Maria Fredriksson-Ahomaa

Zoonotic bacterial pathogens are a major concern for food safety, yet information regarding their occurrence in game meat remains fragmented. This systematic review synthesizes available data on Salmonella spp., Shiga toxin‐producing Escherichia coli (STEC), Listeria spp., Yersinia spp., and Campylobacter spp. in game meat from hunted wild ungulates. Relevant studies published between 2004 and 2024 were identified through structured database searches and screened using predefined criteria. Data on host species, diagnostic methods, prevalence estimates, isolate characterization, and antimicrobial resistance (AMR) were extracted. Pooled prevalence estimates were determined, stratified by detection methods (culture‐based and PCR‐based) and animal groups (suids and ruminants). A total of 46 publications (170 studies; 223 prevalence estimates) were included. Substantial heterogeneity was observed across the studies. PCR‐based methods yielded higher detection rates than culture, though the magnitude of the difference varied between pathogens. Pathogen occurrence was generally higher in meat from suids, except for STEC, which was more prevalent in the game meat of ruminants. Although many strains appeared to have lower pathogenic potential compared with those typically implicated in human disease, the presence of specific virulence‐associated genes, serogroups, and sequence types linked to human infections indicates that game meat may act as a potential source of infection. AMR was reported in a limited number of studies. Overall, this review highlights substantial methodological variability and important data gaps, particularly regarding virulence‐associated genes, genomic characterization, and AMR. More comprehensive studies spanning a broader range of ecological and production contexts are needed to strengthen the evidence base for the microbiological safety of game meat.

The study aimed to characterize Salmonella and Yersinia enterocolitica detected in fattening pigs in Sardinia, examining genetic similarity and antimicrobial resistance of isolates from farms and slaughterhouses and evaluating carcass hygiene. Environmental samples were collected from six pig farms, and the same pigs were also sampled at the slaughterhouses. Palatine tonsils, mesenteric lymph nodes, colon content, and carcass surface samples were collected and tested for Salmonella and Y. enterocolitica. Antimicrobial resistance testing and whole genome sequencing were performed on all isolates. Carcass surface samples were tested for total aerobic colony count (ACC) and Enterobacteriaceae count (EBC). Y. enterocolitica was found in two farms (33%), while Salmonella was absent in environmental farm samples. At slaughterhouses, 13.1% of pigs were found positive for Salmonella (lymph nodes, colon content, and palatine tonsils samples), but Y. enterocolitica was not detected. Salmonella isolates were typed as monophasic S. Typhimurium ST34 and S. Goldcoast ST358, with few allelic differences among isolates of the same ST. Salmonella ST34 showed resistance towards ampicillin, streptomycin, sulfonamide, and tetracycline (blaTEM-1B, aph(3´´)-Ib, sul2 and tetB genes, R-type ASSuT). Y. enterocolitica isolates (biotype 2, ST853, and ST859) showed resistance to ampicillin and amoxicillin-clavulanic acid (blaA gene). Process hygiene criteria were generally met, with mean (log10 CFU/cm2 ± standard deviation) values for ACC and EBC being 2.23±0.74 and 0.75±0.81. Pigs of Sardinia are confirmed carriers of Salmonella and Y. enterocolitica, but overall hygienic status in farms and slaughterhouses in Sardinia is acceptable. Monophasic S. Typhimurium and Y. enterocolitica isolates showed typical resistance patterns. Monophasic S. Typhimurium ST34 isolates with R-type ASSuT are confirmed as epidemic clones.

This study investigated commensal and pathogenic E. coli from pigs at farms and slaughterhouses in Sardinia, focusing on genetic relatedness and antimicrobial resistance (AMR). Samples were collected from six fattening pig farms (A-F) and five slaughterhouses (S1-S5). In the farms, environmental fecal sampling from the fattening pigs’ pens was carried out and information regarding farm management and biosecurity measures were collected. Pigs that had been in the sampled pens were selected for sampling at the slaughterhouse. Mesenteric lymph nodes, colon content and carcass surface samples were collected at the five slaughterhouse (S1-S5), in a total of 38 samples form 152 animals. At the slaughterhouses, also environmental samples were collected from food-contact surfaces and non-food-contact surfaces (36 samples overall). E. coli was detected in all farms, 97% of pigs, and 100% of slaughterhouses. Whole genome sequencing and antimicrobial susceptibility testing were per-formed on 96 isolates, revealing 13.5% pathogenic isolates, including ExPEC, ETEC, STEC-ETEC hy-brids, and UPEC. A total of 40 sequence types (STs) were identified, with ST10 being the most com-mon. High-risk clones (ST88, ST101, ST410, and ST648) were also detected. Over half of the isolates (52.1%) carried at least one AMR gene, with 42.7% harboring multiple AMR genes, particularly tet (37.5%) and blaTEM (32.3%). High phenotypic resistance was observed for tetracycline, ampicillin, and sulfamethoxazole-trimethoprim. The study highlights the widespread presence of pathogenic E. coli in pigs, even in isolated environments, and emphasizes the need for continuous surveillance due to the significant AMR found in both pathogenic and non-pathogenic isolates.

