This study compares Salmonella monitoring data obtained from food business operator (FBO) self-monitoring and competent authority (CA) official sampling on pig carcasses in a high-throughput Italian slaughterhouse over 10 years (2012-2021 for FBO; 2014-2021 for CA). A total of 1560 FBO and 377 CA samples were analyzed. Salmonella prevalence was 3.46% [95% confidence interval (CI): 2.6-4.5] for FBO and 10.34% (95% CI: 7.3-13.5) for CA, with statistically significant yearly differences in 2015, 2017, 2018, and 2020 (p<0.05). Derby was the predominant serovar (22.6%); however, 20.4% of the FBO isolates were classified only as “No Typhimurium and Enteritidis”, highlighting gaps in serotyping protocols. Discrepancies likely reflect differences in sampling frequencies, carcass origins, and the use of different accredited laboratories by FBO and CA (private and official ones, respectively). The study identifies regulatory ambiguities, including a mistranslation in the Italian Ministerial Note, and recommends enhanced farm-level controls and harmonized surveillance.

Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens commonly carried by cattle and responsible for severe human diseases, as bloody diarrhoea (BD) and haemolytic uraemic syndrome (HUS). In an Italian slaughterhouse, 150 dairy cows were tested by swabbing the hides after stunning and the carcasses before refrigeration. STEC prevalence was 6.7% on hides and 4.0% on carcasses. No hide-to carcass contamination in the same animal was observed. Twenty isolates belonging to the serotypes O26:H11, O55:H9, O55:H12, O109:H10, O116:H28, O127:H12, O150:H2 (hides only), O157:H7 and O177:25 (hides and carcasses), O84:H2 and O177:H11 (carcasses only) were detected and analysed by Whole Genome Sequencing. Following published risk ranking schemes, STEC isolates were classified into seven groups according to their virulence gene profiles (stx1 and stx2 variants and the presence/absence of eae), in descending order from those most frequently associated with BD and HUS (groups I-V) to those considered least pathogenic (groups VI and VII). Overall, 75% of the isolates were assigned to groups I-V, highlighting the substantial pathogenic potential of the bovine strains. Regarding antimicrobial resistance, only one isolate (5%) was resistant to four or more antimicrobial classes, while 15% of the isolates carried ESBL-genes (blaCTX-M-1, or blaTEM-1 A, or blaTEM-1B) and displayed phenotypic resistance to ampicillin. Nevertheless, current therapeutic options of STEC infections suggest the use of azithromycin, a bacteriostatic agent that can avoid the progression of BD to HUS. Notably, all STEC isolates classified within groups I-V were susceptible to azithromycin, thus suggesting its potential usefulness in patient treatments.

Wild boars are the most widespread large wild mammals globally, capable of reaching high population densities due to their ecological adaptability and human-related factors. This leads to significant environmental, economic, and public health issues, making effective management essential. Hunting remains the most efficient control strategy and offers the potential to develop a game meat supply chain. However, wild boars are known carriers of foodborne pathogens and antimicrobial-resistant bacteria, and various hunting-related factors can influence carcass hygiene. This study aimed to assess microbial hygiene indicators—aerobic colony count (ACC), Enterobacteriaceae count (EntC), Salmonella, and Escherichia coli—in wild boars hunted in the Emilia-Romagna, northern Italy, during the 2022/2023 and 2023/2024 hunting seasons. A total of 115 sponge samples from carcasses and 78 diaphragm muscle samples were collected from eight game-handling establishments (GHEs), with biometric and process-related data also recorded. Results showed average ACC and EntC levels of 4.22 and 2.27 log CFU/cm2, respectively. Salmonella was found in 3.48% of samples, with limited resistance detected (only one isolate resistant to sulfamethoxazole). E. coli was detected in 97.43% of the samples, with no resistance observed to third-generation cephalosporins or carbapenems. Of these E. coli isolates, 39.5% harboured at least one virulence gene, and the majority were classified as atypical enteroaggregative E. coli (aEAEC). The study highlighted that time intervals between killing, evisceration, and skinning had a significant impact on hygiene, recommending completion of all steps ideally within 4 h. Although specific hygiene criteria for wild game are lacking, the observed microbial levels were within acceptable limits set for livestock by Regulation (EC) No 2073/2005. The findings underscore the need for standardized processing practices to ensure safety in wild boar meat production.

