title: Therapeutic Dose Monitoring for Linezolid in a Patient with MRSA Pneumonia with Bacteremia in Diabetes Insipidus.
abstract: BACKGROUND
  Few studies have investigated the effect of increased creatinine clearance (CrCl) on linezolid (LZD) concentration. Herein, we report the pharmacokinetic/pharmacodynamic (PK/PD) profile of LZD used in the management of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia with concomitant bacteremia in a patient with high CrCl caused by diabetes insipidus (DI).
  
  
  METHODS
  A 19-year-old man was admitted to the intensive care unit following a traumatic brain injury. After admission, he underwent a craniotomy for the severe brain injury. However, he developed DI after the operation. Despite treatment with vasopressin, his urine output reached 5-6 L/day as a result of the DI, and his CrCl increased to 180-278 mL/min. We were required to administer 6-7 L of fluid a day to compensate for the high urinary fluid output. On day 55, MRSA pneumonia with sepsis was suspected and, consequently, LZD was administrated intravenously (600 mg every 12 h). He was treated with LZD for 14 days. The patient has since successfully recovered from MRSA pneumonia with concomitant bacteremia, and was transferred to the general ward on day 82. Blood LZD levels from days 60-68, which were measured after the patient's transfer to the general ward, showed that the trough levels were lower than the threshold level of detection. The blood 24-h area under the plasma LZD concentration-time curve (AUC)24/minimum inhibitory concentration (MIC) was 69.3.
  
  
  CONCLUSIONS
  In spite of the low level of LZD AUC24/MIC caused by the high CrCl with DI, MRSA pneumonia with concomitant bacteremia was successfully treated with LZD.
authors.affiliation: Department of Emergency and Critical Care Medicine, Faculty of Medicine, Fukuoka University, Fukuoka, Japan. pdmxy827@yahoo.co.jp.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: Department of Pharmacy, Fukuoka University Hospital, Fukuoka, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Uchiyama
authors.affiliation: Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, Japan.
authors.forename: Shuuji
authors.initials: S
authors.lastname: Hara
authors.affiliation: Department of Emergency and Critical Care Medicine, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Mizunuma
authors.affiliation: Department of Pharmacy, Fukuoka University Hospital, Fukuoka, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Nakano
authors.affiliation: Department of Emergency and Critical Care Medicine, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Ishikura
authors.affiliation: Department of Emergency and Critical Care Medicine, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: Kota
authors.initials: K
authors.lastname: Hoshino
authors.affiliation: Department of Emergency and Critical Care Medicine, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Kawano
authors.affiliation: Department of Oncology, Hematology, and Infectious Diseases, Fukuoka University School of Medicine, Fukuoka, Japan.|Department of Infection Control, Fukuoka University Hospital, Fukuoka, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Takata
keywords: Area under the plasma drug concentration–time curve/minimum inhibitory concentration; Bacteremia; Blood concentration; Diabetes insipidus; Linezolid; Methicillin-resistant Staphylococcus aureus; Pneumonia