An Outbreak of Multidrug-Resistant Acinetobacter baumannii-calcoaceticus Complex Infection in the US Military Health Care System Associated with Military Operations in Iraq

Paul Scott 1 3 4 Gregory Deye 1 3 5 Arjun Srinivasan 1 3 9 Clinton Murray 1 3 7 Kimberly Moran 1 3 6 Ed Hulten 1 3 6 Joel Fishbain 1 3 6 David Craft 1 3 6 Scott Riddell 1 3 5 8 Luther Lindler 1 3 4 James Mancuso 1 3 11 Eric Milstrey 1 3 8 11 Christian T. Bautista 1 3 4 Jean Patel 1 3 9 Alessa Ewell 1 3 6 Tacita Hamilton 1 3 4 Charla Gaddy 1 3 4 Martin Tenney 1 3 8 10 George Christopher 1 3 5 8 Kyle Petersen 1 2 3 Timothy Endy 1 3 4 8 Bruno Petruccelli 0 1 3 0 United States Army Center for Health Promotion and Preventive Medicine , Aberdeen, Maryland 1 This manuscript has been reviewed by the Walter Reed Army Institute of Research and the Centers for Disease Control and Prevention. There is no objection to its publication. The opinions or assertions contained herein are the private views of the authors , and are not to be construed as official, or as reflecting true views of the Department of Defense, the National Institutes of Health or the Department of Health and Human Services , or other organization listed. This work was prepared as part of their official duties and, as such, there is no copyright to be transferred 2 National Naval Medical Center , Bethesda 3 Received 1 December 2006; accepted 28 February 2007; electronically published 8 May 2007 4 Walter Reed Army Institute of Research , Silver Spring 5 Landstuhl Regional Medical Center 6 Walter Reed Army Medical Center , Washington, DC 7 Brooke Army Medical Center , Fort Sam Houston, Texas 8 Present affiliations: State University of New York, Upstate Medical University , Syracuse (S.R. and T.E.); US Army Center for Health Promotion and Preventive Medicine , Aberdeen, MD (E.M.); United States Army Medical Command , Ft. Sam Houston, TX (M.T.); and Defense Threat Reduction Agency , Ft. Belvoir, VA (G.C.). Army Institute of Research , 1 Taft Ct., Ste. 250, Rockville, MD 20850 (pscott @hivresearch.org). Clinical Infectious Diseases 2007 ; 44:1577-84 This article is in the public domain , and no copyright is claimed. 1058-4838/2007/4412-0009 DOI: 10.1086/518170 9 Centers for Disease Control and Prevention , Atlanta, Georgia 10 28th Combat Support Hospital , Baghdad, Iraq 11 United States Army Center for Health Promotion and Preventive Medicine Europe , Landstuhl, Germany Background. We investigated an outbreak of multidrug-resistant Acinetobacter baumannii-calcoaceticus complex infection among US service members injured in Iraq. Methods. The investigation was conducted in Iraq and Kuwait, in the 2 military hospitals where the majority of injured service members were initially treated. After initially characterizing the outbreak, we evaluated 3 potential sources of infection for the period March 2003 to December 2004. The evaluation included screening samples that were obtained from the skin of patients for the presence of colonization and assessing the soil and health care environments for the presence of A. baumanii-calcoaceticus complex organisms. Isolates obtained from samples from patients in US Military treatment facilities, as well as environmental isolates, were genotypically characterized and compared using pulsed-field gel electrophoresis. Results. A. baumanii-calcoaceticus complex organisms were present on the skin in only 1 (0.6%) of 160 patients who were screened and in 1 (2%) of 49 soil samples. A. baumanii-calcoaceticus complex isolates were recovered from treatment areas in 7 of the 7 field hospitals sampled. Using pulsed-field gel electrophoresis, we identified 5 cluster groups in which isolates from patients were related to environmental isolates. One cluster included hospitalized patients who had not been deployed to Iraq. Among the clinical isolates, only imipenem, polymyxin B, and colistin demonstrated reliable in vitro antimicrobial activity. Generally, the environmental isolates were more drug susceptible than were the clinical isolates. Conclusions. Our findings suggest that environmental contamination of field hospitals and infection transmission within health care facilities played a major role in this outbreak. On the basis of these findings, maintaining infection control throughout the military health care system is essential. Novel strategies may be required to prevent the transmission of pathogens in combat field hospitals. Acinetobacter baumannii-calcoaceticus complex (ABC) A. baumannii Outbreak in the US Military CID 2007:44 (15 June) 1577 - organisms are gram-negative bacteria found in soil and water [1]. They are an emerging cause of health care associated outbreaks of infection, especially among critically ill and immunocompromised patients [2, 3]. In March 2003, soon after the beginning of the US Militarys combat operations in Iraq known as Operation Iraqi Freedom (OIF), a marked increase was observed in the number of multidrug-resistant ABC infections among inpatients at Landstuhl Regional Medical Center (LRMC; Landstuhl, Germany) and at Walter Reed Army Medical Center (WRAMC; Washington, DC). Most injured service members were initially treated at these 2 facilities after evacuation from Iraq. Many of these infections were detected at or soon after hospital admission to LRMC or WRAMC, but the source of the infections was not apparent [4]. Here we present the results of our investigation of several possible sources for this outbreak, which include preinjury skin colonization, introduction at the time of injury from environmental soil contamination, and acquisition after injury during treatment in health care facilities. MATERIALS AND METHODS Characterizing the Outbreak From March through October 2003, we used an electronic data collection form to gather demographic, clinical, and microbiological data for the initial 70 inpatients at LRMC and WRAMC who had clinical culture results that were positive for ABC. Data sources included paper medical records, electronic medical records (Clinical Information System; CliniComp), the Composite Healthcare System computerized hospital information system, and the Vitek 1 and 2 (bioMerieux). We also collected information on the specific movements through the military aeromedical evacuation system of 19 (27%) of these 70 patients using the Department of Defense Transportation Command Regulating and Command and Control Evacuation System (TRAC2ES) [5]. Outbreak Source Investigation Evaluation for ABC skin colonization. We evaluated 2 independent groups. From 23 September through 20 October 2004, we screened 96 ambulatory US casualties who had been evacuated from Iraq to LRMC and who had no known prior hospitalization in Iraq. From 25 October through 23 December 2004, we screened 102 casualties (including both US and Iraqi patients), either at initial presentation to the Emergency Treatment Area or at admission to the intensive care unit in the US Military field hospital in Baghdad (Iraq). We used either a single culture swab (BBL culturette with liquid Amies; BD Diagnostics) to sample the skin in both the axilla and groin areas, or 2 swabs to (...truncated)