IntroductionAntimicrobial resistance (AMR) is a global concern, particularly worsened by the spread of multidrug-resistant (MDR) bacteria such as Klebsiella pneumoniae.MethodsThis study investigated the presence of extended-spectrum β-lactamase (ESBL) and carbapenemase-producing K. pneumoniae in wild birds (corvids and waterfowl) and in red foxes in Northern Italy.Results and discussionAlthough the overall prevalence of K. pneumoniae in the present study was relatively low (2.0, 95% CI: 1.0–3.7%), its isolation from multiple wild species confirms the environmental circulation of this clinically relevant AMR bacterium in ecosystems not directly exposed to antibiotic pressure. In particular, the isolation of a carbapenemase-producing strain from a fox highlights the introduction of clinically significant carbapenemase genes into wildlife reservoirs. The phenotypic AMR profiles of K. pneumoniae isolates revealed a high prevalence of MDR strains that were largely confirmed by the genomic analysis. In-silico analyses of K. pneumoniae sequencing data led to the identification of the most frequent resistance genes and the in-silico typing reveals the prevalence of the ST307 high-risk clone. Remarkably, wildlife could be considered a significant AMR sentinel, serving as carriers of MDR K. pneumoniae in different and even distant geographic areas. These findings underscore the importance of integrating wildlife surveillance to monitor the environmental spread of AMR within a One Health approach.

Regulation (EU) 625/2017 emphasizes prevention over inspection, assigning primary responsibility for food safety to the food business operator. At the same time, official control systems ensure compliance with the European Union regulations. In recent years, voluntary third-party assurance programs have emerged as a complement to public regulations. This review explores their role, advantages, and challenges within this evolving regulatory landscape. Private standards have expanded rapidly in response to consumer demand for safer and more ethically produced food. While these certifications offer benefits, they also pose challenges, requiring continuous oversight and potential harmonization to ensure reliability. Some European countries now integrate private standards into official controls, recognizing their potential to strengthen regulatory frameworks. Certified food safety management systems, such as the British Retail Consortium or ISO 22000, can complement official control by improving compliance and efficiency. However, discrepancies between official inspections and third-party audits persist, necessitating careful coordination. To ensure effective integration, competent authorities must monitor the performance of private systems through audits and random checks. Despite some challenges, integrating private systems into official controls could be mutually beneficial. Future advancements will depend on effective collaboration among policymakers, industry, regulatory agencies, and other stakeholders, fostering a more robust food safety system.

The exploration of chemical space is crucial for advancing antibacterial drug discovery and developing novel therapeutic agents. We used a bismuth compound that restores carbapenem sensitivity in NDM-1-producing bacterial strains as a starting point to design a library of compounds through modifications of both the central metal core and ligand structure. The metal was substituted with other p-block metals like gallium(III) and antimony(III), while the ligand, a thiosemicarbazone, was derivatized, yielding a library of 16 compounds for biological evaluation. The synthesized compounds were tested for antimicrobial activity. Synergistic studies with resistant strains identified new lead compounds that restored antibiotic sensitivity. In vivo toxicity using Galleria mellonella larvae showed favorable safety profiles for several compounds. Despite strong in vitro activity, the compounds did not significantly improve survival rates in infected larvae, either as monotherapies or in combination with antibiotics. This study highlights the potential of rational lead compound modifications to identify novel antimicrobial agents.

Hospital-acquired infections (HAIs) are a significant concern in human medicine and have increasingly been reported in veterinary settings as well. Veterinary Teaching Hospitals may present a heightened risk for HAIs, partly due to the lack of standardized infection control measures and screening protocols. In May 2022, a cat previously hospitalized at a Veterinary Teaching Hospital for urinary tract obstruction developed a catheter-associated urinary tract infection (CAUTI). A multidrug-resistant (MDR) strain of Klebsiella pneumoniae was isolated. To investigate the suspected HAI and assess the presence of other MDR Gram-negative bacteria, an environmental screening of different hospital surfaces was conducted using both phenotypic and genotypic analyses. A total of 70 swabs were collected from environmental surfaces, 51 before and 19 after cleaning procedures. Sterility was observed in 19.6

