Cholera outbreak: antibiofilm activity, profiling of antibiotic- resistant genes and virulence factors of toxigenic Vibrio cholerae isolates reveals concerning traits

Abstract

Vibrio cholerae is a biofilm-forming pathogen with various virulence phenotypes and antimicrobial resistance traits. Phenotypic characteristics play a critical role in disease transmission and pathogenesis. The current study elucidated antibiofilm formation activity, profiled antibiotic-resistant genes and virulence factors of toxigenic Vibrio cholerae isolates from the cholera outbreak in Kisumu County, Kenya. Vibrio cholerae O1 isolates collected during the 2017 cholera outbreak in Kisumu County, Kenya, were utilized. Biofilm and virulence factors were profiled using standard procedures. The study confirmed 100 isolates as Vibrio cholerae, with 81 of them possessing cholera toxin gene (ctxA). Additionally, 99 of the isolates harboured the toxR gene. The study further revealed that 81 and 94 of the isolates harboured the class I integron (encoded by inDS gene) and integrating conjugative element (ICE), respectively. Antibiotic resistance assays confirmed tetracycline resistance genes as the most abundant (97 isolates). Among them were seven isolates resistant to commonly used antibiotics. The study further screened the isolates for antibiofilm formation using various antibiotics. Unlike the four strains (03/17–16, 02/17–09, 04/17–13), three of the strains (04/17–07, 06/17–14 and 05/17–03) did not form biofilms. Further, all the seven isolates that exhibited extensive antibiotic resistance produced haemolysin while 71.42%, 85.71 and 71.42% of them produced protease, phospholipases andlipase, respectively. This study provides and in-depth understanding of essential features that were possibly responsible for V. cholerae outbreak. Understanding of these features is critical in the development of strategies to combat future outbreaks.