Bile-Salt Stress Activation of cadF and flaA Virulence Gene Expression in Zoonotic Campylobacter jejuni from Poultry with HPLC-Based Organic Acid Profiling in Al-Diwaniyah City, Iraq
DOI:
https://doi.org/10.65329/wjeb.v14.02.04Keywords:
Campylobacter jejuni, bile salts, foodborne pathogens, organic acids, poultry, RT-qPCR, virulence gene expression, zoonotic bacteriaAbstract
Campylobacter jejuni is a major zoonotic foodborne pathogen associated with poultry and poultry-derived products. This study evaluated whether bile-salt stress alters the expression of cadF and flaA in poultry-origin C. jejuni isolates and whether these changes correlate with HPLC-detected extracellular organic acid remodeling. A total of 160 poultry samples were tested for Campylobacter using selective culture, biochemical, and molecular methods. Twenty-two isolates of C. jejuni positive for cadF and flaA were exposed to 42 oC and bile-salt stress (0.15%, 6 h). Gene expression was quantified by RT-qPCR using rrs as the reference gene, while organic acids were measured by HPLC. Campylobacter spp. were recovered from 38/160 samples, giving an overall isolation rate of 23.8%. C. jejuni represented 26/38 isolates, or 68.4%. Among C. jejuni isolates, 22/26 (84.6%) were positive for both cadF and flaA. Bile-salt stress significantly increased cadF expression by 2.36-fold and flaA expression by 2.91-fold compared with the control condition. HPLC showed increased acetate from 34.5 ± 11.8 to 64.8 ± 18.6 mg/L, succinate from 8.9 ± 3.7 to 19.6 ± 7.4 mg/L, and format from 12.7 ± 5.1 to 24.3 ± 8.9 mg/L, while lactate decreased from 55.2 ± 17.4 to 31.7 ± 12.8 mg/L. flaA expression correlated positively with format accumulation, while cadF expression correlated positively with acetate concentration. Bile salts did not act only as an inhibitory intestinal barrier for poultry-origin C. jejuni; instead, bile exposure promoted coordinated virulence and metabolic adaptation that may support intestinal colonization and zoonotic transmission.
Article History:
Received August 17, 2026
Revised September 23, 2026
Accepted: September 27, 2026
Published: October 12, 2026
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Copyright (c) 2026 Hussein Kareem, Amaar Nabeel Al-Jubouri, Mustafa Sabbar Mhr, Mohammed Mahdi Yaseen (Author)
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