Lymphadenitis in free-range pigs: contributions to diagnosis and implications for the food chain

La linfadenitis se puede definir como el proceso que cursa con la inflamación de los nódulos linfáticos superficiales o profundos como respuesta a la infección por diferentes microorganismos y se caracteriza macroscópicamente por la aparición de granulomas, piogranulomas o abscesos, que pueden extenderse desde los nódulos linfáticos a otros órganos por difusión linfohemática, principalmente a pulmones, hígado y bazo, dando lugar a la aparición de lesiones similares. Debido al carácter subclínico de estas infecciones, las lesiones pasan desapercibidas en la mayoría de los casos y no son detectadas hasta la inspección postmortem en el matadero, siendo su generalización responsable del decomiso total de las canales afectadas. Entre los agentes causales de la linfadenitis porcina destacan las micobacterias del complejo Mycobacterium tuberculosis (CMT), las micobacterias del complejo Mycobacterium avium (CMA) y otros géneros bacterianos, como Rhodococcus, Corynebacterium o Streptococcus, que poseen un riesgo zoonósico variable. El primer objetivo de esta tesis doctoral ha sido evaluar técnicas de diagnóstico rápido de la tuberculosis (TB) en ganado porcino, incluyendo una dúplex PCR a tiempo real y cinco ensayos serológicos basados en distintos antígenos de Mycobacterium bovis. El segundo objetivo ha consistido en identificar los principales microorganismos aislados a partir de cuadros de linfadenitis del cerdo en extensivo. Como tercer y último objetivo de este trabajo se ha evaluado cómo el proceso de curación de lomos y paletas del cerdo ibérico afecta a la viabilidad de los principales microorganismos no tuberculosos aislados en nuestro estudio (Streptococcus suis, Streptococcus dysgalactiae y Trueperella pyogenes)

Multi-Etiological Nature of Tuberculosis-Like Lesions in Condemned Pigs at the Slaughterhouse

Tuberculosis-like lesions (TBL) in pigs have been associated with microorganisms other than mycobacteria. In this work a histopathological and microbiological evaluation of TBL in pigs is shown. A total of 352 samples belonging to 171 pigs totally condemned at slaughterhouse due to generalized TBL were sampled and selected for analysis. Pyogranulomatous (56.2%) and granulomatous lesions (20.2%) were observed in all analysed organs. Most of the granulomas observed in both lymph nodes and lungs belonged to more advanced stages of development (stages III and IV) whereas in the liver and the spleen most of lesions belonged to intermediate stages (stages II and III). Different microorganisms were simultaneously detected from TBL in the 42.7% of the animals. Mycobacterium tuberculosis complex (MTC) (38%), coryneform bacteria (40.3%) and streptococci (28.1%) were the main groups of microorganisms detected after bacteriological analysis, with Trueperella pyogenes and Streptococcus suis as the most frequently isolated species. Mycobacteria belonging to MTC were the most frequently detected pathogens in granulomatous and pyogranulomatous lesions in submandibular lymph nodes (32.7%) and coryneform bacteria were the microorganisms more frequently isolated from lungs (25.9%) and spleen samples (37.2%). These results may provide new insights into the pathogenesis and diagnosis of this pathology. The importance of coryneform bacteria and streptococci in such processes must be evaluated in future studie

Multi-Etiological Nature of Tuberculosis-Like Lesions in Condemned Pigs at the Slaughterhouse.

Tuberculosis-like lesions (TBL) in pigs have been associated with microorganisms other than mycobacteria. In this work a histopathological and microbiological evaluation of TBL in pigs is shown. A total of 352 samples belonging to 171 pigs totally condemned at slaughterhouse due to generalized TBL were sampled and selected for analysis. Pyogranulomatous (56.2%) and granulomatous lesions (20.2%) were observed in all analysed organs. Most of the granulomas observed in both lymph nodes and lungs belonged to more advanced stages of development (stages III and IV) whereas in the liver and the spleen most of lesions belonged to intermediate stages (stages II and III). Different microorganisms were simultaneously detected from TBL in the 42.7% of the animals. Mycobacterium tuberculosis complex (MTC) (38%), coryneform bacteria (40.3%) and streptococci (28.1%) were the main groups of microorganisms detected after bacteriological analysis, with Trueperella pyogenes and Streptococcus suis as the most frequently isolated species. Mycobacteria belonging to MTC were the most frequently detected pathogens in granulomatous and pyogranulomatous lesions in submandibular lymph nodes (32.7%) and coryneform bacteria were the microorganisms more frequently isolated from lungs (25.9%) and spleen samples (37.2%). These results may provide new insights into the pathogenesis and diagnosis of this pathology. The importance of coryneform bacteria and streptococci in such processes must be evaluated in future studies

