Portal de Periódicos da CAPES

Actividad in vitro de retapamulina frente a cepas de Staphylococcus aureus resistente a meticilina y a linezolid

2011; Volume: 24; Issue: 3 Linguagem: Espanhol

1130-331X

Francisco Javier Candel, Gracia Morales, Juan José Picazo de la Garza,

Veterinary medicine and infectious diseases

espanolObjetivos: Determinar la actividad in vitro de retapamulina y otros antibioticos topicos (mupirocina, bacitracina y acido fusidico) usados habitualmente para la descolonizacion nasal, contra Staphylococcus aureus sensible a meticilina (SASM), Staphylococcus aureus resistente a meticilina (SARM) y Staphylococcus aureus resistente a meticilina y linezolid (SARM-L). Material y metodos: Se determinaron las concentraciones minimas inhibitorias (CMIs) en agar Mueller-Hinton de siguiendo los estandares del Clinical and Laboratory Standards Institute (CLSI) y European Committee for Antimicrobial Susceptibility Testing (EUCAST). La presencia del gen cfr en las cepas SARM-L se realizo usando la reaccion en cadena de la polimerasa (PCR). Resultados: Retapamulina inhibio todas las cepas de SASM and SARM alcanzando CMIs sobre 0,125 mg/L, pero las 18 cepas SARM-L se mostraron resistentes, con CMIs en torno a 32 mg/L. La mayoria de los aislados de SASM (9/10) fueron sensibles a mupirocina con CMIs inferiores a 0,19 mg/L, aunque entre las cepas de SARM tan solo fueron sensibles la mitad. La mayoria de las cepas SARM-L (17/18) fueron resistentes a mupirocina con CMIs entre 8 mg/L y 28 mg/L. La CMI de acido fusidico aumento sustancialmente frente a las cepas SARM-L. Frente a la bacitracina no se observaron diferencias. Conclusiones: Retapamulina demostro una excelente actividad in vitro frente a cepas SASM y SARM, pero no frente a las cepas de SARM portadoras del gen cfr. Los resultados in vitro de este estudio refrendan los puntos de corte de retapamulina de ≤0,5, 1, y ≥2 mg/L para sensible, intermedio y resistente, respectivamente. EnglishObjectives: To determine the in vitro activity of retapamulin and other topical antibiotics (mupirocin, bacitracin, and fusidic acid) usually employed for nasal decolonization, against methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), and linezolid and methicillin–resistant S. aureus. Methods: The minimum inhibitory concentrations (MICs) were determined on Mueller-Hinton agar according to the guidelines of the Clinical and Laboratory Standards Institute and of the European Committee for Antimicrobial Susceptibility Testing. Presence of the cfr gene in linezolid and methicillin–resistant S. aureus isolates was detected using polymerase chain reaction. Results: Retapamulin inhibited all the isolates of MSSA and MRSA at 0.125 mg/L, but the 18 linezolid-resistant-MRSA strains proved resistant, with MICs over 32 mg/L. Most MSSA isolates (9/10) were susceptible to mupirocin with MICs under 0.19 mg/L, although this value decreased to half against MRSA, and almost all linezolid-resistant MRSA (17/18) strains were resistant to mupirocin with an MIC range of between 8 mg/L and 28 mg/L. The MIC of fusidic acid increased substantially against linezolid-resistant MRSA, whereas that of bacitracin showed no differences. Conclusions: Retapamulin demonstrated excellent in vitro activity against MSSA and MRSA strains, but not against MRSA isolates harbouring the cfr gene. The results of this in vitro study support cut-off values for retapamulin of ≤ 0.5, 1, and ≥ 2 mg/L for susceptible, intermediate, and resistant strains, respectively.