Cluster of Serratia marcescens Associated with Tap Water Utilization in High-Flow Nasal Cannula: Identification, Investigation, and Correction

BACKGROUND: Providence St. Vincent Hospital (PROVSTV), a 450-bed acute-care facility in Portland, was alerted to a significant increase in hospital-associated Serratia marcescens isolates from respiratory sources during March–May 2003. OBJECTIVES: Identify processes putting patients at risk, correct process breakdowns, and share information for future prevention with other clinical staff. METHODS: Data-mining services are provided to PROVSTV. Monthly reports are generated to detect unsuspected patterns of infection within the hospital and community. In June 2003, Infection Control (IC) received an alert describing a 310% increase (p=0.041) in patients with non-duplicate hospital-associated Serratia marcescens isolates from upper respiratory sources among post cardiac surgery and critical care patients. Upon IC investigation it was discovered that respiratory care staff on the units involved were utilizing tap water in the humidifiers on the ventilators. Cost was given as the reason sterile water was not being used. Respiratory Therapy investigated the cost impact of utilizing sterile water for this purpose. A pre-packaged humidifier with sterile water was discovered which would be cheaper than the old system. This system was implemented. RESULTS: Continuing electronic surveillance for hospital-associated Serratia marcescens respiratory isolates revealed only five isolates in the subsequent 6 months following the implementation of corrective measures. Compared with the 3-month period in which the alert was generated, this was a 58% reduction. CONCLUSION: Investigation of a cluster of Serratia marcescens respiratory isolates yielded improved respiratory care at lower cost.