P26

Due to limitations of classical phenotypic drug susceptibility testing (DST), sequencing technologies hold great promise in the detection of pyrazinamide (PZA) resistance in Mycobacterium tuberculosis (MT). In this study we compared two sequencing technologies/approaches, Ion Torrent targeted sequencing (Ion ApliSeq TB Research Panel, Thermo Fisher Scientific) with Illumina whole genome sequencing (WGS), to detect mutations most commonly linked with PZA resistance in MT. For 18 MT isolates sequencing data obtained by both Ion Torrent targeted sequencing and Illumina WGS were available. For all 18 MT isolates included phenotypic drug resistance to PZA was determined using the BACTEC MGIT 960 System (BD Diagnostic Systems) from pure cultures of MT isolates. All MT isolates included were resistant to any antibiotic. Among them, majority (16/18; 88.8%) were phenotypically resistant to PZA. Using either Ion Torrent targeted sequencing or Illumina WGS mutations in pncA were detected in 13 and 14 MT cases, respectively; in one case WGS detected Thr135Pro in pncA gene which was not detected by targeted sequencing. In one isolate that was phenotypically sensitive to PZA, a mutation in the pncA (specifically, Pro69Leu) linked with PZA resistance was detected by both sequencing technologies. In three phenotypically PZA resistant MT isolates no genetic alterations were found, not even with WGS. With limited MT isolates included in this study, both sequencing technologies showed similar performance and proved to be a valuable tool for surveillance of MT drug resistance.