TABLE 3.
Summary of time-to-positive data for different mycobacterial groups analyzed by culture method and processing method
| Species | Total no. of culture-positive specimens | Time to detection by decontamination and culture methoda
|
|||||||
|---|---|---|---|---|---|---|---|---|---|
| NALC/NaOH
|
CB-18
|
||||||||
| Solid media
|
Liquid media
|
Solid media
|
Liquid media
|
||||||
| n | Avg ttp (days) | n | Avg ttp (days) | n | Avg ttp (days) | n | Avg ttp (days) | ||
| MTBC | 29 | 22 | 27.5 ± 11.9b | 28 | 19.6 ± 13.4 | 24 | 19.4 ± 11.1 | 19 | 7.2 ± 6.8 |
| MAC | 29 | 13 | 27.7 ± 17.1 | 21 | 17.3 ± 17.8 | 21 | 19.5 ± 18.6 | 20 | 8.9 ± 7.4 |
| M. kansasii | 5 | 5 | 16.2 ± 9.7 | 5 | 13.8 ± 10.9 | 5 | 16.0 ± 5.1 | 4 | 29.2 ± 22.9 |
| Rapid growersc | 22 | 4 | 7.0 ± 0.0 | 5 | 31.8 ± 24.6 | 20 | 14.4 ± 13.2 | 7 | 3.4 ± 4.2 |
| All other AFB | 21 | 4 | 24.8 ± 4.8 | 5 | 21.2 ± 13.7 | 7 | 32.7 ± 13.0 | 8 | 30.5 ± 23.8 |
| Total | 106 | 48 | 24.4 ± 13.7 | 64 | 19.4 ± 15.9 | 77 | 19.1 ± 14.5 | 58 | 12.1 ± 14.9 |
ttp, time to positive. Statistical analyses were performed by using a two-tailed, heteroscediastic Student’s t test. Calculated t test values for all isolates, MTBC isolates, and all MOTT isolates were <0.01, <0.01, and >0.05, respectively, in liquid culture and 0.041, 0.022, and >0.05, respectively, on solid media. All t test values for the various MOTT groups were >0.05 in liquid culture. For the various MOTT groups on solid media, only the reduction in the time to a positive result for rapid growers was statistically significant (P = 0.023).
Mean ± standard deviation.
Rapid growers include all M. chelonae, M. fortuitum, and M. neoaurum isolates.