Thesis:

Study of the prevalence of Campylobacter jejuni in slaughtered chickens in Qain County in 1404.

Campylobacter jejuni is one of the most common bacterial pathogens responsible for gastrointestinal infections in humans, particularly following the consumption of contaminated poultry meat. This study aimed to determine the prevalence of C. jejuni in slaughtered chicken carcasses in Qaen County in 2025 and to analyze the factors influencing contamination, including slaughtering and processing methods, seasonality, rearing systems, and antibiotic resistance patterns. In this cross-sectional and applied study, 100 chicken carcass samples were randomly collected from slaughterhouses in Qaen. The samples were examined using standard microbiological culture techniques, Gram staining, biochemical tests, and observation of bacterial motility under microaerophilic conditions. Additionally, antibiotic resistance of the isolated C. jejuni strains was evaluated against four commonly used antibiotics: erythromycin, ciprofloxacin, tetracycline, and gentamicin. The findings showed that 49% of the carcasses were contaminated with C. jejuni. The highest contamination rate was observed in July (66%), while the lowest was recorded in April (40%). Carcass samples showed a higher contamination rate than intestinal samples. High levels of resistance were detected against tetracycline, gentamicin, erythromycin, and ciprofloxacin. Moreover, a significant positive correlation was found between contamination rates and environmental temperature and humidity (P value < 0.01). There was also a significant association between the slaughtering month and contamination levels, indicating an increase in contamination during warmer months (P value < 0.05). The relatively high prevalence of C. jejuni in poultry carcasses in Qaen, along with notable resistance to commonly used antibiotics, underscores the need to improve hygienic practices during slaughter and processing, and to enhance monitoring of antibiotic use in poultry farming. Effective control measures can play a crucial role in reducing the transmission of this pathogen to humans

Keywords: Chicken carcass contamination, slaughterhouse contamination, Campylobacter jejuni, antibiotic resist