been witnessed worldwide in recent years. In the state of Odisha, India, the spread of the V. cholerae O1 El Tor variant strains was studied during outbreaks in 2008 and 2009. Analysis of 194 V. cholerae O1 Ogawa strains revealed that V. cholerae O1 El Tor variant strains are spreading gradually th...

BACKGROUND & OBJECTIVES El Tor Vibrio cholerae O1 carrying ctxB C trait, so-called El Tor variant that causes more severe symptoms than the prototype El Tor strain, first detected in Bangladesh was later shown to have emerged in India in 1992. Subsequently, similar V. cholerae strains were isolated in other countries in Asia and Africa. Thus, it was of interest to investigate the characteristic...

Vibrio cholerae O1 El Tor variant strains produced much more cholera toxin than did prototype El Tor strains. The amount of cholera toxin produced by El Tor variant strains both in vitro and in vivo was more or less equivalent to that produced by classical strains.

To the Editor: The traditional causative agent of cholera, Vibrio chol-erae O1, has 2 biotypes, classical and El Tor. The current seventh pandemic that began in 1961 and has spread to much of the world is caused by the El Tor biotype. This biotype has replaced the classical biotype responsible for the previous pandemics. The classical and El Tor biotypes are differentiated by phenotypic tests (...

Considering the recent emergence of "hybrid biotype" and "El Tor variant", we propose to redefine the biotyping scheme for Vibrio cholerae O1 serogroup. The existing biotyping scheme has limitations and causes confusion as many of the hybrid biotype and El Tor variant strains have phenotypic and genetic changes. A revised biotyping scheme will play a significant role to understand the ecology, ...

Vibrio cholerae O1 is the causative agent of cholera with classical and El Tor, two well-established biotypes. In last 20 years, hybrid strains of classical and El Tor and variant El Tor which carry classical ctxB have emerged worldwide. In 2004-2005, Senegal experienced major cholera epidemic with a number of cases totalling more than 31719 with approximately 458 fatal outcomes (CFR, 1.44%). I...

UNLABELLED Vibrio cholerae genome sequences were analyzed for variation in the rtxA gene that encodes the multifunctional autoprocessing RTX (MARTX) toxin. To accommodate genomic analysis, a discrepancy in the annotated rtxA start site was resolved experimentally. The correct start site is an ATG downstream from rtxC resulting in a gene of 13,638 bp and deduced protein of 4,545 amino acids. Amo...

2. Nusrin S, Khan GY, Bhuiyan NA, Ansaruzzaman M, Hossain MA, Safa A, et al. Diverse CTX phages among toxigenic Vibrio cholerae O1 and O139 strains isolated between 1994 and 2002 in an area where cholera is endemic in Bangladesh. J Clin Microbiol. 2004;42:5854–6. DOI: 10.1128/JCM.42.12.5854-5856.2004 3. Nair GB, Faruque SM, Bhuiyan A, Kamruzzman M, Siddique AK, Sack DA. New variants of Vibrio c...

UNLABELLED An outbreak of cholera occurred in 1991 in Mexico, where it had not been reported for more than a century and is now endemic. Vibrio cholerae O1 prototype El Tor and classical strains coexist with altered El Tor strains (1991 to 1997). Nontoxigenic (CTX(-)) V. cholerae El Tor dominated toxigenic (CTX(+)) strains (2001 to 2003), but V. cholerae CTX(+) variant El Tor was isolated durin...