The invention relates to the identification of microbes in a sample by calculating the similarities between a mass spectrum of the sample and all reference spectra in a spectral library; it particularly concerns the detection of microbe mixtures. Microbe mixtures are probably present if several microbe species which are not closely related to each other are among the score list containing the most similar reference spectra. Methods are proposed which (1) operate with a list of the relationships, (2) determine the similarity between the reference spectra of the different microbe species of the score list, or (3) always carry out a mixture analysis in accordance with document DE 10 2009 007 266 A1 from the score list, with the generation of combination spectra, and only afterwards check the similarity of the combined spectra and thus the relationship between the microbe strains concerned.