Table 2.
Identification of NTM isolates using ASTA microIDSys MALDI-TOF MS with the MycoDB v1.95s and upgraded MycoDB v2.0-beta databases, along with percentages of species correctly identified using ASTA MALDI-TOF MS with MycoDB v2.0-beta
| NTM species confirmed by reverse blot hybridization assay (reference method) | N | MALDI-TOF MS identification results | |||||||
|---|---|---|---|---|---|---|---|---|---|
|
| |||||||||
| MycoDB v1.95s | MycoDB v2.0-beta | ||||||||
|
|
|
||||||||
| ≥140 (N=33) | 130–139 (N=54) | Total (N=124) | Correctly identified* isolates N (%) | ≥140 (N=117) | 130–139 (N=5) | Total (N=124) | Correctly identified* isolates N (%) | ||
| M. fortuitum group | 5 | 1 | 1 | 2 | 1 (20.0) | 5 | 0 | 5 | 5 (100.0) |
| M. abscessus | 53 | 12 | 14 | 26 | 12 (22.6) | 50 | 3 | 53 | 50 (94.3) |
| M. abscessus subsp. abcessus | 39 | ||||||||
| M. abscessus subsp. massiliense | 14 | ||||||||
| M. kansasii | 5 | 1 | 4 | 5 | 1 (20.0) | 5 | 0 | 5 | 5 (100.0) |
| M. avium | 35 | 9 | 27 | 36 | 9 (25.7) | 32 | 1 | 33† | 32 (91.4) |
| M. intracellulare | 22 | 10 | 7 | 17 | 10 (45.5) | 20 | 1 | 21‡ | 20 (90.9) |
| M. chelonae | 0 | 0 | 1 | 1§ | 0 (0.0) | 0 | 0 | 0 | |
| M. gordonae | 3 | 0 | 0 | 0 | 0 (0.0) | 4 | 0 | 4‡ | 3 (100.0) |
| M. szulgai | 1 | 0 | 0 | 0 | 0 (0.0) | 1 | 0 | 1 | 1 (100.0) |
| Invalid identificationll | 37 | 2† | |||||||
Abbreviations: NTM, nontuberculous mycobacteria; MALDI-TOF MS, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
*Only isolates with an identification score ≥140 were deemed correctly identified; †Two M. avium isolates were unidentified by MALDI-TOF MS; ‡One M. intracellulare isolate was misclassified as M. gordonae by MALDI-TOF MS; §One M. chelonae isolate misidentified by MALDI-TOF MS was confirmed as M. abscessus subsp. abscessus by the reference method; llIsolates with an identification score <130 were labeled as invalid identifications.