The food business operators (FBOs) hold the main responsibility for food safety, based on the Regulation (EC) No 852/2004 and realized by the application of the hazard analysis and critical control point (HACCP) principles. They should implement a self-checking system (SCS) and may adopt voluntary food safety management system based on international standards, that are believed to strengthen HACCP functioning. Both official controls conducted by the Competent Authorities (CAs) and private voluntary standards play essential roles in maintaining food safety. In addition, customer complaints are highlighted as valuable feedback for FBOs, contributing to continuous improvement efforts. The present study aimed (i) to compare the non-compliances assigned by the CA during official inspections and audits carried out in a large slaughterhouse with the non-conformities registered by the FBO in the SCS during a five-year period, (ii) to evaluate, in the same period of time, the customer complaints managed by the FBO as non-conformities being part of the Food Safety Management System, and (iii) to examine potential overlapping of SCS and official controls. The majority of non-conformities/non-compliances in the slaughterhouse were related to the finding of non-conforming products, maintenance deficiencies, and lack in housekeeping and hygiene. The types of observations varied among the three groups—FBO, CA, and customers—with different areas of focus. Both official controls and SCS are of crucial importance and can sometimes overlap, but the suggestion to reduce the frequency of official inspections should not be considered because such controls have different values and are both crucial. Moreover, those controls should nevertheless be complemented by attentive consideration of customer complaints.

Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens frequently carried by cattle, responsible in humans of mild to bloody diarrhoea, haemolytic uraemic syndrome (HUS) and even death. In 2023-2024, a study on STEC contamination of hide and carcasses of dairy cattle at slaughter was planned in Emilia-Romagna region (northern Italy). When the study was still in progress and 60 animals were sampled, the detection of STEC O177 isolates reached high rates and gained our attention. A total of five O177 STEC strains were detected, namely four from three carcasses (5.0 %) and one from a hide sample (1.7 %). The isolates were typed by WGS as following: 1) STEC O177:H11 sequence type (ST) 765 (stx2a+, eae+), detected from one carcass; 2) STEC O177: H25 ST659 (stx2c+, eae+) detected from three carcasses and one hide sample. One carcass was contaminated by both STEC serotypes. The isolates carried other virulence determinants often found in STEC strains associated with HUS, namely the exha, astA and espP genes, together with genes for adhesion to the epithelial cells of the gut (lpfA, fdeC, fimH) and non-Locus for Enterocyte Effacement (LEE) effector protein genes (nleA, nleB). The STEC O177:H11 isolate harboured antimicrobial resistance (AMR) genes to beta-lactams (blaTEM-1A), aminoglycosides (aadA1, aph(3 '')-Ib, aph(6)-Id), trimethoprim (dfrA1), sulphonamides (sul1, sul2), tetracyclines (tetA), (tetB), streptothricin (sat2), and quaternary ammonium compounds (qacEdelta1). On the contrary, the STEC O177:H25 isolates carried no AMR genes. Persistent carriage of STEC O177:H25 ST659 (stx2c+, eae+) at farm level was assessed by testing animals of the same herd sent to slaughter. Interestingly, the colonies of STEC O177:H11 and STEC O177:H25 had different morphology on CHROMagarTM STEC plates, being mauve and colourless, respectively. Since mauve is the colour STEC colonies commonly have on the CHROMagarTM STEC medium, our findings can help microbiologists in the selection of uncommon serotypes. To the best of our knowledge, this is the first detection of STEC O177 from carcasses and hides of dairy cattle at slaughter. Noteworthy, the STEC-positive hide was classified as "very dirty" thus stressing the need of clean animals entering the slaughter chain, as required by Regulation (EC) No 853/2004. Since STEC O177 has been responsible of HUS in Europe, our data could add information on the source of uncommon serogroups in human infections.

