Jornal Brasileiro de Patologia e Medicina Laboratorial (Oct 2011)
Stenotrophomonas maltophilia: resistência emergente ao SMX-TMP em isolados brasileiros. uma realidade? Stenotrophomonas maltophilia: emerging resistance to TMP-SMX in Brazilian isolates. a reality?
Abstract
INTRODUÇÃO: Stenotrophomonas maltophilia é um importante patógeno hospitalar emergente, naturalmente resistente aos carbapenêmicos, que possui sulfametoxazol/trimetoprima (SMX-TMP) como opção terapêutica. Porém, relatos de resistência a essa droga começaram a aparecer. OBJETIVO: Avaliar o perfil de sensibilidade das cepas de S. maltophilia e comparar os resultados obtidos por diferentes metodologias. MÉTODOS: As cepas isoladas na rotina microbiológica do Hospital das Clínicas de São Paulo em 2007 foram avaliadas quanto ao perfil de suscetibilidade por disco-difusão e microdiluição. Respeitando a padronização do Clinical and Laboratory Standard Institute (CLSI), SMX-TMP e levofloxacino foram testados pelas duas técnicas, bem como a tigeciclina, interpretada segundo a agência norte-americana Food and Drug Administration (FDA). Ticarcilina/clavulanato, ceftazidima, imipenem, meropenem e moxifloxacino foram avaliados apenas por microdiluição. O percentual de correlação entre as metodologias foi analisado pelo programa WHONET®. RESULTADOS: Das 126 cepas, 1,6% apresentaram resistência a SMX-TMP; 2,4%, a levofloxacino; 23%, a ticarcilina/clavulanato; 54%, a ceftazidima. Todas apresentaram concentração inibitória mínima (CIM) INTRODUCTION: Stenotrophomonas maltophilia is an important emerging nosocomial pathogen naturally resistant to carbapenems. Although trimethoprim/sulfamethoxazole (TMP-SMX) is commonly used as a treatment option, resistance to this drug has been recently reported. OBJECTIVE: To evaluate the susceptibility profile of S. maltophilia strains and compare the results obtained by different methods. METHODS: As to susceptibility profile, all strains, which had been routinely isolated at Hospital das Clínicas, São Paulo, in 2007, were evaluated through disk diffusion and microdilution. In accordance with the Clinical and Laboratory Standard Institute (CLSI), TMP-SMX and levofloxacin were tested through both techniques, as well as tigecycline, which was interpreted in conformity with Food and Drug Administration (FDA) regulations. Ticarcillin/clavulanate, ceftazidime, imipenem, meropenem and moxifloxacin were evaluated only through microdilution. The correlation between these methods was assessed by WHONET®. RESULTS: 1.6% of 126 strains were resistant to TMP-SMX, 2.4% to levofloxacin, 23% to ticarcillin/clavulanate, and 54% to ceftazidime. All strains showed minimum inhibitory concentration (MIC) < 2 µg/mL for tigecycline and 96.8% MIC < 2 µg/mL for moxifloxacin. The correlation index between both methods was 100% for TMP-SMX and 89.6% for levofloxacin, respectively. DISCUSSION AND CONCLUSION: Although TMP-SMX is the standard treatment for S. maltophilia infections, there may be resistance to this antibiotic, which hinders the therapeutic approach, hence the significance of susceptibility tests. The disk diffusion technique showed a good correlation with microdilution. Among the new therapeutic options, both tigecycline and moxifloxacin presented significant activity in vitro.
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