ABSTRACT
Salmonella Typhimurium is the predominant serotype isolated from humans in Europe. Pork and pork products are recognized vehicles of Salmonella and are responsible for outbreaks of human salmonellosis. Pigs can become infected with Salmonella on the breeding or fattening farm and during transport, lairage, and slaughter. The aim of this study was to investigate selected points of Salmonella contamination from the time pigs entered the lairage to the time the carcass was processed in the boning hall and to determine the importance of different sources of Salmonella along the Irish pork production chain. A second objective was to evaluate whether the serological status or category of a herd influenced the levels of bacteriological contamination detected on individual carcasses and pork cuts during slaughter and dressing operations. All samples were tested for the presence and numbers of Salmonella. Enterobacteriaceae numbers were also determined. Serotype, phage type, and pulsed-field gel electrophoresis were utilized to determine similarity among Salmonella isolates. Lairage was a major source of cross-contamination with Salmonella as were the hands of evisceration operatives, conveyor belts, and equipment in the boning hall. Cross-contamination within the slaughter plant environment accounted for up to 69 % of Salmonella carcass contamination. In general, herd category reflected the bacteriological status of carcasses and pork cuts. Major findings were a strong association (P < 0.01) between Enterobacteriaceae counts and Salmonella occurrence on prechill carcasses and a significant association (P < 0.05) between Enterobacteriaceae counts and Salmonella occurrence on pork cut samples.
Subject(s)
Abattoirs , Food Contamination/analysis , Meat/microbiology , Salmonella Food Poisoning/prevention & control , Salmonella/isolation & purification , Abattoirs/standards , Abattoirs/statistics & numerical data , Animals , Colony Count, Microbial , Enterobacteriaceae/isolation & purification , Food Contamination/prevention & control , Food Handling/methods , Humans , Ireland/epidemiology , Salmonella Infections, Animal/transmission , Salmonella typhimurium/isolation & purification , SwineABSTRACT
Salmonella is a common contaminant of raw pork and represents a public health risk. Both qualitative and quantitative data on Salmonella in pork at retail are required for assessment of consumer exposure to the pathogen. Pork samples (n=500) were collected at random from butchers' shops and supermarkets in the Republic of Ireland between January and November, 2007 and examined for prevalence and numbers of Salmonella using a PCR screen followed by cultural examination of positive samples. Salmonella numbers were assessed using a three tube most probable number (MPN) technique. Any Salmonella recovered were characterised by serotype, phage type and antibiogram, and subtyped by pulsed-field gel electrophoresis (PFGE). Enterobacteriaceae were also enumerated to see if there was a correlation between the Salmonella status of the pork and hygiene levels at retail outlets. Salmonella spp. were detected on 13/500 (2.6%) pork cuts at numbers between <0.03 and 2.10 MPN/g. The mean Enterobacteriaceae counts was 3.12 log(10) CFU/g (range -0.26-6.52 log(10) CFU/g). Salmonella Typhimurium was the most common serotype and the majority of isolates were multi antibiotic resistant. PFGE analysis showed evidence of persistence of some strains, with an S. Typhimurium U310 recovered from a pork abattoir being identical (100%) to a strain found a year later in a sample from a retail outlet. There was also evidence of cross contamination of Salmonella isolates between samples. There was a direct association between Salmonella contamination of pork and Enterobacteriaceae numbers, which indicates the need for good hygiene practices at retail for control of this pathogen.
Subject(s)
Enterobacteriaceae/isolation & purification , Food Contamination/analysis , Food Microbiology , Salmonella/isolation & purification , Animals , Colony Count, Microbial , Drug Resistance, Bacterial , Electrophoresis , Enterobacteriaceae/genetics , Environmental Exposure , Food Supply/standards , Ireland , Meat , Polymerase Chain Reaction , Prevalence , Salmonella/classification , Salmonella/genetics , SwineABSTRACT
AIMS: This study aimed to determine the numbers and types of Salmonella spp. and Enterobacteriaceae on pork cuts in the meat cutting room environment of four commercial pork abattoirs in the Republic of Ireland. METHODS AND RESULTS: Pork oysters (M. gluteus medius; n = 720) and swabs (n = 56) from equipment and surfaces were screened for Salmonella spp. using a DNA-based PCR method and confirmed by culture. Salmonella numbers were assessed using a three-tube most probable number (MPN) technique. Salmonella spp. was detected on 24/720 (3.3%) pork cuts (range of <0.03-0.36 MPN g(-1)) and in 7/56 (12.5%) environmental swabs (range of <0.03-1.10 MPN cm(-2)). There was significant variation in the prevalence of Salmonella on pork between different abattoirs and days of sampling (range of 0-31.7%). The predominant serotype was Salmonella serotype Typhimurium followed by Salmonella serotype Derby. CONCLUSIONS: Overall prevalence data conceal the key finding that there was considerable variation in the incidence of Salmonella on different days. A direct association between Salmonella contamination of pork cuts and equipment/surfaces was observed. SIGNIFICANCE AND IMPACT OF THE STUDY: Prevalence and numbers of Salmonella were low; however, results clearly demonstrate the potential for cross-contamination from equipment and meat contact surfaces in the cutting room environment.
