Influence of a visible-light continuous environmental disinfection system on microbial contamination and surgical site infections in an orthopedic operating room

Enhanced antimicrobial efficacy and energy efficiency of low irradiance 405-nm light for bacterial decontamination

Due to its increased safety over ultraviolet light, there is interest in the development of antimicrobial violet-blue light technologies for infection control applications. To ensure compatibility with exposed materials and tissue, the light irradiances and dose regimes used must be suitable for the target application. This study investigates the antimicrobial dose responses and germicidal efficiency of 405 nm violet-blue light when applied at a range of irradiance levels, for inactivation of surface-seeded and suspended bacteria. Bacteria were seeded onto agar surfaces (101-108 CFUplate-1) or suspended in PBS (103-109 CFUmL-1) and exposed to increasing doses of 405-nm light (≤ 288 Jcm-2) using various irradiances (0.5-150 mWcm-2), with susceptibility at equivalent light doses compared. Bacterial reductions ≥ 96% were demonstrated in all cases for lower irradiance (≤ 5 mWcm-2) exposures. Comparisons indicated, on a per unit dose basis, that significantly lower doses were required for significant reductions of all species when exposed at lower irradiances: 3-30 Jcm-2/0.5 mWcm-2 compared to 9-75 Jcm-2/50 mWcm-2 for low cell density (102 CFUplate-1) surface exposures and 22.5 Jcm-2/5 mWcm-2 compared to 67.5 Jcm-2/150 mWcm-2 for low density (103 CFUmL-1) liquid exposures (P ≤ 0.05). Similar patterns were observed at higher densities, excluding S. aureus exposed at 109 CFUmL-1, suggesting bacterial density at predictable levels has minimal influence on decontamination efficacy. This study provides fundamental evidence of the greater energy efficacy of 405-nm light for inactivation of clinically-significant pathogens when lower irradiances are employed, further supporting its relevance for practical decontamination applications.

Effectiveness of dry hydrogen peroxide in reducing air and surface bioburden in a multicenter clinical setting

OBJECTIVE

To determine the effectiveness of dry hydrogen peroxide (DHP) in reducing environmental bioburden in occupied areas.

DESIGN

Prospective environmental cohort study.

SETTING

The study was conducted in 2 tertiary-care hospitals and 1 free-standing emergency department.

INTERVENTION

Environmental air and surface sites were cultured before and after continuous deployment of DHP systems in targeted hospital areas.

METHODS

In total, 1,554 surface and 1,036 air samples were collected from 74 patient areas among the 3 facilities on 3 consecutive days before DHP deployment and on days 14, 30, 60, and 90 after deployment. At each sampling time, 2 air samples were collected at each facility from 1 room without DHP, along with 2 outdoor samples from each facility. The impact of negative-pressure usage on the efficacy of DHP was also evaluated, with 1 hospital continuously using negative pressure, another utilizing it only in patient isolation scenarios, and another without negative pressure.

RESULTS

In the 2 facilities without continuous negative pressure, exposure to DHP was associated with a significant reduction in surface bioburden, characterized as total colony-forming units (P = .019; P = .002). Significant associations between DHP exposure and reductions in airborne bacterial load at the 2 hospitals were observed (P ≤ .001; P = .041), and the free-standing emergency department experienced a reduction that did not achieve statistical significance (P = .073).

CONCLUSIONS

Our findings confirm that DHP has the potential to reduce microbial air and surface bioburden in occupied patient rooms with standard ventilation parameters.

Environmental cleaning and disinfection in the operating room: a systematic scoping review through a human factors and systems engineering lens

OBJECTIVE

To synthesize evidence and identify gaps in the literature on environmental cleaning and disinfection in the operating room based on a human factors and systems engineering approach guided by the Systems Engineering Initiative for Patient Safety (SEIPS) model.

DESIGN

A systematic scoping review.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched 4 databases (ie, PubMed, EMBASE, OVID, CINAHL) for empirical studies on operating-room cleaning and disinfection. Studies were categorized based on their objectives and designs and were coded using the SEIPS model. The quality of randomized controlled trials and quasi-experimental studies with a nonequivalent groups design was assessed using version 2 of the Cochrane risk-of-bias tool for randomized trials.

