Management of a multidrug-resistant Acinetobacter baumannii outbreak in an intensive care unit using novel environmental disinfection: A 38-month report

Background: Between June 1, 2004, and March 14, 2005, 16 patients in the surgical/medical intensive care unit (ICU) were infected and another 2 were colonized with multidrug-resistant (MDR) Acinetobacter baumannii. We describe the systematic investigation initiated to discover an environmental reservoir and a novel measure taken to terminate the outbreak. Methods: Cultures were taken from moist areas in the ICU, including sink traps, sink and counter surfaces, drains, and faucets. Strains were characterized using restriction endonuclease analysis. A weekly full drainpipe chase cleansing protocol with sodium hypochlorite (bleach) solution for all 24 ICU and waiting room area sinks connected by common plumbing was initiated in March 2005. Results: Eleven of 16 infected patients (69%) had a clonal MDR strain, 1 patient (6%) was infected with an unrelated strain, and in 4 patients (25%) strains were not available for typing. The reservoir for the A baumannii clone was detected in a sink trap within one of the ICU patient rooms that likely represented contamination of the entire horizontal drainage system. The bleaching protocol initiated in March 2005 successfully decontaminated the reservoir and eliminated the MDR A baumannii infections. Conclusion: A systematic search for an environmental reservoir followed by decontamination significantly reduced (P<.01) the incidence of MDR A baumannii infection.