Utility of the microcolony method for evaluation of multidrug-resistant tuberculosis patients in Karachi, Pakistan

Document Type



Pathology and Laboratory Medicine


Objective: To compare the microcolony method (MCM) with the reference culture method to evaluate culture conversion in multidrug-resistant tuberculosis (MDR-TB) patients.
Material and Methods: Adult patients with Mycobacterium tuberculosis culture-positive MDR-TB undergoing second-line anti-tuberculosis treatment were recruited from two tertiary care chest clinics from January 2013 to October 2014. The MCM was performed in addition to MGIT™ and Löwenstein-Jensen medium (reference method) on sputum samples submitted on a monthly basis.
Results: Of 140 patients, culture conversion could be evaluated in 95 patients. The MCM showed 100% agreement with the reference M. tuberculosis culture in 83 of 95 patients who achieved culture conversion. In smear-positive and smear-negative cases, the mean time to positivity was 9.1 and 11.4 days for the MCM and 16.1 and 23.2 days for the reference M. tuberculosis culture respectively. The contamination rate for the MCM was 4.5% in comparison with 6.1% for the reference M. tuberculosis culture. The cost of MCM was estimated to be 30% that of the reference method.
Conclusion: The MCM can be used in non-urban laboratories as a safe, rapid and cost-effective substitute for the reference M. tuberculosis culture to assess culture conversion in MDR-TB patients.
Note: Abstract has been published in International Journal of Mycobacteriology 2015; 4: 159-160.


International Journal of Tuberculosis and Lung Disease