Mgit 960 pza kit

Determination of the minimal inhibitory concentration (MIC) was performed in MGIT 960 (Becton Dickinson, USA). To define the MIC for isolates from Bangladesh, a PZA stock solution (Acros Organics, Belgium; 15 000 μg/mL) was prepared in MGIT 960 PZA medium. By adding respectively 27.7, 55.3, 110.7 and 221.3 μL of stock solution to a MGIT 960 PZA tube, test concentrations of 50, 100 (critical test concentration), 200 and 400 μg/mL PZA were achieved. To define the MIC for isolates from Pakistan, the same final concentrations were used, yet a PZA stock solution was prepared by reconstituting 1 vial of lyophilized PZA (BACTEC MGIT 960 PZA kit) in dimethyl sulfoxide (33600 μg/mL), with subsequent serial dilutions in sterile distilled water and transfer of 100 μL of the respective working solutions (16800, 8400 and 4200 μg/mL) to the MGIT 960 PZA tubes. The H37Rv reference strain and ten EQA strains from the WHO project [15] (link) were tested for each stock solution and did not reveal a difference in result between the different preparations. Isolates from South Africa had been previously tested by standard MGIT 960 PZA [12] (link).