Listeria monocytogenes in beef: a hidden risk.

Listeria monocytogenes in beef receives less attention compared to other pathogens such as Salmonella and Escherichia coli. To address this gap, we conducted a literature review focusing on the presence of L. monocytogenes in beef. This review encompasses the pathogenic mechanisms, routes of contamination, prevalence rates, and the laws and regulations employed in various countries. Our findings reveal a prevalence of L. monocytogenes in beef and beef products ranging from 2.5% to 59.4%. Notably, serotype 4b was most frequently isolated in cases of beef contamination during food processing, with the skinning and evisceration stages identified as critical points of contamination.

Shiga toxin-producing Escherichia coli isolated from pasteurized dairy products from Bahia, Brazil.

The presence of pathogenic Shiga toxin-producing Escherichia coli (STEC) in dairy products represents a public health concern because of its ability to produce the toxins Stx1 and Stx2, which cause intestinal diseases. Monitoring the stages of milk production and checking dairy products for contamination are crucial steps to ensure dairy safety. This study aimed to report the occurrence of thermotolerant coliforms, E. coli, and STEC strains in pasteurized dairy products and to evaluate the antibiotic resistance profiles, serotypes, and characterizations of the STEC isolates by pulsed-field gel electrophoresis. We obtained a total of 138 pasteurized dairy products from 15 processing plants in Bahia, Brazil, to examine coliforms, E. coli, and STEC strains. We found that 43% of samples (59/138) contained thermotolerant coliforms, and 30% (42/138) did not comply with Brazilian regulations. Overall, 6% (9/138) were positive for E. coli and 4% (5/138) were positive for STEC. We recovered 9 STEC isolates from pasteurized cream (2/9), Minas Padrão cheese (2/9), Minas Frescal cheese (4/9), and ricotta (1/9). All isolates were stx2-positive, and 2 were eae-positive. All isolates were negative for the "big 6" STEC serogroups, belonging instead to serotypes ONT:HNT, ONT:H12, O148:H-, OR:H40, OR:HNT, and O148:HNT. Pulsed-field gel electrophoresis revealed 100% genetic similarity among 3 isolates from 2 different samples produced in the same production facility, which may suggest cross-contamination. As well, we found isolates that were 98% similar but in samples produced in different production facilities, suggesting a mutual source of contamination or a circulating strain. Two STEC strains exhibited resistance to streptomycin. Although the isolates presented a low resistance profile and no strain belonged to the "big 6" pathogenic group, the circulation of stx2-positive STEC strains in ready-to-eat products highlights the importance of epidemiological surveillance inside the Brazilian dairy chain.

Listeria monocytogenes in Export-approved Beef from Mato Grosso, Brazil: Prevalence, Molecular Characterization and Resistance to Antibiotics and Disinfectants.

The Brazilian state of Mato Grosso is the largest producer and exporter of beef in the country, but few studies of relevance have been conducted to evaluate the microbiological safety of its products. This study aimed to estimate the prevalence of Listeria monocytogenes (LM) in export-approved beef from Mato Grosso and to characterize the isolates in terms of molecular properties and antimicrobial resistance. From a total of 50 samples analyzed, Listeria sp. was isolated in 18 (36% prevalence). Listeria monocytogenes was confirmed in 6 (12% prevalence). Among the serotype groups assessed by multiplex PCR, serotype 4 (4b, 4d or 4e) was the most prevalent. Although antibiotic resistance was not an issue, two strains isolated from different plants showed high resistance to sodium hypochlorite. Overall, this scenario causes concern because it puts at risk not only the Brazilian customer, but also the population of countries that import beef from Mato Grosso.

Worldwide Epidemiology of Salmonella Serovars in Animal-Based Foods: a Meta-analysis.

