Molecular Analysis of Campylobacter Jejuni Virulence Genes From Clinical Isolates In Qatar

Abstract

Background: Campylobacter jejuni is the main cause of gastroenteritis worldwide. Symptoms of C. jejuni infections range from asymptomatic to bloody diarrhea. Previous studies showed a strong association between diversity in presence of bacterial virulence factors including: Campylobacter invasion protein B (CiaB), fibronectin-binding outer membrane protein (CadF), cytolethal distending toxin B (CdtB), Clp ATP dependent protease (ClpP) and HtrB protein. The aim of this project was to study the association between prevalence of the aforementioned genes, the antimicrobial resistance patterns of the isolates, and the demographic data of patients. Methodology: A total of 174 archived isolates of C. jejuni were obtained from stool samples of symptomatic patients in the Microbiology Laboratory at Hamad Medical Corporation (HMC). Isolates were revived using selective media and DNA was extracted from posititve colonies. C. jejuni isolates were screened by real-time PCR for the presence of five of virulence-associated genes. Isolates were also tested for the antimicrobial susceptibility to common antimicrobial agents used in HMC including: chloramphenicol, ciprofloxacin, erythromycin and gentamicin. Demographic data such as age, gender and nationality were also collected fromt he medical charts of subjects included in this study. Results: 75% of the isolates were obtained from patients younger than 5 years old. 60.3% of the participants were males and 57% of the subjects were from the Arabian Peninsula. All the virulence genes were detected with different percentages. There was a significant association between gender (male) and presence of two of the virulence genes cadF and clpP (P value: 0.022 for both). No clear associations were found between presence of the remaining virulence genes and demographic data; or between antimicrobial susceptibility patterns with age, gender and nationality. Isolates were highly sensitive to all antimicrobial agents except ciprofloxacin, where high resistance was observed. Conclusion: Gender (male) was strongly associated with presence of cadF and clpP genes. Other correlations between prevalence of virulence genes, antimicrobial susceptibility and demographic data were found to be insignificant. Further investigation on the characteristics Campylobacter jejuni, and how they induce different symptoms and responses to their infection are needed.