Table 1.

Impact of culture medium and type of matrix on the identification level of investigated S. aureus strains expressed as an average score value (the logarithm of the result of matching the investigated spectrum with patterns in the reference database) calculated from the results of 4 repetitions for each variant of the experiment (mean ± standard deviation). Statistical significance of differences was tested using one-way ANOVA (ANalysis Of VAriance) with post-hoc Tukey HSD (Honestly Significant Difference) post-hoc test. The influence of the medium is marked in large font while the small font is used to indicate differences between matrices.

	RAW Data
Medium	HCCA	DHB	SDHB	General
MHA	2.09 $\pm$ 0.12Bb	2.27 $\pm$ 0.13Aa	2.27 $\pm$ 0.09Aa	2.21 $\pm$ 0.14
TSA	2.11 $\pm$ 0.09Bb	2.29 $\pm$ 0.12Aa	2.26 $\pm$ 0.09Aa	2.22 $\pm$ 0.13	universal
COL	2.13 $\pm$ 0.11Bb	2.31 $\pm$ 0.14Aa	2.34 $\pm$ 0.11Aa	2.26 $\pm$ 0.15
BHI	2.07 $\pm$ 0.09Bb	2.29 $\pm$ 0.11Aa	2.27 $\pm$ 0.11Aa	2.21 $\pm$ 0.14	enriched
BLA	2.25 $\pm$ 0.13Aa	2.36 $\pm$ 0.12Aa	2.27 $\pm$ 0.20Aa	2.31 $\pm$ 0.17
CHRA	2.27 $\pm$ 0.14Aa	2.30 $\pm$ 0.11Aa	2.18 $\pm$ 0.18Aa	2.24 $\pm$ 0.16	differentiating
VRE	2.04 $\pm$ 0.07Cb	2.24 $\pm$ 0.15Aa	2.29 $\pm$ 0.15Aa	2.19 $\pm$ 0.17	selective
MAN	1.90 $\pm$ 0.15Da	1.80 $\pm$ 0.17Ba	1.76 $\pm$ 0.18Ba	1.82 $\pm$ 0.18
	MSP data
MHA	1.94 $\pm$ 0.12Ab	2.17 $\pm$ 0.18Aa	2.18 $\pm$ 0.11Aa	2.07 $\pm$ 0.18
TSA	2.12 $\pm$ 0.11Ab	2.30 $\pm$ 0.11Aa	2.26 $\pm$ 0.09Aa	2.20 $\pm$ 0.13	universal
COL	2.07 $\pm$ 0.10Ab	2.29 $\pm$ 0.12Aa	2.35 $\pm$ 0.24Aa	2.21 $\pm$ 0.20
BHI	2.00 $\pm$ 0.12Ab	2.22 $\pm$ 0.12Aa	2.23 $\pm$ 0.08Aa	2.13 $\pm$ 0.15	enriched
BLA	2.12 $\pm$ 0.16Aa	2.25 $\pm$ 0.33Aa	2.22 $\pm$ 0.21Aa	2.17 $\pm$ 0.25
CHRA	2.10 $\pm$ 0.18Aa	2.21 $\pm$ 0.12Aa	2.14 $\pm$ 0.21Aa	2.13 $\pm$ 0.18	differentiating
VRE	2.01 $\pm$ 0.11Ab	2.19 $\pm$ 0.15Aa	2.23 $\pm$ 0.12Aa	2.12 $\pm$ 0.16	selective
MAN	1.77 $\pm$ 0.21Ba	1.69 $\pm$ 0.21Ba	1.65 $\pm$ 0.24Ba	1.68 $\pm$ 0.22

TSA-Tryptic Soy Agar, MHA-Mueller Hinton Agar, COL-Columbia Agar Base, BHI-Brain Heart Infusion Agar, BLA-Columbia Blood Agar, CHRA-CHROMagarTM Orientation, MAN-Mannitol Salt Agar, VRE-Vancomycin Resistant Enterococci Agar Base, HCCA-α-Cyano-4-hydroxycinnamic acid, DHB-2,5-dihydroxybenzoic acid, SDHB-mixture of DHB and 2-hydroxy-5-methoxybenzoic acid (9:1 w/w), MSP-main spectrum (peak lists generated from raw spectra by algorithms included in MALDI Biotyper), RAW data-Score values obtained for the whole spectra, MSP data-Score values obtained for main spectra.