title: Failure of clindamycin treatment of methicillin-resistant Staphylococcus aureus expressing inducible clindamycin resistance in vitro.
abstract: 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.
authors.affiliation: Division of Pediatric Infectious Diseases, Department of Pediatrics, Johns Hopkins Hospital, Baltimore, Maryland 21287, USA. gksiberr@jhmi.edu
authors.forename: George K
authors.initials: GK
authors.lastname: Siberry
authors.forename: Tsigereda
authors.initials: T
authors.lastname: Tekle
authors.forename: Karen
authors.initials: K
authors.lastname: Carroll
authors.forename: James
authors.initials: J
authors.lastname: Dick
mesh_terms: D002675:Child, Preschool; D002981:Clindamycin / Q000627:therapeutic use*; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006801:Humans; D008712:Methicillin / Q000494:pharmacology*; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D002981:Clindamycin; D008712:Methicillin