Abstract
Rapid identification of methicillin-resistantStaphylococcus aureus(MRSA) is essential for proper initial antibiotic therapy and timely set up of hygienic measures. Recently, detection of MRSA using MALDI-TOF mass spectrometer mediated by the peptide-phenol-soluble modulin (PSM-mec)-linked to the class Amecgene complex present in SCCmeccassettes types II, III, and VIII of MRSA strains, has been commercially available.
We present here a multicentre study on MALDI-TOF MS detection of MRSA evincing a poor repeatability and reproducibility of the assay. The sensitivity of the assay varies between 50 and 90% in strains carryingpsm(MEC)andpsm(delta)genes encoding for PSM-mec and delta-toxin (a member of the PSM peptide family), respectively.
No false positive results were found. The very major error calculation was 30% and the major error achieved 0%.
Interlaboratory repeatability varies between 0 and 100%. No significant difference was observed with the use of different cultivation media.
Our data showed a poor sensitivity of the method excluding it from the use in routine laboratory testing.