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Damjanovic, H.K.F. van Saene * Department of Medical Microbiology, University of Liverpool, Liverpool, UK E-mail address: rick.vansaene@rlch-tr.nwest.nhs.uk * Corresponding author. Tel.: þ 44-151-252-5006; fax: þ 44- 151-252-5356 doi:10.1016/j.jhin.2003.09.009 Ralstonia pickettii outbreak associated with contaminated distilled water used for respiratory care in a paediatric intensive care unit Sir, Ralstonia pickettii is a non-fermentative Gram- negative bacillus that grows well in moist environments. It has been implicated in nosoco- mial outbreaks associated with contaminated solutions used for patient care 1–5 and pseudo- outbreaks associated with contaminated solutions used for laboratory diagnosis. 6,7 We report an outbreak involving two patients in a paediatric intensive care unit (PICU). The source of this outbreak was contaminated distilled water used for respiratory care. Case 1 was a two-month-old girl, who had undergone surgery because of congenital heart disease. She developed ventilator-associated pneu- monia on the third postoperative day. Tracheal aspirate cultures were positive for Escherichia coli. Five days later, after antibiotic therapy with meropenem, the patient was afebrile and her chest radiography, white blood cell count and C-reactive protein level were within normal limits. On the 10th day of antibiotic therapy, she became febrile again with an abnormal WBC count. Blood and tracheal aspirate cultures were positive for R. pickettii and the antibiotic treatment was changed to piperacillin–tazobactam. In spite of the fact that the patient’s clinical and laboratory findings improved, piperacillin – tazobactam suscep- tible R. pickettii persisted in 17 consecutive blood cultures over 13 days. Case 2 was a 14-year-old boy with cerebral oedema due to central nervous system Burkitt’s lymphoma. The patient was mechanically venti- lated, had multiple indwelling catheters (including central venous catheter, urinary catheter, external ventricular shunt and radial arterial catheter) and was treated with meropenem. He was afebrile and there were no clinical, laboratory or radiological findings of infection for 10 days. On the 12th day of antibiotic therapy (the eighth day of R. pickettii bacteraemia of case 1), he became febrile with a raised white cell count. Cerebrospinal fluid, urine analysis and chest X-ray were normal but peripheral blood and tracheal aspirate cultures were positive for R. pickettii. Antibiotic therapy was changed to piperacillin – tazobactam. We initiated a surveillance study. Fluids used in the care of the patients (e.g. total parenteral nutrition fluids, intravenous fluids, distilled water used for respiratory therapy, antiseptic and anti- biotic solutions) were cultured. R. pickettii with the same antibiotic susceptibility pattern as the patient strains (meropenem resistant but pipera- cillin – tazobactam susceptible) was isolated from distilled water used for humidification of the air in the ventilator circuit. All R. pickettii strains were identified by the use of the API NE identification system (bioMe ´rieux). The distilled water had been stored in a container, and this stored distilled water was also contaminated. The container and the ventilators of two patients were sterilized. After this the patients improved, their acute phase reactants returned to normal within three days, and blood cultures were sterile. After 14 days of therapy, piperacillin – tazobactam was discontinued in case 1 who was discharged uneventfully. How- ever, case 2 died from cerebral herniation due to his primary illness. No further cases of infection or contamination with R. pickettii were observed during the following year. R. pickettii (formerly called Pseudomonas pick- ettii or Burkholderia pickettii) has been well described as a contaminant of solutions used for patient care. Characteristics of R. pickettii that enable it to contaminate sterile solutions include its ability to grow at a wide range of temperatures (15 8C to 42 8C) and in saline solution. In addition, R. pickettii may not be completely retained by a Letters to the Editor 77