Evaluation of rapid methods for diagnosis of tuberculosis in slaughtered free-range pigs

Free-range pigs can be infected by Mycobacterium tuberculosis complex (MTC) and may contribute to the spread of bovine tuberculosis (bTB). In the present study, the diagnostic values of bacteriological culture, a duplex real-time quantitative PCR and an antibody ELISA were evaluated in an abattoir study of submandibular lymph nodes and serum samples from 73 pigs with and without lesions consistent with bTB. The duplex qPCR was an accurate method for diagnosis of TB in pigs (specificity 100%; sensitivity 80%). Combining qPCR with histopathology improved sensitivity and had very good concordance (κ = 0.94) with the reference method. Serological results suggest that the antibody ELISA can be used for monitoring herds but not individuals

Evaluation of four ELISA assays to diagnose Mycobacterium tuberculosis complex infection in pigs

Resumen del trabajo presentado al 8th European Symposium of Porcine Health Management and 24th International Pig Veterinary Society Congress, celebrados en Dublin (Irlanda) del 7 al 10 de junio de 2016.[Introduction]: In countries in which bovine tuberculosis (bTB) is still prevalent or is re-emerging the contact among different animal species in extensive systems may contribute to the circulation of Mycobacterium bovis and other members of the Mycobacterium tuberculosis complex (MTC) and the spread of this disease. Thus, free-range pigs may be infected by MTC, developing subclinical infections, which are not detected until meat inspection procedures at slaughterhouse. Serodiagnosis has been recently proposed as a reliable screening tool for detecting infected herds. In this study four ELISA assays using different M. bovis peptides/proteins (MPB70+MPB83, INGENASA; treated bovine purified protein derivative, t-bPPD; bPPD1; and bPPD2 VACUNEK) as coating antigens were evaluated to diagnose MTC infection in pigs. [Materials and Methods]: Submandibular lymph nodes (SLN) and blood samples from 129 free-range pigs raised on Southern Spain farms with a history of condemnation due to tuberculosis-like lesions were sampled at slaughterhouse. SLN were tested by gross examination, histopathology, bacteriological culture and qPCR. Ninety-seven out of these animals were classified as bTB positive cases (compatible lesions and MTC detection by means of culture and qPCR) or bTB negative cases (absence of compatible lesions and negative MTC detection) and used as reference method. When necessary different cut-off values were evaluated. [Results]: All assays had a very good concordance between them (k ≥ 0.82). The MPB70+MPB83 based ELISA had the best sensitivity (Se) (78%, CI95 67.4%>88.5%) and a good concordance with the reference method (k=0.69). The t-bPPD and the bPPD1 in-house assays presented a slightly reduced Se (71.2%, CI95 59.6%>82.7%; and 66.1%, CI95 54%>78.2%; respectively) and a moderate concordance with the reference method (k=0.57 and 0.52, respectively). When the bPPD2 based ELISA was evaluated, similar Se to the previous ones was obtained using a cut-off of 0.35 (Se: 66.1%, CI95 54%>78.2%; k=0.52). Conclusion` +: These results suggest that despite the fact that MPB70+MPB83 ELISA presented the best results all four evaluated ELISA assays could be used as a screening tool to conduct TB surveillance in pigs at a population level. In addition, a cut-off of 0.35 is recommended for bPPD2 ELISA in order to obtain better diagnostic values.This study was financially supported by the Council of Economy, Science, Innovation and Employment of the Andalusian Government (AGR-2685-2012) and by the European Project WILDTBVAC (FP7-KBBE-613799).Peer Reviewe