RESULTS

In total, 40 studies were reviewed and categorized into 3 groups: observational studies examining the effectiveness of operating-room cleaning and disinfections (11 studies), observational study assessing compliance with operating-room cleaning and disinfection (1 study), and interventional studies to improve operating-room cleaning and disinfection (28 studies). The SEIPS-based analysis only identified 3 observational studies examining individual work-system components influencing the effectiveness of operating-room cleaning and disinfection. Furthermore, most interventional studies addressed single work-system components, including tools and technologies (20 studies), tasks (3 studies), and organization (3 studies). Only 2 studies implemented interventions targeting multiple work-system components.

CONCLUSIONS

The existing literature shows suboptimal compliance and inconsistent effectiveness of operating-room cleaning and disinfection. Improvement efforts have been largely focused on cleaning and disinfection tools and technologies and staff monitoring and training. Future research is needed (1) to systematically examine work-system factors influencing operating-room cleaning and disinfection and (2) to redesign the entire work system to optimize operating-room cleaning and disinfection.

The influence of physical environment on health care-associated infections: A literature review

BACKGROUND

Health care-associated infections (HAIs) are a common issue in health care settings, caused by environmental microorganisms, leading to health risks and financial strain. Despite efforts to reduce HAIs, the role of the physical environment in reducing HAIs is not fully understood. This literature review aimed to identify physical environment variables contributing to HAIs.

METHODS

A literature search was conducted in scientific databases between 2016 and 2022 using keywords associated with infections and physical environment variables. After screening retrieved articles for eligibility, the articles were analyzed for relevant environmental and infection variables.

RESULTS

Out of 145, 27 articles were identified. The findings were grouped into 8 categories, including layout design, surfaces, behavior, lighting, Internet of Things, materials, airflow, and air quality, with sub-themes in each group.

CONCLUSIONS

The physical environment in health care facilities plays a crucial role in reducing and preventing the spread of HAIs. Proper design and construction of health care buildings, including ventilation and air conditioning systems, help prevent infection spread between functional areas. Antimicrobial materials, cleaning and disinfection protocols, and personal hygiene practices, such as hand hygiene, are key factors in infection control. The positioning of hand hygiene stations is also essential to improve compliance among health care professionals.

Efficacy of Violet-Blue (405 nm) LED Lamps for Disinfection of High-Environmental-Contact Surfaces in Healthcare Facilities: Leading to the Inactivation of Microorganisms and Reduction of MRSA Contamination

Effective disinfection procedures in healthcare facilities are essential to prevent transmission. Chemical disinfectants, hydrogen peroxide vapour (HPV) systems and ultraviolet (UV) light are commonly used methods. An emerging method, violet-blue light at 405 nm, has shown promise for surface disinfection. Its antimicrobial properties are based on producing reactive oxygen species (ROS) that lead to the inactivation of pathogens. Studies have shown significant efficacy in reducing bacterial levels on surfaces and in the air, reducing nosocomial infections. The aim of this study was to evaluate the antimicrobial effectiveness of violet-blue (405 nm) LED lamps on high-contact surfaces in a hospital infection-control laboratory. High-contact surfaces were sampled before and after 7 days of exposure to violet-blue light. In addition, the effect of violet-blue light on MRSA-contaminated surfaces was investigated. Exposure to violet-blue light significantly reduced the number of bacteria, yeasts and moulds on the sampled surfaces. The incubator handle showed a low microbial load and no growth after irradiation. The worktable and sink showed an inconsistent reduction due to shaded areas. In the second experiment, violet-blue light significantly reduced the microbial load of MRSA on surfaces, with a greater reduction on steel surfaces than on plastic surfaces. Violet-blue light at 405 nm has proven to be an effective tool for pathogen inactivation in healthcare settings Violet-blue light shows promise as an additional and integrated tool to reduce microbial contamination in hospital environments but must be used in combination with standard cleaning practices and infection control protocols. Further research is needed to optimise the violet-blue, 405 nm disinfection method.

