Quality of MALDI-TOF mass spectra in routine diagnostics: results from an international external quality assessment including 36 laboratories from 12 countries using 47 challenging bacterial strains.

Objectives: Matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is a widely used method for bacterial species identification. Incomplete databases and mass spectral quality (MSQ) still represent major challenges. Important proxies for MSQ are the number of detected marker masses, reproducibility, and measurement precision.

[A very slow growing ankle swelling in a healthy male].

We describe the case report of a 66-year-old man with a very slow growing ankle tumour caused by a subcutaneous fungal abscess. Phaeoacremonium inflatipes, a member of the Dematiaceae family, was identified by needle puncture and culture of the non-odorous creamy yellow brown fluid. The fungal pseudocyst was surgically removed in toto and no further fungicidal drug therapy was required.

Identification of dermatophytes by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

In this study we evaluated the suitability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of dermatophytes in diagnostic laboratories. First, a spectral database was built with 108 reference strains belonging to 18 species of the anamorphic genera Epidermophyton, Microsporum and Trichophyton. All strains were well characterized by morphological criteria and ITS sequencing (gold standard).