Evaluation of the performance of two liquid-phase culture media for the diagnosis of pulmonary tuberculosis in a national hospital in Lima, Peru

SummaryObjectiveTo evaluate the diagnostic performance of two liquid-phase culture media for the diagnosis of pulmonary tuberculosis.Patients and methodsFrom May to July 2003, sputum samples for culture were obtained from patients with respiratory symptoms attending the Hospital Nacional Cayetano Heredia. These were cultured in Ogawa medium, mycobacteria growth indicator tube (MGIT), and modified Middlebrook 7H9. Results were compared against a composite reference standard.ResultsOne hundred sputum specimens from 100 patients were included. Of these, 33 had culture-proven tuberculosis. The sensitivity of MGIT was found to be 100%. The modified Middlebrook 7H9 medium was found to have a sensitivity of 72.73%, while the sensitivity of Ogawa medium was found to be 69.70%. The mean growing time for MGIT was 12.18 days (95% confidence interval 10.24 to 14.12; p<0.01 vs. Ogawa and modified Middlebrook 7H9); for modified Middlebrook 7H9 was 16.65 days (95% confidence interval 14.85 to 18.80; p