Viricidal Efficacy of a 405-nm Environmental Decontamination System for Inactivation of Bacteriophage Phi6: Surrogate for SARS-CoV-2

The highly transmittable nature of SARS-CoV-2 has increased the necessity for novel strategies to safely decontaminate public areas. This study investigates the efficacy of a low irradiance 405-nm light environmental decontamination system for the inactivation of bacteriophage phi6 as a surrogate for SARS-CoV-2. Bacteriophage phi6 was exposed to increasing doses of low irradiance (~0.5 mW cm-2 ) 405-nm light while suspended in SM buffer and artificial human saliva at low (~103-4  PFU mL-1 ) and high (~107-8  PFU mL-1 ) seeding densities, to determine system efficacy for SARS-CoV-2 inactivation and establish the influence of biologically relevant suspension media on viral susceptibility. Complete/near-complete (≥99.4%) inactivation was demonstrated in all cases, with significantly enhanced reductions observed in biologically relevant media (P < 0.05). Doses of 43.2 and 172.8 J cm-2 were required to achieve ~3 log10 reductions at low density, and 97.2 and 259.2 J cm-2 achieved ~6 log10 reductions at high density, in saliva and SM buffer, respectively: 2.6-4 times less dose was required when suspended in saliva compared to SM buffer. Comparative exposure to higher irradiance (~50 mW cm-2 ) 405-nm light indicated that, on a per unit dose basis, 0.5 mW cm-2 treatments were capable of achieving up to 5.8 greater log10 reductions with up to 28-fold greater germicidal efficiency than that of 50 mW cm-2 treatments. These findings establish the efficacy of low irradiance 405-nm light systems for inactivation of a SARS-CoV-2 surrogate and demonstrate the significant enhancement in susceptibility when suspended in saliva, which is a major vector in COVID-19 transmission.

Hospital, Catheter, Peritoneal Dialysis Acquired Infections: Visible Light as a New Solution to Reduce Risk and Incidence

Healthcare-associated infections, often identified as hospital-acquired infections (HAIs), are typically not present during patient contact or admission. Healthcare-associated infections cause longer lengths of stay, increasing costs and mortality. HAI occurring in trauma patients increases the risk for length of stay and higher inpatient costs. Many HAIs are preventable. Antibiotic resistance has increased to a high level making proper treatment increasingly difficult due to organisms resistant to common antibiotics. Therefore, there is a need for alternate forms of attack against these pathogens. Currently, the application of light for the treatment of topical infections has been used. Ultraviolet (UV) light has well-documented antimicrobial properties. UV is damaging to DNA and causes the degradation of plastics, etc., so its use for medical purposes is limited. Using visible light may be more promising. 405-nm light sterilization has been shown to be highly efficacious in reducing bacteria. Light Line Medical, Inc.'s (LLM) patented visible-light platform technology for infection prevention may create a global shift in the prevention of healthcare-associated infections. LLM has developed a proprietary method of delivering light to prevent catheter-associated infections. This technology uses non-UV visible light and can kill both bacteria and prevent biofilm inside and outside a luminal catheter. This is significant as prevention is key. Independent analysis of the prototype system showed the application of the device met the acceptance criterion of 4 x 109-10 reduction in Candida albicans, Staphylococcus aureus, Pseudomonas aeruginosa, and other bacteria and fungal species. Further design evolution for this technology continues, and the FDA submission process is underway.

Laboratory evaluation of the broad-spectrum antibacterial efficacy of a low-irradiance visible 405-nm light system for surface-simulated decontamination

Purpose

Lighting systems which use visible light blended with antimicrobial 405-nm violet-blue light have recently been developed for safe continuous decontamination of occupied healthcare environments. This paper characterises the optical output and antibacterial efficacy of a low irradiance 405-nm light system designed for environmental decontamination applications, under controlled laboratory conditions.

