ENHANCED IN-VITRO ACTIVITY OF WR99210 IN COMBINATION WITH DAPSONE AGAINST MYCOBACTERIUM-AVIUM COMPLEX

WR99210, a dihydrofolate reductase inhibitor, has promising in vitro a ctivity against Mycobacterium avium complex (MAC). The in vitro activi ties of WR99210 alone and in combination with a fixed concentration of dapsone (0.5 mu g/ml) were evaluated against 35 clinical MAC isolates by a broth dilution method. The MIC at ,which 50% of isolates were in hibited (MIC(50)) and MIC(90) of WR99210 alone were 2 and 8 mu g/ml, r espectively, The MIC(50) and MIC(90) of WR99210 in combination with da psone were 0.25 and 4 mu g/ml, respectively. Overall, 75% of the MAC i solates displayed enhanced susceptibility to the combination.