title: Identification of agr-positive methicillin-resistant Staphylococcus aureus harbouring the class A mec complex by MALDI-TOF mass spectrometry.
abstract: A small peptide called PSM-mec is encoded on the type II, III and VIII SCCmec cassettes present in the genomes of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) strains. This peptide is excreted by agr-positive strains, which represent about 89% of the strains of our collection and can be identified by the presence of delta toxin in mass spectrometry. The presence of the peptide in the MALDI-TOF MS spectra of whole cells was proved by a knock-down experiment employing a clone that expressed antisense RNA to psm-mec. Furthermore, evaluation of a collection of clinical agr-positive MRSA and MSSA isolates and type strains showed that, using a detection window of m/z 2411-2419, the PSM-mec is detected by mass spectrometry of whole cells with a sensitivity of 0.95 and a specificity of 1, thereby enabling rapid identification of a subgroup of MRSA with a method that is used during routine identification procedures.
authors.affiliation: Institute of Medical Microbiology, Immunology and Parasitology, University Clinic of Bonn, D-53105 Bonn, Germany.
authors.forename: Michaele
authors.initials: M
authors.lastname: Josten
authors.affiliation: Institute of Medical Microbiology, Immunology and Parasitology, University Clinic of Bonn, D-53105 Bonn, Germany. Electronic address: jasmin@mibi03.meb.uni-bonn.de.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Dischinger
authors.affiliation: Institute of Medical Microbiology, Immunology and Parasitology, University Clinic of Bonn, D-53105 Bonn, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Szekat
authors.affiliation: Institute of Medical Microbiology, Immunology and Parasitology, University Clinic of Bonn, D-53105 Bonn, Germany.
authors.forename: Marion
authors.initials: M
authors.lastname: Reif
authors.affiliation: Institute of Medical Microbiology, Immunology and Parasitology, University Clinic of Bonn, D-53105 Bonn, Germany.
authors.forename: Nahed
authors.initials: N
authors.lastname: Al-Sabti
authors.affiliation: Institute of Medical Microbiology, Immunology and Parasitology, University Clinic of Bonn, D-53105 Bonn, Germany.
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Sahl
authors.affiliation: Institute of Medical Microbiology, Immunology and Parasitology, University Clinic of Bonn, D-53105 Bonn, Germany.
authors.forename: Marijo
authors.initials: M
authors.lastname: Parcina
authors.affiliation: Institute of Medical Microbiology, Immunology and Parasitology, University Clinic of Bonn, D-53105 Bonn, Germany.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Bekeredjian-Ding
authors.affiliation: Institute of Medical Microbiology, Immunology and Parasitology, University Clinic of Bonn, D-53105 Bonn, Germany. Electronic address: bierbaum@mibi03.meb.uni-bonn.de.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Bierbaum
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins / Q000032:analysis*; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D046915:Penicillin-Binding Proteins; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D015534:Trans-Activators / Q000235:genetics
chemical_list: C095698:Agr protein, Staphylococcus aureus; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D046915:Penicillin-Binding Proteins; D015534:Trans-Activators; C487789:mecA protein, Staphylococcus aureus; C025971:staphylococcal delta toxin
keywords: Class A mec gene complex; MALDI-TOF MS; MRSA; PSM-mec; SCCmec.; Staphylococcus aureus