The development of a screening protocol for Salmonella spp. and enteropathogenic Yersinia spp. in samples from wild boar (Sus scrofa) also generating MLVA-data for Y. enterocolitica and Y. pseudotuberculosis

Comparison of Multiple-Locus Variable-Number Tandem Repeat Analysis Profiles of Enteropathogenic Yersinia spp. Obtained from Humans, Domestic Pigs, Wild Boars, Rodents, Pork and Dog Food

The enteropathogenic Yersinia genus is commonly detected in wildlife including wild boars. Difficulties in its cultivation may hamper subsequent epidemiological studies and outbreak investigations. Multiple-locus variable-number tandem repeat analysis (MLVA) of Yersinia (Y.) enterocolitica and Y. pseudotuberculosis has proven useful in source attribution and epidemiological studies but has hitherto relied on the analysis of isolates. In the present study, MLVA profiles generated from 254 isolates of Y. enterocolitica indicated similarities between human, pig and rodent isolates. Further, MLVA analyses of 13 Y. pseudotuberculosis pure-cultured isolates were compared to MLVA analyses performed directly on the 14 PCR-positive enrichment broths from which the isolates originated, which showed matching MLVA profiles. This indicates that MLVA analysis performed directly on enrichment broths could be a useful method for molecular epidemiological investigations. In addition, 10 out of 32 samples of wild boar minced meat obtained from private hunters and from approved wild-game-handling establishments were PCR-positive for the presence of Y. enterocolitica and may indicate a risk for public health.

Zoonotic Campylobacter spp. and Salmonella spp. carried by wild boars in a metropolitan area: occurrence, antimicrobial susceptibility and public health relevance

Campylobacter spp. and Salmonella spp. are the most reported zoonotic agents in Europe. They can be transmitted from wildlife to humans, and wild boars (Sus scrofa) can harbour them. In the Metropolitan Area of Barcelona (MAB, NE Spain) wild boars are found in urbanized areas. To assess the potential public health risk of this increasing wild boar population, we collected stool samples from 130 wild boars from the MAB (June 2015 - February 2016), to determine the Campylobacter and Salmonella occurrence and the antimicrobial susceptibility of the isolates. We also investigated the genetic diversity and virulence potential of Campylobacter. Campylobacter prevalence in wild boars was 61%. Forty six percent of wild boars carried Campylobacter lanienae, 16% carried Campylobacter coli, and 1% carried Campylobacter hyointestinalis; 4% carried both C. lanienae and C. coli, and 1% carried both C. lanienae and C. hyointestinalis. This is the first report of C. hyointestinalis in wildlife in Spain. Using pulse-field gel electrophoresis and multilocus sequence typing, we observed a high genetic diversity of Campylobacter and identified new sequence types. Thirty-three percent of C. coli and 14% of C. lanienae isolates showed a high virulence potential. All of the Campylobacter isolates analysed were resistant to at least one antimicrobial agent. Multidrug resistance was only detected in C. coli (67%). Salmonella enterica subsp. enterica was detected in four wild boars (3%) and included a S. Enteritidis serovar (1/4 wild boars) and a multidrug-resistant (ASSuT) monophasic S. Typhimurium serovar (1/4 wild boars) which is associated with human infections and pig meat in Europe. The characteristics of some of the Campylobacter and Salmonella isolates recovered suggest an anthropogenic origin. Wild boars are a reservoir of Campylobacter and have the potential to spread antimicrobial resistant Campylobacter and Salmonella in urbanized areas in the MAB.

Prevalence, Virulence and Antimicrobial Susceptibility of Salmonella spp., Yersinia enterocolitica and Listeria monocytogenes in European Wild Boar (Sus scrofa) Hunted in Tuscany (Central Italy)

