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

Parissa Farnia, Foroozan Mohammadi, Mehdi Mirsaedi, Abolhasan Zia Zarifi, Javad Tabatabee, Moslem Bahadori, Ali Akbar Velayati, Mohammad Reza Masjedi

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

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 <0.05). The sensitivity of LJ was 99%, Alamar Blue 95% and Malachite Green 93%. The specificity was 100%, 92% and 93%, respectively. The oxidation-reduction method is rapid, sensitive and inexpensive in monitoring the treatment response of patients with pulmonary TB. Thus, using this method can be of paramount importance, particularly in resource-constrained areas.

Original languageEnglish (US)
Pages (from-to)972-976
Number of pages5
JournalMicrobes and Infection
Volume6
Issue number11
DOIs
StatePublished - Sep 1 2004
Externally publishedYes

Keywords

  • AFB viability
  • Alamar Blue
  • Malachite Green

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Infectious Diseases

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