Table 17.2.
Studies evaluating the in vitro efficacy of ‘no-touch’ automated room disinfection systems
| Author | Year | Setting | Design | Results |
|---|---|---|---|---|
| H2O2 vapour | ||||
| Barbut et al. (2012) | 2012 | Plastic or laminate carriers with 5–6 log of C. difficile spores exposed to HPV in unfurnished, unoccupied 33–45 m3 rooms. | C. difficile was completely eradicated from the exposed carriers regardless of the C. difficile strain or surface used. | |
| Otter et al. (2012) | 2012 | A 100 m3 test room | MRSA carriers containing 6.1–7.3 log of MRSA suspended in distilled water, 0.3%, 3% or 10% BSA, TSB or 0.9% saline and dried on stainless steel discs were exposed to HPV. | The effectiveness of HPV was reduced in a step-wise manner as type and concentration of simulated soiling increased. No MRSA was recovered from any of the carriers after 60 min exposure to HPV. |
| Havill et al. (2012) | 2012 | 15 patient rooms with bathrooms (46–86 m3) | Carrier disks with ∼ 106C. difficile spores and BIs with 104 and 106 G. stearothermophilus spores were placed in 5 sites (3 sites were not in direct line of sight from the HPV generator). | HPV achieved > 6-log reduction on C. difficile in all 5 sites. HPV inactivated 99% (74/75) of 6-log BIs and 100% (75/75) of 4-log BIs. |
| Fu et al. (2012) | 2012 | Two rooms to simulate a patient room (50.1 m3) and an en-suite bathroom (13.2 m3) | Pouched and unpouched 4- and 6-log G. stearothermophilus BIs and in-house prepared test discs containing ∼ 106 MRSA, C. difficile spores and A. baumannii were placed at 11 locations in the test area. | HPV inactivated 91% (40/44) of the pouched 6-log BIs and 95% (42/44) of the pouched 4-log BIs. The HPV system completely inactivated (> 6-log reduction) MRSA dried in water from all replicates in 9/11 locations, A. baumannii dried in water from all replicates in 6/11 locations, and C. difficile from all replicates in all locations. |
| Bentley et al. (2012) | 2012 | A class II safety cabinet | FCV virus was dried on 1 cm2 carriers of stainless steel, glass, vinyl flooring, ceramic tile or PVC. | > 4-log reduction was achieved on all surfaces after HPV. |
| Holmdahl et al. (2011) | 2011 | A purpose-built 136 m3 test room | 6-log Tyvek-pouched G. stearothermophilus BIs were placed at 20 locations in the first test and 14 locations in another 2 tests. | HPV inactivated 100% (48/48) of 6-log BIs. |
| Berrie et al. (2011) | 2011 | A microbiology safety cabinet | Recombinant adenovirus (Ad5GFP) was dried on 10 mm diameter stainless steel discs at concentrations of 7.6–9.4 log TCID50/disc. | HPV achieved a > 8-log TCID50 reduction in virus titre. |
| Pottage et al. (2012) | 2011 | A test chamber (20.7 m3) | Stainless steel indicators of ∼ 106 MRSA or ∼ 106 commercially available G. stearothermophilus BIs were exposed to Steris VHP in a test chamber. BIs were removed and enumerated at timed intervals. | After 30 min exposure to VHP there was ∼ 3-log reduction in MRSA and ∼ 5-log reduction G. stearothermophilus spores, indicating that the catalase-positive MRSA are less susceptible to VHP than the metabolically inert spores |
| Pottage et al. (2010) | 2010 | A class III safety cabinet | MS2 bacteriophage was dried on 10 mm diameter stainless steel discs at concentrations of 7–9-log pfu/carrier. MS2 phage was also dried in 10% or 50% horse blood. Inoculated carriers were exposed to either VHP (Steris) or HPV (Bioquell). | HPV caused > 6-log reduction on the phage; VHP caused a 5–6 log reduction on the phage. Reductions for HPV were 5.8 and 2.7 when the virus was dried in 10% and 50% horse blood, respectively. Reductions for VHP were > 9 and 3.5 when the virus was dried in 10% and 50% horse blood, respectively. |
