Methicillin susceptibility testing of staphylococci by Etest and comparison with agar dilution and mecA detection

Abstract

The susceptibility to methicillin of 44 Staphylococcus aureus and 120 coagulase-negative staphylococci (CNS) was determined by Etest, agar dilution and presence of the mecA gene. There was agreement between the results of all methods when testing S. aureus. However, discrepancies occurred with CNS when cultural methods were compared with presence of the mecA gene. mecA-positive isolates tested as resistant more often with agar dilution on Columbia agar plus 5% NaCl than by Etest.