Genetic characterization and molecular detection of antimicrobial resistance genes and virulence genes present in campylobacter spp. isolated from broiler chickens and human clinical samples in Durban.

Abstract

Campylobacter jejuni and Campylobacter coli have evolved as the most prevalent Campylobacter species which are responsible for gastroenteritis infections in humans. Successful infection and continued fitness of Campylobacter species depend on virulence determinants and antimicrobial resistance elements which differ amongst strains of different origin. There is a paucity of information regarding Campylobacter virulence genes and the antimicrobial resistance genes in developing countries such as South Africa. Therefore, research is essential to characterize pathogenic markers and to implement strategies for proper control and prevention of infection caused by this pathogen. This study aimed to detect the presence of virulence genes such as: cadF, hipO, asp, ciaB, dnaJ, pldA, cdtA, cdtB and cdtC as well as the detection of genes associated with antimicrobial resistance which included gyrA, blaOXA-61and tetO present in C. jejuni and C. coli. Following ethical approval, 100 commercial chicken fecal samples were collected and 100 human clinical isolates were selected from a collection of Campylobacter spp. which originated from a private pathology laboratory in South Africa. From the 100 chicken fecal samples 78% were positive for Campylobacter growth on mCCDA and from the collection of a 100 human clinical isolates 83% demonstrated positive Campylobacter spp. growth following culturing methods. The cadF gene was present in 100% of poultry and human clinical isolates. This could indicate that the presence of this gene is needed for successful infection in a host. C. jejuni was the main species detected in both poultry and human clinical isolates while C. coli were detected at a low incidence (chicken =13%, human=17%) and therefore, not statistically significant in either host (p>0.05). The resistance genes gyrA(235bp), gyrA(270bp), blaOXA-61 and tetO were also detected at a higher percentage (51%, 36%, 58% and 68% respectively) in chicken samples compared to human clinical samples (49%, 36%, 53% and 64% respectively). In conclusion, this study demonstrated high prevalence of virulence and antibiotic resistance genes in Campylobacter species from South Africa. The high prevalence rates demonstrated the importance of Campylobacter spp. as a food borne zoonotic pathogen capable of causing persistent infection due to acquisition of antimicrobial resistance genes and virulence genes via the food chain. The study finally recommended limited and prudent use of antimicrobial agents as a mitigating measure to combat the evolution of multiple drug resistance.