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Pork meat is estimated to be responsible for 10-20% of human salmonellosis cases in Europe. Control strategies at the farm could reduce contamination at the slaughterhouse. One of the targeted sectors of production is maternity, where sows could be Salmonella reservoirs. The aim of this study was to assess the dynamics of shedding of Salmonella in terms of variation in both shedding prevalence and strains excreted during gestation in Quebec's maternity sector. The evolution of the fecal microbiota of these sows during gestation was also assessed to detect bacterial populations associated with these variations. A total of 73 sows both at the beginning and the end of the gestation were randomly selected and their fecal matter was analyzed. Salmonella detection was conducted using a method that includes two selective enrichment media (MSRV and TBG). Nine isolates per positive samples were collected. Among the 73 sows tested, 27 were shedding Salmonella. Sows in the first third of their gestation shed Salmonella significantly more frequently (21/27) than those in the last third (6/46) (χ² P < 0.05). The shedding status of 19 of the sows that were previously sampled in the first third of their gestation was followed, this time in the last third of their gestation, which confirmed reduction of shedding. Using 16S rRNA gene sequencing and qPCR, significant differences between the fecal flora of sows at the beginning and the end of the gestation, shedding Salmonella or not and with different parity number were detected. Using MaAsLin, multiple OTUs were found to be associated with the time of gestation, the status of Salmonella excretion and parity number. Some of the identified taxa could be linked to the reduction of the shedding of Salmonella at the end of gestation. In this study, we showed that the level of Salmonella shedding was variable during gestation with significantly higher shedding at the beginning rather than at the end of gestation. We also observed for the first time a significant change in the microbiota during sow gestation and identified interesting taxa which could be linked to a reduced Salmonella shedding. [ABSTRACT FROM AUTHOR]

In order to ascertain the contamination status of Salmonella from carcass, equipment, environment and the intestinal contents in a pig slaughterhouse in Huaian, China, we investigated the prevalence and characteristics of Salmonella isolates in one slaughterhouse. A total of 636 samples were collected; Salmonella was laboratory-confirmed from 154/441 (34.9%) carcass swab-samples, 13/57 (22.8%) pieces of equipment, 30/86 (34.9%) environmental samples and the intestinal contents of 19/52 (36.5%) animals. Salmonella was found to be at its highest and lowest frequency during splitting (55.9%) and flaming (17.2%) processes, respectively. All Salmonella isolates were characterized by serotyping, multilocus sequence typing (MLST) and 69 S . Derby isolates were analyzed using pulsed-field gel electrophoresis (PFGE). Four serovars ( S . Derby, S . Rissen, S . Typhimurium, and S . London) were shared from the four sources and predominant serovars were S . Derby and S . Rissen. MLST results indicated that ten different STs were distinguished, of which ST40 was identified as the most prominent ST. Moreover, ST40, ST469, ST34 and ST155 comprised Salmonella isolates obtained from carcass, equipment, the slaughterhouse environment and intestinal contents. PFGE results showed that 33 pulsotypes (PF1-PF33) were identified. PF21, PF25 and PF29 suggested that many isolates from carcass-swab samples at different slaughterhouse process points were of the same pulsotype which also partly comprised isolates from equipment, the environment and intestinal contents. The present study provides an insight into Salmonella distribution in a pig slaughterhouse and revealed that cross-contamination occurs frequently at different sites, which provides data support for proposing some interventions to control Salmonella . [ABSTRACT FROM AUTHOR]

Contaminated pork is a significant source of foodborne Salmonella infections. Pork is contaminated at the slaughterhouse; however, the mechanisms driving Salmonella contamination of carcasses are still poorly understood. The aim of this study was to investigate whether the amount of Salmonella carried by slaughtered pigs in their guts has an influence on carcass contamination. On that account, we tested whether the number of carcasses contaminated during a slaughter day was associated with the prevalence of highly contaminated pigs (HCP: Salmonella caecal loads ≥ 3log/g), or with the prevalence of pigs that simply carry Salmonella spp. in their guts. Three hundred and six pigs were sampled in a slaughterhouse from Central Italy. Salmonella loads in the caecum and on the carcass of each pig were estimated by the most probable number (MPN) technique. The overall prevalence of Salmonella was 34.64% and 7.19% for the caeca and carcasses, respectively. S . Derby and Salmonella enterica 4,[5],12:i:– were the most frequently isolated serovars. The prevalence of HCP was 11.44%. We found a higher number of contaminated carcasses on days of high prevalence of HCP than on days of low prevalence of HCP ( p = 0.0011). Conversely, carcass contamination did not vary with the prevalence of pigs that simply carried Salmonella spp. in their guts ( p = 0.7970). Therefore, the prevalence of HCP, but not the prevalence of pigs carrying Salmonella spp., was related to carcass contamination. Taken together, these findings suggest that reduction of Salmonella loads in the guts of slaughtered pigs would result in fewer contaminated carcasses, and consequently, help to minimise the risk of human infection due to the consumption of contaminated pork. [ABSTRACT FROM AUTHOR]

