SUMMARY
Incidence of Listeria monocytogenes and evaluation of the sanitary quality of filleted fresh fish from the Metropolitan Area of San José
Fish constitutes a very important part of human diet due to its protein content. The poor commercialization system existing in Costa Rica for this product causes an important seconary contamination that may include microorganisms such as f,ecal coliforms, Staphylococcus aureus and even pathogens such as Listeria' monocytogenes. There is a lack of recent information about the microbiological quality of the fish that arrives to the Metropolitan Area of San José, Costa Rica, so the aim of this work was to study it through the detection of microbiological indicators and the incidence of L. monocytogene.

Five different samplings were realized to 27 fisheries located in tow different areas from San José, Costa Rica: the Central Market and the rest of the Metropolitan Area. Each time, a 500g sample of fresh filleted fish was taken and transponed to the Food Microbiology Laboratory, Universidad de Costa Rica, for performing the different analysis, which included the presence/absence of L. Monocytogenes, total plate count, total and fecal coliforms count and Most Probable Number of Staphylococcus aureus. Also, a hygiene evaluation of the different fisheries was performed. According to this, 22.2% of the fisheries were classified as excellent, 14,8% as good, 40.8% as regular and 22,2 as bad.

Fisheries hygiene is independent of the incidence of L monocytogenes with a 95% confidence level, and there is no significan! Relationship, between hygiene and the other indicators analyzed. There is a significant relationship between the incidence of Lstleria sp. And the hygiene of the Central Market area.

It was determined that 96,3% and 29,6% of the fisheries accomplish with the microbiological limits established by ICMSF for S aureus and total plate count, respectively. Listeria sp. was found in 65.2% of the fish samples analyzed. From these, 52.3% was L monocytogenes, 43,2% L. i'lnocua, 3,4% L. ivanovii and 1.1% L seeligeri. In 88,9% of the fisheries the presence of L monocytogena was positive at least once.

Key words: Listeria sp., Lisleria monocytogenes, fish. Microbial indicators, hygiene.



Recibido: 20/10/1998
Aceptado: 02/08/1998

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