Virulence potential of Listeria monocytogenes

International audienceBackground: Listeria monocytogenes is a foodborne bacterial pathogen that causes listeriosis, an infectious disease of animals and humans, with pigs acting as asymptomatic reservoirs. In August 2019 a listeriosis outbreak associated with the consumption of pork meat caused 222 human cases in Spain. Determining the diversity as well as the virulence potential of strains from pig origin is important for public health concerns. Methods: The behavior of twenty-three L. monocytogenes strains recovered from pig tonsils, meat and skin was compared by studying: (1) Internalin A (InlA), Internalin B (InlB), Listeriolysin O (LLO), Actin assembly-inducing protein (ActA) and PrfA expression levels, and (2) invasion and intracellular growth in eukaryotic cells. Results: Marked differences were found in the expression of the selected virulence factors and the invasion and intracellular replication phenotypes of the L. monocytogenes strains. Strains obtained from meat samples and belonging to ST 1/2a did not have InlA anchored to the peptidoglycan. Some strains expressed higher levels of the studied virulence factors and invaded and replicated intracellularly more efficiently than an epidemic L. monocytogenes reference strain (F2365). Conclusion: This study demonstrates the presence of virulent L. monocytogenes strains in pigs, with valuable implications in veterinary medicine and food safety

Virulence potential of Listeria monocytogenes strains recovered from pigs in Spain

International audienceBackground: Listeria monocytogenes is a foodborne bacterial pathogen that causes listeriosis, an infectious disease of animals and humans, with pigs acting as asymptomatic reservoirs. In August 2019 a listeriosis outbreak associated with the consumption of pork meat caused 222 human cases in Spain. Determining the diversity as well as the virulence potential of strains from pig origin is important for public health concerns. Methods: The behavior of twenty-three L. monocytogenes strains recovered from pig tonsils, meat and skin was compared by studying: (1) Internalin A (InlA), Internalin B (InlB), Listeriolysin O (LLO), Actin assembly-inducing protein (ActA) and PrfA expression levels, and (2) invasion and intracellular growth in eukaryotic cells. Results: Marked differences were found in the expression of the selected virulence factors and the invasion and intracellular replication phenotypes of the L. monocytogenes strains. Strains obtained from meat samples and belonging to ST 1/2a did not have InlA anchored to the peptidoglycan. Some strains expressed higher levels of the studied virulence factors and invaded and replicated intracellularly more efficiently than an epidemic L. monocytogenes reference strain (F2365). Conclusion: This study demonstrates the presence of virulent L. monocytogenes strains in pigs, with valuable implications in veterinary medicine and food safety

Evaluación de la calidad microbiológica de canales de pollo sacrificadas en el estado de Zulia (Venezuela).: aplicación de la normativa vigente

A study to assess the microbiological quality and safety of chicken carcasses packaged in five chicken slaughterhouses located in San Francisco, Mara and Maracaibo, Zulia State, Venezuela (designed as plants A, B, C, D and E) to detect the presence of Salmonella spp. and count aerobic mesophilic bacteria, based on the Norma Venezolana Covenin 2343-86 pollo beneficiado en Venezuela, was carried out. A total of 30 packaged chicken carcasses were sampled. Also, three areas of processing: evisceration, pre-chiller and chiller were analyzed. A total of 150 samples (30 intestinal content, 90 carcass and 30 samples of water) were obtained. Of the thirty packed chicken carcasses analyzed, we detected the presence of Salmonella spp. in 18 (60%, 95% CI, 42.47-77.53), and the number of carcasses that exceeded tolerable limits for aerobic mesophilic microorganisms was 40 percent (95% CI: 22.47-57.53). The evisceration is considered a critical point of the process; due to the high degree of contamination of the animals arrive at the slaughterhouse. Also, along the processing (pre-chiller and chiller) cross contamination is observed, avoiding the elimination of these microorganisms in the final product. According to the results, the implementation of monitoring and control of Salmonella spp. in primary production; review the sanitary conditions of the slaughterhauses, and the adoption of codes of good practice on the staff responsible for the holdings, transport and slaughter are recommended. Finally we recommend reviewing the Covenin Norma Venezolana in relation to sampling pressure, type of samples, diagnostic techniques and results interpretation according to international standards to facilitate trade of meat products with maximum health guarantees.En este trabajo se ha realizado un estudio para evaluar la calidad y seguridad microbiológica de canales de pollo envasadas en cinco mataderos de pollos ubicados en los municipios San Francisco, Maracaibo y Mara, del estado de Zulia, Venezuela (plantas A, B, C, D y E), para determinar la presencia de Salmonella spp. y el recuento de aerobios mesófilos, basándonos en legislación vigente (Norma Venezolana Covenin 2343-86 pollo beneficiado). Se han analizado 30 muestras de canales de pollo envasado. Asimismo, se han tomado muestras en tres áreas del procesado: evisceración, preenfriamiento y enfriamiento. Se analizaron un total de 150 muestras (30 de contenido intestinal, 90 de canales y 30 de agua de los tanques). Se detectó la presencia de Salmonella spp. en el 60% de las canales envasadas (IC95%, 42,47-77,53%), mientras que un 40 por ciento (IC95% 22,47-57,53%) superó los límites tolerables para aerobios mesófilos. Se comprueba que la evisceración es un punto crítico, debido al alto grado de contaminación de los animales que llegan al matadero. De igual modo, se han detectado contaminaciones cruzadas en el preenfriamiento y enfriamiento de las canales, imposibilitando la eliminación de estos agentes en el producto final. De acuerdo con los resultados obtenidos, se recomienda la aplicación de planes de vigilancia y control de Salmonella en la producción primaria, revisar las condiciones sanitarias en las plantas sacrificadoras, así como la adopción de códigos de buenas prácticas en el personal responsable de las explotaciones, transporte y mataderos. Finalmente se aconseja revisar la Norma Covenin Venezolana, adaptando la presión de muestreo, tipo de muestras, técnicas de diagnóstico y lectura de resultados a la normativa internacional, para favorecer el comercio de productos cárnicos con las máximas garantías sanitarias

