P21 | Molecular characterization of heat-resistant Campylobacter species in poultry meat samples collected within the framework of official control: study of prevalence and antibiotic resistance profile

S. Bartalena¹, F. Campeis², P. Marconi², P. Alba², M. F. Iulietto², A. Tavanti¹, M. Senese², L. Gasperetti² | ¹Dipartimento di Biologia, Università di Pisa; ²Istituto Zooprofilattico Sperimentale del Lazio e della Toscana M. Aleandri, Italy

Purpose. This study aimed to evaluate the prevalence of Campylobacter spp. in poultry meat samples collected from the Northwest Tuscany region, identify the species of the isolated strains, and assess their antibiotic resistance profile. Methods. In samples of fresh poultry meat (chicken and turkey) taken as part of official control, Campylobacter spp. was searched for in each of the 5 sampling units (SUs) that make up the sample. For each UC, both a quantitative and a qualitative analysis were performed by taking test portions (TP) of 25 g of the matrix. Qualitative analysis was performed using the Real-Time PCR method (AOAC iQCheck® n 031209 2012) to assess the presence of DNA in the TPs. Positive TP results were confirmed using the culture method (ISO 10272-1:2017/Amd1:2023). Quantitative analysis was performed using the ISO 10272-2:2017 method. The isolates were subjected to molecular identification by multiplex PCR (ISO 10272-2:2017/Amd1:2023) for the detection of the species C. jejuni, C. coli, and C. lari. The Minimum Inhibitory Concentration (MIC) was calculated using the Sensititre system on at least one isolate per positive sample to assess the antibiotic resistance profile (AMR). The same strains were subjected to Whole Genome Sequencing (WGS) in order to identify the Sequence Type (ST) and their belonging to gene clusters, as well as the genetic determinants of antibiotic resistance. Finally, a statistical correlation analysis was conducted using R software. Results. 34 samples, totaling 170 TP, were collected and analyzed at the Pisa location of the Istituto Zooprofilattico Sperimentale del Lazio e della Toscana (IZSLT). Qualitative analysis detected the presence of Campylobacter spp. DNA in 49% of the TP; Confirmation tests detected the presence of the pathogen in 56 TP, with a frequency of 32.94% of the total TP. Molecular identification detected C. jejuni in 61% of the TP samples and C. coli in 39%. C. lari was not found in any TP sample, while both C. jejuni and C. coli were found in 3 samples. The MIC was calculated for 16 isolated strains of Campylobacter spp. at the National Reference Center for Antibiotic Resistance (IZSLT), revealing: 15 strains resistant (R) to Ciprofloxacin, 12 R to Tetracycline, and 0 R to Gentamicin, Erythromycin, and Chloramphenicol. The two Campylobacter species showed similar antibiotic resistance profiles. From the sequencing of the genomes of the 13 selected strains, the following were identified: 7 strains with the tet(O) gene, 1 with tet(O/32/O), 9 with blaOXA-193, and 2 with blaOXA-466. The STs were different except for two pairs of C. jejuni. The data suggests a correlation between the presence of skin in the samples and the isolation of C. jejuni. The latter appears to have a greater variety of AMR-related genes compared to C. coli. MLST genotyping revealed that the strains, although belonging to the same species, do not originate from the same clone, differing in virulence, antibiotic resistance, and epidemiological behavior. Conclusions. The results obtained, although only representative of a part of the regional territory, offer a useful local overview for improving pathogen monitoring in food, contributing to food safety risk assessment and management.