RESUMO: Listeria monocytogenes é uma notável preocupação para a indústria de alimentos, devido à sua natureza ubíqua e a capacidade de se multiplicar em condições adversas. Este estudo objetivou determinar o perfil genotípico de L. monocytogenes isolada a partir de frangos refrigerados comercializados na região sul do Rio Grande do Sul, Brasil. As cepas de L. monocytogenes foram selecionadas e caracterizadas por sorotipagem e Eletroforese em Gel de Campo Pulsado (PFGE). Três sorotipos diferentes (1/2a, 1/2b e 4e) foram avaliados por PFGE, e a combinação dos padrões de macrorestrição utilizando as enzimas AscI e ApaI revelou cinco diferentes pulsotipos. A presença de diferentes perfis genotípicos demonstra a importância da contaminação no ambiente de processamento de frangos, o qual, juntamente com procedimentos de limpeza ineficazes, permitem a sobrevivência, adaptação e proliferação desses patógenos, não somente no ambiente de processamento, mas também no local de comercialização destes produtos.

ABSTRACT: Listeria monocytogenes is of notable concern to the food industry, due to its ubiquitous nature and ability to grow in adverse conditions. This study aimed to determine the genotypic profile of L. monocytogenes strains isolated from refrigerated chickens marketed in the southern part of Rio Grande do Sul, Brazil. The strains of L. monocytogenes isolated were characterized by serotyping and Pulsed Field Gel Electrophoresis (PFGE). Three different serotypes (1/2a, 1/2b and 4e) were evaluated by PFGE, and the macrorestriction patterns utilizing enzymes AscI and ApaI, revealed five different pulsotypes. The presence of such varied genotypic profiles demonstrates the prevalence of L. monocytogenes contamination of chicken processing environments, which combined with ineffective cleaning procedures, allowing the survival, adaptation and proliferation of these pathogens, not only in the processing environment, but also in local grocery stores.

The present study was conducted to assess carcass features, physicochemical and sensory parameters of meat from steers finished on three types of pastures: natural pasture; natural pasture improved, fertilized and oversown with winter species; and annual summer grassland. The experiment was conducted from December 14, 2009 to November 30, 2010, with treatments distributed in a completely randomized design with a different number of replicates. Animals were used as experimental units. Experimental animals were Aberdeen Angus steers with twenty months of initial age and 354±27.4 kg of live weight, on average. The highest average daily gains were obtained for the annual summer grassland. There was no effect of treatments on carcass conformation. The highest carcass yield was obtained on the improved natural pasture. Forequarter yield, side cut yield and longissimus muscle area were similar between the pastures. Moisture and total lipids were not affected by the pasture. Thawing and cooking losses were higher in improved natural pasture and lower in sorghum pasture. Regardless of the treatment, the meat had luminosity ranging from intermediate to dark, high in red, high in yellow, and considered within the normal range for beef. Meat of higher shear force was found in natural pasture, and lower shear force was observed in meat from annual summer grassland. Average live weight daily gain explained 18% of the shear force. Sensory evaluation by duo-trio test showed differences between samples from distinct pastures in flavor. All the studied systems allow for desirable characteristics in carcass and meat.

Listeria monocytogenes é uma bactéria patogênica que se tornou um grande desafio para as indústrias de alimentos, entre elas a de frangos, assim como para os órgãos de vigilância sanitária. Apesar da produção de frangos estar em expansão na região sul do Rio Grande do Sul, não há relatos sobre esse patógeno, dessa forma, objetivou-se avaliar a prevalência de L. monocytogenes e de seus sorotipos nos diversos segmentos dessa cadeia produtiva. Nos aviários isolou-se L. monocytogenes em 2,9% (1/35) das amostras de swabs cloacais, não se isolando o microrganismo em amostras provenientes das camas de aviários. No abatedouro, 11,7% (15/128) das amostras apresentaram contaminação por L. monocytogenes e nos frangos resfriados procedentes do comércio, a prevalência foi de 33,3% (15/45).Observou-se que 51,6% (16/31) das cepas de L. monocytogenes pertenciam ao sorotipo 1/2b; 22,5% (7/31) ao sorotipo 4e; 16,1% (5/31) ao sorotipo 1/2a; 6,4% (2/31) ao sorotipo 4b; e 3,2% (1/31) ao sorotipo 1/2c. Há disseminação de L. monocytogenes na cadeia produtiva de frangos da região sul do Rio Grande do Sul e a presença de sorotipos prevalentes em casos/surtos de listeriose traz preocupação à saúde pública.

Listeria monocytogenes is a pathogenic bacterium which has become a huge challenge to the food industries, including the poultry industry, and to the health surveillance agencies. Although poultry production is in expansion in southern of Rio Grande do Sul, Brazil, there are not reports about this pathogen thus this study aimed at assessing the prevalence of L monocytogenes and its serotypes in the several segments of this productive chain. In the broilers flocks L. monocytogenes were isolated in 2.9% (1/35) from cloacal swabs samples. This microorganism was not isolated from broiler houses samples. In the abattoir, 11% of the samples presented L. monocytogenes contamination, and in the chilled chicken from retailers its prevalence was 33.3% (15/45). It was observed that 51.6% (16/31) from L. monocytogenes strains belonged to serotype 1/2b, 22.5% (7/31) to serotype 4e, 16,1% (5/31) to serotype 1/2a, 6,4% (2/31) to serotype 4b, and 3,2% (1/31) to serotype 1/2c. The spread of L. monocytogenes in the poultry production chain in southern Rio Grande do Sul and the presence of poultry serotypes in cases/outbreaks of listeriosis cause concern to public health.