Antimicrobial susceptibility testing using MYCO test-system and MIC distribution of 8 drugs against clinical isolates from Shanghai of Nontuberculous Mycobacteria

Abstract

AbstractGiven the increased incidence and prevalence of nontuberculous mycobacteria (NTM) diseases and the natural resistance of NTM to multiple antibiotics, in vitro susceptibility testing of different NTM species against drugs from the MYCO test system and new applied drugs are required. 241 NTM clinically isolates were under analyzed, including 181 slowly growing mycobacterium (SGM) and 60 rapidly growing mycobacterium (RGM). The Sensititre SLOMYCO and RAPMYCO panels were used for the drug susceptibility testing to commonly used anti-NTM antibiotics. Furthermore, Minimum inhibitory concentration (MIC) distributions were determined against 8 potential anti-NTM drugs, including vancomycin (VA), bedaquiline (BDQ), delamanid (DLM), faropenem (FAR), meropenem (MPM), clofazimine (CFZ), avibactam (CAZ), and Cefoxitin (FOX) and epidemiological cut-off values (ECOFFs) were analyzed using ECOFFinder. The results showed that most of the SGM strains were susceptible to clarithromycin (CLA), rifampicin (RFB) from the SLOMYCO panels and BDQ, CFZ from the 8 applied drugs, while, RGM strains were susceptible to tigecycline (TGC) from the RAPMYCO panels and also BDQ, CFZ. The ECOFF values of CFZ were 0.25μg/ml, 0.25μg/ml, 0.5μg/ml, and 1μg/ml for M. kansasii, M. avium, M. intracellulare, and M. abscessus, respectively, and BDQ was 0.5μg/ml for the same four prevalent NTM species. Due to the weak activity of the other 6 drugs, no ECOFF was determined. This study on the susceptibility of NTM includes 8 potential anti-NTM drugs and a large sample size of Shanghai clinical isolates. and demonstrated that BDQ and CFZ had efficient activities against different NTM species in vitro, which can be applied for the treatment of NTM diseases.