Methods

In the current study, the irradiance output of a ceiling-mounted 405-nm light source was profiled within a 3×3×2 m (18 m3) test area; with values ranging from 0.001-2.016 mWcm-2. To evaluate antibacterial efficacy of the light source for environmental surface decontamination, irradiance levels within this range (0.021-1 mWcm-2) at various angular (Δ ϴ=0-51.3) and linear (∆s=1.6-2.56 m) displacements from the source were used to generate inactivation kinetics, using the model organism, Staphylococcus aureus. Additionally, twelve bacterial species were surface-seeded and light-exposed at a fixed displacement below the source (1.5 m; 0.5 mWcm-2) to demonstrate broad-spectrum efficacy at heights typical of high touch surfaces within occupied settings.

Results

Results demonstrate that significant (P≤0.05) inactivation was successfully achieved at all irradiance values investigated, with spatial positioning from the source affecting inactivation, with greater times required for inactivation as irradiance decreased. Complete/near-complete (≥93.28%) inactivation of all bacteria was achieved following exposure to 0.5 mWcm-2 within exposure times realistic of those utilised practically for whole-room decontamination (2-16 h).

Conclusion

This study provides fundamental evidence of the efficacy, and energy efficiency, of low irradiance 405-nm light for bacterial inactivation within a controlled laboratory setting, further justifying its benefits for practical infection control applications.

Recommendations for change in infection prevention programs and practice

Fifty years of evolution in infection prevention and control programs have involved significant accomplishments related to clinical practices, methodologies, and technology. However, regulatory mandates, and resource and research limitations, coupled with emerging infection threats such as the COVID-19 pandemic, present considerable challenges for infection preventionists. This article provides guidance and recommendations in 14 key areas. These interventions should be considered for implementation by United States health care facilities in the near future.

Novel chlorine-extending polymer coating with prolonged antiviral activity against SARS-CoV-2

We previously reported a novel polymeric surface coating, namely HaloFilm^TM , that can immobilize and extend the antimicrobial activity of chlorine on surfaces. In this study, we demonstrated the continuous antiviral efficacy of HaloFilm^TM when applied on stainless steel and cotton gauze as two representative models for non-porous and porous surfaces against SARS-CoV-2. Forty-eight hours post HaloFilm application and chlorination, and 2 hours post the viral challenge, the inoculum titer was reduced by 2.25±0.33 and ≥4.36±0.23 log₁₀ TCIDA₅₀ on non-porous and porous surfaces, respectively. The half-life of the virus was shorter (13.86 min) on a HaloFilm^TM -coated surface compared to what has been reported on copper (46.44 min).

Microbial Air Monitoring in Turbulent Airflow Operating Theatres: Is It Possible to Calculate and Hypothesize New Benchmarks for Microbial Air Load?

Multiple studies have demonstrated the presence of microorganisms commonly associated with surgical site infections (SSIs), in the air within the operating theatre (OT). In some countries such Italy, the limit of microbial concentration in the air for OT with turbulent airflows is 35 CFU/m³ for an empty OT and 180 CFU/m³ during activity. This study aims to hypothesize new benchmarks for the airborne microbial load in turbulent airflow operating theatres in operational and at rest conditions using the percentile distribution of data through a 17-year environmental monitoring campaign in various Italian hospitals that implemented a continuous quality improvement policy. The quartile distribution analysis has shown how in operational and at rest conditions, 75% of the values were below 110 CFU/m³ and 18 CFU/m³, respectively, which can be considered a new benchmark for the monitored OTs. During the initial stages of the monitoring campaign, 28.14% of the concentration values in operational conditions and 29.29% of the values in at rest conditions did not conform to the Italian guidelines’ reference values. In contrast, during the last 5 years, all values in both conditions conformed to the reference values and 98.94% of these values were below the new benchmarks. Continuous improvement has allowed contamination to be reduced to levels well below the current reference values.

