To Sample or Not to Sample? An Analysis of the Need for Salmonella Sampling of Smaller Poultry Processors.

Within the European Union (EU), microbiological criteria (MC) sampling for Salmonella in poultry was introduced in 2005. In particular, processors had to meet a target of fewer than seven positive samples out of 50. However, processors producing small amounts of poultry meat did not have to sample if national authorities determined this was an acceptable risk. The U.K. Food Standards Agency (FSA) thus has a sampling regime based on throughput that allows smaller processors not to sample. In 2011, the limit of 7/50 was reduced to 5/50. Given the current uncertainty regarding U.K. trade relations with the EU, the U.K. FSA decided to conduct a new risk assessment of the risks of Salmonella produced by smaller processors, to determine whether sampling was now necessary. Current evidence suggests that an MC sampling regime in smaller slaughterhouses is not warranted from a national public health perspective. Because of the insensitivities of the MC sampling scheme, the introduction of MC sampling into smaller slaughterhouses would only be necessary if the suspected carcass prevalence was 15% or more. While our analysis is prone to uncertainty, we estimated that the carcass prevalence in smaller processors is below this. Thus, we recommended that the current sampling framework, allowing smaller processors not to sample, was still applicable.

Microbial pathogen control in the beef chain: recent research advances.

Within a recent EU research project ("ProSafeBeef"), research on foodborne pathogens in the beef chain was conducted by using a longitudinally integrated (fork-to-farm) approach. There is not any "single intervention-single chain point" combination by which the pathogens would be reliably and entirely eliminated from the chain resulting in total prevention of pathogens in beef and products thereof at the consumption time. Rather, a range of control interventions have to be applied at multiple points of the chain, so to achieve an acceptable, ultimate risk reduction. Various novel interventions were developed and evaluated during the project, and are briefly summarized in this paper. They include on-farm measures, risk categorisation of cattle presented for slaughter, hygiene-based measures and antimicrobial treatments applied on hides and/or carcasses during cattle slaughter, those applied during beef processing-storage-distribution, use of Time Temperature Integrator-based indicators of safety, and effective sanitation of surfaces.

Toward harmonization of the European food hygiene/veterinary public health curriculum.

Prompted by developments in the agri-food industry and associated recent changes in European legislation, the responsibilities of veterinarians professionally active in veterinary public health (VPH), and particularly in food hygiene (FH), have increasingly shifted from the traditional end-product control toward longitudinally integrated safety assurance. This necessitates the restructuring of university training programs to provide starting competence in this area for veterinary graduates or a sub-population of them. To date, there are substantial differences in Europe in the way in which graduate programs in FH/VPH are structured and in the time allocated to this important curricular group of subjects. Having recognized this, the European Association of Establishments for Veterinary Education (EAEVE) recently instituted a working group to analyze the current situation, with a view to produce standard operating procedures allowing fair and transparent evaluations of universities/faculties constituting its membership and in concurrence with explicit European legislation on the professional qualifications deemed necessary for this veterinary discipline. This article summarizes the main conclusions and recommendations of the working group and seeks to contribute to the international efforts to optimize veterinary training in FH/VPH.

A study of haptoglobin levels in groups of cattle and pigs with and without abnormalities at meat inspection.

A total of 96 bovines originating from 36 farms and 97 pigs from five farms were slaughtered in two multispecies abattoirs and subjected to official meat inspection and haptoglobin (Hp) testing using a single radial immunodiffusion method. No direct correlation between Hp level and specific postmortem abnormalities was found at individual cattle/pig level. However, at animal group level, the mean of Hp values (in both cattle and pigs) were statistically significantly higher in animals with abnormalities than in those without. The study indicated that the mean Hp value in groups of cattle or pigs can be useful as an overall objective indicator of the overall status of cattle/pig batches when analyzing the food chain information as a part of the antemortem inspection at abattoirs, but related specific Hp criteria are currently missing. Because of the large variability and nonspecific nature of Hp-related responses in cattle and pigs, establishing a single, reliable cutoff Hp value differentiating batches that may pose public health risks does not appear as a realistic approach presently. Rather, establishing wider, unsatisfactory/marginal/satisfactory ranges of batch-based Hp values indicating general appropriateness of the cattle/pigs source appears more promising. For that, wider Hp baseline studies are necessary at abattoir.