The aim of this work is to explore a new library of coordination compounds for medicinal applications. Gallium is known for its various applications in this field. Presently, indium is not particularly important in medicine, but it shares a lot of chemical traits with its above-mentioned lighter companion, gallium, and is also used in radio imaging. These metals are combined with thiosemicarbazones, ligating compounds increasingly known for their biological and pharmaceutical applications. In particular, the few ligands chosen to interact with these hard metal ions share the ideal affinity for a high charge density. Therefore, in this work we describe the synthesis and the characterization of the resulting coordination compounds. The yields of the reactions vary from a minimum of 21% to a maximum of 82%, using a fast and easy procedure. Nuclear Magnetic Resonance (NMR) and Infra Red (IR) spectroscopy, mass spectrometry, elemental analysis, and X-ray Diffraction (XRD) confirm the formation of stable compounds in all cases and a ligand-to-metal 2:1 stoichiometry with both cations. In addition, we further investigated their chemical and biological characteristics, via UV-visible titrations, stability tests, and cytotoxicity and antibiotic assays. The results confirm a strong stability in all explored conditions, which suggests that these compounds are more suitable for radio imaging applications rather than for antitumoral or antimicrobic ones.

Enterococci are considered valuable sentinel Gram-positive bacteria for monitoring vancomycin antibiotic resistance due to their widespread presence and characteristics. The use of antimicrobials in farming animals has a role in the increasing of Antimicrobial Resistance (AMR) and the anthropogenic transformation of the landscape has forced wildlife into greater contact with humans and their livestock. The transmission of resistant bacteria by their meat products is a significant contributor to AMR development.The present study aimed to assess the prevalence of vancomycin resistant Enterococci spp. In antimicrobial-treated farmed pigs meat and in antimicrobial-free wild boars meat.A total of 341 Enterococci were isolated from 598 pork meat samples (57 %) and 173 Enterococci were isolated from 404 wild boar meat samples (42.8 %). Data found showed that low-resistance was detected more in wild boars meat Enterococci (52.6 %) than in pork meat once (48.4 %). However, the prevalence of resistance genes was at low level (33.9 % in pork meat Enterococci and 4.4 % in wild boar meat ones) and the only gene found was vanC1/C2, related to intrinsic AMR. Normally, Enterococci persist in the normal intestinal flora of animals including humans. However, the presence of resistance genes was frequently linked to the detection of pathogenic genes, mostly gelE in pork meat isolates and asa1 in wild boars meat isolates. Pathogenic bacteria can cause severe infections in human that can become more risky if associated to the presence of AMR. Pathogenic bacteria were characterized and a high presence of E. gallinarum and E. casseliflavus was found.Given the growing interest in wild game meat consumption the monitoring of AMR in these matrices is essential. Further surveillance studies are needed to fully evaluate the emergence and spread of vancomycin-resistant Enterococci (VRE) and pathogenic Enterococci from animal-derived food to humans, including the role of wildlife in this phenomenon. Giving the higher interest in wild animals meat consumption, it is important to better evaluate the spread of AMR phenomenon in the future and intensify hygienic control of wild animals derived food.

Salmonella contamination in pig slaughterhouses is linked to infection rate on farms. Accurate diagnosis in heavy pigs relies on isolating pathogens from the gut wall or lymph nodes. A key technique is Immunocapture using Magnetic Beads (IMS), which purifies target bacteria from Salmonella enrichment broths. This is followed by an Enzyme-Linked Immunomagnetic Electrochemical (ELIME) assay for rapid detection. In our study, we developed an ELIME-IMS hybrid assay to detect Salmonella in swine mesenteric lymph nodes (MNL), involving a clean-up with N-acetylcysteine and centrifugation. Detection limits for S. Typhimurium and S. Derby were estimated at 2.80 and 3.52 Log CFU/ml, respectively. We analysed 103 MNL samples from a northern Italy slaughterhouse. Additionally, we examined 15 carcass swabs. Both the ELIME assay and the IMS-based culture method showed strong agreement with the ISO 6579-1:2017 method, especially after 20 h of enrichment (89.47% concordance). The clean-up step significantly influenced the results, as samples processed without it showed higher variability. A logistic regression model indicated high classification accuracy for negative samples using ELIME values. The ELIME-IMS assay facilitates rapid Salmonella screening and isolation in swine mesenteric lymph nodes.