Salmonella spp. are among the most important foodborne pathogens and the third leading cause of human death among diarrheal diseases worldwide. Animals are the primary source of this pathogen, and animal-based foods are the main transmission route to humans. Thus, understanding the global epidemiology of Salmonella serovars is key to controlling and monitoring this bacterium. In this context, this study aimed to evaluate the prevalence and diversity of Salmonella enterica serovars in animal-based foods (beef, pork, poultry, and seafood) throughout the five continents (Africa, the Americas [North and Latin America], Asia, Europe, and Oceania). The meta-analysis consisted of a chemometric assessment (hierarchical cluster analysis and principal component analysis) to identify the main epidemiological findings, including the prevalence and diversity of the Salmonella serovars in each matrix. Regarding the serovar distribution, S Typhimurium presented a cosmopolitan distribution, reported in all four assessed matrices and continents; poultry continues to play a central role in the dissemination of the Enteritidis serovar to humans, and Anatum and Weltevreden were the most frequently found in beef and seafood, respectively. Additionally, we recommended careful monitoring of certain serovars, such as Derby, Agona, Infantis, and Kentucky. Finally, given the scientific data regarding the most frequently reported serovars and which matrices constitute the main vehicles for the transmission of this pathogen, control programs may be improved, and specific interventions may be implemented in an attempt to reduce the risk of this pathogen reaching humans.IMPORTANCE Salmonellosis is caused by Salmonella spp. and is the third leading cause of death among food-transmitted diseases. This pathogen is commonly disseminated in domestic and wild animals, and the infection's symptoms are characterized by acute fever, nausea, abdominal pain, and diarrhea. The animals are the primary source of salmonellae, and animal-based foods are the main transmission route to humans. Therefore, data collected from these sources could contribute to future global interventions for effective control and surveillance of Salmonella along the food chain. In light of this, the importance of our research is in identifying the prevalence of Salmonella serovars in four animal-based food matrices (pork, poultry, beef, and seafood) and to evaluate the importance that each matrix has as the primary source of this pathogen to humans.

The urban and rural capybaras (Hydrochoerus hydrochaeris) as reservoir of Salmonella in the western Amazon, Brazil / As capivaras urbanas e rurais (Hydrochoerus hydrochaeris) como reservatório de Salmonella no oeste da Amazônia, Brasil

The capybara (Hydrochoerus hydrochaeris) is the largest rodent in the world. In the state of Acre, Brazil, populations of capybaras have been increasing significantly. The role of capybaras in the transmission of certain bacterial zoonotic infections is not well understood, including bacteria of the genus Salmonella. Salmonella spp. generally cause enteritis or septicemia in mammals, however many mammalian species can carry the bacteria asymptomatically and shed it in their feces. To better understand the possible role of capybaras as reservoirs of Salmonella spp., we conducted a study of Salmonella within fecal samples from capybara in Acre. In a convenience sample, 54 capybaras from two urban and two rural areas of Acre were captured and kept for three to four days for sampling. None of the animals were symptomatic of any intestinal illness. Three separate fecal samples were collected from each animal, during their stays in captivity. Each sample was cultured for the presence of Salmonella spp. at the bacteriology laboratory of the Veterinary College of the Federal University of Acre. Samples were seeded in tetrationate pre-enrichment broth and in pre-enrichment broth peptone. After a 24 hour of incubation all samples were streaked on MacConkey Agar (MC) and Salmonella-Shigella Agar (SS). Suggestive colonies were submitted to biochemical analysis. Salmonella compatible colonies according to biochemical profile were submitted to serotyping (Sorokit for Salmonella - Probac do Brasil). In addition, the first sample from each of the 54 capybara was tested for Salmonella spp. using PCR targeting gene hilA. Eight (5%) of the 162 samples examined by bacterial culture were positive for Salmonella spp., while four (7%) of the 54 examined by PCR were positive. From the eight positive animals on culture, five were from urban area and three from rural area. On PCR, only one positive animal was from urban area and four were from rural area. Overall, by either test, one of the 54 animals was positive. All samples were collected in free - living animals with no apparent clinical signs of salmonellosis, indicating the potential of capybara as reservoir on this ecosystem.(AU)

