Table 2. Results of diagnostic tests for mycobacterial infection, causative species and outcome in the three groups with nontuberculous mycobacterial disease.
| NTM all cases (n = 140) | NTM lymphadenitis (n = 107) | NTM skin & soft tissue infections (n = 25) | NTM other sites of infection (n = 8) | p-value * | |
|---|---|---|---|---|---|
| Diagnostic tests | |||||
| Positive TST, no. (%) ** | 2/11 (18.4%) | 1/7 (14.3%) | 0/1 (0.0%) | 1/3 (33.3%) | 0.6850 |
| Positive QFT, no. (%) | 1/12 (8.3%) | 0/6 (0.0%) | 1/2 § (50.0%) | 0/4 (0.0%) | 0.0654 |
| Positive stain for acid-fast bacilli,no. (%) | 46/129 (35.7%) | 30/99 (30.3%) | 13/23 (56.5%) | 3/7 (42.9%) | 0.0562 |
| Positive culture, no. (%) | 80/119 (67.2%) | 59/91 (64.8%) | 13/20 (65.0%) | 8/8 (100.0%) | 0.1236 |
| Positive PCR, no. (%) | 92/100 (92.0%) | 63/69 (91.3%) | 21/23 (91.3%) | 8/8 (100.0%) | 0.6852 |
| Causative species | |||||
| MAC, no. (%) | 71 (78.9%) | 61 (98.4%) | 3 (15.0%) | 7 (87.5%) | - |
| M. ulcerans, no. (%) | 13 (14.4%) | - | 13 (65.0%) | - | - |
| M. marinum, no. (%) | 3 (3.3%) | - | 3 (15.0%) | - | - |
| M. simae, no. (%) | 1 (1.1%) | 1 (1.6%) | - | - | - |
| M. flavescens, no. (%) | 1 (1.1%) | - | 1 (5.0%) | - | - |
| M. terrae, no. (%) | 1 (1.1%) | - | - | 1 (12.5%) | - |
| Outcome | |||||
| Symptomatic cure at 6 months, no. (%) | 122/123 (99.2%) | 92/92 (100%) | 24/24 (100%) | 7/8 (87.5%) | 0.0007 |
| Recurrence, no. (%) | 25/139 (18.0%) | 19/107 (17.8%) | 4/24 (16.7%) | 0/8 (0.0%) | 0.4010 |
* Three-group comparison of continuous variables with Kruskal Wallis test or of categorical variables with chi-square test.
** Positive TST defined as induration of ≥10 mm at 48 to 72 hours.
§ The patient with the positive QFT result had Mycobacterium marinum infection.
Abbreviations used: IQR = interquartile range; no. = number; NTM = nontuberculous mycobacteria; PCR = polymerase chain reaction; QFT = QuantiFERON-TB Gold assay; TST = tuberculin skin test.