MALDI-TOF MS entering the microbiological diagnostic laboratory - from fast identification to resistance testing

Recently, a novel method for differentiation of bacteria and fungi entered clinical microbiology laboratories, the identification by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). This differentiation relies on the exact measurement of species-specific protein spectra, mainly of abundant ribosomal proteins. It is even more accurate than conventional biochemical differentiation methods. However, most importantly it provides results within minutes compared to several hours when using biochemical assays. In addition to differentiation of bacteria and yeasts grown on agar plates, direct identification is feasible from positive blood cultures as well as from urine samples of patients suffering from urinary tract infections. Future developments of MALDI-TOF MS for clinical microbiological diagnostic include the detection of β-lactamase and carbapenemase-activity, phenotypic antibiotic resistance testing as well as genotyping of bacteria below the species level.