A capivara (Hydrochoerus hydrochaeris) é o maior roedor do mundo. No estado do Acre, Brasil, as populações de capivaras têm aumentado significativamente. O papel das capivaras na transmissão de certas infecções zoonóticas bacterianas não é bem compreendido, incluindo as bactérias do gênero Salmonella. Salmonella spp. geralmente causam enterite ou septicemia em mamíferos, porém muitas espécies de mamíferos podem carregar a bactéria de forma assintomática e eliminá-la em suas fezes. Para entender melhor o possível papel das capivaras como reservatórios de Salmonellaspp., realizamos um estudo para identificação de Salmonella spp. em amostras fecais de capivaras no Acre. Em uma amostra de conveniência, 54 capivaras de duas áreas urbanas e duas áreas rurais do Acre foram capturadas e mantidas por três a quatro dias para amostragem. Nenhum dos animais era sintomático de qualquer doença intestinal. Três amostras fecais foram coletadas de cada animal, durante sua permanência em cativeiro. Cada amostra foi cultivada para a presença de Salmonella spp. no Laboratório de Bacteriologia Veterinária da Universidade Federal do Acre. As amostras foram semeadas em caldo de pré-enriquecimento tetrationato e em peptona de caldo de pré-enriquecimento. Após 24 horas de incubação, todas as amostras foram semeadas em ágar MacConkey (MC) e ágar Salmonella-Shigella (SS). Colônias sugestivas foram submetidas a análises bioquímicas. Colônias compatíveis com Salmonella de acordo com o perfil bioquímico foram submetidas à sorotipagem (Sorokit para Salmonella - Probac do Brasil). Além disso, a primeira amostra de cada uma das 54 capivaras foi testada para Salmonella spp. usando PCR, visando gene hilA. Oito (5%) das 162 amostras examinadas por cultura bacteriana foram positivas para Salmonella spp. Enquanto quatro (7%) das 54 examinadas pela PCR foram positivas. Dos oito animais positivos em cultura, cinco eram de área urbana e três de área rural. Na PCR, apenas um animal positivo era de área urbana e quatro de área rural. Considerando o diagnóstico conjunto por ambos os testes, PCR e cultura, um animal foi considerado positivo. Todas as amostras foram coletadas em animais livres, sem sinais clínicos aparentes de salmonelose, indicando o potencial da capivara como reservatório nesse ecossistema.(AU)

Uso de métodos complementares na inspeção post mortem de carcaças com suspeita de tuberculose bovina / Use of complementary methods in post mortem inspection of carcasses with suspected bovine tuberculosis

O objetivo foi utilizar métodos complementares de diagnóstico (histopatológicos, bacteriológicos e moleculares), no julgamento de lesões suspeitas de tuberculose observadas durante a inspeção post mortem de rotina em abatedouros. Foi acompanhado o abate e a inspeção de 41.193 bovinos, sadios ao exame ante mortem, em sete abatedouros no estado de Mato Grosso. Carcaças de 198 (0,48%) animais apresentaram lesões, sendo 182 (92,0%) classificadas como granulomatosas ou piogranulomatosas na avaliação histopatológica. Entretanto, na baciloscopia, não foi evidenciada a presença de bacilo álcool-ácido resistente (BAAR). Mycobacterium bovis foi isolado em três (1,5%) lesões, provenientes de linfonodos retrofaringeanos de bovinos com até três anos de idade. Quando usado a PCR múltipla (m-PCR) diretamente nos fragmentos de tecido, detectou-se a presença de DNA de M. bovis em 14 (7,0%) lesões, incluindo as três amostras identificadas na análise bacteriológica. O julgamento das lesões pelo exame macroscópico concordou em 93,0% (184/198) com os resultados obtidos por meio da PCR. A fim de evitar equívocos durante a avaliação, principalmente das lesões paucibacilares, como as encontradas neste estudo, recomenda-se a utilização de testes complementares rápidos e confirmatórios. A m-PCR, associada à inspeção post mortem de rotina, demonstrou ser uma técnica promissora para a vigilância da tuberculose bovina em abatedouros, contribuindo para o sucesso do programa de erradicação da tuberculose bovina.

