Staphylococcus aureus osteo-articular infection: usefulness of the determination of daptomycin serum concentration to explain a treatment failure

Int J Clin Pharmacol Ther. 2016 Nov;54(11):923-927. doi: 10.5414/CP202538.


We report two cases of treatment failure in patients with osteoarticular infection associated with <i>Staphylococcus aureus</i> bacteremia and receiving daptomycin. Using a published population-pharmacokinetic model and daptomycin blood level in these patients, area under the curve (AUC) was calculated and compared to the pharmacological target. For the first patient, treated with 6 mg/kg every 48 hours due to acute renal failure and then every 24 hours, the AUC was 820 mg×h×L<sup>-1</sup>, with a minimal concentration of 23.5 mg/L confirming the right dose adjustment and the absence of underdosing. The methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) strain was still susceptible to daptomycin, but it was not sufficient to observe a favorable outcome. For the second patient, treated with 10 mg/kg/d, the steady state residual concentration was 10.4 mg/L, and the calculated AUC value was 550 mg×h×L<sup>-1</sup>. AUC/MIC values evolved during treatment to be under the cut-off for bactericidal effects (> 800 hours), and the <i>Staphylococcus aureus</i> (SA) strain became daptomycin resistant. This study highlights the inter-individual pharmacokinetic variation leading sometimes to drug underdosing. Drug monitoring should be encouraged in order to avoid treatment failure.

Publication types

  • Case Reports

MeSH terms

  • Aged, 80 and over
  • Anti-Bacterial Agents / blood*
  • Anti-Bacterial Agents / pharmacokinetics
  • Anti-Bacterial Agents / therapeutic use*
  • Area Under Curve
  • Bone Diseases, Infectious / drug therapy*
  • Bone Diseases, Infectious / microbiology*
  • Cartilage Diseases / drug therapy*
  • Cartilage Diseases / microbiology*
  • Cartilage, Articular*
  • Daptomycin / blood*
  • Daptomycin / pharmacokinetics
  • Daptomycin / therapeutic use*
  • Drug Monitoring
  • Female
  • Humans
  • Male
  • Methicillin-Resistant Staphylococcus aureus*
  • Osteomyelitis / drug therapy
  • Osteomyelitis / microbiology
  • Staphylococcal Infections / drug therapy*
  • Treatment Failure
  • Vancomycin / therapeutic use


  • Anti-Bacterial Agents
  • Vancomycin
  • Daptomycin