The virucidal effects of 405 nm visible light on SARS-CoV-2 and influenza A virus

The germicidal potential of specific wavelengths within the electromagnetic spectrum is an area of growing interest. While ultra-violet (UV) based technologies have shown satisfactory virucidal potential, the photo-toxicity in humans coupled with UV associated polymer degradation limit their use in occupied spaces. Alternatively, longer wavelengths with less irradiation energy such as visible light (405 nm) have largely been explored in the context of bactericidal and fungicidal applications. Such studies indicated that 405 nm mediated inactivation is caused by the absorbance of porphyrins within the organism creating reactive oxygen species which result in free radical damage to its DNA and disruption of cellular functions. The virucidal potential of visible-light based technologies has been largely unexplored and speculated to be ineffective given the lack of porphyrins in viruses. The current study demonstrated increased susceptibility of lipid-enveloped respiratory pathogens of importance such as SARS-CoV-2 (causative agent of COVID-19) and influenza A virus to 405 nm, visible light in the absence of exogenous photosensitizers thereby indicating a potential alternative porphyrin-independent mechanism of visible light mediated viral inactivation. These results were obtained using less than expected irradiance levels which are considered safe for humans and commercially achievable. Our results support further exploration of the use of visible light technology for the application of continuous decontamination in occupied areas within hospitals and/or infectious disease laboratories, specifically for the inactivation of respiratory pathogens such as SARS-CoV-2 and Influenza A.

Effect of ultraviolet-C light on the environmental bacterial bioburden in various veterinary facilities

OBJECTIVE

To determine the effect of a mobile UV-C disinfection device on the environmental bacterial bioburden in veterinary facilities.

SAMPLES

40 swab samples of surfaces from the operating theaters of 3 veterinary hospitals and 1 necropsy laboratory.

PROCEDURES

Various surfaces were swabbed, and collected material was eluted from the swabs in PBSS. Then, an aliquot of the sample fluid was processed with a bacteria-specific rapid metabolic assay to quantify bacterial bioburden. Each site was then treated with UV-C light with an automated disinfection device for approximately 45 minutes. The same surfaces were swabbed following UV-C treatment, and bioburden was quantified. The bioburden at additional time points, including after a second UV-C treatment, was determined for the small animal operating theater.

RESULTS

All surfaces at all sites had a persistent viable bacterial population following manual cleaning. Disinfection with UV-C achieved a mean bioburden reduction of 94% (SD, 5.2%; range, 91% to 95%) for all surfaces, compared with manual disinfection alone. Repeated UV-C treatment of the small animal operating theater reduced mean bioburden by 99% (SD, 0.8%), including no detectable bacteria on 4 of 10 surfaces.

CONCLUSIONS AND CLINICAL RELEVANCE

Disinfection with UV-C light may be a beneficial adjunct method for terminal disinfection of veterinary operating theaters to reduce environmental bioburden. (Am J Vet Res 2021;82:582-588).

Quantifying and interpreting inequality of surgical site infections among operating rooms

PURPOSE

The incidence of surgical site infection differs among operating rooms (ORs). However, cost effectiveness of interventions targeting ORs depends on infection counts. The purpose of this study was to quantify the inequality of infection counts among ORs.

METHODS

We performed a single-centre historical cohort study of elective surgical cases spanning a 160-week period from May 2017 to May 2020, identifying cases of infection within 90 days using International Classification of Diseases, Tenth Revision, Clinical Modification diagnosis codes. We used the Gini index to measure inequality of infections among ORs. As a reference, the Gini index for inequality of household disposable income in the US in 2017 was 0.39, and 0.31 for Canada.

RESULTS

There were 3,148 (3.67%) infections among the 85,744 cases studied. The 20% of 57 ORs with the most and least infections accounted for 44% (99% confidence interval [CI], 36 to 52) and 5% (99% CI, 2 to 8), respectively. The Gini index was 0.40 (99% CI, 0.31 to 0.50), which is comparable to income inequality in the US. There were more infections in ORs with more minutes of cases (Spearman correlation ρ = 0.68; P < 0.001), but generally not in ORs with more total cases (ρ = 0.11; P = 0.43). Moderately long (3.3 to 4.8 hr) cases had a large effect, having greater incidences of infection, while not being so long as to have just one case per day per OR. There was substantially greater inequality in infection counts among the 557 observed combinations of OR specialty (Gini index 0.85; 99% CI, 0.81 to 0.88).

