Culture remains the cornerstone of diagnosis for pulmonary tuberculosis, but the fastidiousness of Mycobacterium tuberculosis
may delay culture-based diagnosis for weeks. We evaluated the performance of real-time high-resolution imaging for the rapid
detection of M. tuberculosis colonies growing on a solid medium. A total of 50 clinical specimens, including 42 sputum specimens,
4 stool specimens, 2 bronchoalveolar lavage fluid specimens, and 2 bronchial aspirate fluid specimens were prospectively
inoculated into (i) a commercially available Middlebrook broth and evaluated for mycobacterial growth indirectly detected by
measuring oxygen consumption (standard protocol) and (ii) a home-made solid medium incubated in an incubator featuring
real-time high-resolution imaging of colonies (real-time protocol). Isolates were identified by Ziehl-Neelsen staining and matrix-assisted
laser desorption ionization–time of flight mass spectrometry. Use of the standard protocol yielded 14/50 (28%) M.
tuberculosis isolates, which is not significantly different from the 13/50 (26%) M. tuberculosis isolates found using the real-time
protocol (P 1.00 by Fisher’s exact test), and the contamination rate of 1/50 (2%) was not significantly different from the contamination
rate of 2/50 (4%) using the real-time protocol (P 1.00). The real-time imaging protocol showed a 4.4-fold reduction
in time to detection, 82 54 h versus 360 142 h (P < 0.05). These preliminary data give the proof of concept that real-time
high-resolution imaging of M. tuberculosis colonies is a new technology that shortens the time to growth detection and the laboratory
diagnosis of pulmonary tuberculosis.
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