Molecular profiling of virulent, multidrug-resistant Campylobacter jejuni isolates from broiler flocks in Ismailia, Egypt.

Multidrug-resistant, virulent C. jejuni in Egyptian broilers poses a serious zoonotic and food safety threat.

This study investigated the prevalence, antimicrobial resistance, and virulence gene profiles of Campylobacter jejuni isolated from broiler chicken samples collected at slaughterhouses in Ismailia, Egypt. A total of 100 samples were examined, including drippings, neck skin, and cecal swabs, with C. jejuni identified in 18% of samples using 23S rRNA and mapA gene molecular confirmation. All isolates demonstrated complete resistance to tetracycline, while high resistance rates were also observed against amoxicillin (83.3%), sulphamethoxazole-trimethoprim (72.2%), and erythromycin (66.7%). Meropenem remained universally effective. Five distinct phenotypic resistance profiles were identified, with multidrug resistance predominating. Genotypically, tet(O) was detected in 100% of isolates and blaOXA-61 in 83.3%, confirming the genetic basis of resistance. Virulence gene analysis revealed universal presence of cadF and dnaJ (100%), with flaA in 44.4% and cdtB in 22.2% of isolates, producing three distinct virulence profiles. The co-occurrence of multidrug resistance genes and key virulence determinants—particularly those involved in host cell adhesion, stress response, motility, and cytolethal distending toxin production—represents a significant public health concern. These findings highlight the role of broiler chickens as a reservoir for virulent, multidrug-resistant C. jejuni strains capable of causing severe human campylobacteriosis through carcass contamination at slaughter, emphasizing the need for improved biosecurity, antimicrobial stewardship, and slaughterhouse hygiene practices in Egypt.

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