The cultivation of oyster species of the genus Crassostrea is expanding in the
northeast of the Brazilian state of Pará. This study analyzes the sanitary quality of the
oysters and the water in which they are cultivated in the local municipality of São
Caetano de Odivelas and Curuçá. Samples were collected monthly between June,
2009, and May, 2010. Water samples were collected from the flood and the ebb
tides, and approximately 15 oysters were obtained each month. Coliform
concentrations were determined using the multiple-tube fermentation technique,
followed by the biochemical identification of the bacteria and determination the
susceptibility profile of Escherichia coli isolated from oysters and water samples. The
geometric mean concentration of thermotolerant coliforms in the water was 119
MPN/100 mL in São Caetano de Odivelas and 163,21 MPN/100 mL in Curuçá, well
above the limit of 43 MPN/100 mL established by the Brazilian National Environment
Council (CONAMA). As Brazilian legislation on the sanitary quality of bivalve
mollusks covers only the processed product, the European Union legislation, which
assigns oysters for raw consumption to three sanitary classes, was adopted for the
evaluation of the results of the present study. In São Caetano de Odivelas only two of
the samples collected during this study were assigned to class A, seven samples to
class B and three samples to class C. While in Curuçá three samples were assigned
to class A, seven samples to class C and two samples to class C. The results
suggest the need for mitigation measures to ensure the health quality of the oysters,
such as the application of methods of depuration.
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