Further information: SchoutenR@zgv.nl jon.otter@bioquell

1. o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o Environmental decontamination of an intensive care unit to control outbreaks of multidrug-resistant Gram-negative rods using hydrogen peroxide vapour (HPV) Further information: SchoutenR@zgv.nl jon.otter@bioquell.com Poster # M.A. Schouten1 J.A. Otter2 A.R.H. van Zanten1 G. Houmes-Zielman1 M.K.E. Nohlmans-Paulssen1 1. Gelderse Vallei Hospital, Ede, The Netherlands, 2. BIOQUELL (UK) Ltd., Andover, Hampshire, UK. 4. Results 1. Abstract 1. Abstract 1. Abstract 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 cm^2 sterile cotton gauzes were moistened in sterile water and used to sample 41 x 1 m^2 areas after cleaning (which included 1000ppm 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. Forty commercially-available G. stearothermophilus biological indicators (BIs) with an inoculum of >1.0x10^6 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 re-introduction is currently unknown. • HPV decontamination of the unit took approximately 12 hours and was completed without incident or damage to the materials and equipment in the ICU (figures 1, 2). • 9 (22%) of 41 areas cultured after cleaning but before HPV yielded MDR-GNR, including patient strains of E. cloacae and A. baumannii (figure 3). • 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 40 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. Figure 1: Clarus™ R HPV generator in a patient bay Figure 2: Central view of the ICU during HPV decontamiantion 2. Introduction and Purpose 5. Discussion and Conclusions • We have experienced problems with multidrug-resistant Gram- negative rods (MDR-GNR) on our intensive care unit (ICU) since 20041 • 25 patients on our 12-bed intensive care unit (ICU) aquired (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 inproved environmental hygiene. • We investigated the microbiological and clinical impact of hydrogen peroxide vapour (HPV) decontamination of the ICU. • 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. • Environmental contamination has been shown to be involved in the transmission of MDR-GNR in other studies2 • HPV has been used previously for enhanced environmental decontamination during an outbreak of GNR on a critical care unit3 • HPV appeared to break the cycle of transmission on our unit, but MDR-GNR re-occurred a few months later. • The source of re-introduction is currently unknown; possible sources include an occluded environmental surface or an unrecognised patient or staff carrier. 3. Methods • All patients were temporarily relocated from the ICU and the entire unit was decontaminated using HPV. • 100 cm^2 sterile cotton gauzes were moistened in sterile water and used to sample 41 x 1 m^2 areas after cleaning (which included 1000ppm 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. • Forty commercially-available G. stearothermophilus biological indicators (BIs) with an inoculum of >1.0x106 were located around the periphery of the unit, collected at the end of the HPV cycle and cultured according to the manufacturer’s instructions. Figure 3: Plan of the ICU showing: o biological indicator locations room sampled before and after HPV sites positive for MDR-GNR 6. References 1. Idzenga et al. Outbreak of Acinetobacter genomic species 3 in a Dutch intensive care unit. J Hosp Infect 2006;63:485-487. 2. Denton et al. Role of environmental cleaning in controlling an outbreak of Acinetobacter baumannii on a neurosurgical intensive care unit. J Hosp Infect 2004;56:106-110. 3. Bates & Pearse. Use of hydrogen peroxide vapour for environmental control during a Serratia outbreak in a neonatal intensive care unit. J Hosp Infect 2005;61:364-366.