Brief communication Peer reviewed Microbiological evaluation of pork offal products collected from processing facilities in a major United States pork-producing region Alan K. Erickson, PhD; Monte Fuhrman, DVM; William Benjy Mikel, PhD; Jon Ertl, DVM; Laura L. Ruesch, MS; Debra Murray; Zachary Lau, BS Summary Resumen – Evaluación microbiológica Résumé – Évaluation microbiologique d’abats de porc prélevés dans des établisse- Analysis of 370 offal samples from 15 US de menudencias porcinas recolectadas ments de transformation dans une région pork-processing facilities detected Yersinia de centros procesadores en un región importante de producción porcina de los de production porcine importante aux enterocolitica-positive (2.4%) and Salmonella- États-Unis positive (21.8%) samples and mesophilic Estados Unidos aerobic plate counts > 107 colony-forming El análisis de 370 muestras de menudencias L’analyse de 370 échantillons d’abats prov- units/g (3.2%). A risk assessment showed de 15 centros procesadores de cerdo de EUA enant de 15 établissements de transformation américain a permis de détecter des échan- intestine (20%), brain (21%), liver and heart detectó muestras positivas al Yersinia entero- tillons positifs pour Yersinia enterocolitica (73%), and kidney (87%) sampling batches colitica (2.4%) y positivas a la Salmonella (2.4%) et Salmonella (21.8%) ainsi que des were acceptable for human consumption. (21.8%), y conteo de placa aeróbica de mesó- dénombrements de bactéries mésophiles aéro- filos > 107 unidades/g formadoras de colonias biques > 107 unités formatrices de colonies/g Keywords: swine, offal,Salmonella , Yer- (3.2%). Una evaluación de riesgo mostró que sinia, Toxoplasma (3.2%). Une évaluation du risque a démontré los lotes de muestreo de intestino (20%), cere- que les lots échantillonnés d’intestins (20%), Received: March 20, 2018 bro (21%), hígado y corazón (73%), y riñón de cerveau (21%), de foie et de cœur (73%), Accepted: August 21, 2018 (87%) eran aceptables para consumo humano. ainsi que de reins (87%) étaient acceptables pour consommation humaine. dible offal products from slaughtered and sell the edible offal products to consum- consumption by worldwide populations. hogs represent about 14% of the ers in countries that prefer strong tasting To evaluate the microbiological status of animal’s live weight.1 These edible pork products, like variety meats.3 The pork offal products, sampling batches of five Eoffal products include variety meats, which desirability of pork offal in foreign markets types of pork offal were tested for general are the edible organs and glands including makes them higher value products in those contamination and specific human patho- brain, heart, kidney, liver, thymus gland, and markets than in the United States, which gens including Salmonella spp., Yersinia tongue. In the United States, it is estimated would likely increase the value of live hogs enterocolitica, and Toxoplasma gondii, which that five million metric tons of pork variety for US producers. have been identified as three of the most meats and other byproducts are generated common foodborne hazards in pork.4 Sal- The purpose of the current study was to de- each year with a large amount of this mate- monella spp. and Y enterocolitica are normal termine if pork offal products (brain, heart, rial being rendered to generate low value components of the intestinal microflora intestine, kidney, and liver) as currently products like blood meal, fat, grease, meat of healthy pigs that can easily contaminate produced in US pork-processing facilities and bone meal, and pet food.2 An alterna- other pork products within the processing are acceptable as food products for human tive use of US pork offal would be to market facility environment.5,6 Both Salmonella spp. and Y enterocolitica cause intestinal infec- 7 AKE, LLR, DM, ZL: Department of Veterinary and Biomedical Sciences, South Dakota State tions in humans leading to diarrhea. Severe University, Brookings, South Dakota. Salmonella infections, which occur more MF: Pipestone Veterinary Services, Pipestone, Minnesota. commonly in young and elderly persons, can lead to bloody diarrhea, vomiting, and rarely WBM: WPF Technical Services, Lexington, Kentucky. death, while severe Y enterocolitica infections JE: Sioux Nation Ag Center, Sioux Falls, South Dakota. can cause extraintestinal sequelae, such as reactive arthritis, that can persist for years.7 Corresponding author: Dr Alan K. Erickson, Department of Veterinary and Biomedical Sciences, Toxoplasma gondii is a protozoan parasite 1155 N. Campus Drive, Box 2175, South Dakota State University, Brookings, SD 57007; Tel: 605- that can infect a variety of porcine organs in- 688-6544; Email: [email protected]. cluding brain, heart, and lungs.8 Toxoplasma This article is available online at http://www.aasv.org/shap.html. gondii causes mild influenza-like symptoms Erickson AK, Fuhrman