Total coliforms and Escherichia coli in oysters marketed at the municipal market of Guaratuba, Paraná - Brazil

Abstract

Bivalves filter feeders play as vectors of human pathogens micro-organisms and its consumption may present serious risk to public health. Thus, this study investigated the contamination of oysters sold in the municipal market of Guaratuba from November 2005 at March 2006 by total coliforms and Escherichia coli, the variation of the contamination, considering the three size classes (up to 7 cm, 7 to 9 cm and above 9 cm), and the relationship between contamination and condition index. Values of condition index and E. coli were not significantly different among size classes. However, total coliforms values were significantly higher in oysters with up to 7 cm. In soft tissues of oysters, the most probable number of total coliforms ranged between 0 and 42.442 g^-1, and E. coli, between 0 and 11.946 g^-1. In December, the lowest values of total coliforms and E. coli and the highest condition indexes in oysters from all size classes were registered. However, high values of these bacteria were observed in the remaining months of research. These results suggest that although there are no limits on Brazilian legislation for total coliforms and/or thermotholerants and/or E. coli for edible marine organisms, the oysters studied would be inappropriate for fresh consumption.