Maria F. Gergen

Bacterial contamination of keyboards: efficacy and functional impact of disinfectants.

BACKGROUND Computers are ubiquitous in the healthcare setting and have been shown to be contaminated with potentially pathogenic microorganisms. This study was performed to determine the degree of microbial contamination, the efficacy of different disinfectants, and the cosmetic and functional effects of the disinfectants on the computer keyboards. METHODS We assessed the effectiveness of 6 different disinfectants (1 each containing chlorine, alcohol, or phenol and 3 containing quaternary ammonium) against 3 test organisms (oxacillin-resistant Staphylococcus aureus [ORSA], Pseudomonas aeruginosa, and vancomycin-resistant Enterococcus species) inoculated onto study computer keyboards. We also assessed the computer keyboards for functional and cosmetic damage after disinfectant use. RESULTS Potential pathogens cultured from more than 50% of the computers included coagulase-negative staphylococci (100% of keyboards), diphtheroids (80%), Micrococcus species (72%), and Bacillus species (64%). Other pathogens cultured included ORSA (4% of keyboards), OSSA (4%), vancomycin-susceptible Enterococcus species (12%), and nonfermentative gram-negative rods (36%). All disinfectants, as well as the sterile water control, were effective at removing or inactivating more than 95% of the test bacteria. No functional or cosmetic damage to the computer keyboards was observed after 300 disinfection cycles. CONCLUSIONS Our data suggest that microbial contamination of keyboards is prevalent and that keyboards may be successfully decontaminated with disinfectants. Keyboards should be disinfected daily or when visibly soiled or if they become contaminated with blood.

Room decontamination with UV radiation.

OBJECTIVE To determine the effectiveness of a UV-C-emitting device to eliminate clinically important nosocomial pathogens in a contaminated hospital room. METHODS This study was carried out in a standard but empty hospital room (phase 1) and in a room previously occupied by a patient with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) infection (phase 2) in an acute care tertiary hospital in North Carolina from January 21 through September 21, 2009. During phase 1, 8 x 8 cm Formica sheets contaminated with approximately 10(4)-10(5) organisms of MRSA, VRE, multidrug-resistant (MDR) Acinetobacter baumannii, or Clostridium difficile spores were placed in a hospital room, both in direct line of sight of the UV-C device and behind objects. After timed exposure, the presence of the microbes was assessed. During phase 2, specific sites in rooms that had housed patients with MRSA or VRE infection were sampled before and after UV-C irradiation. After timed exposure, the presence of MRSA and VRE and total colony counts were assessed. RESULTS In our test room, the effectiveness of UV-C radiation in reducing the counts of vegetative bacteria on surfaces was more than 99.9% within 15 minutes, and the reduction in C. difficile spores was 99.8% within 50 minutes. In rooms occupied by patients with MRSA, UV-C irradiation of approximately 15 minutes duration resulted in a decrease in total CFUs per plate (mean, 384 CFUs vs 19 CFUs; P < .001), in the number of samples positive for MRSA (81 [20.3%] of 400 plates vs 2 [0.5%] of 400 plates; P < .001), and in MRSA counts per MRSA-positive plate (mean, 37 CFUs vs 2 CFUs; P < .001). CONCLUSIONS This UV-C device was effective in eliminating vegetative bacteria on contaminated surfaces both in the line of sight and behind objects within approximately 15 minutes and in eliminating C. difficile spores within 50 minutes.

Comparative evaluation of the sporicidal activity of new low-temperature sterilization technologies: Ethylene oxide, 2 plasma sterilization systems, and liquid peracetic acid☆☆☆★

OBJECTIVE This study was undertaken to evaluate the efficacy of 4 new low-temperature sterilization technologies: ethylene oxide with hydrochlorofluorocarbons, a liquid peracetic acid immersion system (Steris System 1 Processor), and 2 plasma sterilization processes that use vaporized hydrogen peroxide (Sterrad 100 and the Sterrad 100S). The Sterrad 100S system potentially improves sterilizer efficacy by using 2 cycles of a diffusion stage and a plasma stage per sterilization cycle. METHODS Flat stainless steel carriers were inoculated with approximately 10(6) Bacillus stearothermophilus spores. These carriers were aseptically placed in the middle of 40 cm long stainless steel lumens (hollow tubes). Two types of lumen were used:(1) a lumen test unit with a removable 5 cm center piece (1.2 cm diameter) of stainless steel sealed to the narrower steel tubing by hard rubber septums and (2) a straight lumen. Three different diameters of the lumen test unit (1, 2, and 3 mm) and a single diameter of the straight lumen (3 mm) were studied. At least 40 replicates were performed for each type of lumen and sterilization method. After inoculation, the test unit was evaluated in 1 of the low-temperature sterilization technologies. After sterilization, the carriers were cultured in trypticase soy broth for 14 days at 55 degrees C and assessed for growth of B stearothermophilus spores. RESULTS Our results demonstrated that ethylene oxide with hydrochlorofluorocarbons, the Sterrad 100s, and the Sterrad 100S half cycle were highly effective in killing approximately 10(6) B stearothermophilus spores present in the center of narrow-lumen stainless steel tubes. As the lumen diameter decreased with the lumen test unit, the Sterrad 100 demonstrated reduced ability to kill B stearothermophilus spores present on the carrier. At the smallest diameter tested (1 mm), the Sterrad 100 system failed 74% of the time. The Steris System 1 was not effective in completely eliminating the 10(6) inoculum under test conditions. CONCLUSION The Sterrad 100S was significantly superior to the Sterrad 100 system and equivalent to ethylene oxide with hydrochlorofluorocarbons. Introduction of this new Sterrad 100S system should improve the margin of safety and reduce processing costs by its use of a shorter cycle time. The Steris System 1 is limited by diffusion of the chemical sterilant into the interior of the lumen test unit.

