Quality indicators in a mycobacteriology laboratory supporting clinical trials for pulmonary tuberculosis

Background: Documentation of structured quality indicators for mycobacteriology laboratories supporting exclusively controlled clinical trials in pulmonary tuberculosis (PTB) is lacking.

Objective: To document laboratory indicators for a solid (Lowenstein-Jensen medium) culture system in a mycobacteriology laboratory for a period of 4years (2007-2010).

Methods: The sputum samples, collected from PTB suspects/patients enrolled in clinical trials, were subjected to fluorescence microscopy, culture and drug sensitivity testing (DST). Data was retrospectively collected from TB laboratory registers and computed using pre-formulated Microsoft Office Excel. Laboratory indicators were calculated and analyzed.

Results: The number of samples processed in a calendar year varied from 6261 to 10,710. Of the samples processed in a calendar year, specimen contamination (4.8-6.9%), culture positives (78.4-85.1%) among smear positives, smear positives (71.8-79.0%) among culture positive samples, smear negatives among culture negative samples (95.2-96.7%), and average time to report DST results (76-97days) varied as shown in parentheses.

Conclusion: Values of quality indicators in mycobacteriology laboratories supporting exclusively clinical trials of PTB have to be defined and used for meaningful monitoring of laboratories.