title: Case report: artificial elevation of prothrombin time by telavancin.
abstract: BACKGROUND
  Methicillin-resistant Staphylococcus aureus infections are a well-documented risk of surgery and are becoming increasingly difficult to treat owing to continued acquired resistance. A new antibiotic for treatment of Staphylococcus aureus is telavancin.
  
  
  METHODS
  A patient at our institution was prescribed telavancin for multiple spinal abscesses before spinal surgery. Routine preoperative testing revealed an international normalized ratio (INR) of 2.05 with no clear cause. Careful review of the patient's medication history and prescriber information revealed that telavancin may interfere with prothrombin time (PT/INR) testing. In vitro testing by our laboratory confirmed an association between telavancin dose and an increase in PT/INR. An alternative reagent for PT/INR testing unaffected by telavancin dose revealed a PT/INR of 0.97.
  
  
  METHODS
  Telavancin interacts with artificial phospholipid surfaces used to monitor coagulation while having no actual effect on coagulation.
  
  
  CONCLUSIONS
  All physicians, especially orthopaedic surgeons, should be aware of the effects of telavancin and ensure proper measures are taken to acquire the true INR by switching the reagent used to test PT/INR or ensuring the PT/INR is drawn before telavancin dosing.
authors.affiliation: Department of Orthopaedic Surgery, University of California, Davis Health System, 4860 Y Street, Suite 3800, Sacramento, CA 95835, USA.
authors.forename: Derek F
authors.initials: DF
authors.lastname: Amanatullah
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Lopez
authors.forename: Robert C
authors.initials: RC
authors.lastname: Gosselin
authors.forename: Munish C
authors.initials: MC
authors.lastname: Gupta
mesh_terms: D000038:Abscess / Q000188:drug therapy* / Q000601:surgery; D000617:Aminoglycosides / Q000494:pharmacology* / Q000627:therapeutic use; D000890:Anti-Infective Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001777:Blood Coagulation / Q000187:drug effects*; D005260:Female; D006801:Humans; D019934:International Normalized Ratio; D000077427:Lipoglycopeptides; D008875:Middle Aged; D011517:Prothrombin Time; D013122:Spinal Diseases / Q000188:drug therapy* / Q000601:surgery; D013123:Spinal Fusion / Q000379:methods*
chemical_list: D000617:Aminoglycosides; D000890:Anti-Infective Agents; D000077427:Lipoglycopeptides; C487637:telavancin