Rapid environmental recontamination of an intensive care unit after decontamination with hydrogen peroxide vapour

Abstract number: p1794

Hardy  K.J., Gossain  S., Hawkey  P.M., Oppenheim  B.A., Henderson  N., Gao  F.


To evaluate the effectiveness of hydrogen peroxide vapour (HPV) to reduce the levels of total bacterial and methicillin resistant Staphylococcus aureus (MRSA) environmental contamination on an Intensive Care Unit (ICU), and to establish the rate of environmental recontamination.


The study took place on a 9 bed open plan ICU. On each environmental screen 3 sites in each bed space (under the bed, the workstation and the monitor) were examined using broth enrichment for the detection of MRSA. In addition total bacterial counts were determined for under the bed and workstation using RODAC plates. Environmental screening was carried out monthly for the 3 months preceding the usage of HPV, increasing to weekly for the 4 weeks prior to usage. Additional sampling was carried out immediately before patients were discharged from ICU, following the subsequent terminal clean and then immediately after HPV use. After readmission of patients sampling was carried out at 24 h, 48 h and then weekly for a period of 8 weeks. Patients were screened for MRSA on admission and then weekly.


Sampling of the environment prior to the usage of HPV revealed contamination of the environment with MRSA on 6/7 occasions, with MRSA colonised patients being present on only 3/7 occasions. After discharge of the patients and terminal cleaning of the environment, MRSA was isolated from 5 (13%) environmental sites. After the use of HPV, MRSA was not isolated from any environmental sites upon immediate sampling, but 24 h after patients were readmitted, including 2 patients known to be colonised with MRSA, MRSA was isolated from 5 sites. These sites were not clustered around the colonised patients but were widespread across the ICU. In the 8 weeks post HPV usage MRSA has been isolated every week. The mean total bacterial counts prior to the use of HPV were 22.0/10 cm2 underneath the beds and 3.8/10 cm2 on the workstations, this was reduced after HPV to 0.1/10 cm2 and 0.2/10 cm2 respectively. After patients readmission the counts were 4.1/10 cm2 underneath the beds and 1.2/10 cm2 on the workstations after 48 h and returned to pre-HPV levels of 16.9/10 cm2 and 4.8/10 cm2 at each site respectively after 1 week.


Hydrogen peroxide vapour is effective in eliminating bacteria from the environment. The rapid rate of recontamination of the environment suggests that the use of HPV is not an effective means of maintaining low levels of environmental contamination on an open plan ICU.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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