Bacteriological follow-up of pulmonary tuberculosis treatment: a study with a simple colorimetric assay

• Published in: Journal of biochemical and biophysical methods 2004-09, Vol.6 (11), p.972-976
• Main Authors: Farnia, Parissa, Mohammadi, Foroozan, Mirsaedi, Mehdi, Zia Zarifi, Abolhasan, Tabatabee, Javad, Bahadori, Moslem, Akbar Velayati, Ali, Reza Masjedi, Mohammad
• Format: Article
• Language: English
• Subjects: AFB viability; Alamar Blue; Antitubercular Agents - therapeutic use; Bacteriological methods and techniques used in bacteriology; Bacteriological Techniques; Bacteriology; Biological and medical sciences; Colorimetry - methods; Follow-Up Studies; Fundamental and applied biological sciences. Psychology; Humans; Malachite Green; Microbiology; Microscopy; Mycobacterium tuberculosis; Mycobacterium tuberculosis - cytology; Mycobacterium tuberculosis - growth & development; Mycobacterium tuberculosis - isolation & purification; Mycobacterium tuberculosis - metabolism; Oxazines - metabolism; Oxidation-Reduction; Rosaniline Dyes - metabolism; Sensitivity and Specificity; Sputum - microbiology; Time Factors; Treatment Outcome; Tuberculosis, Pulmonary - drug therapy; Tuberculosis, Pulmonary - microbiology; Xanthenes - metabolism
• ISSN: 1286-4579; 0165-022X; 1769-714X
• DOI: 10.1016/j.micinf.2004.04.017

The viability of Mycobacterium tuberculosis (MTB) in serial sputum specimens from persistently smear positive patients was evaluated. The assay was based on oxidation–reduction of Alamar Blue and Malachite Green dyes that change their color in response to MTB growth. A total of 280 sputum specimens from 40 persistently smear positive TB patients and 40 sputa from non-tuberculosis patients were digested, decontaminated and examined microscopically. To check the MTB viability, the sediments from decontaminated samples were inoculated into three culture media: Lowenstein–Jensen (LJ) slants, Alamar Blue and Malachite Green culture tubes. We found that out of 280 smear positive specimens, the LJ culture was positive in 124 (44%). The numbers of correctly identified S+/C+ cases by Alamar Blue and Malachite Green were 118 (95%) and 116 (93%), respectively. The mean time required for reporting the positive signal in Alamar Blue culture tubes was 9 versus 11 days by Malachite Green culture tubes. In the standard LJ culture media the average detection time was 27 days ( P