Longitudinal Observation of Pulmonary Tuberculosis Patients by Gen-Probe Mycobacterium tuberculosis Direct Test (MTD)

To study the clinical significance of conducting Gen-Probe Mycobacterium tuberculosis Direct Test (MTD) during the course of the disease, sputum specimens from 19 pulmonary tuberculosis patients were smeared, cultured, and tested by MTD, once a month for five months from the initiation of chemotherapy. 1) MTD-positive rates declined in parallel with decreased pulmonary tuberculosis activity, and the MTD findings of 16 patients who presented mild to moderate pulmonary tuberculosis at admission became negative by four months after the beginning of treatment.Three patients (15.8%) who were consistently positive for MTD during five months after the beginning of treatment were serious pulmonary tuberculosis patients, excreting a large number of organisms at admission. 2) During the course, a total of 43 MTD negative findings were observed, of which one (2.3%) was positive for Ogawa medium culture and the other 42 (92.7%) were negative.MTD was useful in briefly determining the absence of infection, provided that a negative culture on Ogawa medium means no infection. 3) Eleven of the 12 specimens (91.7%) showing positive smears and negative cultures on Ogawa medium were positive for MTD.Since MTD shows negative results for atypical mycobacteria, this is a very useful test in identifying acid fast bacilli which shows a positive smear and a negative culture.