Table 2. Identification score of microbes processed by four different methods of deposition on MALDI target.
| Gram-positive | Gram-negative | Anaerobes | Yeasts | ||
|---|---|---|---|---|---|
| Nr. of strains identified | 100 | 100 | 20 | 20 | |
| Total nr. of identifications | 300 | 300 | 60 | 60 | |
| Direct spotting | Nr. of "score below 1.70" | 46 | 5 | 14 | 40 |
| Nr. of "no peaks found" | 3 | 1 | 0 | 7 | |
| Nr. of total errors | 49 | 6 | 14 | 47 | |
| Total errors [%] | 16.33% | 2.00% | 23.33% | 78.33% | |
| Average identification score w/o errors* | 2.09 | 2.24 | 2.17 | 1.87 | |
| Average identification score with errors** | 1.98 | 2.23 | 2.01 | 1.49 | |
| Semi-extraction | Nr. of "score below 1.70" | 5 | 4 | 3 | 1 |
| Nr. of "no peaks found" | 3 | 0 | 0 | 1 | |
| Nr. of total errors | 8 | 4 | 3 | 2 | |
| Total errors [%] | 2.67% | 1.33% | 5.00% | 3.33% | |
| Average identification score w/o errors* | 2.21 | 2.27 | 2.21 | 2.00 | |
| Average identification score with errors** | 2.21 | 2.27 | 2.18 | 1.99 | |
| Manual wet deposition | Nr. of "score below 1.70" | 6 | 0 | 1 | 7 |
| Nr. of "no peaks found" | 2 | 0 | 0 | 1 | |
| Nr. of total errors | 8 | 0 | 1 | 8 | |
| Total errors [%] | 2.67% | 0.00% | 1.67% | 13.33% | |
| Average identification score w/o errors* | 2.24 | 2.33 | 2.25 | 1.97 | |
| Average identification score with errors** | 2.24 | 2.33 | 2.23 | 1.93 | |
| Automatic deposition | Nr. of "score below 1.70" | 5 | 0 | 1 | 1 |
| Nr. of "no peaks found" | 2 | 0 | 0 | 0 | |
| Nr. of total errors | 7 | 0 | 1 | 1 | |
| Total errors [%] | 2.33% | 0.00% | 1.67% | 1.67% | |
| Average identification score w/o errors* | 2.28 | 2.38 | 2.26 | 2.03 | |
| Average identification score with errors** | 2.26 | 2.38 | 2.25 | 2.02 |
*/** Error is defined as the score with a value below 1.70, or spectra with no peaks (“no peaks found”). The spectra characterized as “no peaks found” were excluded from the calculation of the average identification score.