Molecular Detection of Virulence‐Associated Markers in <i>Campylobacter coli</i> and <i>Campylobacter jejuni</i> Isolates From Water, Cattle, and Chicken Faecal Samples From Kajiado County, Kenya

Abstract

<i>Campylobacter</i> is a zoonotic foodborne pathogen that is often linked with gastroenteritis and other extraintestinal infections in humans. This study is aimed at determining the genetic determinants of virulence-encoding genes responsible for flagellin motility protein A (<i>flaA</i>), <i>Campylobacter</i> adhesion to fibronectin F (<i>cadF</i>), <i>Campylobacter</i> invasion antigen B (<i>ciaB</i>) and cytolethal distending toxin (cdt) A (<i>cdtA</i>) in <i>Campylobacter</i> species. A total of 29 <i>Campylobacter coli</i> isolates (16 from cattle, 9 from chicken, and 4 from water samples) and 74 <i>Campylobacter jejuni</i> isolates (38 from cattle, 30 from chicken, and 6 from water samples) described in an earlier study in Kajiado County, Kenya, were examined for the occurrence of virulence-associated genes using polymerase chain reaction (PCR) and amplicon sequencing. The correlations among virulence genes were analyzed using Pearson's correlation coefficient (<i>R</i>) method. Among the 103 <i>Campylobacter</i> strains screened, 89 were found to harbour a single or multiple virulence gene(s), giving an overall prevalence of 86.4%. <i>C. jejuni</i> strains had the highest prevalence of multivirulence at 64.9% (48/74), compared to <i>C</i>. <i>coli</i> (58.6%, 17/29). The <i>ciaB</i> and <i>flaA</i> genes were the most common virulence genes detected in <i>C</i>. <i>jejuni</i> (81.1% [60/74] and 62.2% [46/74], respectively) and in <i>C. coli</i> (each at 62.1%; 18/29). <i>Campylobacter</i> isolates from chicken harboured the most virulence-encoding genes. <i>C. jejuni</i> strains from chicken and cattle harboured the highest proportions of the <i>cdtA</i> and <i>ciaB</i> genes, respectively. All the <i>C. coli</i> strains from water samples harboured the <i>cadF</i> and <i>flaA</i> genes. The results obtained further revealed a significant positive correlation between <i>cadF</i> and <i>flaA</i> (<i>R</i> = 0.733). <i>C. jejuni</i> and <i>C. coli</i> strains from cattle, chicken, and water harbour virulence markers responsible for motility/colonization, invasion, adherence, and toxin production, evoking their important role in campylobacteriosis development among humans and livestock. The identification of cattle, chicken, and water samples as reservoirs of virulent <i>Campylobacter</i> spp. highlights the possible risk to human health. These data on some virulence genes of <i>Campylobacter</i> will assist food safety and public health officials in formulating policy statements.