Molecular characterization of Virulence and Resistance Genes of Campylobacter Spp. Archived Isolates from Asymptomatic School Going Children at Kibera Slum in Nairobi, Kenya

Abstract

Campylobacter spp. are significant global contributors to food poisoning. These bacteria harbor virulence and resistance genes that play crucial roles in invasion and antibiotic resistance. Understanding the molecular mechanisms of virulence and resistance in Campylobacter spp. is essential for developing intervention strategies. This study aimed to characterize resistance and virulence genes in archived Campylobacter spp. isolated from children at Kibera in Nairobi, Kenya. This was a cross-sectional retrospective laboratory-based study conducted on archived Campylobacter spp. samples at the Department of Public Health, Pharmacology, and Toxicology, University of Nairobi. The frozen Campylobacter isolates were cultured on modified charcoal cefoperazone deoxycholate agar (mCCDA) media to check viability and verified by multiplex polymerase chain reaction (mPCR). The presence of virulence and resistance genes was tested using PCR. The PCR products were sent to Macrogen for Sanger sequencing. Data analysis was performed using STATA13, and logistic regression was used to determine the association between the genes and the Campylobacter spp. isolates at p ≤ 0.05. The nucleotide sequences were analyzed using BLAST, and phylogenetic trees were constructed using MAFFT. The Campylobacter spp. in this study included C. jejuni (50%), C. coli (38%), and C. lari (12%). Among the detected virulence genes, cgtB (25%) was the most prevalent, followed by PldA (20%), cdtA (17%), cdtB (16%), cdtC (6%), wlaN (5%), iam (4%), ciaB (4%), and VirB11 (3%). The virulence gene waac was absent in all isolates. The resistance genes detected were tetA (42%), tetB (26%), gyrB (18%), and gyrA (14%). There was a significant association between the wlaN gene and the Campylobacter spp. (p<0.05). Of the 66 isolates, 64 (97%) were resistant to erythromycin, 63 (95.5%) were resistant to ciprofloxacin, and all were resistant to tetracycline. However, there was no significant association between the resistance genes and the phenotypic antimicrobial profile (p>0.05). Phylogenetic analysis showed that the Campylobacter isolates from Kibera had a common lineage. Missense mutations were observed in various regions of the pldA genes, while no mutations were found in the tetA and tetB genes. The study revealed the presence of various virulence and resistance genes in Campylobacter spp. isolated from children in Kibera, Nairobi, Kenya. This information could help guide the development and enhancement of antimicrobial guidelines for treating Campylobacter infections. Further research is needed to determine protective immunity, enforce antimicrobial stewardship, update information on Campylobacter resistance, and explore phylogenetic relatedness within the One Health concept.