Successful treatment with doripenem of ventriculitis due to Achromobacter xylosoxidans.

A 29-year-old woman was admitted to our hospital with complaints of headache, dizziness and nausea. There was a history of spina bifida and placement of ventriculoperitoneal (VP) shunt in early childhood. One month prior to the current admission there was replacement of a VP shunt with a new system because of a mechanical malfunction. At that time there were no clinical signs of infection and cultures of the old shunt system and the cerebrospinal fluid (CSF) were negative. On examination, temperature was 39.88C, heart rate was 123, respiratory rate was 22 and blood pressure was 108/56mmHg. Body weight was 60 kg. The neck was supple. The surgical sites of the VP shunt replacement showed no evidence of infection. Abdominal exam was unremarkable. Empiric intravenous (i.v.) piperacillin/tazobactam and vancomycin were begun. Computed tomography (CT) of the abdomen showed a small area of fluid collection at the distal portion of the VP shunt. Cultures of the blood and urine were negative. Chest radiograph did not reveal infiltrates. The white blood cell (WBC) count was 14 100 cells/ml. Measurements of renal and hepatic function were normal. CT of the head with i.v. contrast showed right parietooccipital VP shunt and no hydrocephalus. CSF obtained via VP shunt reservoir showed WBC count of 22/mm with 70% neutrophils, glucose of 60mg/dl, and protein of 20mg/dl. CSF Gram stain showed rare Gram negative rods and the culture grew 2+ Achromobacter xylosoxidans. The isolate was resistant to cefotaxime, ceftriaxone, cefepime, ceftazidime, ciprofloxacin, levofloxacin, piperacillin/tazobactam, ticarcillin/clavulanate, gentamicin, tobramycin and amikacin, and was susceptible to imipenem with a minimal inhibitory concentration (MIC) of 2mg/l (MicroScan, Dade Behring Inc., Sacramento, CA, USA). Additional testing of the isolate showed susceptibility to doripenem with a MIC of 1.5mg/l and tigecycline with a MIC of 2mg/l (Etest, AB bioMérieux, Durham, NC, USA). On the second day of hospitalization, antibiotic therapy was changed to doripenem 500mg i.v. infused over 60min every 8 h and a single dose of 300mg of i.v. tobramycin was given. On the third day of hospitalization, the VP shunt was removed and an external ventricular device (EVD) was placed. Culture of the VP shunt grew A. xylosoxidans with identical susceptibilities. The patient became afebrile and the WBC count normalized, but CSF obtained from the EVD on Days 4, 5 and 7 of doripenem therapy grew A. xylosoxidans with susceptibilities identical to those previously reported. Magnetic resonance imaging of the head with gadolinium contrast showed no evidence of an intracranial abscess or fluid collection. On Day 8 of hospitalization, the doripenem dose was increased to 1 gm i.v. every 8 h. Subsequent CSF cultures obtained on Days 10, 11, 12 and 13 of doripenem therapy were negative. On Day 15 of