Salmonella carriage and cutaneous contamination of pigs at slaughter are a major risk for carcass contamination. They depend on Salmonella prevalence at farm, but also on transmission and skin soiling among pigs during their journey from farm to slaughterhouse. To better understand and potentially control what influences Salmonella transmission within a pig batch during this transport and lairage step, we proposed a compartmental, discrete-time and stochastic model. We calibrated the model using pork chain data from Brittany. We carried out a sensitivity analysis to evaluate the impact of the variability in management protocols and of the uncertainty in epidemiological parameters on three model outcomes: prevalence of infection, average cutaneous contamination and number of new infections at slaughter. Each outcome is mainly influenced by a single management factor: prevalence at slaughter mainly depends on the prevalence at farm, cutaneous contamination on the contamination of lairage pens and new infections on the total duration of transport and lairage. However, these results are strongly affected by the uncertainty in epidemiological parameters. Re-excretion of carriers due to stress does not have a major impact on the number of new infections. [ABSTRACT FROM AUTHOR]

Yersinia enterocolitica 4/O:3 is the most important human pathogenic bioserotype in Europe and the predominant pathogenic bioserotype in slaughter pigs. Although many studies on the virulence of Y. enterocolitica strains have showed a broad spectrum of detectable factors in pigs and humans, an analysis based on a strict comparative approach and serving to verify the virulence capability of porcine Y. enterocolitica as a source for human yersiniosis is lacking. Therefore, in the present study, strains of biotype (BT) 4 isolated from Swiss slaughter pig tonsils and feces and isolates from human clinical cases were compared in terms of their spectrum of virulence-associated genes ( yadA , virF , ail , inv , rovA , ymoA , ystA , ystB and myfA ). An analysis of the associated antimicrobial susceptibility pattern completed the characterization. All analyzed BT 4 strains showed a nearly similar pattern, comprising the known fundamental virulence-associated genes yadA , virF , ail , inv , rovA , ymoA , ystA and myfA . Only ystB was not detectable among all analyzed isolates. Importantly, neither the source of the isolates (porcine tonsils and feces, humans) nor the serotype (ST) had any influence on the gene pattern. From these findings, it can be concluded that the presence of the full complement of virulence genes necessary for human infection is common among porcine BT 4 strains. Swiss porcine BT 4 strains not only showed antimicrobial susceptibility to chloramphenicol, cefotaxime, ceftazidime, ciprofloxacin, colistin, florfenicol, gentamicin, kanamycin, nalidixic acid, sulfamethoxazole, streptomycin, tetracycline and trimethoprim but also showed 100% antibiotic resistance to ampicillin. The human BT 4 strains revealed comparable results. However, in addition to 100% antibiotic resistance to ampicillin, 2 strains were resistant to chloramphenicol and nalidixic acid. Additionally, 1 of these strains was resistant to sulfamethoxazole. The results demonstrated that Y. enterocolitica BT 4 isolates from porcine tonsils, as well as from feces, show the same virulence-associated gene pattern and antibiotic resistance properties as human isolates from clinical cases, consistent with the etiological role of porcine BT 4 in human yersiniosis. Thus, cross-contamination of carcasses and organs at slaughter with porcine Y. enterocolitica BT 4 strains, either from tonsils or feces, must be prevented to reduce human yersiniosis. [ABSTRACT FROM AUTHOR]

The probability of contamination by pathogenic Yersinia enterocolitica of carcasses and pluck sets at slaughterhouse was determined by means of a Bayesian analysis. Prior information of the prevalence of Y. enterocolitica in faeces and the seroprevalence of Yersinia in serum of pigs collected at farms were obtained from previous studies and introduced in the models as beta prior informative distributions. Samples of intestinal content, tonsils, and swabs of carcasses and pluck set surfaces were collected at slaughterhouses. The posterior probabilities, odds ratio (OR) and their probability interval (PI) were calculated by means of a generalized linear model constructed in WinBugs. Occurrence of Y. enterocolitica in intestinal content (OR: 35.6, 95%PI 2.8–8285), tonsils (OR: 38.4, 95%PI 5.0–854), and pluck set (OR: 16.6, 95%PI 1.9–1111) was a risk for the contamination of pork carcasses, and an increased risk of contaminated pluck set was observed when Y. enterocolitica was isolated in intestinal content (OR: 40.6, 95%PI 2.1–10510) and tonsils (OR: 17.6, 95%PI 3.4–230.6). This increased risk indicated a potential cross-contamination at the slaughterhouse. [ABSTRACT FROM AUTHOR]

