Microbiological evaluation of oysters sold in the greater Recife, PE. area

Microbiological evaluation of oysters sold in the greater Recife, PE. Area.

THESIS: E. S. Mendes submitted this thesis for her Doctorate in Tropical Diseases at Botucatu School of Medicine, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil, 2001.

Advisor: Professor Carlos Alberto de Magalhães Lopes

^{Address to correspondence}

ABSTRACT: Consumption of raw or partially cooked oysters has been shown to cause several toxin-producing infections. In many, especially in developing countries, most oysters are collected without concern for hygiene. The oysters sold in the Greater Recife, PE, came from Itapissuma, PE, and were microbiologically analyzed between February and December 1999 and January 2000. Freshly-collected and oysters stored for selling were analyzed for coliform contamination, and especially for the following: Escherichia coli, Vibrio, Aeromonas, Shigella, Staphylococcus aureus, and Salmonella. Water samples from collection and storage locations were analyzed for physical, chemical, and microbiological parameters during 3 months of the rainy season and 3 months of the dry season. Data were statistically analyzed using Generalized Linear Models (GLM). The oysters showed contamination by the following. V. parahaemolyticus, V. agynolyticus, Vibrio sp., V. furnissii, V. hollisae, V. angullarum, V. harveyi, V. fluvialis, V. carchariae, V. cincinnatiensis, V. vulnificus, V. cholerae non-O1, and V. damsela, Aeromonas hydrophila and A. caviae, Salmonella enterica serovar Infantis and Albany, E. coli, EPEC, and EIEC. Shigella or Staphylococcus aureus were not found. Water samples were contaminated by several Vibrio species, with a predominance of V. algynolyticus, E. coli, EPEC 025, and Staphylococcus aureus. However, Salmonella or Aeromonas were not detected.

It was concluded that: 1) the level of oyster contamination is influenced by the storage process; 2) the Most Probable Number (MPN) of total and fecal coliforms and Vibrio was influenced by seasonality; 3) seasonality did not significantly influence Vibrio isolation in oysters, and water microbial contamination was especially influenced by density, salinity, and pH. In the molecular study, V. parahaemolyticus strains presented different ribotypes and plasmids of high molecular weight; Aeromonas strains presented plasmids of low molecular weight and different ribotypes.

Key words: oysters, Crassostrea rhizophorae, microbiological examinations, water, Vibrio, Salmonella, Aeromonas, coliforms, Escherichia coli, Staphylococcus aureus, ribotyping, plasmids.

Publication Dates

• Publication in this collection
  09 Dec 2003
• Date of issue
  2003