Rapid identification of viridans streptococci by mass-spectrometric discrimination

Institute for Medical Microbiology and Epidemiology of Infectious Diseases, University of Leipzig, Germany; Department of Microbial Pathogenesis, Helmholtz Center for Infection Research, GBF German Research Centre for Biotechnology, Braunschweig, Germany; Institute for Biochemistry, School of Medicine, University of Leipzig, Germany

^* To whom correspondence should be addressed. Email: claudia.friedrichs{at}medizin.uni-leipzig.de.

	Abstract

Viridans streptococci (VS) are responsible for several systemic diseases such as endocarditis, abscesses and septicemia. Unfortunately, species identification with conventional methods seems to be more difficult than in other groups of bacteria. The aim of the present study was to evaluate the use of cell matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) for rapid identification of 10 different species of VS. A total of 99 VS clinical isolates, ten reference strains and 20 strains from our in house culture collection were analysed with MALDI-TOF-MS. To evaluate the mass-spectrometric discrimination results all strains were identified parallel with phenotypic and genotypic methods. The MALDI-TOF-MS identified 71 isolates as mitis group, 23 as anginosus group and 5 S. salivarius strains. The comparison of the species identification results of the MALDI-TOF-MS analyses and the phenotypic/genotypic identification systems showed a consistency of 100% on the species level. Thus, MALDI-TOF-MS seems to be a rapid and reliable method for species identification of VS from clinical samples.