Identification of Atypical El TorV. cholerae O1 Ogawa Hosting SXT Element in Senegal, Africa.

Bissoume Sambe-Ba,Ahmad I Sow,Mamadou H Diallo,Amy Gassama-Sow,Amy Gassama-Sow,Cheikh S.-B Boye,Abdoul A Wane,Abdoulaye Seck,Guillaume Constantin De Magny,Guillaume Constantin De Magny,Guillaume Constantin De Magny,Guillaume Constantin De Magny

doi:10.3389/fmicb.2017.00748

Abstract

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%). In this retrospective study, fifty isolates out of a total of 403 V. cholerae biotype El Tor serovar Ogawa isolates from all areas in Senegal during the 2004–2005 cholera outbreak were randomly selected. Isolates were characterized using phenotypic and genotypic methods. The analysis of antibiotic resistance patterns revealed the predominance of the S-Su-TCY-Tsu phenotype (90% of isolates). The molecular characterization of antibiotic resistance revealed the presence of the SXT element, a self-transmissible chromosomally integrating element in all isolates. Most of V. cholerae isolates had an intact virulence cassette (86%) (ctx, zot, ace genes). All isolates tested gave amplification with primers for classical CT, and 10/50 (20%) of isolates carried classical and El Tor ctxB. The study reveals the presence of atypical V. cholerae O1 El Tor during cholera outbreak in Senegal in 2004–2005.

Highlights

Cholera is an epidemic diarrheal disease caused by toxigenic Vibrio cholerae, serogroup O1 or O139
Our results showed that class 1, 2, and 3 integrons were not involved in the spread of resistance among Senegalese V. cholerae O1 isolates, even though they have been detected in Mozambican V. cholerae O1 isolates and other Gram-negative enteric bacteria in Senegal (Hochhut and Waldor, 1999; Dalsgaard et al, 2001; Gassama et al, 2004; Gassama-Sow et al, 2006)
Atypical V. cholerae O1 El Tor strains were responsible for cholera outbreak in Senegal in 2004–2005

Summary

Introduction

Cholera is an epidemic diarrheal disease caused by toxigenic Vibrio cholerae, serogroup O1 or O139. There are two biotypes in the serogroup O1, classical and El Tor. The seventh pandemic of cholera were due to V. cholerae O1, biotype El Tor, began in Celebes (Islands) in 1961 and spread in West African countries in the early 1970s while the fifth and the sixth pandemics of cholera were caused by the classical biotype (Kaper et al, 1995). Africa has been the continent most affected by cholera in terms of the number of individuals infected and the frequency of outbreaks recorded. In 2004–2005, cholera outbreaks occurred in eight countries in Africa with 125,082 cases and 2,230 deaths, CFR 1.78 (WHO, 2006). In some areas, the CFR exceeded 10%. In Senegal, the cholera outbreak has caused 31,719 cases with approximately

Objectives

Methods

Results

Discussion

Conclusion