Implementation of compulsory hazard analysis critical control point system and its effect on concentrations of carcass and environmental surface bacterial indicators in United Kingdom red meat slaughterhouses.

Statutory microbiological test results were collected from British meat plants over a 4-year period from June 2002 to May 2006. A total of 49,074 carcass test results from 19,409 cattle, 14,706 sheep, and 14,959 pig swabs and 95,179 environmental test results from surface swabs were obtained. These test results were donated by 94 slaughterhouses, which process about two thirds of the British national annual throughput of cattle, sheep, and pig carcasses. The data were collectively analyzed to determine any historical trends for numbers of total aerobes and Enterobacteriaceae. Significant reductions were observed in the numbers of indicator organisms on carcasses for all three species between 2002 and 2006. Reductions were also observed for numbers of aerobes on environmental and food contact surfaces. There were seasonal differences in bacterial numbers isolated from carcasses. Cattle and sheep carcasses had significantly higher numbers of total aerobes and Enterobacteriaceae in late summer and early autumn, whereas numbers of total aerobes on pig carcasses were higher in winter. Bacterial numbers on environmental surfaces were not influenced by the month that the swab samples were collected. Possible reasons for the observed reductions in bacterial numbers on carcasses and surfaces and the implications for carcass testing for process control purposes are discussed.

A comparison of wet-dry swabbing and excision sampling methods for microbiological testing of bovine, porcine, and ovine carcasses at red meat slaughterhouses.

A comparison of wet-dry swabbing and surface tissue excision of carcasses by coring was undertaken. Samples from 1,352 bovine, 188 ovine, and 176 porcine carcasses were collected from 70 separate visits to commercial slaughterhouses operating under normal conditions. The mean total aerobic viable bacterial counts (TVCs) for all species sampled by excision was 5.36 log units, which was significantly greater than the 4.35 log units measured for swabbing. Poorly correlated linear relationships between swab- and excision-derived bacterial numbers from near-adjacent carcasses were observed for all three animal species. R2 values for least squares regressions for bovine, ovine, and porcine carcasses were 0.09, 0.27, and 0.21, respectively. The reasons why it was not possible to calculate a factor that allowed the interconversion of bacterial numbers between samples collected by each sampling method were investigated. Uncertainty associated with laboratory analyses was a contributing factor because the geometric relative standard deviations measured for TVCs were 0.174 and 0.414 for excision and swabbing, respectively. Uneven distribution of bacteria at identical sampling sites on near-adjacent carcasses on processing lines was also a contributory factor. The implications of these findings for process control verification were investigated by intensive sampling for 13 weeks in three commercial slaughterhouses. As many as 4 log units of difference in TVCs were observed in duplicate samples collected within a narrow timeframe from near-adjacent carcasses on the processing line. We conclude that it might not be appropriate to institute corrective actions in slaughterhouses on the basis of a single week's test results.

Experimental comparison of excision and swabbing microbiological sampling methods for carcasses.

Bovine sides, ovine carcasses, and porcine carcasses were individually inoculated by dipping in various suspensions of a marker organism (Escherichia coli K-12 or Pseudomonas fluorescens), alone or in combination with two meat-derived bacterial strains, and were sampled by two standard methods: cotton wet-dry swabbing and excision. The samples were examined for bacterial counts on plate count agar (PCA plate counts) and on violet red brilliant green agar (VRBGA plate counts) by standard International Organization for Standardization methods. Average bacterial recoveries by swabbing, expressed as a percentage of the appropriate recoveries achieved by excision, varied widely (2 to 100%). Several factors that potentially contributed to relatively low and highly variable bacterial recoveries obtained by swabbing were investigated in separate experiments. Neither the difference in size of the swabbed area (10, 50, or 100 cm2 on beef carcasses) nor the difference in time of swabbing (20 or 60 min after inoculation of pig carcasses) had a significant effect on the swabbing recoveries of the marker organism used. In an experiment with swabs preinoculated with the marker organism and then used for carcass swabbing, on average, 12% of total bacterial load was transferred inversely (i.e., from the swab to the carcass during the standard swabbing procedure). In another experiment, on average, 14% of total bacterial load was not released from the swab into the diluent during standard swab homogenization. Use of custom-made swabs with abrasive butts, around which metal pieces of pan scourers were wound, markedly increased PCA plate count recoveries from noninoculated lamb carcasses at commercial abattoirs compared with cotton swabs. In spite of the observed inferiority of the cotton wet-dry swabbing method compared with the excision method for bacterial recovery, the former is clearly preferred by the meat industry because it does not damage the carcass. Therefore, further large-scale evaluation of the two carcass sampling methods has been undertaken under commercial conditions and reported separately.

