Vibrio cholerae O1 lineages driving cholera outbreaks during seventh cholera pandemic in Ghana

Abstract

In recent years, the frequency of cholera epidemics across Africa has increased significantly with thousands of people dying each year. However, there still exists a lack of information concerning the Vibrio cholerae O1 lineages driving early and contemporary epidemics since the seventh cholera pandemic started in the continent. This compromises the understanding of the forces determining the epidemiology of cholera in Africa and its control. This study aimed to analyze a collection of V. cholerae O1 strains from the beginning of the seventh cholera pandemic in Ghana and to compare them with recent isolates to understand the evolution of the cholera epidemic in Ghana. V. cholerae O1 strains were characterized by means of Multilocus Sequence Analysis (MLSA), genes from the virulence core genome (VCG), and genes related to the choleragenic phenotype. Our results revealed two major clusters of Ghanaian V. cholerae O1 strains, El Tor and Amazonia/Ghana. Concerning the virulence genes, all strains harbored the set of VCG and most were positive for VSP-II genomic island. The ctxB gene of the contemporary strains was characterized as Altered El Tor. The strains from 1970 to 1980 were susceptible to all antibiotics tested, except for the Amazonia/Ghana cluster that was resistant to aminoglycosides and carried the class 2 integron with the sat2-aadA1 arrangement. This study showed that distinct V. cholerae O1 were the determinants of cholera outbreaks in Ghana. Thus, in endemic regions, such as Africa, cholera can be caused by various V. cholerae O1 genotypes.