A Quantitative Risk Assessment of the Human Health Impacts Due to Macrolide Use in Swine

We used a retrospective modeling approach instead of the traditional farm to fork model; back calculating (Cm) the number of human macrolide resistant C. coli mfections caused by eating contaminated pork, due to specific macrolide use in swine. We used the estimated number of culture confirmed human infections (Ct). As a measure of human health risk, we then calculated the expected number among the (Cm) cases that experience an adverse treatment outcome (prolonged illness) due to macrolide resistance, using estimates for fluoroquinolone. We divided the model into Release, Exposure and Consequence assessment sections according to FDA guidance 152 and utilized @Risk software with 20,000 iterations for simulation. The results show the human health risks are negligible. For example, the predicted annual risk, for preventton and growth promotion uses is only 1 in 92 million per U.S. resident, with a 5% chance it could be as high as 1 in 52 million. Our model focuses on the impact of resistance on human treatment. It assumes that macrolide resistance C. coli infection reduces treatment efficacy. However, it is possible that risks less than our estimates

Salmonella enterica prevalence and serotype distribution in swine at slaughter

The objective of this cross-sectional study was to analyze data available from multiple studies conducted by our research team estimating the prevalence of S. enterica, and the serotype d1stribution in swine at slaughter, based on different sample types A total of 1,110 pigs from three large capacity abattoirs located in the Midwestern U S. were individually sampled at slaughter. Individually paired samples collected mcluded. cecal contents and ileocecal lymph nodes. Samples were collected on multiple occasions in all three abattoirs, transported to the laboratory, and processed for the isolation and identification of S. enterica. The overall prevalence of S. enterica, based on cecal contents, mesentenc lymph nodes, and any of the samples (i.e., cecal contents and/or mesenteric lymph nodes) was 54.7%, 27.9%, and 62.6%, respectively. There was a Significant difference (P\u3c0.05) between prevalence estimates based on cecal contents and mesenteric lymph node samples in all three abattoirs, and overall. A variety of S. enterica serotypes was isolated m all abattoirs The average number of serotypes isolated per group was 3.48. This study confirms that the S. entenca prevalence at slaughter in swine is high, requiring attention due to the associated risk of contamination of the abattoir environment. Moreover, our results demonstrate the common occurrence of a high diversity of serotypes in swine at slaughter. This study also shows that both cecal contents and mesenteric lymph nodes should be considered for a better estimate of S. enterica prevalence at slaughter

Resting on transport trailer reduces Salmonella at harvest

A potential intervention strategy to reduce the prevalence of Salmonella enterica at harvest was evaluated, which consisted of resting pigs prior to harvest on their transport vehicle, instead of in the abattoir holding pen. Individual fecal samples were collected at the farm and at the abattoir (n= 120 pigs), where half of the pigs were unloaded, and moved to a holding pen, whereas the other half stayed in the transport trailer

Tradeoffs, the missing link in food safety risk analysis

Many groups, in addition to the producer and veterinarian, are now trying to direct and regulate livestock management practices. For example, in 2008 California passed a law regulating the confinement of certain fann animals ... . The U.S. Congress recently introduced a bill restricting the use of on-farm antibiotics. Some organizations are blaming the April 2009 outbreak of swine flu on intensified pork production (Food and Water Watch, 2009). A rationale fonn of decision making will be needed to address these policy questions. However, for many current food safety issues indecision and stalemate are the rule of the day. Many people are saying the food safety system is in crisis, but no mutually acceptable solutions are forthcoming. salmonella standards for raw product are being lowered periodically, just because . The presence of some pathogens (e.g. E. coli 0157:H7, Listeria monocytogenes) are labeled as adulterants, promoting a zero risk expectation by consumers. Some countries have a zero tolerance for Salmonella on incoming product, while the exporting country is allowed to feed the same product to their own citizens. No product can be tested to one hundred percent safety, therefore, meat producers and processors are working in a constant state of uncertainty because they are only one recall away from bankruptcy

Salmonella prevalence in first pull versus close out market pigs

Identifying potential risk factors to direct intervention strategies is fundamental to reduce the risk of pork contamination with Salmonella. This study was designed to compare the Salmonella prevalence in the first group of pigs selected for slaughter (uFirst pull ) versus the last group of pigs selected for slaughter ( Close out ) from typical commercial finishing barns containing 800 - 1,000 animals. Nine finishing barns from two production sites were included in the study {4 paired samplings from site A, and 5 paired samplings from site B). Each paired sampling consisted in matched groups of pigs from the same barn as the first pair and the close out with a 4-week interval between groups. From each group, individual fecal samples (n = 45) and meat samples (n = 50) were collected, on-farm and at slaughter, respectively. In the laboratory, fecal samples were selectively enriched, and analyzed for the presence of Salmonella by a commercially available antigen-capture ELISA. Meat samples were kept frozen, and thawed for processing. The resulting liquid ( meat juice ) was collected and analyzed for the presence of antibodies against Salmonella by a commercially available ELISA. All lots of pigs housed in the finishing barns studied were Salmonella-positive, based on sampling from first pull and close out . In 7/9 (77.8%) of the studied barns, an increase in Salmonella prevalence was observed, based on both bacteriologic and serologic analysis. Overall, there was an increase of 9.3% (P\u3c0.05) in bacteriologic prevalence, and 25.1% (P\u3c0.05) in serologic prevalence from first pull to close out groups. This study demonstrates that a significant increase of Salmonella prevalence occurs between the first and the last group of pigs from a finishing barn shipped to slaughter. In conclusion, close out groups of finishing pigs constitute a higher risk for Salmonella contamination of pork products