Antilisterial Effects of a Sorbate-Nisin Combination In Vitro and on Packaged Beef at Refrigeration Temperature.

The antilisterial effects of a sorbate-nisin combination were assessed in vitro and on beef at refrigeration temperature. Three hemolytic pathogenic strains of Listeria monocytogenes , reference strain NCTC 7973, food strain L70, and clinical strain L94, were stored at 4°C in phosphate-buffered saline, pH 5.5, containing a combination of sorbate (0.2% wt/vol) and nisin (40 IU/ml). After 4 weeks, hemolysin production by the strains had ceased, their subsequent lag phases at 37°C were extended from an initial 1.23 to 1.32 h to a final 7.13 to 8.06 h and their pathogenicity for chick embryos had decreased from an initial 93.3 to 95.5% to a final 43.3 to 60.0%. Sterile beef steaks of normal pH (5.4 to 5.5) were inoculated with a cocktail of the three strains at approximately 5 log CFU/cm2 and the surface of half the steaks was treated with the antimicrobial solution 1.0% sorbate plus 1,000 IU of nisin per ml. The meat was packaged under vacuum or 100% carbon dioxide and stored at 4°C for 4 weeks. On untreated meat, L. monocytogenes grew by 1.79 log cycles in vacuum packages, but in CO2 packages the initial population decreased by 0.54 log cycle. On treated vacuum-packaged meat, L. monocytogenes decreased during storage to the extent that 96.5% of the initial pathogen load was eliminated, but the lag phase of the remaining cells at 37°C was unaffected. On treated CO2-packaged meat L. monocytogenes decreased during storage to the extent that 89.3% of the initial pathogen load was eliminated, and for surviving cells the lag phase at 37°C was extended. Treatment with the sorbate-nisin combination did not significantly affect pathogenicity of the L. monocytogenes cocktail recovered from vacuum- or carbon dioxide-packages after storage, in contrast to the in vitro study, where pathogenicity was clearly attenuated. The reason for this difference is unknown.

The Fate of Listeria Monocytogenes in Fermented Sausages and in Vacuum-Packaged Frankfurters.

In inoculated fermented sausages, the initial "most probable number" (MPN) of Listeria monocytogenes decreased from 8 × 106/g to 1.1 × 104/g during the production process. When the initial MPN was 6.5 × 102/g, L. monocytogenes were detected in finished sausages only when 25-g samples were used. The MPN of L. monocytogenes in finished experimental sausages remained constant during 20 d of storage at room temperature. The average number of lactobacilli in the experimental sausages was initially 1.2 × 107/g, reached 8 × 107/g after ripening, and decreased to 2.2 × 107/g in finished sausages. Sterilized filtrates of 12 Lactobacillus plantarum broth cultures produced zones of inhibition of L. monocytogenes growth on solid medium, when the pH of the filtrates ranged from 3.47 to 4.52. When the pH of the same filtrates was adjusted to 7.0, only slight zones of inhibition were registered with filtrates of 7 out of the 12 L. plantarum strains examined. In vacuum packages of surface-contaminated frankfurters, the MPN of L. monocytogenes increased from 5 × 102 to 2.1 × 105 per package during 20 d of storage at 4°C. In the same packages, the number of lactobacilli increased from 2.4 × 105 to 6.6 × 109 per package.