| Otter and French (2009) | 2009 | A 100 m3 test room | Five strains of MRSA and three stains of VRE, Acinetobacter spp., K. pneumoniae and C. difficile spores were dried on stainless steel discs at concentrations of 5–7-log cfu/carrier either in water or BSA to simulate soiling. | All carriers were inactivated after exposure to HPV when dried from water or 0.3% BSA. |
| Hall et al. (2007) | 2007 | A biological safety cabinet and a BSL III laboratory room (37 m3) | ∼ 3-log M. tuberculosis dried on stainless steel carriers were exposed to HPV in a biological safety cabinet and at 10 locations in a BSL III laboratory room. 6-log G. stearothermophilus BIs were also exposed to HPV in the room experiment. | No M. tuberculosis BIs grew after 30 min exposure to HPV in the safety cabinet. In the room experiment, all M. tuberculosis and G. stearothermophilus BIs were inactivated at all 10 locations following exposure to HPV for 90 min. |
| Johnston et al. (2005) | 2005 | A 0.4 m3 glovebox enclosure | > 6-log of two strains of C. botulinum spores dried on stainless steel discs and 6-log G. stearothermophilus BIs were exposed to HPV. | After 7 min exposure to HPV, all C. botulinum spores were inactivated. No viable G. stearothermophilus spores were recovered after 6 min exposure to HPV. |
| Kahnert et al. (2005) | 2005 | A 64.5 m3 laboratory room | 8 × 104 – 2.3 × 106 of two strains of M. tuberculosis were dried on tissue culture plates, placed in steam-permeable Tyvek pouches, distributed at 4 locations in the test room and exposed to Steris VHP. | No viable M. tuberculosis was recovered at any of the locations after exposure to VHP. |
| Aerosolised hydrogen peroxide (aHP) | ||||
| Fu et al. (2012) | 2012 | Two rooms to simulate a patient room (50.1 m3) and an en-suite bathroom (13.2 m3) | Tyvek-pouched and unpouched 4- and 6-log G. stearothermophilus BIs and in-house prepared test discs containing ∼ 106 MRSA, C. difficile spores and A. baumannii were placed at 11 locations in the test area. | aHP inactivated 13.6% (6/44) of the unpouched 6-log BIs, and 36.4% of the unpouched 4-log BIs. aHP generally achieved a < 4-log reduction on MRSA, A. baumannii and C. difficile spores. The level of inactivation varied considerably by room location. |
| Holmdahl et al. (2011) | 2011 | A purpose-built 136 m3 test room | 6-log Tyvek-pouched G. stearothermophilus BIs were placed at 20 locations in the first test and 14 locations in another two tests. Three back-to-back aHP cycles using 2 aHP machines was run. | aHP inactivated 50% (24/48) of BIs; 10% (2/20) of BIs in the first test and 79% (22/28) of BIs in the other two tests were inactivted. |
| Piskin et al. (2011) | 2011 | A single hospital isolation room (53 m3) | Stainless steel discs carriers inoculated with ∼ 4.5-log MRSA or A. baumannii dried from water or 5% sterile serum were placed at various locations in the test room. | ∼ 4 log reduction achieved for MRSA and A. baumannii. aHP was less effective for the bacteria dried in serum and in closed or semi-closed locations (e.g. inside a drawer). |
| Koburger et al. (2011) | 2011 | 37 m3 test room | Carriers inoculated with 4.3, 5.5, and 6.5-log of Aspergillus brasiliensis. | aHP achieved 0.4, 1.3 and 4.3-log reductions respectively at the initial fungal loads of 6.5, 5.5, and 4.3-log. |
| Andersen et al. (2010) | 2010 | TB laboratory (BSL3) | Plastic plates inoculated with ∼ 3 × 104 M. tuberculosis and placed in an open box (lid off) on an open bench. This room was treated with 3 or 6 aHP cycles. | M. tuberculosis growth was observed in all TB broth media (20/20) after 10–21 days’ incubation. |
