Determination of disinfectant resistance in salmonella infantis isolates isolated from reformed chicken slaughter line

Salmonellosis is a disease that ranks first in terms of foodborne bacterial diseases worldwide, depending on the development level of countries. Since it is a zoonotic disease, the economic loss it causes, especially to the poultry sector, is also quite significant. In the present study, a total of 12 samples were collected from 17 different regions along the slaughter line in the reformed chicken slaughterhouse at various times (n=206) to isolate Salmonella spp. using classical culture methods and to investigate antibiotic resistance in the isolates. The Salmonella spp. isolates identified through classical culture methods were confirmed at the species level by PCR targeting the invA gene. The resistance of the isolates to selected antibiotic groups was determined using the Kirby-Bauer Disk Diffusion Method, with zone diameter values referenced from EUCAST guidelines. The number of isolates obtained from the samples taken from 17 different regions of the reformed poultry slaughter line and confirmed by invA-based PCR was determined to be 29 (14.21%). In the evaluation based on the slaughter line sampling regions, the highest isolation rates were 33.3% for the electroshock surface and packaging bench; 25.0% for live line hangers, knives, and personnel hands; 16.7% for the transfer belt to the evisceration section, evisceration hangers, evisceration apparatus, cooling water, and final product; and 8.33% for the boiling tank surface and evisceration benches. When evaluating the antibiotic resistance results observed in the isolates, it was found that three isolates obtained from the live line hangers, boiling surface, and packaging counter stages were resistant to all antibiotics tested. The antibiotic with the highest resistance, Cefuroxime, showed resistance in 17 isolates and moderate resistance in 12 isolates. This was followed by Ampicillin with 20 isolates and Amoxicillin/Clavulanic Acid with 19 isolates. The lowest resistance was observed with Imipenem, showing resistance in only 2 isolates. It was noted that the Salmonella spp. isolates from five stages were resistant to all antibiotics except Imipenem. These stages were identified as the electroshock surface, knife surface, cooling, packaging counter, and final product. In conclusion, high levels of antimicrobial resistance were detected in the Salmonella spp. isolates, with resistance profiles particularly against critical antibiotics indicating widespread multidrug resistance. These findings provide valuable data for public health in the development of strategies to combat antimicrobial resistance. Key Words: Antibiotic resistance, reformed chicken, slaughter line, Salmonella spp