Enterobacteriaceae and Salmonella contamination of wild boar (Sus scrofa) carcasses: comparison between different sampling strategies

Silvia Bonardi,Margherita Corradi,Luca Lamperti,Luca Poli,Laura Soliani,Cesare Tansini,Stefano Gilioli,Antonio Cacchioli

doi:10.1007/s10344-021-01531-0

Abstract

During 2020, a total of 64 wild boar carcasses were tested for Enterobacteriaceae count (EBC), Salmonella and Yersinia enterocolitica in the abdominal region (i) within 5 h after hunting in the game collection point and (ii) before dressing and processing in the game-handling establishment (GHE) (49 carcasses—average time interval between (i) and (ii): 4.3 days). Because of COVID-19 restrictions, 15 carcasses were transported to a near slaughterhouse (average time interval between (i) and (ii): 2.3 days). Mesenteric lymph nodes (MLNs) were collected and tested for Salmonella and Y. enterocolitica. Results are shown in relation to sampling A (49 carcasses—GHE) and sampling B (15 carcasses—slaughterhouse). Sampling A: EBC median values were (i) 2.51 log10 CFU/cm2 and (ii) 2.79 log10 CFU/cm2. EBC increase between (i) and (ii) was statistically significant (p = 0.001). Salmonella prevalence on carcasses varied from (i) 2.0 to (ii) 6.1%. Sampling B: EBC median values were (i) 3.1 log10 CFU/cm2 and (ii) 3.32 log10 CFU/cm2. EBC increase between (i) and (ii) was not statistically significant (p = 0.191). Salmonella prevalence on carcasses varied from (i) 6.7 to (ii) 0.0%. The prevalence (sampling A + B) of lymphatic Salmonella carriers was 7.8% (5/64). From carcasses and/or MNLs, the serovars Enteritidis, Typhimurium, Agama, Zaiman and Diarizonae O:50 (z) were detected. Y. enterocolitica was never isolated. Long chilling periods prior to wild game processing should be avoided, and carcasses should be tested at GHE rather than after shooting to proper reflect the microbial load of wild boar meat entering the food chain.

Highlights

Wild boars (Sus scrofa) are among the most common wild ungulates in Italy
Sampling A1—game collection points (GCPs) The Enterobacteriaceae count (EBC) ranged from 0 log10 CFU/cm2 to 5.14 log10 CFU/cm2
Since contamination by Antimicrobial resistance (AMR) bacteria in wild animals is commonly attributed to environmental circulation of microorganisms originating from farmed animals or anthropic sources, our findings suggest a close segregation between wild boar population and farmed food-producing animals, as already observed comparing AMR of Salmonella strains isolated from farmed pigs and wild boars in the study area (Bonardi et al 2019)

Summary

Introduction

Wild boars (Sus scrofa) are among the most common wild ungulates in Italy Their presence has been documented from the north to the south of the country, with higher prevalence through the Apennines mountains (central Italy) (Carnevali et al 2009). Their density has been estimated to range between 1.37–2.31 animals/km in the region of the. Salmonella spp. was assessed as of high priority in wild boar meat safety assurance (EFSA 2013) and it is considered a relevant biological hazard in wild animals (Gortázar et al 2007). In 2019, salmonellosis and yersiniosis were the second and fourth most frequently reported zoonoses in the EU, with notification rates of 20.0 cases/100,000 population and 1.7 cases/100,000 population, respectively (EFSA and ECDC 2021)

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