M, Mikel WB, et al. Microbiological evaluation of pork offal products in most infected humans, but it can cause collected from processing facilities in a major United States pork-producing region. J Swine Health life-threatening infections in fetuses and Prod. 2019;27(1):34-38. immunocompromised individuals.9 34 Journal of Swine Health and Production — January and February 2019 Materials and methods Five samples (> 400 g each) of each type of Assisted Laser Desorption Ionization-Time of The sampling protocol for this study was offal were collected by placing each sample Flight Mass Spectrometer (MALDI-TOF MS; based on a risk assessment model designed in a sterile Whirl-Pak bag (Nasco, Fort Bruker Daltonics, Billerica, Massachusetts). Atkinson, Wisconsin) minimizing cross con- to determine if the offal products coming For detection of Y enterocolitica, minced offal tamination as best as possible. Offal samples from an individual processing facility on a samples (25 g) were homogenized in were obtained every 5 to 10 minutes to en- particular sampling day are acceptable for 225 mL of BPW using a stomacher for 2 min- 10 sure that animals from multiple farms were human consumption. In this model, the utes at 265 rpm. One hundred microliters of represented in each sampling batch. Imme- two criteria used to design the sampling the resulting homogenate were spread onto diately upon collection, samples were placed protocol were: 1) level of concern relative MacConkey and Cefsulodin-Irgasan-Novobi- on ice and stored at 4°C prior to shipment to human health hazards of each potential ocin (CIN) agar plates (BD, Franklin Lakes, for laboratory analysis. Tests for Y enteroco- pathogen (eg, indicator, moderate, serious, New Jersey) and allowed to incubate at 37°C litica, Salmonella, and APC were initiated or severe) and 2) condition of use of the for 48 hours.14 The identity of each suspected within 96 hours of sample collection. Prior food product (eg, if the food has a prepara- Y enterocolitica colony was verified by biotyp- to analysis of the intestine samples, the intes- tion step, such as heating, that would reduce ing using a Bruker MALDI-TOF MS.15 microorganism populations).10,11 The level tinal contents were removed from the lumen of risk to humans for the three pathogens by gently squeezing the contents out of the While it is known that T gondii oocysts are evaluated in this study (Salmonella spp., end of the ileum segment. Approximately partially inactivated by freezing, the DNA- Y enterocolitica, T gondii) is considered 100 g of each offal sample were stored at based PCR assay used in this study is capable serious based on their ability to cause inca- -20°C for T gondii detection. of detecting the presence of T gondii DNA in frozen tissue.15 Ten grams of minced, thawed pacitating, but not usually life-threatening, Mesophilic aerobic plate counts were per- offal were placed into a stomacher bag and disease. To be considered acceptable for formed by homogenizing 25 g of the minced 25 mL of cell lysis buffer containing 100 mM human consumption when testing for a seri- offal sample in 225 mL of buffered peptone Tris hydrochloride (pH = 8.0), 5 mM EDTA, ous human pathogen with decreased risk water (BPW) using a Seward 3500 stom- 0.2% sodium dodecyl sulphate, 200 mM due to inactivation by heating, a sampling acher (Islandia, New York) for 2 minutes at sodium chloride, and 40 mg/L proteinase K batch needs to consist of five samples, all of 265 rpm. The resulting tissue homogenate (30 mAnson U/mg) was added. The sample which need to test negative for the presence was diluted into BPW using 100-fold serial 10 was homogenized using a stomacher at 265 of the pathogen. The mesophilic aerobic dilutions. One milliliter of each dilution was rpm for 2 minutes and then incubated in a plate count (APC) is an indicator test of pipetted onto a 3M Aerobic Count Petrifilm 12 water bath at 55°C for 16 hours to release food acceptability , with counts less than plate (Maplewood, Minnesota) and allowed 7 any T gondii oocysts present. The sample was 1 × 10 colony-forming units/g (CFU/g) to incubate at 37°C for 48 hours. Colonies homogenized using a stomacher at 265 rpm considered a negative result. An acceptable of aerobic bacteria were counted and the for 1 additional minute and then centrifuged APC sampling batch needs to consist of five APC was calculated as CFU/g of tissue. samples with at least two of the five samples for 45 minutes at 3500g. Five milliliters of testing negative. Based on this risk assess- Salmonella spp. detection was performed us- the supernatant were heated at 100°C for ment model, our sampling protocol included ing a method based on the US Department 10 minutes to inactivate proteinase K and one sampling batch of five types of offal of Agriculture’s Microbiology Laboratory then stored at -20°C until PCR testing. The 13 from 15 large pork-processing facilities in Guidebook.