Evaluación de la calidad microbiológica de canales de pollo sacrificadas en el estado de Zulia (Venezuela). Aplicación de la normativa vigente

En este trabajo se ha realizado un estudio para evaluar la calidad y seguridad microbiológica de canales de pollo envasadas en cinco mataderos de pollos ubicados en los municipios San Francisco, Maracaibo y Mara, del estado de Zulia, Venezuela (plantas A, B, C, D y E), para determinar la presencia de Salmonella spp. y el recuento de aerobios mesófilos, basándonos en legislación vigente (Norma Venezolana Covenin 2343-86 pollo beneficiado). Se han analizado 30 muestras de canales de pollo envasado. Asimismo, se han tomado muestras en tres áreas del procesado: evisceración, preenfriamiento y enfriamiento. Se analizaron un total de 150 muestras (30 de contenido intestinal, 90 de canales y 30 de agua de los tanques). Se detectó la presencia de Salmonella spp. en el 60% de las canales envasadas (IC95%, 42,47-77,53%), mientras que un 40 por ciento (IC95% 22,47-57,53%) superó los límites tolerables para aerobios mesófilos. Se comprueba que la evisceración es un punto crítico, debido al alto grado de contaminación de los animales que llegan al matadero. De igual modo, se han detectado contaminaciones cruzadas en el preenfriamiento y enfriamiento de las canales, imposibilitando la eliminación de estos agentes en el producto final...A study to assess the microbiological quality and safety of chicken carcasses packaged in five chicken slaughterhouses located in San Francisco, Mara and Maracaibo, Zulia State, Venezuela (designed as plants A, B, C, D and E) to detect the presence of Salmonella spp. and count aerobic mesophilic bacteria, based on the Norma Venezolana Covenin 2343-86 pollo beneficiado en Venezuela, was carried out. A total of 30 packaged chicken carcasses were sampled. Also, three areas of processing: evisceration, pre-chiller and chiller were analyzed. A total of 150 samples (30 intestinal content, 90 carcass and 30 samples of water) were obtained. Of the thirty packed chicken carcasses analyzed, we detected the presence of Salmonella spp. in 18 (60%, 95% CI, 42.47-77.53), and the number of carcasses that exceeded tolerable limits for aerobic mesophilic microorganisms was 40 percent (95% CI: 22.47-57.53). The evisceration is considered a critical point of the process; due to the high degree of contamination of the animals arrive at the slaughterhouse. Also, along the processing (pre-chiller and chiller) cross contamination is observed, avoiding the elimination of these microorganisms in the final product. According to the results, the implementation of monitoring and control of Salmonella spp. in primary production; review the sanitary conditions of the slaughterhauses, and the adoption of codes of good practice on the staff responsible for the holdings, transport and slaughter are recommended. Finally we recommend reviewing the Covenin Norma Venezolana in relation to sampling pressure, type of samples, diagnostic techniques and results interpretation according to international standards to facilitate trade of meat products with maximum health guarantees..