Abstract:
Cholera outbreaks have been noted in most areas within Kisumu County with little evidence regarding drugs susceptibility and phenotypic patterns in these outbreaks of Vibrio cholerae even though multiple drug resistance has become a major threat to cholera treatment. The objective was to characterize, antibiotics susceptibility, virulence and resistant genes profiling of toxigenic Vibrio cholerae isolates from Kisumu County. Antimicrobial susceptibility, serotypes, genetic relatedness and genetic mechanisms of resistance were determined on V. cholerae O1 and biotype El Tor of 119 isolates in 2017 cholera outbreaks in the County. The API 20E identification system was performed for biochemical identification while for serologic identification slide agglutination was done. The E-test method and disk diffusion was performed for the antimicrobial susceptibility testing. The virulence factors formations among the isolates were also determined by use of established protocols. Of the 119 isolates, 101 were confirmed to be V. cholerae belonging to serotypes Inaba and Ogawa, with Inaba being the predominant serotype 88/101 (73.95%). The isolates were susceptible to ciprofloxacin 101/101 (100%), ofloxacin 101/101 (100%), gentamycin 101/101 (100%), doxycycline 100/101 (99%), ceftriaxone 100/101 (99%) and streptomycin 96/101 (96.04%) antimicrobials, and resistant to erythromycin 54/101 (53.47%), amoxicillin 65/101 (64.4%), nalidixic acid 84/101 (83.2%) and ampicillin 90/101 (89.11%), with high resistance to cotrimoxazole 100/101 (99%) and tetracycline 96/101 (97%). Biofilm and virulence factors were profiled using standard procedures. The study confirmed 81/101 80.2% isolates possessing cholera toxin gene (ctxA). Additionally, 99/101 (98%) of the isolates harboured the toxR gene. The study further revealed that 81/101 (80.2%) and 94/101 (93%) 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 97/101 (96%). Out of the seven isolates which shows multidrug resistance, three of the strains (04/17-07, 06/17-14 and 05/17-03) did not form biofilms. All the seven isolates that exhibited extensive antibiotic resistance produced haemolysin while 5/7 (71.42%), 6/7 (85.71%) and 5/7 (71.42%) produced protease, phospholipases and lipase, respectively. Vibrio cholerae was resistant to multiple antibiotics, including those commonly used in the management of cholera. Taken together, there is a need to carry out regular surveillance on antimicrobial drug resistance during outbreaks. 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.
