TABLE 3.
Species-specific diagnostic performance of the culture-free method compared with that of the culture methoda,b,c
| AFB smear | Species | Sensitivity | Specificity | PPV | NPV |
|---|---|---|---|---|---|
| − |
M. avium subsp. hominissuis |
9.1% (2/22) | 100.0% (46/46) | 100.0% (2/2) | 69.7% (46/66) |
| M. intracellulare subsp. intracellulare | 20.0% (1/5) | 98.4% (62/63) | 50.0% (1/2) | 93.9% (62/66) | |
| M. intracellulare subsp. chimaera | 0.0% (0/2) | 100.0% (66/66) | N.A. (0/0) | 100.0% (68/68) | |
| M. abscessus subsp. abscessus | 33.3% (1/3) | 98.5% (64/65) | 50.0% (1/2) | 97.0% (64/66) | |
| M. abscessus subsp. massiliense | 0.0% (0/1) | 100.0% (67/67) | N.A. (0/0) | 98.5% (67/68) | |
| M. tuberculosis | 100.0% (1/1) | 100.0% (67/67) | 100.0% (1/1) | 100.0% (67/67) | |
| M. paragordonae | 0.0% (0/1) | 100.0% (67/67) | N.A. (0/0) | 98.5% (67/68) | |
| + |
M. avium subsp. hominissuis |
73.1% (19/26) | 93.5% (29/31) | 90.5% (19/21) | 80.6% (29/36) |
| M. intracellulare subsp. intracellulare | 82.4% (14/17) | 97.5% (39/40) | 93.3% (14/15) | 92.9% (39/42) | |
| M. intracellulare subsp. chimaera | 66.7% (2/3) | 100.0% (54/54) | 100.0% (2/2) | 98.2% (54/55) | |
| M. abscessus subsp. abscessus | 100.0% (4/4) | 100.0% (53/53) | 100.0% (4/4) | 100.0% (53/53) | |
| M. abscessus subsp. massiliense | 75.0% (3/4) | 100.0% (53/53) | 100.0% (3/3) | 98.1% (53/54) | |
| M. kansasii | 100.0% (1/1) | 100.0% (56/56) | 100.0% (1/1) | 100.0% (56/56) | |
| M. mucogenicum | 0.0% (0/1) | 100.0% (56/56) | N.A. (0/0) | 98.2% (56/57) | |
| M. simiae | 0.0% (0/1) | 100.0% (56/56) | N.A. (0/0) | 98.2% (56/57) |
AFB: acid-fast bacilli; PPV: positive predictive value; NPV: negative predictive value; −: negative; +: positive; M. avium: Mycobacterium avium; M. intracellulare: Mycobacterium intracellulare; M. abscessus: Mycobacterium abscessus; M. tuberculosis: Mycobacterium tuberculosis; M. paragordonae: Mycobacterium paragordonae; M. kansasii: Mycobacterium kansasii; M. mucogenicum: Mycobacterium mucogenicum; M. simiae: Mycobacterium simiae; subsp.: subspecies; N.A.: not applicable.
Data are presented as number (%).
Performance metrics were calculated for each NTM species using 2 × 2 contingency tables comparing the results of the culture-free and culture methods.