The study assessed the role of equids at slaughter as faecal carriers of Salmonella enterica and the occurrence of contaminated equid carcasses during the slaughter process in Northern Italy (Emilia-Romagna Region). From June to November 2021, 152 equids (146 horses, 5 donkeys and 1 mule) were tested for Salmonella both in caecal contents and through carcass swabs. Antimicrobial resistance (AMR) of recovered strains was tested against 15 antimicrobials. Salmonella was detected in 3/152 of the caecal contents (2.0 %), while all carcass samples were negative. S. enterica serovars Enteriditis, Typhimurium and Stanleyville were identified. The only AMR isolate was S. Typhimurium with AMR profile AmCStxT. Considering the consumption of raw horse meat (i.e., minced raw meat named "pesto di cavallo" and dried and smoked strips named "sfilacci di cavallo") in different areas of Northern Italy, we also investigated the possible link between horse meat eating and salmonellosis cases in the human population in the same area. Specifically, we compared the Salmonella strains collected during the study with those routinely processed in the laboratory surveillance system for human salmonellosis in Emilia-Romagna (a region with about 4.5 million inhabitants). The comparison was based on whole genome sequencing data through core genome multi-locus sequence typing (cgMLST) used in routine surveillance. A genomic match in cgMLST was found between the strain of S. enterica serovar Enteritidis isolated from a horse caecal content and an enduring outbreak of 17 human cases in Emilia-Romagna during the study period. The consequent epidemiological investigation highlighted that a number of cases with known food history reported the consumption of horse meat and traced different batches of the consumed meat, released weeks apart from each other, to the slaughter investigated in the study. The results of the epidemiological investigation suggested the role of horses in the S. enterica serovar Enteritidis outbreak affecting raw horse meat consumers.This study shows that, despite the low prevalence on equid carcasses, S. enterica in horse meat can represent a risk to consumers. From the perspective of the slaughter activities, this highlights the need to maintain a high level of hygiene during the entire process, starting from the hygiene at lairage up to the slaughtering phase and dressing of carcasses.

Bacterial resistance to β-lactam antibiotics, particularly new generation cephalosporins, is a major public health concern. In Escherichia coli, resistance to these antibiotics is mainly mediated by extended-spectrum β-lactamases (ESBL), which complicates a range of health-threatening infections. These infections may also be biofilm-related, making them more difficult to treat because of the higher tolerance to conventional antibiotics and the host immune response. In this study, we tested as potential new drug candidates against biofilm-forming ESBL-producing E. coli four antimicrobial peptides previously shown to have antifungal properties. The peptides proved to be active in vitro at micromolar concentrations against both sensitive and ESBL-producing E. coli strains, effectively killing planktonic cells and inhibiting biofilm formation. Quantitative fluorescence intensity analysis of three-dimensional reconstructed confocal laser scanning microscopy (CLSM) images of mature biofilm treated with the most active peptide showed significant eradication and a reduction in viable bacteria, while scanning electron microscopy (SEM) revealed gross morphological alterations in treated bacteria. The screening of the investigated peptides for antibacterial and antibiofilm activity led to the selection of a leading candidate to be further studied for developing new antimicrobial drugs as an alternative treatment against microbial infections, primarily associated with biofilms.

Antimicrobial resistance (AMR) is a risk for public health that requires management in a One Health perspective, including humans, animals, and the environment. The food production chain has been identified as a possible route of transmission of AMR bacteria to humans. The most critical issue regards resistance to the Critically Important Antimicrobials (CIAs), such as β-lactams antibiotics. Here, pigs were analysed along the entire food producing chain, including feces, carcasses and pork products (fresh meat, fermented and seasoned products) ensuring treaciability of all samples. Escherichia coli were isolated and their ability to produce ESBL and AmpC β-lactamases was evaluated both phenotypically and genotypically. Strains with the same AMR profile from feces, carcasses, and meat products were selected for phylogenetic and comparative genomic analyses to evaluate the possible "farm-to-fork" transmission of β-lactams resistant bacteria. Results showed that the percentage of ESBL strains in fecal E. coli was approximately 7% and increased slightly in the pork food chain: the 10% of ESBL E. coli isolated from carcasses and the 12.5% of isolates from fresh meat products. AmpC E. coli were found only in feces, carcasses, and fresh meat with a low prevalence. Results showed that of the 243 pigs followed along the entire food chain genetic similarities in E. coli isolated from farm-to-fork were found in only one pig (feces, carcasses and fresh meat). Frequent similarities were shown in resistant E. coli isolates from carcasses and fresh meat or fermented product (three pork food chain). Moreover, in one case, bacteria isolated from fresh meat and fermented product were genotypically similar. Concluding, direct transmission of β-lactams resistance from farm-to-fork is possible but not frequent. Further studies are needed to improve risk communication to consumers and access to clear and reliable information and health concerns on food.

