Sulfonamide resistance in isolates of Nocardia spp. from a US multicenter survey

J Clin Microbiol. 2012 Mar;50(3):670-2. doi: 10.1128/JCM.06243-11. Epub 2011 Dec 14.


Recent reports of increasing in vitro sulfonamide resistance in Nocardia prompted us to investigate the findings. Despite the reports, there is a paucity of clinical reports of sulfonamide failure in treatment of nocardia disease. We reviewed 552 recent susceptibilities of clinical isolates of Nocardia from six major laboratories in the United States, and only 2% of the isolates were found to have resistant MICs of trimethoprim-sulfamethoxazole and/or sulfamethoxazole. We hypothesize that the discrepancies in the apparent sulfonamide resistance between our study and the previous findings may be associated with difficulty in the laboratory interpretation of in vitro MICs for trimethoprim-sulfamethoxazole and sulfamethoxazole and the lack of quality controls for Nocardia for these agents.

Publication types

  • Multicenter Study

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Drug Resistance, Bacterial*
  • Humans
  • Microbial Sensitivity Tests / methods
  • Microbial Sensitivity Tests / standards
  • Nocardia / drug effects*
  • Nocardia / isolation & purification*
  • Nocardia Infections / microbiology*
  • Sulfamethoxazole / pharmacology
  • Sulfonamides / pharmacology*
  • Trimethoprim, Sulfamethoxazole Drug Combination / pharmacology
  • United States


  • Anti-Bacterial Agents
  • Sulfonamides
  • Trimethoprim, Sulfamethoxazole Drug Combination
  • Sulfamethoxazole