OPEN ACCESS pISSN : 2288-0585 eISSN : 2288-6850 Ann Clin Microbiol 2025 December, 28(4):24 https://doi.org/10.5145/ACM.2025.28.4.5 Correspondence to Jeong Su Park E-mail: mdmicrobe@gmail.com Received: November 12, 2025 Revised: December 10, 2025 Accepted:

Background: Mycobacterium avium complex (MAC) is a major cause of pulmonary nontuberculous mycobacterial disease; however, treatment outcomes remain suboptimal. Phenotypic drug susceptibility testing (DST) is conditionally recommended; however, conventional broth microdilution is labor-intensive. The Sensititre SLOMYCO® panel offers a standardized platform for DST of slowly growing mycobacteria. Methods: Eighty-six clinical MAC isolates (48 M. avium and 38 M. intracellulare) from respiratory specimens were tested for 13 antimicrobials using the SLOMYCO panel and reference Clinical and Laboratory Standards Institute (CLSI) broth microdilution methods at the Korean Institute of Tuberculosis. Essential agreement (EA) was defined as minimum inhibitory concentrations within ± 1 dilution, and categorical agreement (CA) was based on CLSI 2018 breakpoints for clarithromycin, amikacin, moxifloxacin, and linezolid. Results: The EA was high for amikacin (90%), moxifloxacin (92%), linezolid (92%), and ethambutol (98%). Moderate EA was observed for clarithromycin (79%), ciprofloxacin (67%), and doxycycline (63%), and low EA was observed for trimethoprim-sulfamethoxazole (34%). The CA values were 100%, 77.9%, 69.8%, and 47.7% for clarithromycin, amikacin, moxifloxacin, and linezolid, respectively. All isolates were clarithromycin-susceptible according to both methods, and no clarithromycin- or amikacin-resistant isolates were detected. Conclusion: The SLOMYCO DST system demonstrated high agreement with the reference methods for clarithromycin and amikacin in the tested susceptible population. The variability in the results for moxifloxacin and linezolid highlights the need for refined breakpoints. The validation of resistant isolates is essential before the SLOMYCO system can be recommended for comprehensive clinical applications.