Current status of mycobacterial identification in clinical laboratories in Korea

Accurate identification of the Mycobacterium tuberculosis complex (MTBC) and nontuberculous mycobacteria (NTM) is crucial for effective patient management. With declining tuberculosis and rising NTM infections in South Korea, rapid diagnostics are essential. This review provides a comprehensive overview of current diagnostic methods for mycobacterial identification used in Korean clinical laboratories. The field has shifted from conventional methods, such as acid-fast bacilli staining, culture, and biochemical tests, toward rapid technologies. In Korea, immunochromatographic assays (ICA) targeting the MPT64 antigen are widely used to differentiate MTBC from NTM. For species-level NTM identification, laboratories employ advanced techniques including mycolic acid analysis (HPLC), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDITOF MS), and diverse molecular assays. Prominent molecular diagnostics include real-time PCR, PCR-restriction fragment length polymorphism (RFLP), line probe assays (LPA), and DNA sequencing of genes like 16S rRNA and rpoB. These modern techniques offer significantly improved speed and accuracy, replacing traditional approaches in routine diagnostics. In South Korea, modern tools have supplanted conventional methods for mycobacterial identification. Real-time PCR and antigen detection are the primary assays for identifying MTBC in cultures. For NTM species, laboratories use a range of techniques including PCR-RFLP, HPLC, LPA, MALDI-TOF MS, and sequencing. Next-generation sequencing is poised to become a pivotal future tool, offering comprehensive species identification and simultaneous profiling of drug resistance. Those modern techniques will transform diagnostic and surveillance strategies for mycobacterial diseases.