title: The impact of inadequate terminal disinfection on an outbreak of imipenem-resistant Acinetobacter baumannii in an intensive care unit.
abstract: BACKGROUND
  This study was conducted to investigate an outbreak caused by imipenem-resistant Acinetobacter baumannii (IRAB) in a medical intensive care unit (ICU) in a regional hospital.
  
  
  METHODS
  In response to an IRAB outbreak from October 2012 to February 2013, we developed several infection control measures, including an extensive review process of environmental cleaning and disinfection, and used molecular methods to identify each clinical and environmental IRAB isolate.
  
  
  RESULTS
  During this five-month period, 22 patients were colonized with IRAB and 18 patients had IRAB infections. The in-hospital mortality rate was significantly higher among patients with infections rather than colonizations (44.4% vs 9.1%, p = 0.028). Additionally, nine environmental specimens, including five specimens collected after terminal disinfection, were positive for IRAB. 12 environmental isolates and 28 of 36 available clinical isolates belonged to one unique pulsotype A, which was confirmed by molecular methods. We found the concentration of disinfectant, 0.08% sodium hypochlorite, was inadequate. After correcting the environmental cleansing methods, the surveillance study showed no further IRAB isolates on the control panel surfaces of the medical equipment or in patients in the ICU. Additionally, an in vitro study of IRAB immersed in different concentrations of sodium hypochlorite showed that 0.5% sodium hypochlorite eradicates IRAB after 30 seconds of inoculation, but 0.08% sodium hypochlorite only reduces the bacterial load.
  
  
  CONCLUSIONS
  This study highlights the importance of the preparation of disinfectants to adequately achieve environmental disinfection in the control of IRAB outbreaks in the ICU.
authors.affiliation: Department of Intensive Care Medicine, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
authors.forename: Wei-Lun
authors.initials: WL
authors.lastname: Liu
authors.affiliation: Department of Nursing, Internal Medicine, and Intensive Care Medicine, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
authors.forename: Hsueh-Wen
authors.initials: HW
authors.lastname: Liang
authors.affiliation: Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Mei-Feng
authors.initials: MF
authors.lastname: Lee
authors.affiliation: Department of Nursing, Internal Medicine, and Intensive Care Medicine, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
authors.forename: Hsin-Lan
authors.initials: HL
authors.lastname: Lin
authors.affiliation: The Committee of Infection Control, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
authors.forename: Yu-Hsiu
authors.initials: YH
authors.lastname: Lin
authors.affiliation: Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan; Institute of Biotechnology, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chi-Chung
authors.initials: CC
authors.lastname: Chen
authors.affiliation: Department of Internal Medicine, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
authors.forename: Ping-Chin
authors.initials: PC
authors.lastname: Chang
authors.affiliation: Department of Intensive Care Medicine, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
authors.forename: Chih-Cheng
authors.initials: CC
authors.lastname: Lai
authors.affiliation: Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan; Department of Internal Medicine, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
authors.forename: Yin-Ching
authors.initials: YC
authors.lastname: Chuang
authors.affiliation: Department of Medicine, Chi Mei Medical Center, Tainan, Taiwan; Department of Health and Nutrition, Chia Nan University of Pharmacy and Science, Tainan, Taiwan.
authors.forename: Hung-Jen
authors.initials: HJ
authors.lastname: Tang
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000502:physiology; D000368:Aged; D004196:Disease Outbreaks / Q000517:prevention & control; D004203:Disinfection / Q000379:methods*; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D007362:Intensive Care Units; D008297:Male; D057766:Policy; D012973:Sodium Hypochlorite / Q000494:pharmacology; D013997:Time Factors
chemical_list: D015378:Imipenem; D012973:Sodium Hypochlorite