Prevalence of Campylobacter jejuni in Raw Poultry Meat and the Effect of Zataria multiflora Essential Oil on cdtA Gene Expression

Abstract

Campylobacter jejuni (C. jejuni) is a major foodborne pathogen, and the expression of virulence genes such as cytolethal distending toxin subunit A (cdtA) plays an important role in its pathogenicity. This study determined the prevalence of C. jejuni in retail poultry products and evaluated the effect of Zataria multiflora (Z. multiflora) essential oil on cdtA gene expression. A total of 180 poultry samples, including chicken, quail, and ostrich, were examined using culture and PCR targeting the mapA gene. The antimicrobial activity of Z. multiflora essential oil was evaluated by the broth microdilution method to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). All 22 confirmed C. jejuni isolates (positive for cdtA) were exposed to isolate-specific MIC, 1/2 MIC, and 1/4 MIC concentrations. Relative cdtA expression was quantified by RT-qPCR using the 2−ΔΔCt method, and data were analyzed by one-way ANOVA followed by Tukey’s post hoc test. C. jejuni was detected in 22 of 180 samples (12.2%). MIC and MBC values ranged from 0.25–1.00 mg/mL and 0.50–2.00 mg/mL, respectively. Treatment with Z. multiflora essential oil significantly downregulated cdtA expression in a concentration-dependent manner. Relative expression decreased from 1.00 in the untreated control to 0.88, 0.77, and 0.63 following exposure to 1/4 MIC, 1/2 MIC, and MIC concentrations, respectively (P<0.05). Z. multiflora essential oil exhibited potent antibacterial activity against C. jejuni and significantly reduced cdtA gene expression, highlighting its potential as a natural antimicrobial for controlling this pathogen and attenuating its virulence.