Feasibility and Sensitivity of Genexpert MTB/RIF Ultra on Saliva for Diagnosis of Pulmonary Tuberculosis

Abstract

Background: Tuberculosis (TB) remains a major global health concern, with Indonesia ranking second in TB burden, reporting 1.09 million new cases and 125,000 deaths in 2024. Despite advancements in TB diagnostics, detection gaps persist, particularly due to challenges in sputum sample collection. The GeneXpert MTB/RIF Ultra assay enhances TB detection and rifampicin resistance identification by targeting additional gene sequences (IS1081/IS6110). However, the difficulty in obtaining quality sputum specimens necessitates alternative diagnostic approaches, such as saliva-based testing, to improve accessibility and efficiency.

Objectives: This study aims to assess the feasibility and sensitivity of GeneXpert MTB/RIF Ultra using saliva for pulmonary TB diagnosis.

Methods: This cross-sectional study was conducted at Dr. Wahidin Sudirohusodo Hospital, Makassar, from August to October 2024. Suspected pulmonary TB patients were selected using consecutive sampling based on clinical symptoms, contact history, or thoracic imaging. GeneXpert MTB/RIF Ultra testing was performed on both sputum and saliva samples, with additional MTB culture examination on sputum. Diagnostic feasibility and sensitivity were analyzed.

Results: The study included 47 participants, with an average age of 48.06 ± 14.18 years. Most subjects were male (68.1%), and the predominant symptom was prolonged cough (44.7%). The test demonstrated high specificity but moderate sensitivity, indicating its reliability in confirming TB cases but limited ability to detect all infections.

Conclusion: Saliva-based GeneXpert MTB/RIF Ultra testing offers a non-invasive diagnostic alternative, particularly for patients unable to produce sputum. However, its limited sensitivity suggests the need for further optimization or complementary diagnostic methods to enhance detection rates.