Antimicrobial resistance (AMR) is a public health risk that needs to be faced from a One Health perspective that includes humans, animals, and environmental health. The food production chain has been identified as a possible route of transmission of AMR bacteria to humans. The most critical phenomenon is related to Critically Important Antimicrobial (CIA) resistance. β-lactams antibiotics (cephalosporin of 3rd, 4th generation, carbapenem, monobactams, and penicillins), quinolones, aminoglycosides, polymyxin, and glycylcyclines were the CIAs chosen in this study. Samples derived from all the stages of the pork food production chain were collected, including pig feces, carcasses, and pork food products (fresh meat, fermented, and seasoned). Escherichia coli were isolated, and AMR and MDR profiles were evaluated. Enterobacterial Repetitive Intragenic Consensus (ERIC-PCR) was used to evaluate phylogenetic similarities. Data showed that 50% of phenotypical AMR observed in the entire pork food chain were related phylogenetically. The contamination of fresh meat, in half of the cases, was not directly related to contamination from feces or carcasses. Despite this, some similarities were found between feces and carcasses. In group analysis, phylogenetic similarities were detected in a 3/36 cluster (8.3%). Nevertheless, further studies are needed to improve consumer risk communication and access to clear and reliable information and health concerns on food labels.

The European Food Safety Authority and European Centre of Disease Prevention and Control antimicrobial resistance report published in 2021 shows increasing levels of antimicrobial resistance in Salmonella against antibiotics of choice for human salmonellosis (ß-lactams and fluoroquinolones). The aim of the study was to follow the evolution of resistance against some Critical Important Antimicrobials in Salmonella isolates from fresh pork collected in Emilia-Romagna region, northern Italy, over two decades. Emilia-Romagna region is characterized by production of well-known pork derived products, as Parma Ham. The samples were collected in three different periods, ranging from 2000 to 2003, 2012 to 2016 and 2018 to 2021. After serotyping, the isolates were phenotypically tested for resistance to three classes of antibiotics: ß-lactams, fluoroquinolones and polymyxins. End-point polymerase chain reaction (PCR) and PCRReal Time were used for genotypical analyses. The phenotypical resistance to ß-lactams and fluoroquinolones were clearly increasing when comparing the results obtained from isolates collected in the first period (16.7% and 16.7%, respectively) with those of the third period (29.7% and 32.4%, respectively). On the contrary, the resistance to colistin decreased from 33.3% to 5.4%. Genotypically, the 71.4% and 83.3% of the strains harboured ß-lactams and fluoroquinolones genes, respectively, while colistin resistance genes were not detected in the phenotypically resistant strains.

This study is focused on resistance to carbapenems and third-generation cephalosporins in Gram-negative microorganisms isolated from swine, whose transmission to humans via pork consumption cannot be excluded. In addition, the common carriage of carbapenem-resistant (CR) bacteria between humans and pigs was evaluated. Sampling involved 300 faecal samples collected from slaughtered pigs and 300 urine samples collected from 187 hospitalised patients in Parma Province (Italy). In swine, MIC testing confirmed resistance to meropenem for isolates of Pseudomonas aeruginosa and Pseudomonas oryzihabitans and resistance to cefotaxime and ceftazidime for Escherichia coli, Ewingella americana, Enterobacter agglomerans, and Citrobacter freundii. For Acinetobacter lwoffii, Aeromonas hydrofila, Burkolderia cepacia, Corynebacterium indologenes, Flavobacterium odoratum, and Stenotrophomonas maltophilia, no EUCAST MIC breakpoints were available. However, ESBL genes (blaCTXM-1, blaCTX-M-2, blaTEM-1, and blaSHV) and AmpC genes (blaCIT, blaACC, and blaEBC) were found in 38 and 16 isolates, respectively. P. aeruginosa was the only CR species shared by pigs (4/300 pigs; 1.3%) and patients (2/187; 1.1%). P. aeruginosa ST938 carrying blaPAO and blaOXA396 was detected in one pig as well as an 83-year-old patient. Although no direct epidemiological link was demonstrable, SNP calling and cgMLST showed a genetic relationship of the isolates (86 SNPs and 661 allele difference), thus suggesting possible circulation of CR bacteria between swine and humans.