CONCLUSIONS

Inequality of infections among ORs is substantial and caused by both inequality in the incidence of infections and inequality in the total minutes of cases. Inequality in infections among OR and specialty combinations is due principally to inequality in total minutes of cases.

Effectiveness of dry hydrogen peroxide on reducing environmental microbial bioburden risk in a pediatric oncology intensive care unit

BACKGROUND

Routine manual cleaning and disinfection of the health care environment is often suboptimal. Residual contamination poses an infection risk, particularly for immunocompromised patients. This study evaluates the efficacy of dry hydrogen peroxide (DHP) on microbial surface contamination in a pediatric oncology intensive care unit.

METHODS

Surface samples from 5 high-touch and 2 low-touch surfaces were obtained for culture and adenosine triphosphate readings after manual cleaning on multiple days in 4 intensive care unit rooms, before and after DHP was deployed. Air samples were collected as well at the study site. Data outcomes were measured in terms of total colony-forming units for the cultures and relative light units for adenosine triphosphate.

RESULTS

The overall mean surface microbial burden was significantly reduced in the intervention group compared to the control group (mean 5.50 vs 11.77, P<.001). These reductions in colony-forming units were seen across all sampling sites in the intervention group. A reduction in the mean relative light units levels was also noted in the intervention group when compared to the control group (172.08 vs 225.83, P <.006). Reductions with the air samples were also noted (P = .139).

CONCLUSIONS

Study demonstrates that DHP was effective in reducing microbial surface contamination and improves quality of environmental cleaning.

Light-based technologies for management of COVID-19 pandemic crisis

The global dissemination of the novel coronavirus disease (COVID-19) has accelerated the need for the implementation of effective antimicrobial strategies to target the causative agent SARS-CoV-2. Light-based technologies have a demonstrable broad range of activity over standard chemotherapeutic antimicrobials and conventional disinfectants, negligible emergence of resistance, and the capability to modulate the host immune response. This perspective article identifies the benefits, challenges, and pitfalls of repurposing light-based strategies to combat the emergence of COVID-19 pandemic.

Perioperative Infection Transmission: the Role of the Anesthesia Provider in Infection Control and Healthcare-Associated Infections

PURPOSE OF REVIEW

This review aims to highlight key factors in the perioperative environment that contribute to transmission of infectious pathogens, leading to healthcare-associated infection. This knowledge will provide anesthesia providers the tools to optimize preventive measures, with the goal of improved patient and provider safety.

RECENT FINDINGS

Over the past decade, much has been learned about the epidemiology of perioperative pathogen transmission. Patients, providers, and the environment serve as reservoirs of origin that contribute to infection development. Ongoing surveillance of pathogen transmission among these reservoirs is essential to ensure effective perioperative infection prevention.

SUMMARY

Recent work has proven the efficacy of a strategic approach for perioperative optimization of hand hygiene, environmental cleaning, patient decolonization, and intravascular catheter design and handling improvement protocols. This work, proven to generate substantial reductions in surgical site infections, can also be applied to aide prevention of SARS-CoV-2 spread in the COVID-19 era.

Benefit of systematic selection of pairs of cases matched by surgical specialty for surveillance of bacterial transmission in operating rooms

BACKGROUND

Bacterial transmission within and between successive surgical cases occurs in operating rooms (ORs), often includes anesthesia equipment as a reservoir, and can be monitored by collecting samples and identifying bacteria by genetic testing. We evaluated how to choose cases for active surveillance to quantify the effectiveness of interventions in 2 groups of ORs (eg, rooms with germicidal lighting vs those without).

METHODS

Data were from a 7 OR single-specialty gastrointestinal endoscopy suite and from a typical 8 OR multispecialty surgical suite.

RESULTS

At the multispecialty hospital, 40.3% (SE 1.2%) of the total number of cases could be used for surveillance (ie, followed by another case of the same specialty and matched with a corresponding pair of cases from the other OR group). Random selection obtained fewer matched pairs than deliberate selection: mean ratio of random/deliberate = 0.64 (0.01) for the single-specialty and 0.51 (0.02) for the multispecialty suite (P <.001).

