Fully automated liquid culture system compared with Lowenstein-Jensen solid medium for rapid recovery of mycobacteria from clinical samples

The aim of this study was to compare the rate of recovery of mycobacteria a nd the time to detection in 5208 samples using the MB/BacT culture system ( Organon Teknika, USA) and Lowenstein-Jensen medium. Mycobacteria were recov ered from 301 (5.7%) samples. Two hundred fifty-seven (85.3%) isolates from 114 patients were Mycobacterium tuberculosis [135 (52.5%) smear-positive, 122 (47.4%) smear-negative], and 44 (14.6%) were potentially pathogenic env ironmental mycobacteria. The yield with the MB/BacT was higher than that wi th Lowenstein-Jensen [287 (95.3%) vs. 200 (66.4%), P < 0.001] for both Myco bacterium tuberculosis [247 (96.1%) vs. 187 (72.7%), P < 0.001] and potenti ally pathogenic environmental mycobacteria [40 (90.9%) vs. 13 (29.5%), P < 0.001], mainly at the expense of the smear-negative samples. Moreover, 70 ( 27.2%) samples were positive only in the MB/BacT, whereas ten (3.8%) sample s were positive only in Lowenstein-Jensen. The number of patients with tube rculosis detected by the MB/BacT was higher than that detected by Lowenstei n-Jensen medium [111 (97.3%) vs. 89 (78%), P < 0.001]. In 25 (21.9%) patien ts the diagnosis was established solely by means of the MB/BacT. In smear-p ositive and smear-negative samples, the mean times to detection of Mycobact erium tuberculosis were 16.7 and 26.3 days, respectively, with Lowenstein-J ensen and 11.5 and 19.3 days, respectively, with the MB/BacT. These results indicate that the MB/BacT is more efficient and faster than Lowenstein-Jen sen for the recovery of mycobacteria.