LEADER surveillance program results for 2010: an activity and spectrum analysis of linezolid using 6801 clinical isolates from the United States (61 medical centers)

Diagn Microbiol Infect Dis. 2012 Sep;74(1):54-61. doi: 10.1016/j.diagmicrobio.2012.05.012. Epub 2012 Jun 15.


The LEADER program monitors the in vitro activity of linezolid and comparator agents across the United States using reference broth microdilution and supportive molecular susceptibility-based investigations. This report summarizes the data from the 2010 program, the seventh consecutive year. A total of 61 medical centers from the USA including 7 medical centers specializing in children's healthcare provided a total of 6801 Gram-positive pathogens. The medical centers represented all 9 US Bureau of Census geographic regions. The organisms tested by reference broth microdilution were 3105 Staphylococcus aureus, 944 coagulase-negative staphylococci (CoNS), 934 Enterococci, 803 Streptococcus pneumoniae, 604 β-haemolytic streptococci, and 411 viridans group and other streptococci. The MIC(90) value for each of the above 6 targeted groups of organisms was 1 μg/mL. The "all organism" linezolid-resistant and nonsusceptible rate was 0.38%, which has been constant at 0.34% (2009) to 0.45% (2006) for the last 4 years. For Staphylococcus aureus, only 0.06% of the isolates were linezolid-resistant (MIC, ≥8 μg/mL); however, 2 additional methicillin-resistant Staphylococcus aureus had a cfr and a MIC of only 4 μg/mL. Resistance to linezolid was detected in 7 enterococci (0.75%) and 14 CoNS isolates (1.48%). This also represents a stable rate of resistance noted since the 2006 LEADER program report. Of note, for the first time in the 7 years of the Leader Program a linezolid-resistant Streptococcus pneumoniae was encountered. Overall, the results of the LEADER program demonstrate that linezolid maintains excellent in vitro activity against target Gram-positive pathogens across the USA. The LEADER program continues to provide valuable reference and molecular-level monitoring of linezolid activity.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetamides / pharmacology*
  • Anti-Bacterial Agents / pharmacology*
  • Drug Resistance, Bacterial
  • Humans
  • Linezolid
  • Microbial Sensitivity Tests
  • Oxazolidinones / pharmacology*
  • Staphylococcal Infections / microbiology*
  • Staphylococcus / drug effects*
  • Staphylococcus / isolation & purification
  • Streptococcal Infections / microbiology*
  • Streptococcus / drug effects*
  • Streptococcus / isolation & purification
  • United States


  • Acetamides
  • Anti-Bacterial Agents
  • Oxazolidinones
  • Linezolid