CONCLUSIONS

The efficiency of sampling to obtain pairs of successive surgical cases of the same specialty is impaired markedly by randomly selecting pairs of cases (or using convenience sampling) as compared to choosing pairs deliberately. This is important because the number of cases that can be suitably used for surveillance of bacterial transmission will typically be less than one-half the total case number.

Sample sizes for surveillance of S. aureus transmission to monitor effectiveness and provide feedback on intraoperative infection control including for COVID-19

Reductions in perioperative surgical site infections are obtained by a multifaceted approach including patient decolonization, hand hygiene, and hub disinfection, and environmental cleaning. Associated surveillance of S. aureus transmission quantifies the effectiveness of the basic measures to prevent the transmission to patients and clinicians of pathogenic bacteria and viruses, including Coronavirus Disease 2019 (COVID-19). To measure transmission, the observational units are pairs of successive surgical cases in the same operating room on the same day. We evaluated appropriate sample sizes and strategies for measuring transmission.

There was absence of serial correlation among observed counts of transmitted isolates within each of several periods (all P ≥.18). Similarly, observing transmission within or between cases of a pair did not increase the probability that the next sampled pair of cases also had observed transmission (all P ≥.23).

Most pairs of cases had no detected transmitted isolates. Also, although transmission (yes/no) was associated with surgical site infection (P =.004), among cases with transmission, there was no detected dose response between counts of transmitted isolates and probability of infection (P =.25).

The first of a fixed series of tests is to use the binomial test to compare the proportion of pairs of cases with S. aureus transmission to an acceptable threshold. An appropriate sample size for this screening is N =25 pairs. If significant, more samples are obtained while additional measures are implemented to reduce transmission and infections. Subsequent sampling is done to evaluate effectiveness. The two independent binomial proportions are compared using Boschloo's exact test. The total sample size for the 1^st and 2^nd stage is N =100 pairs.

Because S. aureus transmission is invisible without testing, when choosing what population(s) to screen for surveillance, another endpoint needs to be used (e.g., infections). Only 10/298 combinations of specialty and operating room were relatively common (≥1.0% of cases) and had expected incidence ≥0.20 infections per 8 hours of sampled cases. The 10 combinations encompassed ≅17% of cases, showing the value of targeting surveillance of transmission to a few combinations of specialties and rooms.

In conclusion, we created a sampling protocol and appropriate sample sizes for using S. aureus transmission within and between pairs of successive cases in the same operating room, the purpose being to monitor the quality of prevention of intraoperative spread of pathogenic bacteria and viruses.

Importance of operating room case scheduling on analyses of observed reductions in surgical site infections from the purchase and installation of capital equipment in operating rooms

BACKGROUND

We review the impact of the consequences of operating room (OR) management decision making on power analyses for observational studies of surgical site infections (SSIs) among patients receiving care in ORs with interventions versus without interventions involving physical changes to ORs. Examples include ventilation systems, bactericidal lighting, and physical alterations to ORs.

METHODS

We performed a narrative review of operating room management and surgical site infection articles. We used 10-years of operating room data to estimate parameters for use in statistical power analyses.

RESULTS

Creating pivot tables or monthly control charts of SSI per case by OR and comparing among ORs with or without intervention is not recommended. This approach has low power to detect a difference in SSI rates among the ORs with or without the intervention. The reason is that appropriate OR case scheduling decision making causes risk factors for SSI to differ among ORs, even when stratifying by surgical specialty. Such risk factors include case duration, urgency, and American Society of Anesthesiologists' Physical Status. Instead, analyze SSI controlling for the OR, where the patient had surgery, and matching patients using these variables is preferable. With α = 0.05, 600 cases per OR, 5 intervention ORs, and 5 or 1 control patients for each intervention patient, reasonable power (≅94% or 78%, respectively) can be achieved to detect reductions (3.6% to 2.4%) in the incidence of SSI between ORs with or without the intervention.

CONCLUSIONS

By using this matched cohort design, the effect of the purchase and installation of capital equipment in ORs on SSI can be evaluated meaningfully.

