Table 1.
MALDI-TOF mass spectrometry peak biomarkers useful to discriminate Klebsiella pneumoniae phylogroups.
| Present in Kp phylogroup(s) | Peak position (m/z)1 | Sensitivity2 [95% CI] | Specificity3 [95% CI] | Possible proteins4 |
|---|---|---|---|---|
| Kp1 | 4153 | 10/10, 100% [69.2–100.0%] | 35/36, 97.2% [85.5–99.9%] | YjbJ (double charged ion) |
| 8305 | 10/10, 100% [69.2–100.0%] | 36/36, 100% [90.3–100.0%] | YjbJ | |
| Kp2 | 4136 | 9/9, 100% [66.4–100.0%] | 37/37, 100% [90.5–100.0%] | YjbJ (double charged ion) |
| 8271 | 9/9, 100% [66.4–100.0%] | 37/37, 100% [90.5–100.0%] | YjbJ | |
| Kp3 and Kp5 | 7768 | 15/15, 100% [78.2–100.0%] | 31/31, 100% [88.8–100.0%] | Ribosomal protein L31 |
| Kp4 | 3835 | 7/7, 100% [59.0–100.0%] | 39/39, 100% [91.0–100.0%] | YdgH (chain, double charged ion) |
| 7670 | 7/7, 100% [59.0–100.0%] | 39/39, 100% [91.0–100.0%] | YdgH (chain) | |
| Kp5 | 4777 | 6/6, 100% [54.1–100.0%] | 40/40, 100% [91.2–100.0%] | Ribosomal protein S20 (demethionated form, double charged ion) |
| 9553 | 6/6, 100% [54.1–100.0%] | 40/40, 100% [91.2–100.0%] | Ribosomal protein S20 (demethionated form) | |
| Kp1 and Kp6 | 5278 | 12/15, 80% [51.9–95.7%] | 41/41,100% [88.8–100.0%] | Ribosomal protein S22 |
CI, confidence interval. 1Position in the spectra using a tolerance of ±0.03%. 2Proportion of true positives that are correctly identified as such. 3Proportion of true negatives that are correctly identified as such. 4As determined using TagIdent (https://web.expasy.org/tagident/tagident.html).