Background: European hedgehogs (Erinaceus europaeus) are widely distributed across Europe. They may play an important role by spreading zoonotic bacteria in the environment and to humans and animals. The aim of our work was to study the prevalence and characteristics of the most important foodborne bacterial pathogens in wild hedgehogs. Results: Faecal samples from 148 hospitalised wild hedgehogs originating from the Helsinki region in southern Finland were studied. Foodborne pathogens were detected in 60% of the hedgehogs by PCR. Listeria (26%) and STEC (26%) were the most common foodborne pathogens. Salmonella, Yersinia, and Campylobacter were detected in 18%, 16%, and 7% of hedgehogs, respectively. Salmonella and Yersinia were highly susceptible to the tested antimicrobials. Salmonella Enteritidis and Listeria monocytogenes 2a were the most common types found in hedgehogs. All S. Enteritidis belonged to one sequence type (ST11), forming four clusters of closely related isolates. L. monocytogenes was genetically more diverse than Salmonella, belonging to 11 STs. C. jejuni ST45 and ST677, Y. pseudotuberculosis O:1 of ST9 and ST42, and Y. enterocolitica O:9 of ST139 were also found. Conclusions: Our study shows that wild European hedgehogs should be considered an important source of foodborne pathogens, and appropriate hygiene measures after any contact with hedgehogs and strict biosecurity around farms are therefore important.

Yersiniosis is a common zoonotic enteric disease among humans, which has been linked to pigs and contaminated food, especially pork. The epidemiology of yersiniosis is still obscure, and studies on yersiniosis in pets are very scarce. In this study, we performed pheno- and genotypic characterisation of 50 Yersinia strains isolated from pets in Finland between 2012 and 2023. Y. enterocolitica 4/O:3/ST135, the most common type in human yersiniosis, was also the most common type (68%) found in clinical faecal samples in our study. Also, human pathogenic Y. enterocolitica 2/O:9/ST139 and Y. pseudotuberculosis O:1/ST9 and O:1/ST42 strains carrying all essential pathogenic genes were identified. Three Y. enterocolitica 4/O:3/ST9 strains were multi-drug-resistant and two of them were highly related, showing one allelic difference (AD) with core genome multi-locus sequence typing. Non-pathogenic, genotypically highly diverse Y. enterocolitica 1A strains, showing more than 1000 ADs and missing the essential virulence genes, were also recognised in dogs and cats. Our study demonstrates that pets can excrete human pathogenic Yersinia in their faeces and may serve as an infection source for human yersiniosis, especially in families with small children in close contact with their pets.

Yersiniosis is a common zoonotic enteral disease among humans, which has been linked to pigs and contaminated food, especially pork. Studies on yersiniosis in pets are very scarce. In this study, we performed pheno- and genotypic characterization of 50 Yersinia strains isolated from pets in Finland between 2012 and 2023. Y. enterocolitica 4/O:3/ST135, the most common type in human yersiniosis, was also the most common Y. enterocolitica type (68%) found in clinical faecal samples in our study. Also, human pathogenic Y. enterocolitica 2/O:9/ST139 and Y. pseudotuberculosis O:1/ST9 and O:1/ST42 strains carrying all essential pathogenic genes were identified. Three Y. enterocolitica 4/O:3/ST9 strains were multi-drug resistant and two of them were highly related showing one allelic difference (AD) with core-genome multi-locus sequence typing. Non-pathogenic, genotypically highly diverse Y. enterocolitica 1A strains, showing more than 1000 ADs and missing the essential virulence genes, were also recognized in dogs and cats. Our study demonstrates that pets can excrete human pathogenic Y. enterocolitica and Y. pseudotuberculosis in their faeces and may serve as an infection source for human yersiniosis, especially in families with small children in close contact with their pets.

The objective of this investigation was to evaluate Salmonella and Yersinia enterocolitica prevalence in wild boars hunted in Sardinia and further characterize the isolates and analyse antimicrobial resistance (AMR) patterns. In order to assess slaughtering hygiene, an evaluation of carcasses microbial contamination was also carried out. Between 2020 and 2022, samples were collected from 66 wild boars hunted during two hunting seasons from the area of two provinces in northern and central Sardinia (Italy). Samples collected included colon content samples, mesenteric lymph nodes samples and carcass surface samples. Salmonella and Y. enterocolitica detection was conducted on each sample; also, on carcass surface samples, total aerobic mesophilic count and Enterobacteriaceae count were evaluated. On Salmonella and Y. enterocolitica isolates, antimicrobial susceptibility was tested and whole genome sequencing was applied. Salmonella was identified in the colon content samples of 3/66 (4.5%) wild boars; isolates were S. enterica subs. salamae, S. ser. elomrane and S. enterica subs. enterica. Y. enterocolitica was detected from 20/66 (30.3%) wild boars: in 18/66 (27.3%) colon contents, in 3/66 (4.5%) mesenteric lymph nodes and in 3/49 (6.1%) carcass surface samples. In all, 24 Y. enterocolitica isolates were analysed and 20 different sequence types were detected, with the most common being ST860. Regarding AMR, no resistance was detected in Salmonella isolates, while expected resistance towards β-lactams (blaA gene) and streptogramin (vatF gene) was observed in Y. enterocolitica isolates (91.7% and 4.2%, respectively). The low presence of AMR is probably due to the low anthropic impact in the wild areas. Regarding the surface contamination of carcasses, values (mean ± standard deviation log₁₀ CFU/cm²) were 2.46 ± 0.97 for ACC and 1.07 ± 1.18 for Enterobacteriaceae. The results of our study confirm that wild boars can serve as reservoirs and spreaders of Salmonella and Y. enterocolitica; the finding of Y. enterocolitica presence on carcass surface highlights how meat may become superficially contaminated, especially considering that contamination is linked to the conditions related to the hunting, handling and processing of game animals.