The objective of this prospective, observational study carried out at China-Uganda Friendship Hospital-Naguru in Kampala, Uganda, was to determine the performance of GeneXpert MTB/RIF Ultra (Xpert Ultra) molecular testing on saliva for active tuberculosis (TB) disease among consecutive adults undergoing TB diagnostic evaluation who were Xpert Ultra positive on sputum. We calculated sensitivity to determine TB diagnostic performance in comparison to a composite reference standard of Mycobacterium tuberculosis (Mtb) liquid and solid cultures on two spot sputum specimens. Xpert Ultra on a single saliva sample had a sensitivity of 90% (95% CI 81-95%) relative to the composite sputum culture-based reference standard, similar to the composite sensitivity of 87% (95% CI, 77-94%) fluorescence smear microscopy (FM) for acid-fast bacilli on two sputa. The sensitivity of salivary Xpert Ultra was 24% lower (95% CI for difference 2-48%, p=0.003) among persons living with HIV (71%, 95% CI 44-90%) than among persons living without HIV (95%, 95% CI 86-99%) and 46% higher (95% CI 14-77%, p<0.0001) among FM-positive (96%, 95% CI 87-99%) than among FM-negative patients (50%, 95% CI 19-81%) patients. Semi-quantitative Xpert Ultra  grade was systematically higher in sputum than in a paired saliva sample from the same patient. In conclusion, molecular testing of saliva for active TB diagnosis was feasible and almost as sensitive as molecular testing of sputum in a high TB-burden setting.

Surveys were done with the index patients by the study nurses and data was collected using standard questionnaires to obtain clinical information. Case report forms used to collect the data were then double entered by the data entrant into an access database. Data was downloaded from the database in a text file format and this was imported into the stata 14 script. It was then prepared and cleaned and essential variables kept.