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The emergence of multidrug-resistant Acinetobacter baumanii (MDRAB) poses a serious threat to patients on the ICU. The production of metallo-β-lactamase leaves colistin as the only therapeutic option. Outbreaks due to MDRAB can persist for months. Traditional decontamination methods fail to deal with this level of colonisation and contamination effectively. We tackled a recent outbreak of MDRAB effectively using gaseous ozone. To our knowledge it is the first time ozone has been used to control an outbreak of MDRAB.
An external company (Hydrozone Environmental Ltd) was hired to perform the fumigation. The ICU was divided into three decontamination areas using heavy-duty polythene sheets. Patients were in turn relocated from contaminated to clean areas before each area was sealed and fumigated. Humidity levels within were raised to 70 to 80% using a humidifier. An Ozone Ultra Pro 16 g/hour ozone generator with ozone destruct capability, operated remotely, delivered ozone to a target concentration of >2.0 ppm for 15 minutes. A fan was used to achieve even dispersal. For safety reasons perimeter ozone concentrations were monitored with a UV photometer and kept below 0.05 ppm. The efficacy of the fumigation was measured by environmental microbiological sampling before and after fumigation.
All fumigated areas received ozone concentrations of 4.62 to 5.66 ppm for 21 to 32 minutes. Ozone was not detected outside the treatment areas. Prior to fumigation, 72 (38%) of 188 environmental samples were MDRAB-positive. Following fumigation, nine (5%) of 158 samples were positive. Most of these samples were from nontouch areas, for example ceiling, above door frame with significant dust collection and without daily cleaning. Considering that dust may impede ozone penetration, basic cleaning was improved and duration of fumigation was increased to 30 minutes. Subsequent samples all proved negative and no further cross-infections occurred.
This is the first study using ozone fumigation as a disinfectant to control an outbreak in an ICU. Ozone fumigation is an effective tool for eradicating MDRAB from heavily contaminated clinical sites. Used in conjunction with good infection control measures, ozone can be used to control outbreaks such as MRSA, Clostridium difficile, Norovirus and swine flu.