Cytoderm metabolic-labeling SCMLP-TB for pulmonary tuberculosis diagnosis: a preliminary diagnostic accuracy study

Tuberculosis (TB) remains a significant global health issue. Early diagnosis is crucial, yet current diagnostic technologies are limited by suboptimal sensitivity. Thus, we developed a novel tuberculosis metabolic labeling probe (single cell metabolic labeling probe for tuberculosis, SCMLP-TB) and evaluated its diagnostic performance. In this retrospective study of 70 suspected TB patients, we calculated the sensitivity and specificity of SCMLP-TB and compared it with culture and Xpert MTB/RIF (Xpert) using the final clinical diagnosis as reference standard. Eligible participants were classified as confirmed TB (CT), clinically diagnosed TB (CDxT), or non-TB cases based on the diagnosis criteria for pulmonary tuberculosis (WS 288-2017). Of the 70 participants, 40 (57.0%) were diagnosed with TB, including 30 CT cases and 10 CDxT cases. The overall diagnostic sensitivity and specificity of SCMLP-TB were 97.5% and 96.7%, respectively. Notably, SCMLP-TB identified 10 CDxT cases missed by both culture and Xpert. The overall diagnostic sensitivity of culture and Xpert was 62.5% and 72.5%, respectively, while both showed a specificity of 100.0%, demonstrating that SCMLP-TB was more sensitive than culture and Xpert. Besides, the fluorescence intensity from TB patients was significantly higher than non-TB patients. The fluorescence intensity showed a significant negative correlation with the time to positivity (TTP) of culture, which suggested that SCMLP-TB could also serve as an indicator of bacterial loads in patients' samples. Consequently, SCMLP-TB demonstrated a promising tool for the sensitive and ultra-fast diagnosis of pulmonary TB suspects, particularly for paucibacillary pulmonary TB.