RESUMEN
A new chromogenic medium, denim blue (DB), was compared with methicillin-resistant Staphylococcus aureus (MRSA) Select (MRSAS) for detection of MRSA from surveillance specimens. On DB, MRSA colonies are larger (0.57-0.8 versus 0.45-0.6 mm at 18 and 24 h, respectively). Despite this, sensitivities of DB were 77% and 96% at 18 and 24 h, respectively, and those of MRSAS were 63% and 97.5%. Specificities were significantly higher for MRSAS than DB. The study demonstrates that DB and MRSA are equal for the detection of MRSA from surveillance specimens provided the plates are read after 24 h of incubation. Positive predictive values of both media were less than 95% requiring confirmation of MRSA, by another method, from all new patients.
Asunto(s)
Técnicas Bacteriológicas/métodos , Portador Sano/microbiología , Medios de Cultivo/química , Resistencia a la Meticilina , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/efectos de los fármacos , Canal Anal/microbiología , Compuestos Cromogénicos/metabolismo , Humanos , Nariz/microbiología , Valor Predictivo de las Pruebas , Sensibilidad y Especificidad , Staphylococcus aureus/aislamiento & purificaciónRESUMEN
MRSASelect agar was compared to CHROMagar, mannitol-salt agar with oxacillin, and mannitol-salt agar with cefoxitin (MSA-CFOX) for the isolation of methicillin-resistant Staphylococcus aureus (MRSA). The sensitivities and specificities were 97.3% and 99.8%, 82.9% and 99.1%, 80.2% and 79%, and 99.1% and 84.8%, respectively. MSA-CFOX and MRSASelect had a high sensitivity. MRSASelect, however, was more specific and proved to be a more reliable and rapid medium for the detection of MRSA.