Investigating Campylobacter Contamination of Broiler Chicken in Isfahan Province (Iran) and Evaluating the Antibiotic Resistance Patterns of the Isolates

Thermophilic Campylobacter species are a major cause of bacterial diarrhea transmitted to humans through the consumption of raw or undercooked food derived from livestock and poultry. This study aimed to isolate and identify thermophilic Campylobacter strains in broiler chickens from Isfahan Province using culture and polymerase chain reaction (PCR) methods and to determine the antibiotic susceptibility of the isolates. A total of 200 fecal samples were randomly collected from 20 broiler flocks in Isfahan Province between October 2023 and late March 2024. Samples were cultured in specific media under microaerophilic conditions. Molecular identification was based on the detection of an 816‐base pair band (16S rRNA gene— Campylobacter genus), a 462‐base pair band ( ceuE gene— Campylobacter coli ), and a 589‐base pair band ( mapA gene— Campylobacter jejuni ). Of the 200 fecal samples, 4 (2%) were identified as contaminated with Campylobacter spp., with 2 (50%) identified as C. coli and 2 (50%) as C. jejuni . In antibiotic susceptibility tests, all isolates (100%) were resistant to erythromycin, azithromycin, streptomycin, tetracycline, gentamicin, doxycycline, sultrim, chloramphenicol, and ciprofloxacin. C . jejuni isolates (100%) were susceptible to ceftriaxone, while one C. coli isolate (50%) showed intermediate susceptibility. Additionally, one C. jejuni isolate (50%) was susceptible to lincomycin–spectinomycin. Moreover, all isolates (100%) exhibited multidrug resistance (MDR). The results of this study reveal the presence of Campylobacter contamination in broiler poultry in Isfahan Province, highlighting its role as a zoonotic pathogen. Based on the observed antibiotic resistance patterns, it is recommended to enforce stricter regulations on the use of antibiotics in the poultry industry.