C15 | Official control of bivalve molluscs in the province of Foggia in the period 2023-2024 and study of the antibiotic resistance characteristics of isolates

I. Ciuffreda¹, A. Castelluccio¹, MR. Sasso¹, N. Maino¹, A. Parisi², G. Normanno³, F. Petruzzi², C. Pedarra², V. Rondinone², M. Iammarino², L. Del Sambro², P. Di Taranto². | ¹Servizio igiene degli alimenti di origine animale - Azienda Sanitaria Locale Foggia; ²Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata; ³Dipartimento di Scienze Agrarie, Alimenti, Risorse Naturali e Ingegneria – Università degli Studi di Foggia.

Purpose. The Province of Foggia ranks among the top regions in Italy for the production and consumption of live bivalve molluscs (LBM), filter-feeding organisms capable of concentrating pathogens and chemical contaminants that may be present in the marine environment. LBM are traditionally consumed raw in Puglia and are therefore frequently responsible for foodborne illnesses (FBIs). Based on these assumptions, the purpose of this study was to verify the chemical and microbiological quality of official LVS samples taken in the Province of Foggia and to study the genotypic and phenotypic characteristics of antibiotic resistance and virulence genes of the isolated strains. Methods. From 1 January 2023 to 30 September 2024, staff from the Animal Food Hygiene Service (SIAV B) of the Foggia Local Health Authority collected 384 MBV samples. Of these, 275 samples were taken as part of the MBV monitoring plan in already classified areas (PdM) (74 subjected to microbiological analysis and 201 to chemical analysis), and 109 samples were taken as part of the Multi-Year Regional Control Plan (PCRP) (86 subjected to microbiological analysis and 23 to chemical analysis). The analyses were carried out at the laboratories of the Foggia headquarters of the IZS of Puglia and Basilicata. The samples were analysed using standardised methods for the determination of heavy metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dioxins, algal biotoxins, for the MPN count of E. coliand for the detection of Salmonella spp., Vibrio spp. and hepatitis A virus. The Salmonella spp. isolates were subjected to serotyping, minimum inhibitory concentration (MIC) determination to test for antimicrobial resistance (AMR) characteristics, and genomic sequencing on the Illumina Miseq platform at the Putignano (BA) section. Results. Of the 384 samples analysed, only 6 (1.56%) were found to be non-compliant: 4 taken as part of the PCRP and 2 from the PdM. Five of the non-compliances concerned exceeding the limits for E. coli and one concerned the presence of Salmonellaspp. The serotype isolated was S. Goldcoast, which was sensitive to all the antibiotics tested. Genome sequencing confirmed the absence of AMR-associated genes. However, the isolate harboured virulence genes (avrA, cdtB, invA, iroB, iroC, sinH, sseK2) and stress genes (golS, golT). All analyses for Vibrio spp., hepatitis A virus and chemical contaminants were favourable. Conclusions. The non-conformities led to immediate action by the Competent Authority (CA), i.e. within the PCRP: activation of the rapid alert system (RASSF), issuance of administrative sanctions and transmission of crime reports pursuant to Article 347 of the Italian Code of Criminal Procedure. For the PdM, the following measures were taken: temporary downgrading of the affected areas from A to B, follow-up sampling (DGISAN Note 0004821-P-11/02/2013) and subsequent revocation of the restrictive measures. In conclusion, the results show that the MBVs and water in the province of Foggia are of good sanitary quality, with a limited number of non-conformities. Compliance with control frequencies and timely management of critical issues have proven to be effective tools for protecting public health and preventing MTAs.