INVITRO SUSCEPTIBILITY OF NOCARDIA-ASTEROIDES TO 25 ANTIMICROBIAL AGENTS

Clinical isolates of N. asteroides (52) were tested by agar dilution for their susceptibility to 25 antimicrobial agents. In general, susceptibility could not be predicted based on the antibiotic class tested. The .beta.-lactams, including 3rd-generation cephalosporins, were generally ineffective (minimum inhibitory concentration for 90% of the organisms [MIC90], between 64 and > 256 .mu.g/ml); minocylcine and doxycycline were generally effective (MIC90, 4 and 8 .mu.g/ml, respectively). Cycloserine was not effective below 60 .mu.g/ml. The MIC50 and MIC90 of sulfamethoxazole were 16 and 32 .mu.g/ml, respectively; that of trimethoprim varied widely (16 and > 256 .mu.g/ml, respectively). Based on MIC90 data, only doxycycline, minocycline, sulfamethoxazole and imipenem could be applied empirically.