差分

*====smear/microscopy====*Ziehl-Neelsen of sputum**positive smear needs cavitation*PCR TB DNA*children and HIV-positive tend not to cavitate**specificity 98%*fluorescent ====culture - 4-8weeks====**culture is definitive/reference standard*Lowenstein-Jensen medium*liquid medium 3 weeks ====PCR TB DNA====*Gene Xpert**Xpert MTB/RIF**can detect drug resistant ====histopathology====*tissue biopsy**caseating granuloma***multinucleated giant cells with nuclei arranged like a horseshoe ====urinary LAM antigen detection====*mycobacterial cell wall glycolipid antigen lipoarabinomannan (LAM)*marker of active TB*specificity 98%*sensitivity 40-70% ====Manteau text/tuberculin skin test (TST)====*low value for diagnosis ====Interferon gamma release assay (IGRA)====*T-SPOT/Quantiferon(QFT)*cannot distinguish between latent/active/used be treated