High bacterial contamination of pig tonsils at slaughter
Introduction
Food-borne zoonoses are infectious diseases of major health and economic significance in developed countries. They are most often acquired through ingestion of contaminated foods but they can also be acquired directly from animals. The two most frequently reported zoonotic diseases in humans in the EU in 2007 were Campylobacter and Salmonella infections with incidences of 120 and 31 cases per 100,000 inhabitants, respectively (EFSA, 2009). Yersinia and especially Listeria monocytogenes had lower incidences of 2.0 and 0.3 cases per 100,000 inhabitants, respectively. However, L. monocytogenes infection may be severe, especially in immunocompromised individuals with rather high fatality (Ramaswamy et al., 2007). A high proportion of human campylobacteriosis, salmonellosis, yersiniosis and listeriosis is likely to originate from pigs (Fosse, Seeger, & Magras, in press).
Pigs are mostly asymptomatic carriers of Salmonella enterica, Campylobacter spp., Yersinia enterocolitica and L. monocytogenes. All these bacterial pathogens have been isolated from the intestinal tract of pigs (Fosse et al., in press). However, pathogenic Y. enterocolitica has shown to be a more frequent inhabitant in pig tonsils (Bucher et al., 2008). L. monocytogenes is a ubiquitous organism occasionally present in the intestinal tract of various animal species but this pathogen has also been isolated from tonsils of fattening pigs (Autio et al., 2004). These pathogens can not be detected by macroscopic examination of carcasses during meat inspection.
S. enterica, Campylobacter spp., Y. enterocolitica and L. monocytogenes are food-borne zoonotic hazards which can be transmitted from pigs to humans through the consumption of pork which is today the most frequently consumed meat in Europe (Fosse et al., in press). Fosse, Seeger, and Magras (2008) have demonstrated that S. enterica, Y. enterocolitica and Campylobacter spp. are the three hazards most frequently reported in human clinical cases related to the consumption of pork. L. monocytogenes showed the highest severity score with high hospitalization and lethality rates (Fosse et al., 2008). In 2004, the prevalence rates of Campylobacter spp., Salmonella spp. and Yersinia spp. in pigs in the EU varied between 0.4–79.6%, 0.4–29.4% and 0.9–10.4%, respectively (Nørrung & Buncic, 2008). There was insufficient data available on the prevalence of L. monocytogenes in pigs (Nørrung & Buncic, 2008).
The objectives of this work were to (1) study the isolation rate of enteropathogenic Y. enterocolitica, Salmonella spp., Campylobacter spp. and L. monocytogenes in the tonsils and feces and (2) determine the number of mesophilic aerobic bacteria (MAB) and Escherichia coli in the tonsils of fattening pigs at slaughter.
Section snippets
Materials and methods
Tonsil and fecal samples were collected from 50 fattening pigs at slaughter in 2004. A slaughterhouse in Munich, Germany, was visited five times during January and March. At each visit, tonsil and fecal samples were taken from 10 pigs from at least three to four farms. In total, the pigs originated from 15 farms. The tonsils were collected using sterile plastic gloves and knives, and the fecal samples from the rectum in sterile plastic gloves. The samples were transported to the laboratory in
Results and discussion
The palatine tonsils are a well-known portal of entry and a site of multiplication and persistence for several micro-organisms in humans and animals including pigs (Salles & Middleton, 2000). In this study, the number of MAB and E. coli was very high in the tonsils of fattening pigs (Table 1). The mean number of MAB and E. coli was 7.12 log10 CFU/g and 5.52 log10, respectively. There was no significant difference in the mean number of MAB (p > 0.1, t-test) and E. coli (p > 0.05, t-test) between the
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Bacterial community analysis for investigating bacterial transfer from tonsils to the pig carcass
2019, International Journal of Food MicrobiologyCitation Excerpt :Accordingly, Lowe et al. (2012) defined the ‘core microbiome’ of the palatine tonsils in pigs to include the bacterial families Pasteurellaceae, Moraxellaceae, Fusobacteriaceae, Veillonellaceae, Peptostreptococcaceae and Streptococcaceae. In addition to pathogens as Salmonella spp. and Y. enterocolitica, often described in relation to pig slaughter, the tonsils have also been shown to contain a significant proportion of bacteria belonging to the phylum Fusobacteria, which include members known to have the potential of causing illness in both humans and animals (Aliyu et al., 2004; Fredriksson-Ahomaa et al., 2009; Langworth, 1977; Lowe et al., 2012). The main objective of the present study was to investigate whether bacterial transfer from tonsils and faeces to predefined areas of the pig carcass during pig slaughter could be elucidated by comparing systematic differences between bacterial communities in faeces and tonsils to the composition of the microbiota on the carcass.
Reduced contamination of pig carcasses using an alternative pluck set removal procedure during slaughter
2018, Meat ScienceCitation Excerpt :Regarding the presence of general hygiene indicator bacteria, Van Damme et al. (2018) reported mean levels for total aerobic bacteria, Enterobacteriaceae and E. coli of 6.63, 5.75, and 5.56 log10 CFU/g in tonsils of pigs at slaughter in Belgium, respectively. In a study by Fredriksson-Ahomaa, Gerhardt, and Stolle (2009), executed in Germany, mean values of 7.12 and 5.52 log10 CFU/g tonsil for total aerobic bacteria and E. coli, respectively, were found. Gill and Jones (1998) enumerated E. coli on pig tongues in Canada, which resulted in mean numbers of 2.3 log10 CFU/tongue swab.
Prevalence and diversity of Salmonella spp., Campylobacter spp., and Listeria monocytogenes in two free-range pig slaughterhouses
2018, Food ControlCitation Excerpt :Despite presenting a lower incidence than the other pathogens, listeriosis is the most harmful one in the elderly, pregnant woman and immunocompromised individuals, with the highest hospitalization and mortality rate since 2008 (EFSA, 2017). Pigs can be asymptomatic carriers of Salmonella enterica, Campylobacter and L. monocytogenes, and these pathogens can be isolated from the intestinal tract and tonsils of pigs (Fredriksson-Ahomaa et al., 2009; Farzan, Friendship, Cook, & Pollari, 2010). These animals may be a source of contamination for other pigs and pork meat through the pork production chain (Argüello et al., 2013; Hellström et al., 2010; Hernández et al., 2013; Prencipe et al., 2012).
Unique virulence properties of Yersinia enterocolitica O:3-An emerging zoonotic pathogen using pigs as preferred reservoir host
2014, International Journal of Medical MicrobiologyCitation Excerpt :In particular pigs and wild boars are common asymptomatic carriers and represent a substantial disease-causing potential for humans (Fredriksson-Ahomaa et al., 2011). Pathogenic Y. enterocolitica strains are routinely isolated from domestic pigs; a prevalence of 30–90% was reported in slaughtered pigs in Europe (Bucher et al., 2008; Fredriksson-Ahomaa et al., 2009a; Fredriksson-Ahomaa et al., 2011; Laukkanen et al., 2009; Martinez et al., 2011; Martinez et al., 2009). The pathogens are most frequently detected in the tonsils of fattened pigs (prevalence of 40–70%).