Of 1376 isolates submitted as S. aureus, 13 (< 1%) were misidentified by local laboratories and
comprised various coagulase-negative species, such as Staphylococcus haemolyticus, Staphylococcus
epidermidis, Staphylococcus capitis, Staphylococcus xylosus and Staphylococcus hominis. Of those isolates
identified correctly as S. aureus (n = 1363), 27 (2.0%) were misclassified according to methicillin
susceptibility, in that 25 were reported as MRSA instead of MSSA (a major error: no mecA gene
detected) and two as MSSA instead of MRSA(a very major error). All MRSA isolates were
reported correctly as resistant to all b-lactams.Interpretative errors detected in the testing of
other antimicrobial agents are shown in Table 1.Inducible MLSB resistance was not detected in
one isolate by three laboratories, and in twoisolates by one laboratory