CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / The Most Probable Numbers (NMPs) of enterococci and thermotolerant coliforms were estimated in 60 oyster samples (crassostrea rhizophorea) sold at two beach restaurantes, A and B, at Praia do Futuro, Fortaleza City, Cearà state, during the period between september 2000 and september 2001. Each sample included 25 individuals, therefore reaching a total of approximately 1,500 tested oyster. The enterococci NMPs in the samples collected at A ranged between <3,0/g and >1,100/g, while those sampled at B were between 3,0/g and >1,100/g. For the thermotolerant coliforms the obtained values were between <3,0/g and 9,300/g for A, and between <3,0/g and >110,000/g for B. Of all the tested samples, 40% of the oyster sampled at A and 43% of those sampled at B showed thermotolerant coliforms NMPs values over the limits established by the National Health Safety Agency ( AgÃncia Nacional de VigilÃncia SanitÃria) for human consumption of raw food (BRASIL, 2001). There was no statistical correlation between the enterococci and thermotolerant coliforms NMPs (p<0.05). 90 strains of E. faecalis (71%), 8 of E. hirae (6%), 2 of E. mundtii (2%) and 1 of E. durans (1%) were isolated at A, while at B 76 strains of E. faecalis (63%), 5 of E. hirae (4%), 2 of E. mundtii (2%) were found. Regarding the thermotolerant coliform group, 56 strains of E. coli (82%), 12 of Enterobacter (17%) and 1 of Citrobacter (1%) were confirmed at A, while 40 strains of E. coli (63%), 19 of Enterobacter (30%), 3 of Citrobacter (5%) and 1 of Klebsiella (2%) were found at B. All the E. coli strains isolated at A were sensitive to the following antimicrobial agents: CIP, CN, CRO, FOX, IMP, NA and SXT. 70% of these strains showed resistence to ampiciline. At B, the higher sensitivies (100%) were observed for the following antimicrobial agents: CIP, CN, CRO, FOX, IMP, NA and NIT. The ampiciline-resistence values were similar to those at A. None of the Enterococcus species showed to be capable to produce growth inhibiting substances (bacteriocins) aganist E. coli. / Foram estimados o NÃmero Mais ProvÃvel (NMP) de enterococos e de coliformes termotolerantes de 60 amostras de ostras (Crassostrea rhizophorae) comercializadas em duas barracas: A e B, na Praia do Futuro em Fortaleza â CE, no perÃodo de setembro de 2000 a setembro de 2001. Cada amostra constava de 25 indivÃduos, totalizando assim a anÃlise de aproximadamente 1.500 ostras. Os NMPs de enterococos para as amostras coletadas na Barraca A variaram de <3,0 a >1100/g , enquanto os estimados nas amostras da Barraca B ficaram entre 3,0 e >1100/g. Para coliformes termotolerantes os valores encontrados nas amostras de ostra foram de <3,0 a 9300,0/g e <3,0 a >110000/g para as Barracas A e B, respectivamente. Do total de amostras analisadas, 40% na Barraca A e 43% na Barraca B mostraram valores de coliformes termotolerantes acima dos padrÃes estabelecidos pela AgÃncia Nacional de VigilÃncia SanitÃria (ANVISA) para espÃcies destinadas a alimentaÃÃo humana e que serÃo ingeridas cruas (BRASIL, 2001). NÃo houve correlaÃÃo estatÃstica entre os NMPs de enterococos e de coliformes termotolerantes ( p< 0,05). Na Barraca A foram confirmadas 90 (71%)cepas de E. faecalis; 8 (6%) de E. hirae; 2(2%) de E. mundtii e 1( 1%) de E. durans, enquanto na B foram confirmadas: 76(63%) cepas de E. faecalis; 5 (4%) de E. hirae e 2(2%) de E. mundtii. Com relaÃÃo aos coliformes termotolerantes, foram confirmadas na Barraca A: 56 (82%)cepas de E. coli; 12 (17%) de Enterobacter e 1 (1%) de Citrobacter e na Barraca B, foram confirmadas 40 (63%) de E. coli; 19 (30%) de Enterobacter; 3 (5%) de Citrobacter e 1 (2%) de Klebsiella. Todas as cepas de E. coli da Barraca A foram sensÃveis ao antimicrobianos: CIP,CN, CRO, FOX, IMP, NA e SXT enquanto, que 70% apresentaram resistÃncia a ampicilina. Na Barraca B, As maiores sensibilidades (100%) foram detectadas aos antimicrobianos CRO, CIP, CN, FOX, F, IMP, NA. e NIT. Com relaÃÃo à resistÃncia a ampicilina, o resultado foi similar ao da Barraca A. Frente a Escherichia coli, nenhuma das cepas, das diferentes espÃcies de Enterococcus, testadas, mostrou capacidade de produzir substÃncias inibidoras (bacteriocinas) de crescimento.