Major article Effectiveness and cost of implementing an active surveillance screening policy for Acinetobacter baumannii: A Monte Carlo simulation model Joseph R. Coyle MPH a , Keith S. Kaye MD, MPH a , Thomas Taylor PhD a , Ryan Tansek MD a , Michelle Campbell MD a , Kayoko Hayakawa MD, PhD a , Dror Marchaim MD a, b, c, * a Division of Infectious Diseases, Wayne State University, Detroit, MI b Division of Infectious Diseases, Assaf Harofeh Medical Center, Zerifin, Israel c Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel Key Words: Isolation Contact isolation precautions Transmission Multidrug resistance Nosocomial Background: Acinetobacter baumannii infections are common and associated with high mortality and costs. Early identification of asymptomatic carriers can reduce patient-to-patient transmission, but the sensitivity of A baumannii surveillance tools is poor, and thus active surveillance is not routine practice. This study examined whether an active surveillance screening policy can reduce the transmission, mortality, and costs associated with A baumannii. Methods: A simulation model was developed to determine the impact of active screening on patient outcomes. Model parameters included A baumannii prevalence, screening sensitivity and specificity, probability of transmission, progression from colonization to infection, mortality, and cost of screening, contact precautions, and infection. A scenario analysis was performed to evaluate the robustness of the results when varying the sensitivity of the screening test and the prevalence rate of A baumannii. Results: Assuming a screening sensitivity of 55%, active screening reduced A baumannii transmissions, infections, and deaths by 48%. As the screening sensitivity approached 90%, the reduction in trans- missions, infections, and deaths reached 78%. For all scenarios tested, active surveillance was cost saving (19%-53% reduction in mean hospital cost per patient) except at a carrier prevalence of 2% and screening test sensitivity of 55%. Conclusions: In institutions where A baumannii is endemic or during epidemics, implementing a sur- veillance program is cost-saving and can greatly reduce transmissions and deaths. Methodologies to improve the sensitivity of surveillance testing will help optimize the clinical impact of active screening programs on preventing the spread of A baumannii in health care facilities. Copyright Ó 2014 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. Acinetobacter baumannii is a common gram-negative non- fermentative bacterium that causes outbreaks in various health care settings. 1-6 Antimicrobial resistance is a major concern with A baumannii, and frequently no effective therapeutic options are available to treat infection with extensively drug-resistant (XDR) A baumannii strains isolated in nosocomial settings. 2,4,7-9 Infections due to XDR A baumannii strains are associated with devastating outcomes in terms of mortality, morbidity, and costs. 10 Risk factors for A baumannii infection include advanced age, deteriorated functional status, intensive care unit (ICU) stay, recent exposure to antibiotics, recent invasive procedures or surgeries, prolonged hospitalization, and various immunosuppressive states. 11-19 Individuals who are elderly, permanently institutional- ized, and transit frequently between health care facilities of different levels of care are at particularly high risk for A baumannii carriage. The frequent transit among health care facilities among high-risk patients who are asymptomatically colonized with A baumannii fa- cilitates the spread of A baumannii throughout these facilities. 1 Early identification of asymptomatic carriers (before they develop infection) is an important and well-established infection * Address correspondence to Dror Marchaim, MD, Division of Infectious Diseases, 5 Hudson, Harper University Hospital, 3990 John R. Street, Detroit, MI 48201. E-mail address: drormc@hotmail.com (D. Marchaim). K.S.K. is supported by the National Institute of Allergy and Infectious Diseases (DMID Protocol 10-0065). Conflict of interest: None to report. Contents lists available at ScienceDirect American Journal of Infection Control journal homepage: www.ajicjournal.org American Journal of Infection Control 0196-6553/$36.00 - Copyright Ó 2014 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajic.2013.09.027 American Journal of Infection Control 42 (2014) 283-7