Abstract. Mycobacteria belonging to Mycobacterium (M.) avium complex (MAC) and M. abscessus complex (MABSC) are the most frequent causes of mycobacteriosis in the world. In the last few years MAC and MABSC taxonomy was rapidly changing due to new molecular methods conveying the possibility to differentiate between species. New techniques are able to identify M. chimaera that was previously recognized as M. intracellulare and also differentiate subspecies of MABSC. Due to their natural habitat, non-tuberculous mycobacteria (NTM) are constantly exposed to various concentrations of antimicrobial drugs and other chemicals and consequently they had developed different mechanisms of resistance. Macrolides and aminoglycosides are frequently used drugs to treat MAC and MABSC infections. The aim of our nation-wide survey was to obtain information about MABSC subspecies prevalence in Slovenia and to assess the percentage of misidentifications of M. chimaera isolates as M. intracellulare in the past. Moreover, the purpose of our study was to reveal, which of the two species M. intracellulare or M. chimaera is clinically more relevant in Slovenia. Further, the aim of the study was to detect mutations in erm(41), rrl and rrs genes, which are known to convey macrolide resistance (erm(41) and rrl) and aminoglycoside resistance (rrs). One hundred and thirty-two Slovenian mycobacterial isolates obtained from the National Mycobacterial Collection that belong to MAC and MABSC were analysed. GenoType NTM-DR was used to differentiate M. intracellulare from M. chimaera and subspecies of MABSC. Our results showed that 48% of previously identified M. intracellulare isolates were actually M. chimaera isolates and that M. abscessus subsp. abscessus was the most frequent subspecies of MABSC. Most of the MABSC isolates carried the inducible macrolide resistance genes (erm(41) and rrl), however none of the isolates of MAC and MABSC had mutations in rrs genes for aminoglycoside resistance.

Drug resistant tuberculosis (TB), especially multidrug (MDR) and extensively drug-resistant (XDR) TB, is still a serious problem in global TB control. Slovenia and North Macedonia are low-incidence countries with TB incidence rates of 5.4 and 10.4 in 2017, respectively. In both countries, the percentage of drug resistant TB is very low with sporadic cases of MDR-TB. However, global burden of drug-resistant TB continues to increase imposing huge impact on public health systems and strongly stimulating the detection of gene variants related with drug resistance in TB. Next-generation sequencing (NGS) can provide comprehensive analysis of gene variants linked to drug resistance in Mycobacterium tuberculosis. Therefore, the aim of our study was to examine the feasibility of a full-length gene analysis for the drug resistance related genes (inhA, katG, rpoB, embB) using Ion Torrent technology and to compare the NGS results with those obtained from conventional phenotypic drug susceptibility testing (DST) in TB isolates. Between 1996 and 2017, we retrospectively selected 56 TB strains from our National mycobacterial culture collection. Of those, 33 TB isolates from Slovenian patients were isolated from various clinical samples and subjected to phenotypic DST testing in Laboratory for Mycobacteria (University Clinic Golnik, Slovenia). The remaining 23 TB isolates were isolated from Macedonian patients and sent to our laboratory for assistance in phenotypic DST testing. TB strains included were either mono-, poly- or multidrug resistant. For control purposes, we also randomly selected five TB strains susceptible to first-line anti-TB drugs. High concordance between genetic (Ion Torrent technology) and standard phenotypic DST testing for isoniazid, rifampicin and ethambutol was observed, with percent of agreement of 77%, 93.4% and 93.3%, sensitivities of 68.2%, 100% and 100%, and specificities of 100%, 80% and 88.2%, respectively. In conclusion, the genotypic DST using Ion Torrent semiconductor NGS successfully predicted drug resistance with significant shortening of time needed to obtain the resistance profiles from several weeks to just a few days.