Environmental decontamination of an intensive care unit to control outbreaks of multidrug-resistant Gram-negative rods using hydrogen peroxide vapour

Abstract number: 1733_1188

Schouten M., Otter J., van Zanten A., Houmes-Zielman G., Nohlmans-Paulssen M.

Objectives: 25 patients on our 12-bed intensive care unit (ICU) acquired multidrug-resistant Gram-negative rods (MDR-GNR) over an 8-month period, comprising Enterobacter cloacae (7) and Acinetobacter baumannii (18). Transmission continued despite the implementation of standard infection control measures including an emphasis on hand and environmental hygiene. We investigated the microbiological and clinical impact of hydrogen peroxide vapour (HPV) decontamination of the entire ICU.

Methods: All patients were temporarily relocated from the ICU and the entire unit was decontaminated using HPV. 100 cm2 sterile cotton gauzes were moistened in sterile water and used to sample 41×1 m2 areas after cleaning (which included 1,000 ppm sodium hypochlorite for surfaces and 70% alcohol for equipment) but before HPV. Nine matched adjacent areas were sampled after HPV decontamination. Gauzes were subcultured on blood and MacConkey agar after overnight broth enrichment. Thirty commercially-available Geobacillus stearothermophilus biological indicators (BIs) with an inoculum of >1.0×106 were located around the periphery of the unit, collected at the end of the HPV cycle and cultured according to the manufacturer's instructions.

Results: HPV decontamination of the unit took approximately 12 hours and was completed without incident or damage to the materials and equipment in the ICU. 9 (22%) of 41 areas cultured after cleaning but before HPV yielded MDR-GNR, including patient strains of E. cloacae and A. baumannii. These areas were sampled after HPV and yielded no MDR-GNR; however Bacillus sp. was cultured from 5 sites and Staphylococcus aureus (sensitive to methicillin) from 1 site. All BIs were killed by the process. No acquisition of MDR-GNR occurred on the unit for approximately two months after HPV decontamination. However, transmission of MDR-GNR has since been identified on the unit.

Conclusions: HPV proved to be more efficacious than conventional cleaning methods for reducing the bio-burden on our ICU. Although several sites remained contaminated following HPV, none were contaminated with MDR-GNR and we sampled large areas, including surfaces which may have been occluded from HPV. HPV appeared to break the cycle of transmission on the unit, but MDR-GNR re-occurred a few months later. The source of reintroduction is currently unknown.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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