Detection of Campylobacter in Chicken Parts by Conventional Methods and Polymerase Chain Reaction with Identification of Antibiotic Resistance Profile

Background & Objective(s): Campylobacteriosis is a zoonotic, food-borne bacterial disease caused by Campylobacter spp. The most common pathogenic species are Campylobacter jejuni (C. jejuni) and C. coli. Multiple reservoirs harbor Campylobacter but chicken are considered the most common. Different chicken parts can harbour Campylobacter, particularly the intestine while chicken breasts usually have minimal counts. Antibiotics are used as feed as well as for therapeutic purposes in animals, and thus antimicrobial resistance of some Campylobacter isolates to common antibiotics is an issue of public health importance. The aim of this study was to detect C. jejuni and C. coli in chicken using conventional methods (culture followed by biochemical tests) and PCR, with identification of antimicrobial resistance of isolates.
Methods: In the present study, Campylobacter was isolated from 100 different chicken parts (thigh, neck, intestine and wings) collected from 40 different chickens. Culture on charcoal cefoperazone deoxycholate agar (CCDA) was followed by biochemical confirmation of Campylobacter spp then by matrix-associated laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Simultaneously, DNA of Campylobacter was detected from chicken broth by multiplex polymerase chain reaction (PCR). Both conventional and PCR methods were compared. Campylobacter colony count was determined for different chicken parts, and the antimicrobial resistance of isolates was identified. 
Results: Out of the 100 examined chicken samples, 79 were presumptively positive on CCDA while only 15 isolates were MALDI-TOF confirmed (18.98%). All samples had Campylobacter counts exceeding 104 cfu/g. Colony counts ≥105 cfu/gm were encountered in 77.7% of PCR positive samples. Multiplex PCR had low sensitivity (60%) for detection of Campylobacter in chicken broth compared to confirmed cultures. Despite this drawback, PCR was advantageous over culture in detecting samples with mixed Campylobacter species. The intestine had the highest frequency (27.5%) of Campylobacter, with 72.7% of its samples yielding ≥105 cfu/g. C. jejuni responded better to erythromycin, ciprofloxacin and chloramphenicol (susceptibility= 100%, 80% and 80% respectively) while C. coli had a poorer susceptibility profile. Tetracycline and nalidixic acid had a poor antibacterial effect on both C. jejuni and C. coli.
Conclusion: The distribution of Campylobacter species varied according to chicken part, with the intestine having the highest counts. All chicken samples had Campylobacter counts more than 10 4 cfu/g. PCR had 60% sensitivity compared to culture, but was more superior in detecting mixed cultures. C. jejuni was more sensitive to erythromycin, ciprofloxacin and chloramphenicol antibiotics than C. coli.