Predictors of delayed culture conversion among Ugandan patients

Abstract

BackgroundEstimates of month-2 culture conversion, a proxy indicator of tuberculosis (TB) treatment efficacy in phase-2 trials can vary by culture-type and geographically with lower rates reported among African sites. The sub-study aimed at comparing TB detection rates of different culture media, within and across rifampicin-based regimens (R10, 15 and 20 mg/Kg) over a 6-month treatment follow-up period, and to establish predictors of month-2 culture non-conversion among HIV-negative TB patients enrolled at RIFATOX trial site in Uganda.MethodsUnlike in other Rifatox Trial sites, it is only in Uganda were Lowenstein-Jensen (LJ) and Mycobacteria growth indicator tube (MGIT) were used throughout 6-months for treatment monitoring. Conversion rates were compared at month-2, 4 and 6 across cultures and treatment-type. Binomial regression analysis performed for predictors of month-2 non-conversion.ResultsOf the 100 enrolled patients, 45% had converted based on combined LJ and MGIT by month-2, with no significant differences across treatment arms, p = 0.721. LJ exhibited higher conversion rates than MGIT at month-2 (58.4% vs 56.0%, p = 0.0707) and month-4 (98.9% vs 88.4%, p = 0.0391) respectively, more so within the high-dose rifampicin arms. All patients had converted by month-6. Time-to-TB detection (TTD) on MGIT and social service jobs independently predict month-2 non-conversion.ConclusionThe month-2 culture conversion used in phase 2 clinical trials as surrogate marker of treatment efficacy is influenced by the culture method used for monitoring mycobacterial response to TB treatment. Therefore, multi-centric TB therapeutic trials using early efficacy endpoint should use the same culture method across sites. The Time-to-detection of MTB on MGIT prior to treatment and working in Social service jobs bear an increased risk of culture non-conversion at month-2.Trial registrationISRCTN ISRCTN55670677. Registered 09th November 2010. Retrospectively registered.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-017-2335-7) contains supplementary material, which is available to authorized users.

Development and validation of a nomogram for the prediction of late culture conversion among multi-drug resistant tuberculosis patients in North West Ethiopia: An application of prediction modelling

“…These were; registration group (new/previously treated), HIV co-infection (yes/no), BMI (<18.5/≥18.5), baseline sputum smear grade (<3+/≥3+) and radiological findings (cavitary lesions/ no cavitary lesions). This finding on significant predictors of late culture conversion was also supported by different studies conducted across the world [ 9 , 10 , 16 , 23 , 27 – 29 ].…”

“…This might be because of variation in the status of the setting and other patient characteristics. In fact, this extent of the outcome is lower than the finding of a study conducted in Uganda (55%) [ 23 ].…”

“…The outcome variable is late culture conversion (yes/no). Culture conversion at month two is widely used as a proxy measure of the success of tuberculosis (TB) chemotherapy [ 22 , 23 ]. Late culture conversion was defined as sputum culture conversion that occurred after two months of treatment initiation.…”

Impact of emphysema on sputum culture conversion in male patients with pulmonary tuberculosis: a retrospective analysis

“…Baseline time to TB detection (TTD) was defined as time (in days) until MGIT culture showed a positive result at initial sputum culture [ 6 , 16 ]. Atwine et al reported a twofold increase in risk of culture conversion at 2 months in patients with baseline TTD < 14 days compared with ≥14 days [ 17 ]. This study was approved by the Ethics Committee of Jikei University School of Medicine [No.…”

Impact of emphysema on sputum culture conversion in male patients with pulmonary tuberculosis: a retrospective analysis

“…Atwine et al reported a twofold increase in risk of culture conversion at 2 months in patients with baseline TTD <14 days compared with ≥14 days [17]. This study was approved by the Ethics Committee…”