Risk Factors for Salmonella and Hygiene Indicators in the 10 Largest Belgian Pig Slaughterhouses

Abstract

A survey was conducted to collect data on Salmonella prevalence, Escherichia coli counts (ECCs), and aerobic bacteria colony counts (ACCs) on pig carcasses after chilling at the 10 largest Belgian pig slaughterhouses during 2000 through 2004. Potential risk factors of contamination associated with production parameters, technical descriptions of the installations, and cleaning and disinfection methods were assessed during investigations in the slaughterhouses. These variables were used first in a univariate analysis and then were extended to a multivariate analysis with a logistic mixed regression model for Salmonella and a linear mixed model for ECCs and ACCs with slaughterhouses as the random effect. The results indicated high variability concerning Salmonella contamination among the 10 slaughterhouses, with prevalence ranging from 2.6 to 34.3% according to the area of origin. The median ECC and median ACC ranged from -0.43 to 1.11 log CFU/cm2 and from 2.37 to 3.65 log CFU/cm2, respectively. The results of the logistic and linear regressions revealed that some working practices such as scalding with steam, second flaming after polishing, and complete cleaning and disinfection of the splitting machine several times a day were beneficial for reducing Salmonella prevalence, ECCs, and ACCs. Changing the carcass hooks just before chilling, using water as the cleaning method, and a higher frequency of disinfection of the lairage seemed to be protective against E. coli in the multivariate mixed linear model. The monitoring of critical points, slaughterhouse equipment, good slaughtering practices, and effective washing and disinfection are the keys to obtaining good microbiological results.

Pre-harvest risk factors for Salmonella enterica in pork production

“…Carcass contamination essentially results not only from the carriage of pathogens by the pig itself, but also from contact with other contaminated carcasses and/or surfaces in the abattoir. Hygiene varies between abattoirs and has been shown to have an important impact on carcass contamination (Baptista et al, 2010;Botteldoorn et al, 2004;Delhalle et al, 2008;Eblen et al, 2006), in addition to pre-slaughter transportation and lairage/holding, which have been shown to increase the contamination risk of the abattoir's slaughter and processing lines (Hurd et al, 2002;Rostagno et al, 2003).…”

Assessment of lamb carcass hygiene before and after chilling at five Irish abattoirs

“…The Enterobacteriaceae family comprises a large number of organisms, not all of faecal origin, and are more useful as an indicator of overall process hygiene in the abattoir. E. coli are considered to be a more suitable choice of indicator as they are a single species more specifically associated with faeces (Delhalle et al, 2008;Ghafir, China, Dierick, De Zutter, & Daube, 2008;McEvoy et al, 2004). Studies have found that the presence of E. coli on carcasses were a reliable index for enteric zoonotic agents such as Salmonella (Delhalle et al, 2008;Ghafir et al, 2008).…”

Scientific Opinion on a Quantitative Microbiological Risk Assessment of Salmonella in slaughter and breeder pigs

“…Recently, a survey was carried out in the ten largest Belgian pig slaughterhouses (Delhalle et al, 2008). The carcasses were sampled in the chilling room two to four hours after slaughter.…”

“…Monitoring of critical points, the condition and cleanliness of equipment, good slaughtering practices, and effective cleaning and disinfection of equipment were considered as the key elements contributing to food safety during the slaughter process (Delhalle et al, 2008).…”

“…To date, little interest has been given to airborne transmission of bacteria within the slaughterhouse, a situation rather contrasting with the high number of papers published about airborne transmission of bacteria between live pigs, including Salmonella enterica (Dee et al, 2009;Proux et al, 2001). Moreover, equipment-mediated contamination (direct contact) was considered important by Prendergast (2008).In epidemiological studies of slaughterhouses aspects of internal climate and air flow were not clearly targeted (Delhalle et al, 2008). The conjunction of the common bacterial airborne transmission on short distances especially under indoor conditions, the surface-type of Salmonella contamination (only the carcass surface is contaminated) and the often highly twisted shape of the slaughterline, combined with a humid internal climate and a loose separation between the slaughter "per se" area and the evisceration area, is worth considering.…”