Comparative Virulence Gene Profiling of Campylobacter jejuni and Campylobacter coli Isolates from Avian and Human Sources in Egypt

Campylobacter species are considered to be the leading bacterial cause of human gastroenteritis globally. Consumption of undercooked or contaminated food, such as chicken, is the main cause of human campylobacteriosis. Despite this significant zoonotic link, comparative data on virulence determinants in Campylobacter isolates across avian and human sources remain limited. This study aimed to characterize the prevalence and expression of virulence determinants in Campylobacter jejuni and Campylobacter coli isolates from chicken and human sources in Ismailia governorate, Egypt. A total of twenty C. jejuni and C. coli isolates (ten of each species) were screened for 14 virulence genes using PCR. All isolates harbored virB11, iam, racR, and tetO. Chicken isolates exhibited a significantly higher prevalence: C. jejuni (chicken): pldA, dnaJ, flaA (100%), cdtB (80%), ciaB (60%), and wlaN (0%); C. coli (chicken): pldA, dnaJ (100%), flaA (60%), cdtB (60%), ciaB (40%), and wlaN (20%). In contrast, human isolates showed a markedly lower prevalence: C. jejuni (human): dnaJ, flaA, and cdtB (20%); C. coli (human): dnaJ, flaA, and cdtB (40%). Crucially, pldA, ciaB, and wlaN were absent in all human isolates. plda and dnaJ genes showed statistically significant prevalence differences. qPCR revealed a significant upregulation (p < 0.05) of dnaJ, virB11, flaA, and iam in chicken isolates compared to human isolates, with log2 fold changes of 3.52, 2.84, 2.43, and 1.90 for C. jejuni and 3.06, 2.38, 1.51, and 1.32 for C. coli. Differential expressions of racR, cdtB, and tetO were not significant, with log2 fold changes ranging from −0.51 to 0.14. Ganglioside mimicry genes (Cst11, wlaN, Waac, ggt, and cgtB) and the carbon storage regulator gene (csrA) were absent in all human isolates. These findings underscore the significant variability in virulence gene profiles in chicken and human C. jejuni and C. coli isolates and highlight the importance of molecular characterization in the risk assessment and epidemiological surveillance of Campylobacter infections.