2001 Volume 75 Issue 4 Pages 300-306
The ability of the AccuProbe (Kyokuto) to identify mycobacteria directly from the positive cultures in an automatic detector for mycobacteria (BACTEC MGIT960, Becton Dickinson) was evaluated.
Sputum samples were collected from patients with suspected mycobacteriosis between February and April 1999 and conventionally incubated in MGIT960 (37°C for 42 days). The MGIT-positive cultures were successively incubated for several days and were directly identified with the AccuProbe.
Monomycobacterial strains were detected from 93 (93.9%) of the 99 sputum samples and polymycobacterial strains were detected from 6 sputum samples (6.1%). Viable cell counts in the positive cultures in MGIT960 were determined using Middlebrook 7H10 agar. The cell counts of Mycobacterium tuberculosis and Mycobacterium avium-intracellulare complex (MAC) varied greatly among the individual samples; the former, 3.8×102-2.5×106cfu/ml and the latter 1.5×103-1.9×108cfu/ml. The great differences in the cell counts were observed among these samples. Although the cultures in MGIT were estimated as positive, the early stage of bacterial growth might be used as the samples for the cell counting. By this method, 96 of the total 101 cases were successfully identified as follows: M. tuberculosis 57 cases (56.4%) and MAC 39 cases (38.6%).
In conclusion, the present results indicate that the direct identification of mycobacteria from the positive cultures in MGIT960 using AccuProbe is useful for a rapid diagnosis in microbiological testing for mycobacteriosis which has tended to increase in recent years.
