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. 2014 Sep 25;9(9):e107975.
doi: 10.1371/journal.pone.0107975. eCollection 2014.

The impact of inadequate terminal disinfection on an outbreak of imipenem-resistant Acinetobacter baumannii in an intensive care unit

Wei-Lun Liu  1 , Hsueh-Wen Liang  2 , Mei-Feng Lee  3 , Hsin-Lan Lin  2 , Yu-Hsiu Lin  4 , Chi-Chung Chen  5 , Ping-Chin Chang  6 , Chih-Cheng Lai  1 , Yin-Ching Chuang  7 , Hung-Jen Tang  8
Affiliations

The impact of inadequate terminal disinfection on an outbreak of imipenem-resistant Acinetobacter baumannii in an intensive care unit

Wei-Lun Liu et al. PLoS One. .

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.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Case numbers of imipenem-resistant Acinetobacter baumannii colonization and infections over time.
Figure 2
Figure 2. Pulsed-field gel electrophoresis (PFGE) profiles of 48 imipenem-resistant A. baumannii isolates digested with ApaI.
Red line indicated the 85% similarity values of PFGE profiles. P: clinical isolate from patient; E: environmental isolate.
Figure 3
Figure 3. The number of imipenem-resistant Acinetobacter baumannii in different concentration of sodium hypochlorite after 30 and 60 seconds.
See this image and copyright information in PMC

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