Ocorrência de Listeria monocytogenes (Murray, 1911) em queijos artesanais comercializados na cidade de Manaus – AM

Abstract

The occurrence of Listeria monocytogenes in cheeses craft type Coalho, Manteiga and Mussarela marketed in the city of Manaus - AM was researched. The collection of the 39 samples of the craft cheeses was made in a random way in free markets and they happened in the period of May to August of 2002. The microbiological analyses were accomplished at the Laboratory of Microbiology of Faculdade de Farmácia. The applied methodology the this research was adapted of Bacteriological Analytical Manual (BAM, 2001) and of the Compendium of Methods goes the Microbilogical Examination of Foods (APHA, 1992), Consisting of two pré-enrichments, before the selective isolation. Of the 39 collected samples, 19 (49%) samples were of cheese type Coalho, 14(36%) of cheese type Manteiga and 6(15%) of cheese type Mussarela. The absence of Listeria monocytogenes was observed in 100% of the samples, in the ones which 13 (33,33%) they were negative in the secondary enrichment and 26 (66,66%) in the isolation in Ágar OXA and Ágar PALCAM. The absence could be explained by the presence of some factors that they propitiate the inhibition of this bacterium, such as: the index very loud of Enterococcus spp. and also the presence some microorganisms producing of bacteriocins and commonly found in the milk, as the Lactobacillus lactis. By the inhibition possibility for coliformes, they were made countings of NMP/g for total coliformes, fecal coliformes and Escherichia coli, in 10 samples of cheeses of the type Manteiga and the obtained results were 70% of the polluted samples for total coliformes, 100% for fecal coliformes and Escherichia coli. Indicating the possibility, among other factors of inhibition of the Listeria monocytogenes in the analyzed cheeses. Then, in agreement with the cases told in the inhibition literature by polluting microbiota and the inadequate hygienic-sanitary conditions during the production, manipulation, packing, stockpiling and commercialization of the craft cheeses can be ended that all those factors might have inhibited the cresceimento of Listeria monocytogenes.