Isolation of Listeria monocytogenes in milk, craft and vegetables

Abstract

Listeria monocytogenes a common soil bacterium, is long known for its veterinary importance causing major economic losses. Today is a recognized pathogen for humans that primarily affect newborn infants, pregnant women and immunosuppressed people. Its transmission is usually through contaminated food like dairy products and vegetables consumed raw, are the main vehicles. The aim of this study was to evaluate the microbiological quality of dairy products produced by hand and vegetables ready for use through the analysis of L. monocytogenes. The methodology used for this purpose is specified in the Bacteriological Analytical Manual (BAM) of the Food and Drug Administration (FDA) of the United States. This involves the use of medias to get a highly and selective enrichment and isolation of the bacteria. Results: A total of 80 samples of milk products (butter cream and thin, dry and fresh cheese, cheese and cottage cheese) also analyzed 20 samples of vegetables (lettuce, cabbage, broccoli, spinach and cauliflower) where analyzed. Only one isolate was obtained from a sample of cheese, which represents only 1% positivity. Conclusions: Listeria is a bacterium that is contaminating the food, especially those who do not undergo any process of preparation prior to consumption. Despite the low percentage of isolation obtained should not be dismiss the potential risk of this type of food to final the consumers in particular those that are at greatest risk.

DOI: http://dx.doi.org/10.5377/rct.v0i7.1802

Revista Ciencia y Tecnología No. 7, diciembre 2010: 35-46