| Grare et al. (2008) | 2008 | 80 m3 BSL3 laboratory | Cotton tissues inoculated with 105−106 dried M. tuberculosis were placed in various room locations. | aHP achieved > 5-log reduction on M. tuberculosis in all room locations. |
| Bartels et al. (2008) | 2008 | Hospital room | 5 different locations (20–100 cm2) in the room were inoculated with 100 cfu/cm2 (3–4-log) of MRSA cultures diluted in urine. One or three aHP decontamination cycles were run. | All samples were negative after one or three aHP cycles. |
| Andersen et al. (2006) | 2006 | Hospital rooms (4–58 m3) and garages (120–200 m3) | 6-log B. atrophaeus spore BIs were used. BIs were placed at various locations in rooms, ambulances parked in garages, and on the outside and inside of medical equipment. | One or two aHP cycles had no effect on BIs. Three aHP cycles inactivated 87% (127/146) of BIs in two test rooms, 62% (137/220) of BIs on or in medical equipment and all BIs (60/60) in the ambulances. |
| Ultraviolet-C radiation (UVC) | ||||
| Havill et al. (2012) | 2012 | 15 patients rooms (with bathrooms) (46–86 m3) | Carrier disks with ∼ 106C. difficile spores and BIs with 104 and 106 G. stearothermophilus spores were placed in 5 sites (3 sites were not in direct line of sight from the UVC unit) and exposed to 22 000 μWs/cm2. | UVC achieved a mean of 2.2 log reduction on C. difficile (range 1.7–3 log reduction). UVC inactivated 29% (22/75) of 4-log BIs (range 7–53%) and 0% (0/75) of 6-log BIs. UVC was significantly less effective out of direct line of sight. |
| Boyce et al. (2011) | 2011 | 25 patients rooms (with bathrooms) (46–86 m3) | Carrier disks with ∼ 105C. difficile spores were placed in 5 sites (3 sites were not in direct line of sight from the devices) using a 1-(22 000 μ Ws/cm2) or 2-stage procedure. | 1-stage procedure: 68 min median cycle time and mean of 2.2 log reduction (range 1.7–2.9 log reduction). 2-stage procedure: 84 min median cycle time and mean of 2.3 log reduction (range 1.4–3.2 log reduction). UVC was significantly less effective out of direct line of sight. |
| (Nerandzic et al., 2010) | 2010 | Laboratory bench top | C. difficile spores, MRSA and VRE suspended in PBS or 10 mg/ml BSA were dried on bench tops (1 cm2) at 3–5 log. Inactivation of pathogens was assessed at reflected doses ranging from 5 000 to 22 000 μWs/cm2. | Sporicidal cycle (22 000 μWs/cm2) achieved reductions of > 2–4 for MRSA, C. difficile and VRE. Increasing the dose from 5 000 to 20 000 μWs/cm2 increased efficacy for C. difficile spores (from 1.1 to 2.7 log) but not for VRE or MRSA. Suspending medium or room location did not affect log reductions significantly. |
| Hospital rooms | Plastic carriers with ∼ 105C. difficile spores were placed around the room and exposed to 22 000 μWs/cm2 (sporicidal cycle). | UVC achieved a 2.6-log reduction on carriers in direct line of sight and 1-log reduction on carriers out of direct line of site. | ||
| Staphylococcus warneri was dried on 1 cm2 areas on 26 frequently touched sites and on 20 portable equipment sites at 4–5 log and exposed to 12 000 μW/cm2 (vegetative cycle). | UVC achieved a ∼ 3.5-log reduction on the 26 environmental sites and a 2-log reduction on equipment. | |||
| Rutala et al. (2010) | 2010 | Patient rooms with bathroom | MRSA, VRE, A. baumannii or C. difficile spores were dried on Formica sheets (64 cm2) at ∼ 104–105 cfu, placedat various room locations and exposed to 36 000 μWs/cm2 for C. difficile (sporicidal cycle) or 12 000 μWs/cm2 (vegetative cycle) for the other organisms. | UVC achieved mean log reduction of 2.79 for C. difficile, 3.88 for A. baumannii, 3.46 for VRE and 3.94 for MRSA. UVC was less effective for sites that are out of line of sight. |