Klebsiella pneumoniae is the most common Klebsiella species infecting animals and is one of the causing agents of mastitis in cows. The rise of antimicrobial resistance in K. pneumoniae, particularly in strains producing extended-spectrum β-lactamases (ESBLs) and/or carbapenemases, is of concern worldwide. Recently (Regulation UE No 2022/1255), carbapenems and cephalosporins in combination with β-lactamase inhibitors have been reserved only to human treatments in the European Union. The aim of this study was to investigate the role of cattle as carrier of human pathogenic carbapenem-resistant (CR) and ESBL-producing K. pneumoniae. On this purpose, a study involving 150 dairy farms in Parma province (Northern Italy) and 14 non replicate K. pneumoniae isolates from patients admitted at Parma University-Hospital was planned. Four multidrug resistant (MDR) K. pneumoniae strains were detected from 258 milk filters collected between 2019 and 2021. One carbapenemase KPC-3-positive K. pneumoniae ST307 (0.4 %; 95 % CI - 0.07 - 2.2) was detected in milk filters. The isolate also harboured OXA-9, CTX-M-15 and SHV-106 determinants, together with genes conferring resistance to aminoglycosides (aac(3')-IIa, aph (3″)-Ib, aph (6)-Id), fluoroquinolones (oqxA, oqxB, qnrB1), phosphonic acids (fosA6), sulphonamides (sul2), tetracyclines (tet(A)6) and trimethoprim (dfrA14). One KPC-3-producing K. pneumoniae ST307 was identified also among the human isolates, thus suggesting a possible circulation of pathogens out of the clinical settings. The remaining three bovine isolates were MDR ESBL-producing K. pneumoniae characterized by different genomic profiles: CTX-M-15, TEM-1B and SHV-187 genes (ST513); CTX-M-15 and SHV-145 (ST307); SHV-187 and DHA-1 (ST307). Occurrence of ESBL-producing K. pneumoniae in milk filters was 1.2 % (95 % CI 0.4-3.4). All the isolates showed resistance to aminoglycosides, 3rd-generation cephalosporins, and fluoroquinolones. Among the human isolates, two multidrug resistant ESBL-producing K. pneumoniae ST307 were found, thus confirming the circulation of this high-risk lineage between humans and cattle. Our findings suggest that food-producing animals can carry human pathogenic microorganisms harboring resistance genes against carbapenems and 3rd-generation cephalosporins, even if not treated with such antimicrobials. Moreover, on the MDR K. pneumoniae farms, the antimicrobial use was much higher than the Italian median value, thus highlighting the importance of a more prudent use of antibiotics in animal productions.

Resistant bacteria represent an urgent worldwide threat. NDM-1-producing strains are rendering the last line antibiotics less effective. Six bismuth complexes of general formula BiLCl2, where L is a thiosemicarbazone bearing a quinoline moiety, have been synthesized and fully characterized, including their X-ray crystal structures. The synergistic relationship between the compounds and meropenem have been tested in a combination therapy in carbapenem-resistant Klebsiella pneumoniae (NTCT14331) carrying the NDM-1 gene. Quinoline-2-carboxaldehyde-N4-phenyl-3-thiosemicarbazone bismuth dichloride and carbapenem showed synergism in a dose dependent manner with negligible antibacterial activity when used in a monotherapy and could restore antibiotic sensitivity in the strain producing NDM-1 enzyme. The minimum inhibitory concentration (MIC) of meropenem lowered down 128 folds up to 2 μgmL-1, a concentration lower to the sensitivity level. The IC50 of the compound against A549 human lung carcinoma cells and HuDe human epithelial tissue was 46.96 ± 16.66 μM and 54.26 ± 9.89 μM respectively. The cytotoxicity against human cells was higher than the effective concentration needed for the synergistic effect in bacterial cells, indicating that a structural optimization of the compounds is needed.