Futility of Cluster Designs at Individual Hospitals to Study Surgical Site Infections and Interventions Involving the Installation of Capital Equipment in Operating Rooms

Anesthesia workspaces are integral components in the chains of many intraoperative bacterial transmission events resulting in surgical site infections (SSI). Matched cohort designs can be used to compare SSI rates among operating rooms (ORs) with or without capital equipment purchases (e.g., new anesthesia machines). Patients receiving care in intervention ORs (i.e., with installed capital equipment) are matched with similar patients receiving care in ORs lacking the intervention. We evaluate statistical power of an alternative design for clinical trials in which, instead, SSI incidences are compared directly among ORs (i.e., the ORs form the clusters) at single hospitals (e.g., the 5 ORs with bactericidal lights vs. the 5 other ORs). Data used for parameter estimates were SSI for 24 categories of procedures among 338 hospitals in the State of California, 2015. Estimated statistical power was ≅8.4% for detecting a reduction in the incidence of SSI from 3.6% to 2.4% over 1 year with 5 intervention ORs and 5 control ORs. For ≅80% statistical power, >20 such hospitals would be needed to complete a study in 1 year. Matched paired cluster designs pair similar ORs (e.g., 2 cardiac ORs, 1 to intervention and 1 to control). With 5 pairs, statistical power would be even less than the estimated 8.4%. Cluster designs (i.e., analyses by OR) are not suitable for comparing SSI among ORs at single hospitals. Even though matched cohort designs are non-randomized and thus have lesser validity, matching patients by their risk factors for SSI is more practical.

Operating room PathTrac analysis of current intraoperative Staphylococcus aureus transmission dynamics

BACKGROUND

Operating room (OR) reservoir Staphylococcus aureus isolates have been linked to 50% of surgical site infections. We aimed to assess S aureus transmission dynamics in today's ORs to further guide health care-associated infection prevention.

METHODS

Forty OR case-pairs were randomly selected for observation in a 5-month prospective cohort study. Case-pair S aureus transmission dynamics were mapped using OR PathTrac.

RESULTS

S aureus pathogens were isolated from ≥1 OR reservoirs in 45.7% (37 of 81) of surgical cases, and epidemiologically related transmission events were confirmed in 22.5% (9 of 40) of case-pairs. Patient skin sites and provider hands provided comparable risk of OR S aureus exposure (19 of 481 patient vs 35 of 1,173 provider hands, relative risk [RR], 1.32; 95% confidence interval [CI], 0.77-2.29; P = .32). Environmental contamination at case 2 start was higher than at case 1 start (case 2 start 32 of 152 sites with >20 colony-forming units vs case 1 start 7 of 163 sites with >20 colony-forming units; RR, 4.90; 95% CI, 2.23-10.77; P < .0001). The stopcock contamination rate was not significantly different than our prior study in 2008 (19 of 164 2008 vs 8 of 77 2018; RR, 1.12; 95% CI, 0.51-2.43; P = .78). All epidemiologically related transmission events involved the between-case mode of transmission and phenotype H.

CONCLUSIONS

Current OR S aureus exposure threats reliably include patient skin sites and provider hands. Perioperative S aureus preventive measures should extend from patient decolonization to include improved hand decontamination efforts.

Continuous room decontamination technologies

The contaminated surface environment in the rooms of hospitalized patients is an important risk factor for the colonization and infection of patients with multidrug-resistant pathogens. Improved terminal cleaning and disinfection have been demonstrated to reduce the incidence of health care-associated infections. In the United States, hospitals generally perform daily cleaning and disinfection of patient rooms. However, cleaning and disinfection are limited by the presence of the patient in room (eg, current ultraviolet devices and hydrogen peroxide systems cannot be used) and the fact that after disinfection pathogenic bacteria rapidly recolonize surfaces and medical devices/equipment. For this reason, there has been great interest in developing methods of continuous room disinfection and/or "self-disinfecting" surfaces. This study will review the research on self-disinfecting surfaces (eg, copper-coated surfaces and persistent chemical disinfectants) and potential new room disinfection methods (eg, "blue light" and diluted hydrogen peroxide systems).