Lack of heteroresistance among Staphylococcus aureus isolates with vancomycin MICs of 2 micrograms per milliliter by automated testing.

摘要

Susceptibility testing of methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) isolates from blood cultures collected at Emory University Hospital from March 2008 to July 2008 using the MicroScanWalkaway96 (software version 2.01; Siemens Healthcare Diagnostics, Inc., Deerfield, IL) identification/susceptibility system with the POS Combo29 broth microdilution panel and the PROMPT inoculation method revealed a modal vancomycin MIC of 2 μg/ml. All clinical MRSA blood isolates (collected between 26 March 2008 and 6 July 2008 with vancomycin MICs of 2 μg/ml were evaluated by additional MIC testing methods and for evidence of heteroresistant vancomycin-intermediate Staphylococcus aureus (hVISA) isolates by the population analysis profile-area-under-the-curve (PAP-AUC) method.