Failure of Clindamycin Treatment of Methicillin-Resistant Staphylococcus Aureus Expressing Inducible Clindamycin Resistance in Vitro

Clin Infect Dis. 2003 Nov 1;37(9):1257-60. doi: 10.1086/377501. Epub 2003 Oct 3.


We report a case of a surgical site infection caused by clindamycin-susceptible, erythromycin-resistant methicillin-resistant Staphylococcus aureus (MRSA) that did not respond to treatment with clindamycin. The MRSA isolate obtained after treatment was resistant to clindamycin but was found to be identical by pulsed-field gel electrophoresis to the clindamycin-susceptible isolate obtained before treatment. A post hoc erythromycin-induction test (D test) confirmed the presence of in vitro inducible macrolide-lincosamide-streptogramin B resistance (iMLS) in the pretreatment isolate. Erythromycin induction testing confirmed in vitro iMLS in 90 (56%) of 161 erythromycin-resistant, clindamycin-susceptible clinical S. aureus isolates overall and in a significantly higher proportion (78%) of methicillin-susceptible S. aureus isolates from pediatric patients. Our clinical laboratory currently tests all S. aureus isolates for iMLS before reporting clindamycin susceptibility.

Publication types

  • Case Reports

MeSH terms

  • Child, Preschool
  • Clindamycin / therapeutic use*
  • Drug Resistance, Multiple, Bacterial*
  • Female
  • Humans
  • Methicillin / pharmacology*
  • Methicillin Resistance
  • Microbial Sensitivity Tests
  • Staphylococcal Infections / drug therapy*
  • Staphylococcal Infections / microbiology
  • Staphylococcus aureus / drug effects*


  • Clindamycin
  • Methicillin