title: MALDI-TOF MS fingerprinting facilitates rapid discrimination of phylotypes I, II and III of Propionibacterium acnes.
abstract: Matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is widely used today for species determination of bacteria and fungi in routine microbiological laboratories, and can also be used for subtyping of bacteria, such as Bacteroides fragilis. Propionibacterium acnes is frequently referred to as an anaerobic skin commensal of relatively low pathogenicity. In addition to its accepted pathogenic role in acne, P. acnes is now emerging as an important opportunistic pathogen in many other clinical situations, including late-stage prosthetic joint infections, osteomyelitis, endocarditis, endophthalmitis, post-neurosurgical infections and possibly prostate cancer. At the population genetic level, P. acnes can be differentiated into a number of distinct phylogroups, known as types IA1, IA2, IB, IC, II and III, which may be associated with different types of infections and clinical conditions. The aim of the present study was to evaluate MS-based typing for resolution of these genetic groups after routine identification by MALDI-TOF MS (Bruker MALDI Biotyper). The software package ClinProTools 2.2 was used to analyze the protein based mass spectra of reference strains belonging to types IA, IB, IC, II and III. Phylogroup-specific peaks and peak shifts were then identified visually. In addition, peak variations between the different types of P. acnes were investigated by using FlexAnalysis 3.3 software (Bruker). A differentiating library was created, which was used to type further 48 clinical isolates of P. acnes. Typing data obtained by MALDI-TOF MS were then compared with the results from Multilocus Sequence Typing (MLST). Most of the clinical isolates (n = 19) belonged to the type IA grouping according to MALDI-TOF MS. By MLST, all isolates were identified as type IA1. Twenty-one clinical isolates belonged to the type IB cluster based on both MALDI-TOF MS and MLST typing. Eight clinical isolates were identified as type II strains by both typing methods and all the type III reference strains could be distinguished by the presence of a unique type III-specific peak (7238 Da) by the MALDI-TOF MS. Our study demonstrates that MALDI-TOF MS is a reliable and powerful tool for rapid identification and typing of P. acnes strains from the main genetic divisions of the species.
authors.affiliation: Hungarian Anaerobe Reference Laboratory, Institute of Clinical Microbiology, University of Szeged, 6725 Szeged, Semmelweis u 6, Hungary. nagy.erzsebet@med.u-szeged.hu
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Nagy
authors.forename: Edit
authors.initials: E
authors.lastname: Urbán
authors.forename: Simone
authors.initials: S
authors.lastname: Becker
authors.forename: Markus
authors.initials: M
authors.lastname: Kostrzewa
authors.forename: Andrea
authors.initials: A
authors.lastname: Vörös
authors.forename: Judit
authors.initials: J
authors.lastname: Hunyadkürti
authors.forename: István
authors.initials: I
authors.lastname: Nagy
mesh_terms: D015373:Bacterial Typing Techniques / Q000379:methods*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology*; D006801:Humans; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D011425:Propionibacterium acnes / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D012984:Software; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D004269:DNA, Bacterial