**5. Conclusions**

The new RAPMYCOI test is a rapid tool for the determination of drug resistance profile in RGM. The obtained results are reliable and reproducible, and the test setup is not time-consuming. The broth microdilution method on which the test is based and the selection of antibiotics are consistent with the CLSI guidelines.

Taken together, the findings from the presented study highlight the importance of a correct identification of clinical isolates to the species and subtype level and the role of antimicrobial susceptibility testing, especially for highly resistant rapidly growing mycobacteria (RGM). The obtained results confirm previous assumptions published worldwide according to which there are predictable drug resistance profiles depending on the identified mycobacterial species. However, there are some exceptions to this rule, and therefore the drug resistance of individual strains should be tested as standard practice. The correlation between data obtained from AST with clinical findings proving the effectiveness of treatment will enable the development of new therapeutic regimens. As a result, effective drugs can be selected and the patient's treatment optimized at an early stage.

**Author Contributions:** Conceptualization, A.B. and E.A.-K.; methodology, A.B., A.G. and D.F.; formal analysis, A.B.; writing—original draft preparation, A.B.; writing—review and editing, A.G., A.Z. and E.A.-K.; supervision, A.Z. and E.A.-K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the statutory activity of National Tuberculosis and Lung Diseases Research Institute, Task No 1.8/2019.

**Institutional Review Board Statement:** The study was approved by the Ethics Committee of the National Tuberculosis and Lung Diseases Research Institute (KB-64/2018, 14 December 2018) as a part of research on mycobacterial diseases in human.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data supporting reported results can be found in source data collected in National Tuberculosis and Lung Diseases Research Institute.

**Conflicts of Interest:** The authors declare no conflict of interest.
