Resistência à oxacilina em Staphylococcus aureus provenientes de pacientes do Hospital das Clínicas da Faculdade de Medicina de Botucatu
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Data
2008-02-22
Autores
Martins, André [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A oxacilina é a principal droga de escolha no tratamento das infecções causadas por S. aureus. Contudo, a resistência a esta droga tem se tornado um grande problema nas últimas décadas. O objetivo deste estudo foi verificar as taxas de resistência à oxacilina em amostras de S. aureus provenientes do Hospital das Clínicas da Faculdade de Medicina de Botucatu, UNESP e a comparação de métodos fenotípicos com o método padrão ouro (detecção do gene mecA) na detecção de amostras MRSA. Um total de 102 amostras previamente isoladas no período de 2002 a 2006 e estocadas na Coleção de Culturas do Departamento de Microbiologia e Imunologia, Instituto de Biociências, UNESP, foram analisadas quanto a resistência à oxacilina por meio da técnica de difusão da droga em ágar com disco de oxacilina e cefoxitina, teste de triagem em Ágar Mueller-Hinton com 6 μg/mL de oxacilina e 4% de NaCl, E-test e detecção do gene mecA. Das amostras estudadas, 46 (45,1%) foram positivas para o gene mecA. A sensibilidade obtida para o disco de oxacilina foi de 86,9%, com 91,1% de especificidade. O disco de cefoxitina apresentou sensibilidade de 91,3% e especificidade de 91,1%. O método de triagem apresentou os mesmos valores de sensibilidade (91,3%) e especificidade (91,1%) verificados no método do disco de cefoxitina. A fita de E-test mostrou melhor taxa de sensibilidade, com 97,8% e a mesma especificidade encontrada nos outros métodos (91,1%). Das amostras estudadas, 93% foram produtoras de - lactamase, sendo 05 destas negativas na detecção do gene mecA. Verificou-se um aumento gradativo no número de amostras resistentes à oxacilina no período de 2002 a 2004, entretanto, de 2004 a 2006 os resultados revelaram uma redução no número de amostras resistentes, de 55% de MRSA em 2004 para 45% em 2005 e 34,6% em 2006. Os dados revelaram que o E-test obteve melhores resultados, com alta sensibilidade comparada aos outros métodos.
Oxacillin is the main drug of choice for the treatment of S. aureus infections. However, S. aureus resistance to oxacillin has become a major problem in the past decades. To assess the rates of oxacillin resistance in S. aureus samples obtained at the Botucatu Medical School Hospital - Sao Paulo State University/UNESP, Brazil, and to compare phenotypic techniques for the detection of MRSA against the gold standard method (mecA gene detection) in these samples. A total of 102 samples, previously isolated between 2002 and 2006, and kept at the Culture Collection of the Department of Microbiology and Immunology, Botucatu Institute of Biosciences, São Paulo State University/UNESP, Brazil were included. Oxacillin resistance was assessed by oxacillin and cefoxitin disk diffusion and agar dilution tests, screening tests using Mueller-Hinton agar with 6 μg/mL of oxacillin and 4% of NaCl, E-test, and mecA gene detection. Of the samples analyzed, 46 (45.1%) were mecA-positive. Oxacillin disk sensitivity and specificity were 86.9% and 91.1%, respectively. Cefoxitin disk sensitivity and specificity were 91.3% and 91.1%, respectively. The screening test showed same level of sensitivity (91.3%) e specificity (91.1%) found with the cefoxitin disk. With E-test strips, sensitivity was higher (97.8%) and specificity was comparable to that found with the other methods (91.1%). Ninety-three percent of the samples produced - lactamase, and 05 of them were mecA-negative. There was a gradual increase in the number of oxacillin-resistant S. aureus samples between 2002 and 2004. However, from 2004 to 2006, the number of resistant samples dropped from 55% of MRSA in 2004, to 45% in 2005 and 34.6% in 2006. The data obtained reveal that, among phenotypic methods, E-test yielded the best results, with higher sensitivity levels when compared to the other methods.
Oxacillin is the main drug of choice for the treatment of S. aureus infections. However, S. aureus resistance to oxacillin has become a major problem in the past decades. To assess the rates of oxacillin resistance in S. aureus samples obtained at the Botucatu Medical School Hospital - Sao Paulo State University/UNESP, Brazil, and to compare phenotypic techniques for the detection of MRSA against the gold standard method (mecA gene detection) in these samples. A total of 102 samples, previously isolated between 2002 and 2006, and kept at the Culture Collection of the Department of Microbiology and Immunology, Botucatu Institute of Biosciences, São Paulo State University/UNESP, Brazil were included. Oxacillin resistance was assessed by oxacillin and cefoxitin disk diffusion and agar dilution tests, screening tests using Mueller-Hinton agar with 6 μg/mL of oxacillin and 4% of NaCl, E-test, and mecA gene detection. Of the samples analyzed, 46 (45.1%) were mecA-positive. Oxacillin disk sensitivity and specificity were 86.9% and 91.1%, respectively. Cefoxitin disk sensitivity and specificity were 91.3% and 91.1%, respectively. The screening test showed same level of sensitivity (91.3%) e specificity (91.1%) found with the cefoxitin disk. With E-test strips, sensitivity was higher (97.8%) and specificity was comparable to that found with the other methods (91.1%). Ninety-three percent of the samples produced - lactamase, and 05 of them were mecA-negative. There was a gradual increase in the number of oxacillin-resistant S. aureus samples between 2002 and 2004. However, from 2004 to 2006, the number of resistant samples dropped from 55% of MRSA in 2004, to 45% in 2005 and 34.6% in 2006. The data obtained reveal that, among phenotypic methods, E-test yielded the best results, with higher sensitivity levels when compared to the other methods.
Descrição
Palavras-chave
Medicina tropical, Staphylococcus aureus
Como citar
MARTINS, André. Resistência à oxacilina em Staphylococcus aureus provenientes de pacientes do Hospital das Clínicas da Faculdade de Medicina de Botucatu. 2008. 51 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Medicina de Botucatu, 2008.