Efficacy of Hospital Germicides against Adenovirus 8, a Common Cause of Epidemic Keratoconjunctivitis in Health Care Facilities

ABSTRACT The inactivation of virus-contaminated nonporous inanimate surfaces was investigated using adenovirus type 8, a common cause of epidemic keratoconjunctivitis. A 10-μl inoculum of adenovirus was placed onto each stainless steel disk (1-cm diameter), and the inoculum was allowed to air dry for 40 min. Twenty-one different germicides (including disinfectants and antiseptics) were selected for this study based on their current uses in health care. After a 1- or 5-minute exposure to 50 μl of the germicide, the virus-germicide test mixture was neutralized and assayed for infectivity. Using an efficacy criterion of a 3-log10 reduction in the titer of virus infectivity and regardless of the virus suspending medium (i.e., hard water, sterile water, and hard water with 5% fetal calf serum), only five disinfectants proved to be effective against the test virus at 1 min: 0.55% ortho-phthalaldehyde, 2.4% glutaraldehyde, 2.65% glutaraldehyde, ∼6,000 ppm chlorine, and ∼1,900 ppm chlorine. Four other disinfectants showed effectiveness under four of the five testing conditions: 70% ethanol, 65% ethanol with 0.63% quaternary ammonium compound, 79.6% ethanol with 0.1% quaternary ammonium compound, and 0.2% peracetic acid. Of the germicides suitable for use as an antiseptic, 70% ethanol achieved a 3-log10 reduction under four of the five test conditions. These results emphasize the need for proper selection of germicides for use in disinfecting noncritical surfaces and semicritical medical devices, such as applanation tonometers, in order to prevent outbreaks of epidemic keratoconjunctivitis.

Enhanced terminal room disinfection and acquisition and infection caused by multidrug-resistant organisms and Clostridium difficile (the Benefits of Enhanced Terminal Room Disinfection study): a cluster-randomised, multicentre, crossover study

BACKGROUND Patients admitted to hospital can acquire multidrug-resistant organisms and Clostridium difficile from inadequately disinfected environmental surfaces. We determined the effect of three enhanced strategies for terminal room disinfection (disinfection of a room between occupying patients) on acquisition and infection due to meticillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, C difficile, and multidrug-resistant Acinetobacter. METHODS We did a pragmatic, cluster-randomised, crossover trial at nine hospitals in the southeastern USA. Rooms from which a patient with infection or colonisation with a target organism was discharged were terminally disinfected with one of four strategies: reference (quaternary ammonium disinfectant except for C difficile, for which bleach was used); UV (quaternary ammonium disinfectant and disinfecting ultraviolet [UV-C] light except for C difficile, for which bleach and UV-C were used); bleach; and bleach and UV-C. The next patient admitted to the targeted room was considered exposed. Every strategy was used at each hospital in four consecutive 7-month periods. We randomly assigned the sequence of strategies for each hospital (1:1:1:1). The primary outcomes were the incidence of infection or colonisation with all target organisms among exposed patients and the incidence of C difficile infection among exposed patients in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT01579370. FINDINGS 31 226 patients were exposed; 21 395 (69%) met all inclusion criteria, including 4916 in the reference group, 5178 in the UV group, 5438 in the bleach group, and 5863 in the bleach and UV group. 115 patients had the primary outcome during 22 426 exposure days in the reference group (51·3 per 10 000 exposure days). The incidence of target organisms among exposed patients was significantly lower after adding UV to standard cleaning strategies (n=76; 33·9 cases per 10 000 exposure days; relative risk [RR] 0·70, 95% CI 0·50-0·98; p=0·036). The primary outcome was not statistically lower with bleach (n=101; 41·6 cases per 10 000 exposure days; RR 0·85, 95% CI 0·69-1·04; p=0·116), or bleach and UV (n=131; 45·6 cases per 10 000 exposure days; RR 0·91, 95% CI 0·76-1·09; p=0·303) among exposed patients. Similarly, the incidence of C difficile infection among exposed patients was not changed after adding UV to cleaning with bleach (n=38 vs 36; 30·4 cases vs 31·6 cases per 10 000 exposure days; RR 1·0, 95% CI 0·57-1·75; p=0·997). INTERPRETATION A contaminated health-care environment is an important source for acquisition of pathogens; enhanced terminal room disinfection decreases this risk. FUNDING US Centers for Disease Control and Prevention.

