Listeria monocytogenes, the leading cause of fatalities among foodborne pathogens, exhibits remarkable resilience in food industry environments. This study aims to isolate and characterize L. monocytogenes strains along the beef production chain of a vertically integrated industry. Sampling included carcass, hide, and environmental samples collected from a cattle unit and partner slaughterhouse. The samples were examined for the presence of Listeria monocytogenes. The isolates were characterized via molecular serotyping and MALDI-TOF proteomic analysis. Further analyses included antimicrobial susceptibility testing, biofilm formation assessment, and virulence gene investigation. A total of 24 L. monocytogenes strains were isolated. The prevalence in carcasses, hide and slaughterhouse environment was 21.7%, 6.7% and 8.8% respectively. Molecular serogroup IIc predominated, followed by serogroups IIa, IIb, and IVb. Almost all strains showed a moderate or strong ability to produce biofilms and resistance to at least one antimicrobial, with clindamycin, vancomycin, and tetracycline demonstrating the highest rates of resistance. Three strains were also characterized as multidrug-resistant, while all strains possessed at least six virulence genes. The proteomic analysis organized the isolated strains in three clusters, whereas the transmission pathways primarily implicated carcass washing water and hides. Understanding L.monocytogenes dissemination along the beef production chain is vital for preventing transmission to humans and emergence of a listeriosis outbreak.

Extended-spectrum-β-lactamase (ESBL) and carbapenemase-producing Escherichia coli, Klebsiella pneumoniae and Acinetobacter spp. are associated with hospital-acquired infections and are commonly isolated across the poultry food production chain. Comprehensive data regarding the prevalence, spatiotemporal variations, and characterization of β-lactam-resistant bacteria in poultry farms and slaughterhouses is scarce. This study examines the prevalence and characteristics of β-lactam-resistant E. coli, K. pneumoniae, and Acinetobacter spp. isolated from poultry farms, slaughterhouses, and associated personnel in Greece. Strains were selectively isolated and identified via MALDI-TOF MS, which was also employed to identify possible relatedness. E. coli isolates were further classified into phylogenetic groups. The prevalence of β-lactam-resistant strains in farm and slaughterhouse environments was 15.0% (n = 15 strains)/57.3% (n = 71 strains) for E. coli, 11.0% (n = 11 strains)/1.6% (n = 2 strains) for K. pneumoniae, and 1.0% (n = 1 strain)/25.8% (n = 38 strains) for Acinetobacter spp., respectively. The prevalence of Acinetobacter spp. and E. coli on farmers’ skin was 16.7% (n = 2 strains) and 8.3% (n = 1 strain), correspondingly. Significantly higher E. coli isolation rates were observed in warmer seasons. All strains were multidrug-resistant and most carried ESBL/AmpC genes. Most E. coli isolates belonged to phylogroups A (41.4%, n = 36) and B1 (24.1%, n = 21). Proteomic analysis indicated relatedness among strains from different regions and seasons. Thus, poultry farms and slaughterhouses may serve as significant reservoirs of β-lactam-resistant strains of E. coli, K. pneumoniae, and Acinetobacter spp.

Background: Extended-spectrum-β-lactamase (ESBL) and carbapenemase-producing Enterobacterales and Acinetobacter spp. pose significant challenges as nosocomial pathogens, demonstrating resistance against various antimicrobials. Their presence in food suggests that hospital kitchens could serve as antibiotic resistance reservoirs leading to patients’ infection. Objectives: The aim of this study was to assess the prevalence and characteristics of β-lactam-resistant strains of Escherichia coli, Klebsiella pneumoniae, and Acinetobacter spp. isolated from the kitchen environment and from the staff of two Greek hospitals. Methods: Strains were recovered after selective isolation with β-lactams and were identified with MALDI–TOF MS. Antimicrobial susceptibility and presence of common β-lactamase genes were evaluated. Protein profiles were examined to analyze potential relationships of the strain with those from hospital patients. E. coli strains were further categorized into phylogenetic groups. Results: The overall prevalence in the kitchen environment was 4.5%, 1.5%, and 15.0% for E. coli, K. pneumoniae, and Acinetobacter spp., respectively, whereas the prevalence of Acinetobacter spp. in human skin was 4.0%. Almost all strains were multidrug-resistant. All E. coli strains were ESBL producers and belonged to phylogroups A and B1. All K. pneumoniae and seven Acinetobacter strains were carbapenemase-producers. A protein profile analysis showed relatedness between chicken and kitchen environment strains, as well as between kitchen environment and patient strains originated either from the same or from different hospitals. Conclusions: The results suggest that hospital kitchens may act as important pathogen hotspots contributing to the circulation of resistant strains in the hospital environment.