A rough variant of nontoxigenic Vibrio cholerae O139 imported from Vietnam

Abstract

Purpose (stating the main purposes and research question) Vibrio cholerae is classified in O-antigen polysaccharide outer membrane properties where O1 and O139 are strains that cause pandemics and epidemics while non-O1/non-O139 usually cause mild disease. The dynamic evolution of Vibrio cholerae involves new virulence factors through horizontal gene transfer and formerly nontoxigenic serogroups are being reported as causing increasingly severe forms of human disease. Our purpose was to investigate serogroup and virulence factors in one imported isolate from Vietnam and compare these to virulence factors seen in different strains of Vibrio cholerae. Methods This is an observational study where we have serotyped one isolate of imported Vibrio cholerae from Vietnam to Denmark and performed whole genome sequencing to identify known virulence genes and furthermore studied the epidemiology of virulence in pathogenic strains of Vibrio cholerae. Results We have identified virulence factors in our isolate that are recently discovered and one toxin, MakA, has not previously been reported from an Asian strain. The isolate was found to be a serogroup non-O1/non-O139 strain, however, sequence analysis gave a 96, 6% ID match of the wbfZ gene, stipulating our isolate to belong to either serogroup O22 or O139. Conclusions Looking at the combination of virulence factors of the isolate we suggest the finding of a rough variant of a nontoxigenic Vibrio cholerae O139 rather than a O22 serogroup version. This is a rare finding in a clinical isolate.