Wild boar is an animal the population of which constantly increases in Europe. This animal plays an important role as a reservoir for several pathogens, including three of the most important zoonoses: salmonellosis, yersiniosis and listeriosis. The aim of this investigation was to evaluate the occurrence of antimicrobial-resistant and virulence factor genes of Salmonella spp., Yersinia enterocolitica and Listeria monocytogenes isolated from wild boar in Tuscany (Central Italy). During two consequent hunting seasons (2018/2019 and 2019/2020), rectal swabs, spleens and livers were collected from 287 hunted wild boar to isolate strains. Each isolate was tested to investigate its antimicrobial resistance and to detect virulence factor genes by PCR. Eighteen Salmonella strains (6.27%) were isolated. Of these, 66.7% were resistant to streptomycin, 13.4% to cephalothin, 6.67% to imipenem and one isolate (6.67%) was resistant simultaneously to five antimicrobials. Moreover, the most detected genes were sopE (73.4%), pipB (66.7%), sodCI (53.3%), spvR and spvC (46.7%). In total, 54 (17.8%) Yersinia enterocolitica were isolated; of them, 26 (48.1%), 9 (16.7%), 17 (31.5%), 1 (1.85%) and 1 (1.85%) belonged to biotypes 1, 2, 3, 4 and 5, respectively. All strains (100%) demonstrated resistance to cephalothin and 70.4% to amoxicillin-clavulanic acid, 55.6% to ampicillin, and 37.0% to cefoxitin. Additionally, the most detected genes were ystA (25.9%), inv (24.1%), ail (22.2%), ystB (18.5%) and virF (14.8%). Finally, only one Listeriamonocytogenes isolate (0.35%) was obtained, belonging to serogroup IVb, serovar 4b, and it was found to be resistant to cefoxitin, cefotaxime and nalidixic acid. The results highlighted the role of wild boar as a carrier for pathogenic and antimicrobial-resistant Salmonella spp., Yersinia enterocolitica and Listeria monocytogens, representing a possible reservoir for domestic animals and human pathogens.

A Pilot Study to Investigate the Feasibility of a Multiple Locus Variable Number Tandem Repeat Analysis to Understand the Epidemiology of Dichelobacter nodosus in Ovine Footrot

Dichelobacter nodosus is the essential pathogen in ovine footrot, an important cause of lameness in sheep that reduces productivity and welfare. The aim of this study was to investigate the feasibility of using multiple locus variable number tandem repeat analysis (MLVA) developed to investigate isolates to understand the molecular epidemiology of Dichelobacter nodosus in ovine footrot by investigation of communities of strains. MLVA sensitivity was improved by optimizing PCR conditions to 100% specificity for D. nodosus. The improved MLVA scheme was used to investigate non-cultured DNA purified from swabs (swab DNA) and cultured DNA from isolates (isolate DNA) from 152 foot and 38 gingival swab samples from 10 sheep sampled on four occasions in a longitudinal study. Isolate DNA was obtained from 6/152 (3.9%) feet and 5/6 yielded complete MLVA profiles, three strains were detected. Two of the three isolate strains were also detected in isolate DNA from 2 gingival crevice cultures. Complete MLVA profiles were obtained from swab DNA from 39 (25.7%) feet. There were 22 D. nodosus community types that were comprised of 7 single strain and 15 multi-strain communities. Six community types were detected more than once and three of these were detected on the same four sheep and the same two feet over time. There were a minimum of 17 and a maximum of 25 strain types of D. nodosus in the study. The three isolate strain types were also the most frequently detected strain types in swab DNA. We conclude that the MLVA from swab DNA detects the same strains as culture, is much more sensitive and can be used to describe and differentiate communities and strains on sheep, feet and over time. It is therefore a sensitive molecular tool to study D. nodosus strains directly from DNA without culture.

Fallow Deer (Dama dama) as a Reservoir of Shiga Toxin-Producing Escherichia coli (STEC)

Shiga toxin-producing Escherichia (E.) coli (STEC) are responsible for the outbreaks of serious diseases in humans. Only a few reports on fallow deer as a reservoir of foodborne pathogens have been published to date. The purpose of this study was to determine the occurrence of STEC strains in the fallow deer population in Poland. In all, 94 fallow deer swabs were tested. Polymerase chain reaction (PCR) was performed to detect the virulence profile of stx1, stx2 and eae or aggR genes, to identify the subtypes of stx1 and stx2 genes and to perform O and H serotyping. STEC and attaching and effacing (AE)-STEC were identified in 13 isolates (13.83%). The most hazardous virulence profile was detected in three strains, namely stx2d serotype O103:HNM, eae/stx1a serotype O26:HNM and eae/stx1a serotype O157:H7. The predominant stx gene was stx2, which was identified in 76.92% of isolates. E. coli O157 was detected in 4/94 (4.26%). Other E. coli serogroups, O26, O103, O111 and O145, were identified in 14/94 fallow deer (14.89%). The present findings suggest that fallow deer are carriers of STEC/AE-STEC that are potentially pathogenic to humans.

