title: The presence of a single MALDI-TOF mass spectral peak predicts methicillin resistance in staphylococci.
abstract: The class A mec gene complex also carries the psm-mec gene. The psm-mec gene product can be detected as a peak near 2415m/z using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). The correlation of a 2415m/z peak with methicillin resistance (mecA carriage) in consecutive staphylococcal blood culture isolates was evaluated. A 2415±2.00m/z peak was observed in 37% (51/137) of methicillin-resistant Staphylococcus aureus, in none (0/146) of the methicillin-susceptible S. aureus, in 6% (10/180) of methicillin-resistant S. epidermidis, and in 2% (1/63) of methicillin-susceptible S. epidermidis isolates. Although the sensitivity of the 2415m/z peak for mecA carriage in S. aureus and S. epidermidis was low (37% and 6%, respectively), the specificity was high (≥98%). This peak can be identified during routine MALDI-TOF MS clinical testing, and the analysis adds no reagent cost and requires minimal time expenditure.
authors: Department of Laboratory Medicine, Cleveland Clinic, 9500 Euclid Avenue, LL1-2, Cleveland, OH, 44195, USA. Electronic address: Daniel.Rhoads@case.edu.
authors: Daniel D
authors: DD
authors: Rhoads
authors: Department of Laboratory Medicine, Cleveland Clinic, 9500 Euclid Avenue, LL1-2, Cleveland, OH, 44195, USA. Electronic address: wangh@ccf.org.
authors: Hannah
authors: H
authors: Wang
authors: Department of Laboratory Medicine, Cleveland Clinic, 9500 Euclid Avenue, LL1-2, Cleveland, OH, 44195, USA. Electronic address: karichj@ccf.org.
authors: James
authors: J
authors: Karichu
authors: Department of Laboratory Medicine, Cleveland Clinic, 9500 Euclid Avenue, LL1-2, Cleveland, OH, 44195, USA. Electronic address: richtes@ccf.org.
authors: Sandra S
authors: SS
authors: Richter
mesh_terms: D016470:Bacteremia / Q000382:microbiology; D001431:Bacteriological Techniques / Q000379:methods*; D006801:Humans; D016106:Methicillin Resistance; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013203:Staphylococcal Infections / Q000382:microbiology; D013210:Staphylococcus / Q000737:chemistry* / Q000187:drug effects*
keywords: Antimicrobial resistance; MALDI-TOF; MRSA; PFGE; Strain typing; mecA