The objective of this study was to establish the time–temperature combinations required to ensure the thermal inactivation of Yersinia enterocolitica during scalding of pork carcasses. A 2 strain cocktail of Y. enterocolitica (bioserotypes 2/O:5,27 and 1A/O:6,30) was heat treated at 50, 55 and 60°C in samples of scald tank water obtained from a commercial pork slaughter plant. Samples were removed at regular intervals and surviving cells enumerated using (i) Cefsulodin–Irgasan–Novobiocin Agar (CIN) supplemented with ampicillin and arabinose and (ii) Tryptone Soya Agar (TSA), overlaid with CIN agar with ampicillin and arabinose. The data generated was used to estimate D- and z-values and the formula Dx =log−1(log D 60 − ((t 2 −t 1)/z)) was applied to calculate thermal death time–temperature combinations from 55 to 65°C. D 50, D 55 and D 60-values of 45.9, 10.6 and 2.7min were calculated from the cell counts obtained on CIN agar, respectively. The corresponding D-values calculated from the TSA/CIN counts were 45.1, 11 and 2.5min, respectively. The z-value was 7.8. It was concluded that a time–temperature combination of 2.7min at 60°C is required to achieve a 1 log reduction in Y. enterocolitica in pork scald tank water. The predicted equivalent at 65°C was 0.6min. This study provides data and a model to enable pork processors to identify and apply parameters to limit the risk of carcass cross-contamination with Y. enterocolitica in pork carcass scald tanks. [ABSTRACT FROM AUTHOR]

In a 3-year study (2008 to 2011) to estimate the prevalence and the contamination sources of Listeria monocytogenes in pork meat in Sardinia, Italy, 211 samples were collected from five Sardinian swine slaughterhouses: 171 samples from slaughtered pigs and 40 from the slaughterhouse environment. Fifty L. monocytogenes isolates were characterized by PCR-based serotyping, presence of virulence-associated genes, and pulsed-field gel electrophoresis restriction analysis. The overall prevalence of L. monocytogenes was 33% in swine carcasses, 7% in cecal material, 23% on meat contact surfaces, and 25% on noncontact surfaces. Only two serotypes were detected: l/2c (78%) and l/2a (22%). In all, based on the presence of virulence-associated genes, eight pathogenic profiles were detected. Only 42% of all isolates carried the full complement of virulence-associated genes and were allotted to profile 1. Six pulsed-field gel electrophoresis profiles persisted in the slaughterhouses; restriction profiles appeared to be specific to each plant. [ABSTRACT FROM AUTHOR]

A total of 339 Enterococcus faecalis strains were isolated from pork production chain, slaughterhouses, processing plants and retails, and were compared with human infection strains for investigating the transmission from animal to human via food production chain. From slaughterhouses to retails, most of antimicrobial resistances and multidrug resistance rates decreased or were not changed significantly. Meanwhile, the prevalence rate of strong or moderate biofilm-forming isolates was highest at retails. In the result of random amplified polymorphic DNA-polymerase chain reaction analysis, there was no strain persisting along the pork production chain or being similar to human strains. Consequently, it is suggested that E. faecalis strains from pork meat would not be delivered to humans by consumption of pork. Practical Applications Through investigation of antimicrobial resistant bacteria of the pork production chain of Korea, more information and relief would be provided to consumers and its results could help policy making in public health and food safety. [ABSTRACT FROM AUTHOR]

Abstract: In this study the occurrence of Salmonella in swine, pork meat and meat handlers along with their clonal relatedness is evaluated at abattoir level. Samples from the lymph nodes, carcass surface and meat of 100 pigs and 45 meat handlers were collected in eight abattoirs (July 2007–August 2008). Salmonella isolates were serotyped and genotyped by pulsed-field gel electrophoresis (PFGE). From the pigs tested, 42 produced at least one positive sample. A relatively high frequency of Salmonella occurrence was found in the ileoceacal lymph node samples (26.0%), followed by carcass (16.0%) and meat samples (14.0%). However, ileoceacal lymph nodes that test positive for Salmonella are not found to be a predictor of positive test results further on in the process. Besides the slaughterhouse environment, meat handlers were identified as a possible source of subsequent contamination, with 9.3% of the sample testing positive. Diverse Salmonella enterica serotypes were detected, mainly S. Typhimurium and the monophasic variant S. 4,[5],12:i:-, but also S. Derby, S. Rissen, S. Mbandaka, S. London, S. Give, S. Enteritidis and S. Sandiego, in total corresponding to 17 PFGE types. Our results demonstrate that besides a high level of Salmonella swine contamination at pre-harvest level, slaughtering, dressing, cutting and deboning operations are contributing to the occurrence of clinically relevant clones (e.g. S. Typhimurium DT104 and S. 4,[5],12:i:-) in pork products. This study also highlights the possibility of an ongoing Salmonella community being spread by abattoir workers. [Copyright &y& Elsevier]