Shiga toxin-producing Escherichia coli isolates from red deer (Cervus elaphus), roe deer (Capreolus capreolus) and fallow deer (Dama dama) in Poland

Shiga toxin-producing Escherichia (E.) coli (STEC) pathogens are responsible for the outbreaks of serious diseases in humans, including haemolytic uraemic syndrome (HUS), bloody diarrhoea (BD) and diarrhoea (D), and they pose a significant public health concern. Wild ruminants are an important environmental reservoir of foodborne pathogens that can cause serious illnesses in humans and contaminate fresh products. There is a general scarcity of published data about wildlife as a reservoir of foodborne pathogens in Poland, which is why the potential epidemiological risk associated with red deer, roe deer and fallow deer as reservoirs of STEC/AE-STEC strains was evaluated in this study. The aim of the study was to investigate the prevalence of STEC strains in red deer (Cervus elaphus), roe deer (Capreolus capreolus) and fallow deer (Dama dama) populations in north-eastern Poland, and to evaluate the potential health risk associated with wild ruminants carrying STEC/AE-STEC strains. We examined 252 rectal swabs obtained from 134 roe deer (Capreolus capreolus), 97 red deer (Cervus elaphus) and 21 fallow deer (Dama dama) in north-eastern Poland. The samples were enriched in modified buffered peptone water. Polymerase chain reaction (PCR) assays were conducted to determine the virulence profile of stx1, stx2 and eae or aggR genes, to identify the subtypes of stx1 and stx2 genes, and to perform O and H serotyping. E. coli O157:H7 isolates were detected in the rectal swabs collected from 1/134 roe deer (0.75%) and 4/97 red deer (4.1%), and they were not detected in fallow deer (Dama dama). The remaining E. coli serogroups, namely O26, O103, O111 and O145 that belong to the "top five" non-O157 serogroups, were detected in 15/134 roe deer (11.19%), 18/97 red deer (18.56%) and 2/21 fallow deer (9.52%). STEC/AE-STEC strains were detected in 33 roe deer isolates (24.63%), 21 red deer isolates (21.65%) and 2 fallow deer isolates (9.52%). According to the most recent FAO/WHO report, stx2a and eae genes are the primary virulence traits associated with HUS, and these genes were identified in one roe deer isolate and one red deer isolate. Stx2 was the predominant stx gene, and it was detected in 78.79% of roe deer and in 71.43% of red deer isolates. The results of this study confirmed that red deer and roe deer in north-eastern Poland are carriers of STEC/AE-STEC strains that are potentially pathogenic for humans. This is the first report documenting the virulence of STEC/AE-STEC strains from wild ruminants in Poland.

Distribution of enteropathogenic Yersinia spp. and Salmonella spp. in the Swedish wild boar population, and assessment of risk factors that may affect their prevalence

BACKGROUND

Pure Eurasian wild boars and/or hybrids with domestic pigs are present in the wild on most continents. These wild pigs have been demonstrated to carry a large number of zoonotic and epizootic pathogens such as Salmonella spp., Yersinia enterocolitica and Y. pseudotuberculosis. Wild boar populations throughout Europe are growing and more and more wild boar meat is being consumed, the majority within the homes of hunters without having passed a veterinary inspection. The aim of this study was to investigate if factors such as population density, level of artificial feeding, time since establishment of a given population, and the handling of animal by-products from slaughtered animals could influence the presence of these pathogens in the wild boar.

RESULTS

In total, 90 wild boars from 30 different populations in Sweden were sampled and analysed using a protocol combining pre-cultivation and PCR-detection. The results showed that 27% of the sampled wild boars were positive for Salmonella spp., 31% were positive for Y. enterocolitica and 22% were positive for Y. pseudotuberculosis. In 80% of the sampled populations, at least one wild boar was positive for one of these enteropathogens and in total, 60% of the animals carried at least one of the investigated enteropathogens. The presumptive risk factors were analysed using a case-control approach, however, no significant associations were found.

CONCLUSION

Human enteropathogens are commonly carried by wild boars, mainly in the tonsils, and can thus constitute a risk for contamination of the carcass and meat during slaughter. Based on the present results, the effect of reducing population densities and number of artificial feeding places might be limited.