Decontamination of Targeted Pathogens from Patient Rooms Using an Automated Ultraviolet-C-Emitting Device

OBJECTIVE. To determine the effectiveness of an automated ultraviolet-C (UV-C) emitter against vancomycin-resistant enterococci (VRE), Clostridium difficile, and Acinetobacter spp. in patient rooms. DESIGN. Prospective cohort study. SETTING. Two tertiary care hospitals. PARTICIPANTS. Convenience sample of 39 patient rooms from which a patient infected or colonized with 1 of the 3 targeted pathogens had been discharged. INTERVENTION. Environmental sites were cultured before and after use of an automated UV-C-emitting device in targeted rooms but before standard terminal room disinfection by environmental services. RESULTS. In total, 142 samples were obtained from 27 rooms of patients who were colonized or infected with VRE, 77 samples were obtained from 10 rooms of patients with C. difficile infection, and 10 samples were obtained from 2 rooms of patients with infections due to Acinetobacter. Use of an automated UV-C-emitting device led to a significant decrease in the total number of colony-forming units (CFUs) of any type of organism (1.07 log10 reduction; P < .0001), CFUs of target pathogens (1.35 log10 reduction; P < .0001), VRE CFUs (1.68 log10 reduction; P < .0001), and C. difficile CFUs (1.16 log10 reduction; P < .0001). CFUs of Acinetobacter also decreased (1.71 log10 reduction), but the trend was not statistically significant (P = .25). CFUs were reduced at all 9 of the environmental sites tested. Reductions similarly occurred in direct and indirect line of sight. CONCLUSIONS. Our data confirm that automated UV-C-emitting devices can decrease the bioburden of important pathogens in real-world settings such as hospital rooms.

Efficacy of Different Cleaning and Disinfection Methods against Clostridium difficile Spores: Importance of Physical Removal versus Sporicidal Inactivation

We tested the effectiveness of disinfectants and wipe methods against Clostridium difficile spores. Wiping with nonsporicidal agents (physical removal) was effective in removing more than 2.9 log(10) C. difficile spores. Wiping with sporicidal agents eliminated more than 3.90 log(10) C. difficile spores (physical removal and/or inactivation). Spraying with a sporicide eliminated more than 3.44 log(10) C. difficile spores but would not remove debris.

Sporicidal activity of a new low-temperature sterilization technology: the Sterrad 50 sterilizer.

This study was undertaken to evaluate the efficacy of a new low-temperature sterilization system that recently has been cleared by the Food and Drug Administration, the Sterrad 50. Flat stainless steel carriers were inoculated with approximately 10(6) Bacillus stearothermophilus spores. These carriers were placed aseptically in the middle of 40-cm-long stainless steel-lumened test units of varying diameters (1 mm, 2 mm, and 3 mm). After inoculation, the test units were processed in the Sterrad 50. After sterilization, the carriers were assayed for growth of the B. stearothermophilus spores. Our data demonstrated that the Sterrad 50 was highly effective in killing the B. stearothermophilus spores (no positive carriers with 30 tests of each lumen-diameter test unit). The Sterrad 50 is likely to be clinically useful for the sterilization of heat-sensitive medical equipment.

Rapid Hospital Room Decontamination Using Ultraviolet (UV) Light with a Nanostructured UV-Reflective Wall Coating

We tested the ability of an ultraviolet C (UV-C)-reflective wall coating to reduce the time necessary to decontaminate a room using a UV-C-emitting device (Tru-D SmartUVC). The reflective wall coating provided the following time reductions for decontamination: for methicillin-resistant Staphylococcus aureus, from 25 minutes 13 seconds to 5 minutes 3 seconds ([Formula: see text]), and for Clostridium difficile spores, from 43 minutes 42 seconds to 9 minutes 24 seconds ([Formula: see text]).

Room Decontamination Using an Ultraviolet-C Device with Short Ultraviolet Exposure Time

Results:  UV-C Technology effectively reduces environmental contamination and should be considered when environmental transmission is significant.  The Optimum UV TM device achieved an overall 3.56-log10 reduction for MRSA in 5 minutes and an overall 2.78-log10 reduction for C. difficile spores in 10 minutes in typical patient rooms (not treated with UV reflective wall coating).  When the patient room walls were treated with Lumacept UV reflective wall coating, the Optimum UV achieved an overall 4.5-log10 reduction for MRSA in 5 minutes and an overall 3.05-log10 reduction for C. difficile spores in 10 minutes.  The use of UV reflective wall coating (Lumacept) significantly increased the overall Log reduction obtained, primarily by increasing the UV-C irradiation and Log reduction for indirect surfaces.