Abstract: Contamination of pork products during slaughter represents an important vehicle for Salmonella spp. dissemination to humans. Salmonellosis poses an important risk for public health and presents an important economic issue to pork producers. This study aimed to evaluate the occurrence of this foodborne pathogen in pork carcasses and risk tissues (ileum, ileocolic and mandibular lymph nodes and tonsils) by two methods: the reference culture method (ISO 6579:2002) and a rapid Fluorescent In Situ Hybridization (FISH) method. The culture method identified the presence of Salmonella spp. in 13.7% of the samples, while the FISH technique revealed that 38.2% of the samples were positive. From these FISH positive samples, only 58 were concordant to the positive results obtained by the culture method. These results confirm the potential risk that pork represents in salmonellosis transmission, suggesting that additional measures should be taken during evisceration practices and extraction of tonsils and mandibular lymph nodes after slaughter, in order to achieve a better control of Salmonella contamination during slaughter. The FISH method showed to be a rapid screening tool for Salmonella spp. detection in pork samples. [Copyright &y& Elsevier]

Abstract: Salmonella can either be controlled pre-harvest, post-harvest or by a combination of both approaches. This paper describes the lessons learned in Danish Salmonella surveillance and control programme for finisher pigs and pork. Initially, main focus was on pre-harvest initiatives and correct identification of herds with respect to the risk for Salmonella that they represented. However, an analysis of risk-mitigating actions applied along the chain from stable to table showed that it would be more cost-effective to deal with Salmonella on the abattoirs than in the herds. This knowledge moved focus from pre- to post-harvest without giving up on pre-harvest surveillance. First of all, this meant increased attention on slaughter hygiene and individual interventions in the abattoirs. In brief, we learned that for a programme to be successful it must be based on standardised methods for sampling and testing to be able to evaluate and compare performance of the programme. More specifically, meat-juice samples taken from finisher pigs at the time of slaughter are an effective way of identifying high-risk herds for Salmonella. In addition, a penalty system might act as an incentive for farmers to deal with Salmonella in their herd. Additionally, common targets for all abattoirs allowing for unique control solutions should be adapted. Finally, decontamination techniques like hot water decontamination are a feasible way of dealing with high-risk pigs (Level-3 pigs). The current prevalence in Danish pork is around 1.2%, and a target is set to <1.0% to be reached by the end of 2013. The experience obtained by use of the Danish programme might be used to develop and implement appropriate types of surveillance programs as well as risk-mitigating measures in other countries. [Copyright &y& Elsevier]

Pork tissue samples that tested positive and negative by the Charm II tetracycline test screening method in the slaughter plant laboratory were tested with the modified AOAC International liquid chromatography tandem mass spectrometry (LC-MS-MS) method 995.09 to determine the predictive value of the screening method at detecting total tetracyclines at 10 µg/kg of tissue, in compliance with Russian import regulations. There were 218 presumptive-positive tetracycline samples of 4,195 randomly tested hogs. Of these screening test positive samples, 83% (182) were positive, >10 µg/kg by LC-MS-MS; 12.8% (28) were false violative, greater than limit of detection (LOD) but <10 µg/kg; and 4.2% (8) were not detected at the LC-MS-MS LOD. The 36 false-violative and not-detected samples represent 1% of the total samples screened. Twenty-seven of 30 randomly selected tetracycline screening negative samples tested below the LC-MS-MS LOD, and 3 samples tested <3 µg/kg chlortetracycline. Results indicate that the Charm II tetracycline test is effective at predicting hogs containing >10 µg/kg total tetracyclines in compliance with Russian import regulations. [ABSTRACT FROM AUTHOR]

In our study we aimed at deriving performance objectives (POs) for Salmonella in fresh pork meat intended to be eaten cooked, using loin chop as a model. Moreover, sampling plans to verify the compliance of meat lots to such POs are presented. Ten lots of product, collected in the same slaughterhouse along a one-year period, were tested for Salmonella detection under four different storage stages through the product shelf life. The POs were considered as different target values from Salmonella prevalence and were calculated at the 50th percentile of prevalence distributions under each stage. Results obtained indicated that values increased between a minimum of 26.10% of positives after final storage at 14°C to a maximum of 46.70% of positives after storage at retail. The number of samples to be tested in order to detect at least one positive and verify the compliance to the estimated POs ranged between five, for samples after storage at retail, and ten, for samples stored at 14°C before the expiration date. For risk management purposes, percentiles different from the 50th can be selected in order to derive the POs as well as the number of samples to be tested in order to verify their fulfillment. Thus, the approach presented in this paper offers different options to risk managers for improving the decision-making process. [ABSTRACT FROM AUTHOR]