Carmine Pedarra

Poultry is the main reservoir of Campylobacter spp. and most human cases result from consuming undercooked poultry or handling raw meat. In 2022, a total of 55 samples, including neck skin, cecal contents, and processing waters, were collected at two poultry slaughterhouses in Italy and analysed according to ISO 10272-2:2017 at the Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata laboratories. Overall, 51/55 (92.72%) samples tested positive for Campylobacter. Among the isolates, 64.71% were identified as C. coli, and 35.29% as C. jejuni. Phenotypic and genotypic analysis were performed to assess antimicrobial resistance and virulence characteristics. All C. jejuni isolates and 72.72% of C. coli showed resistance to fluoroquinolones. Resistances to tetracycline and carbapenem were observed in 60.78% and 45.09% of isolates, respectively. Genomic analysis confirmed the presence of the tet(O) gene, conferring tetracycline resistance. In addition, OXA-450 and OXA-466 genes, conferring beta-lactam resistance, were detected in 78.43% and 3.92% of isolates. Virulence-associated genes were detected. Specifically, the ciaB gene was found in 50/51 (98.04%) of isolates, whereas jlpA, cdtA, cdtB, and ctdC genes were exclusively identified in C. jejuni strains. The high prevalence of pathogenic and antimicrobial-resistant Campylobacter strains highlights the need for strengthened control measures along the poultry production chain.

Salmonellosis is one of the most frequent foodborne zoonoses, and the consumption of contaminated poultry meat is considered the main source of Salmonella infections in humans. From 2021 to 2023, 384 chicken samples were collected from retailers in Apulia and Basilicata regions and analysed at the Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata (IZSPB) laboratories. The Salmonella isolates were investigated to evaluate their phenotypic characteristics of antimicrobial resistance. A total of 125 (32.55%) samples tested positive for Salmonella spp. Three samples were simultaneously infected with strains of two different serotypes. Strains were classified into nine serotypes. Out of 128 strains, 112 (87.5%) isolates showed multidrug-resistant (MDR) profiles. Moreover, 16 isolates (12.5%) were ESBL producers with MDR profiles. Our data confirm that chicken products are a common source of Salmonella and highlight how S. Infantis was the most prevalent serotype (85.93%). Furthermore, Salmonella isolates showed antimicrobial resistance, which is very worrisome for animals and consumers. The high rate of antibiotic resistance along with the appearance of numerous MDR isolates is considered an actual concern and requires a robust surveillance network in a One Health concept.

Salmonella Infantis is one of the most frequent serovars reported in broilers and is also regularly identified in human salmonellosis cases, representing a relevant public health problem. In the laboratories of the Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata (IZSPB), six Salmonella Infantis strains with antigenic formula -:r:1,5 have been isolated from the litter and carcass of broilers between 2018 and 2022. The strains were investigated to evaluate their phenotype, antibiotic resistance and genomic profiles. Genomic analysis confirmed that the isolates belonged to the Infantis serotype and to the sequence type ST32. Moreover, all strains showed a multidrug-resistant (MDR) profile and were characterised by the presence of the IncFIB plasmid incompatibility group. Three strains had the bla_CTX-M-1 gene, and one of them carried IncX1. The presence of this new variant of S. Infantis is particularly relevant because it could expand the landscape of the S. Infantis population. The absence of the somatic antigen could pose a problem in both isolation and serotyping and a consequent public health concern due to the spread of Salmonella infection.

The emergence of antimicrobial resistance (AMR) is increasingly common across the globe and aquatic ecosystems could be considered a reservoir of antibiotic-resistant bacteria. This study aimed to determine prevalence and antibiotic susceptibility of the potential pathogenic bacteria Salmonella spp. and Vibrio spp. in bivalve molluscs intended for human consumption, collected over a period of 19 months along the northern coast of Apulia region. The AMR profile was also determined in non-pathogenic Vibrio species, common natural inhabitants of seawater and a useful indicator for the surveillance of AMR in the environment. The current study presents data on the AMR of 5 Salmonella and 126 Vibrio isolates by broth microdilution MIC. Multidrug resistance (MDR) was observed in one S. Typhimurium strain towards sulfamethoxazole, trimethoprim, tetracycline, gentamicin, and ampicillin and in 41.3% of the Vibrio strains, mostly towards sulphonamides, penicillin, and cephems. All Vibrio isolates were sensitive to azithromycin, chloramphenicol, tetracycline, amoxicillin/clavulanic acid, gentamicin, streptomycin, amikacin, and levofloxacin. The AMR phenomenon in the investigated area is not highly worrying but not entirely negligible; therefore, in-depth continuous monitoring is suggested. Results concerning the antibiotic agents without available specific clinical breakpoints could be useful to upgrade the MIC distribution for Vibrio spp. but, also, the establishment of interpretative criteria for environmental species is necessary to obtain a more complete view of this issue.