OBJECTIVES: The aim of the study was to clarify how HIV infection affects tuberculosis liquid and solid culture results in a resource-limited setting.
METHODS: We used baseline data from the Study on Outcomes Related to Tuberculosis and HIV Drug Concentrations in Uganda (SOUTH), which included 268 HIV/tuberculosis (TB)-coinfected individuals. Culture results from Löwenstein-Jensen (LJ) solid culture and mycobacteria growth indicator tube (MGIT) liquid culture systems and culture-based correlates for bacillary density from the sputum of HIV/TB-coinfected individuals at baseline were analysed.
RESULTS: Of 268 participants, 243 had a CD4 cell count available and were included in this analysis; 72.2% of cultures showed growth on solid culture and 82.2% in liquid culture systems (P < 0.015). A higher CD4 cell count was predictive of LJ positivity [adjusted odds ratio (OR) 1.14; 95% confidence interval (CI) 1.03-1.25 per 50 cells/μL increase; P = 0.008]. The same, but insignificant trend was observed for MGIT positivity (adjusted OR 1.09; 95% CI 0.99-1.211 per 50 cells/μL increase; P = 0.094). A higher CD4 cell count was associated with a higher LJ colony-forming unit grade (adjusted OR 1.14; 95% CI 1.05-1.25 per 50 cells/μL increase; P = 0.011) and a shorter time to MGIT positivity [adjusted hazard ratio (HR) 1.08; 95% CI 1.04-1.12 per 50 cells/μL increase; P < 0.001].
CONCLUSIONS: In a resource-limited setting, the MGIT liquid culture system outperformed LJ solid culture in terms of culture yield and dependence on CD4 cell counts in HIV/TB-coinfected individuals. We therefore suggest considering an adaptation of diagnostic algorithms: when resources allow only one culture method to be performed, we recommend that MGIT liquid culture should be used exclusively in HIV-positive individuals as a first-line culture method, to reduce costs and make TB culture results accessible to more patients in resource-limited settings.