The Impact of Pig Health on Public Health: Quantitative Data for Risk Assessments

Management practices can play an important role in affecting animal health. Sub-clinically ill animals entering harvest can have pleural adhesions known as peel-outs. The focus of this study was to examine how these pleural adhesions can be associated with Salmonella and respiratory pathogens, as well as to get a national estimate of peel-outs. The results suggest pleural adhesions are not significantly associated with Salmonella or respiratory bacterial contamination

Sampling cecal contents or ileocecal lymph nodes: is it different?

The objective of this study was to compare the prevalence of Salmonella enterica in swine populations estimated by sampling cecal contents versus ileocecal lymph nodes. In each of two abattoirs, four groups of pigs (n=30 pigs per group) were studied. Cecal contents and ileocecal lymph nodes were individually collected and processed for isolation and identification of S. enterica. The overall prevalence found by cecal contents was 40%, whereas by ileocecal lymph nodes it was 22.9% (p\u3c0.05). Combining results from both samples, the prevalence found was 50.8%. The relative sensitivity of cecal content sampling was 79.3%, whereas for ileocecal lymph node sampling it was 45.5%. The agreement (Kappa statistic) between both sample types was 13.1%. This study demonstrates that sampling either cecal contents or ileocecal lymph nodes affects results of S. enterica epidemiological studies. It is recommended that both samples be used

Quantity and Distribution of Salmonella Recovered from Three Swine Lairage Pens

The quantity of Salmonella recoverable from three lairage pens in a swine abattoir was determined. Using dry four-ply cotton gauze pads measuring 10 by 10 cm, 100 fecal slurry samples were collected from each of the three pens. Salmonella recovery was expressed as the log CFU per milliliter of sample. Mean values were 2.5 log CFU/ml in pen A, 2.7 log CFU/ ml in pen B, and 0.89 log CFU/ml in pen C. Median values were 2.6 log CFU/ml in pen A, 2.0 log CFU/ml in pen B, and below the detectable limit in pen C. In pen C, Salmonella was not recoverable from a high number of samples. Pen B results suggested spatial dependency, i.e., samples close together were more similar than samples farther apart. These results indicate that Salmonella concentrations vary within and between lairage pens. Because of the limited number of pens assessed, it was not possible to identify factors that were associated with the observed variation in Salmonella concentrations within and between pens. However, this variation suggests that numerous samples are required to adequately describe the concentration of Salmonella in a lairage pen

The Association between Cleaning and Disinfection of Lairage Pens and the Prevalence of Salmonella enterica in Swine at Harvest

A series of four field trials were conducted to evaluate the ability of a cleaning and disinfection procedure in swine lairage pens to reduce the prevalence of Salmonella enterica in slaughtered pigs. A cleaning and disinfection procedure was applied to lairage pens at a large Midwest abattoir. Each trial consisted of a cleaned (alkaline chloride detergent) and disinfected (H2O2 plus peracetic acid sanitizer) pen (treated) and a control pen, each holding 90 to 95 pigs for 2 to 3 h before slaughter. Ileocecal lymph nodes, cecal contents, and rectal contents were collected from 45 pigs from each study pen at harvest and cultured for S. enterica. In all trials, cleaning and disinfection reduced the prevalence of S. enterica–positive floor swabs in the treated pen (P , 0.05). However, the postharvest prevalence of S. enterica–positive pigs varied between trials. In trial 1, there was no significant difference in the prevalence of S. enterica in pigs between treatment and control groups. In trials 2 and 3, the prevalence of S. enterica was higher in pigs from treated pens versus pigs from control pens (91% versus 40%, P , 0.0001, and 91% versus 24%, P , 0.0001, respectively). In trial 4, the prevalence of S. enterica was lower in pigs from treated pens compared with pigs from control pens (5% versus 42%, P , 0.0001). This study indicates that cleaning and disinfection effectively reduces the amount of culturable S. enterica in lairage pens, but the ability of cleaned and disinfected pens to reduce the prevalence of S. enterica in market-weight pigs remains inconclusive

Eliminating the Abattoir Pen Lairages to Decrease the Prevalence of Salmonella in Cull Sows

The study objective, to determine the role of abattoir antemortem pens in preharvest Salmonella enterica contamination, was conducted over 4 sampling periods, February-April 2002. A total of 40 sows were selected for each period at the same collection point and transported to the abattoir. Twenty (20) were unloaded and sent directly to harvest and 20 held in antemortem pen for 2 h before harvest. Samples collected included ileocecal and subiliac lymph nodes, cecal and transverse colon contents, pre-rinse carcass sponge swabs for the right and left carcass sections and chopped meat blocks composited from these carcasses. The percentage of positive samples (all tissues) and cecal content from sows held in the antemortem pens (59%, 55 %, respectively) were significantly higher (P \u3c 0.05) compared to direct delivered (44%, 39 % respectively). This study demonstrates that normal antemortem holding practices contributed to increased Salmonella enterica contamination of the digestive tract