The aim of this study was used diagnostic methods (histopathological, bacteriological and molecular) in the trial of suspected tuberculosis lesions observed during routine post mortem inspection in abattoirs. A total of of 41,193 cattle, which appeared healthy in ante mortem examination, slaughtered in seven abattoirs in the state of Mato Grosso, Brazil were examined. The carcasses of 198 (0.48%) animals showed lesions, of which 182 (91.9%) were classified as granulomatous or pyogranulomatous by histopathological analysis. However, at bacilloscopy, the presence of acid-fast bacilli (AFB) was not detected. Mycobacterium bovis was recovered from 3 (1.5%) samples, all from retropharyngeal lymph nodes in cattle up to three years old. When multiplex PCR (m-PCR) was performed directly on fragments of injured tissue, M. bovis DNA was detected in 14 (7.0%) samples including the same 3 bacteriologically positive samples. Evaluation of lesions by macroscopic analysis agreed 93% (184/198) with bacteriological culturing and the molecular test. To avoid misinterpretation during the examination, mainly of paucibacillary lesions such as those found in the samples analyzed, the use of rapid and unequivocal complementary tests such as mPCR is recommended. Molecular diagnosis, combined with routine post mortem inspection, proved to be a promising technique to improve the surveillance of TB in abattoirs, contributing to the success of the bovine tuberculosis eradication program.

Assessing the histopathology to depict the different stages of bovine tuberculosis infection in a naturally infected herd / Avaliação da histopatologia na descrição dos diferentes estágios da tuberculose bovina em rebanhos naturalmente infectados

The standard method for detection of bovine tuberculosis (TB) is the single intradermal tuberculin test (SITT). Nevertheless, current studies suggest that a single test is not enough to detect all cattle infected by TB, particularly when animals present different stages of infection. A dairy herd comprised of 270 cows was studied and 15 were reactive to SITT plus nine inconclusive animals. Blood samples (for IFN and ELISA) were collected from these 24 cows. At 30 days after injection of PPD, all the cows that were reactive to any of the employed tests were slaughtered, and tissues were processed by Bacteriology, Histopathology (HP) and PCR. According to HP 33.4% of the animals were positive, 45.8% inconclusive and 20.8% were negative. The inconclusive samples came from IFN positive animals, signalizing recent infection. Regarding the animals that were negative to HP, all of them were identified by IFN while ELISA was negative. Immune responses are different in recent and advanced infections, what supports the identification between chronically or recently infected animals. This multidisciplinary approach is mandatory for the interpretation of the various tools that are frequently employed for the diagnosis of TB and mainly to identify all infected animals.

O método padrão para detecção de tuberculose bovina (TB) é o Teste Cervical Simples (TCS). No entanto, estudos atuais sugerem que um único teste não é su[1]iciente para detectar todos os bovinos infectados por TB, particularmente quando os animais de uma rebanho apresentam diferentes estágios de infecção. Um rebanho leiteiro composto de 270 vacas foi estudado e no TCS 15 animais foram reagentes e nove animais inconclusivos. Amostras de sangue (para IFN e ELISA) foram coletadas destas 24 vacas. Trinta dias após a injeção do PPD, todas as vacas que foram reativas a qualquer um dos testes utilizados foram abatidas e os tecidos foram processados por bacteriologia, histopatologia (HP) e PCR. De acordo com a HP 33,4% dos animais foram positivos, 45,8% inconclusivos e 20,8% foram negativos. As amostras classi- [1]icadas como inconclusivas foram provenientes de animais IFN positivo, sinalizando infecção recente. Em relação aos animais negativos na HP, todos eles foram identi[1]icados por IFN enquanto no ELISA apresentaram resultados negativos. Respostas imunes são diferentes em infecções recentes e avançadas, o que suporta a identi[1]icação entre os animais cronicamente ou recentemente infectados. Esta abordagem multidisciplinar é obrigatória para a interpretação das várias ferramentas que são freqüentemente empregadas para o diagnóstico da TB e, principalmente, para identi[1]icar todos os animais infectados em um rebanho.