The risk of carriage of Salmonella spp. and Listeria monocytogenes in food animals in dynamic populations

Abstract

Salmonella spp. and Listeria monocytogenes are foodborne pathogens of global importance. We assessed their risks and associated factors in a highly dynamic population of animals. Animal and environmental samples were collected from dairy cattle, sheep, camel and chickens at either the farms or the abattoirs. The pathogens were detected using a combination of bacterial enrichment culture and real‐time polymerase chain reaction (PCR). Data on putative risk factors were collect and analysed for their significance of association with these pathogens. Salmonella spp. were detected at higher proportions in sheep faeces and sheep carcasses in comparison to cattle faeces (odds ratio = 2.4 and 2.2, respectively). This pathogen was less common in milk or carcasses samples from cattle or chickens. Sheep and camel carcass samples were highly contaminated with Salmonella spp. Faecal samples from cattle had the most diverse serovars of Salmonella enterica including S. Newport, S. Haifa, S. Kedougou, S. Kentucky, S. Mbandaka and S. Goettingen. Exotic serovars in sheep included S. Eastbourne, S. Chester and S. Kottnus. Serovars that were shed in camel faeces included S. Newport, S. Bovismorbificans and S. Infantis. In all sampled populations, detection of Salmonella spp. was more likely during warmer months than cold months. Listeria monocytogenes was not common in the targeted populations and was detected at a rate of 2.4%, mainly from sheep carcasses. The study highlights the role of food animals as reservoirs of pathogens across boundaries since all feed are imported in that population from different parts of the world.

Nontyphoid Salmonella Prevalence, Serovar Distribution and Antimicrobial Resistance in Slaughter Sheep

“…This finding is in contrast to previous reports indicating S. Typhimurium to be either the predominant (Kidanemariam et al, 2010;Molla et al, 2006;Moussa et al, 2012;Stipetic et al, 2016;Tadesse, 2015;Wani et al, 2013;Yang et al, 2014) or the second-most dominant (Lewerin et al, 2011;Tadesse and Tessema, 2014) serovar isolated. There are only a few reports that mention S. Newport as the second-most dominant serovar and one of the lesser isolated serovars in sheep FC (Dargatz et al, 2015;Stipetic et al, 2016;USDA, 2013). Additionally, parallel to our findings, S. Kentucky was indicated as the second-most predominant serovar by Dargatz et al (2015).…”

“…Additionally, there was less fecal contamination risk during evisceration due to the natural pellet form of sheep feces, which does not stick and smear to the carcass. Previous studies have indicated the absence (Kuma et al, 2017;Ranucci et al, 2014) or presence (Duffy et al, 2010;Stipetic et al, 2016;Tekelu and Negussie, 2011) of Salmonella in sheep carcasses. Differences observed in prevalence rates in these studies were reported to arise from the general hygiene status of slaughterhouses; whether slaughtering is applied in monorail conveyors or on the floor; sheep's initial pathogen carriage rate, increasing risk of shedding during transport stress leading to higher fecal contamination of carcass, and differences in sensitivity of Salmonella detection procedures.…”

“…by Chatzopoulos et al (2016) in Greece, 3.6% by Yang et al (2017) in Australia, and 6.08% by Hurtado et al (2017) and Hanlon et al (2018) in Spain. In Qatar, Stipetic et al (2016) found a contamination rate of 22.5% in fecal content samples by PCR and attributed this finding to high cross-contamination between carcasses, poor sanitary handling by workers and equipment in the slaughterhouse. Likewise, Kuma et al (2017) from Ethiopia linked their high Salmonella contamination rate of 11.36% in the fecal contents of sheep to their close contact during transport and prolonged holding time before slaughter.…”

“…Additionally, the Turkish Food Codex (TFC) Regulation on Microbiological Criteria (TFC, 2011) has zero tolerance for the detection of Salmonella from ovine carcasses assessed with EN/ISO 6579 (ISO, 2002) as the reference method. Accordingly, several studies have reported Salmonella prevalence in sheep carcasses (0%-26.7%) (Kuma et al, 2017;Ranucci et al, 2014;Stipetic et al, 2016), in fecal samples (0%-26.90%) (Dargatz et al, 2015;Hanlon et al, 2018;McAuley et al, 2014), in edible organs such as liver (0.9%-4.3%) and spleen (0%-2.27%) (Kuma et al, 2017;Molla et al, 2006;Woldemariam et al, 2005), in gallbladder (3%) (Zubair and Ibrahim, 2012) and in mesenteric lymph nodes (3.85%-13.6%) (Hanlon et al, 2018;Kuma et al, 2017;Tadesse and Tessema, 2014), where S. Typhimurium was reported as the predominant serovar regardless of the sample type.…”

Prevalencia de Salmonella spp., en ganglios mesentéricos de porcinos en plantas de beneficio Colombianas

“…A study performed in Uganda reported S. Newport, S. Guildford, S. Coleypark, S. Damman as frequent pig serotypes (26), previously described in humans. Osman et al (27), evidenced S. Haifa in duck embryos, this serotype has also been isolated from bovine feces (28), and humans (26), suggesting adaptation to different animal species. Additionally, S. London an unusual serotype was also identified.…”