An outbreak of multidrug-resistant Acinetobacter baumannii associated with pulsatile lavage wound treatment

Context Pulsatile lavage is a high-pressure irrigation treatment used increasingly in a variety of health care settings to debride wounds. Infection control precautions are not routinely used during the procedure and are not included in pulsatile lavage equipment package labeling. Objectives To investigate an outbreak of multidrug-resistant Acinetobacter baumannii and to test the hypothesis that pulsatile lavage wound treatment was the mode of transmission for the organism. Design Outbreak case-control investigation including case identification, review of medical records, environmental cultures, and pulsed-field gel electrophoresis. Setting A 1000-bed tertiary care hospital in Baltimore, Md, during September and October 2003. Patients The investigation included 11 patients infected or colonized with multidrug-resistant A baumannii. Seven of these patients met the case definition for the case-control study and were compared with 28 controls randomly selected from a list of inpatients without multidrug-resistant A baumannii who had a wound care consultation. Main Outcome Measure Infection or colonization with multidrug-resistant A baumannii. Results Eleven patients had cultures that grew multidrug-resistant A baumannii during the outbreak period. Of the 10 health care-associated cases, 8 had received pulsatile lavage treatment. One strain of multidrug-resistant A baumannii was recovered from all 6 pulsatile lavage patients who had isolates available for pulsed-field gel electrophoresis analysis and from multiple surfaces in the wound care area. Six of 7 cases (86%) were treated with pulsatile lavage vs 4 of 28 controls (14%) (odds ratio, 36; 95% confidence interval, 2.8-1721; P<.001). These results confirm that pulsatile lavage was a significant risk factor for acquisition of multidrug-resistant A baumannii. Conclusions Transmission was apparently caused by dissemination of multidrug-resistant A baumannii during the pulsatile lavage procedure, resulting in environmental contamination. Appropriate infection control precautions should be used during pulsatile lavage therapy and should be included in pulsatile lavage equipment labeling.