Infection Control & Hospital Epidemiology

Decontamination of N95 respirators has become critical to alleviate PPE shortages for healthcare workers in the current COVID-19 emergency. The factors that are considered for the effective reuse of these masks are the fit, filter efficiency and decontamination/disinfection level both for SARS-CoV2, which is the causative virus for COVID-19, and for other organisms of concern in the hospital environment such as Staphylococcus aureus or Clostridium difficile. The efficacy of inactivation or eradication against various pathogens should be evaluated thoroughly to understand the level of afforded disinfection. Methods commonly used in the sterilization of medical devices such as ionizing radiation, vaporized hydrogen peroxide, and ethylene oxide can provide a high level of disinfection, defined as a 6 log10 reduction, against bacterial spores, considered the most resistant microorganisms. CDC guidance on the decontamination and reuse of N95s also includes the use of moist heat (60{degrees}C, 80% relative humidity, 15-30 min) as a possible recommendation based on literature showing preservation of fit efficiency and inactivation of H1N1 on spiked masks. Here, we explored the efficacy of using moist heat under these conditions as a decontamination method for an N95 respirator (3M 1860S, St. Paul, MN) against various pathogens with different resistance; enveloped RNA viruses, Gram (+/-) bacteria, and non-enveloped viruses.

SARS-CoV-2 spread has proven to be especially difficult to mitigate in high risk settings, including nursing homes, cruises, prisons and various industrial settings. Among industrial settings, meat processing facilities in the United States have experienced particularly challenging outbreaks. We have sequenced SARS-CoV-2 whole viral genomes from individuals testing positive in an integrated regional healthcare system serving 21 counties in southwestern Wisconsin, northeastern Iowa and southeastern Minnesota, providing an overview of SARS-CoV-2 introduction and spread in a region spanning multiple jurisdictions with differing mitigation policies. While most viral introductions we detected were contained with only minor transmission chains, a striking exception was an outbreak associated with a meatpacking plant in Postville, IA. In this case, a single viral introduction led to unrestrained spread within the facility, affecting many staff and members of their households. Importantly, by surveilling viral sequences from the surrounding counties, we have documented the spread of this SARS-CoV-2 substrain from this epicenter to individuals in 13 cities in 7 counties in Iowa, Wisconsin and Minnesota, a region spanning 185 square miles. This study highlights the regional public health consequences of failures to rapidly act to mitigate viral spread in a single industrial setting.

BackgroundHealthcare workers treating patients with SARS-CoV-2 are at risk of infection from patient-emitted virus-laden aerosols. We quantified the reduction of airborne infectious virus in a simulated hospital room when a ventilated patient isolation (McMonty) hood was in use. MethodsWe nebulised 109 plaque forming units (PFU) of bacteriophage PhiX174 virus into a 35.1m3 room with a hood active or inactive. The airborne concentration of infectious virus was measured by BioSpot-VIVAS and settle plates using plaque assay quantification on the bacterial host Escherichia coli C. The particle number concentration (PNC) was monitored continuously using an optical particle sizer. ResultsMedian airborne viral concentration in the room reached 1.41 x 105 PFU.m-3 with the hood inactive. Using the active hood as source containment reduced infectious virus concentration by 374-fold in air samples. This was associated with a 109-fold reduction in total airborne particle number escape rate. The deposition of infectious virus on the surface of settle plates was reduced by 87-fold. ConclusionsThe isolation hood significantly reduced airborne infectious virus exposure in a simulated hospital room. Our findings support the use of the hood to limit exposure of healthcare workers to airborne virus in clinical environments. Lay summaryCOVID-19 patients exhale aerosol particles which can potentially carry infectious viruses into the hospital environment, putting healthcare workers at risk of infection. This risk can be reduced by proper use of personal protective equipment (PPE) to protect workers from virus exposure. More effective strategies, however, aim to provide source control, reducing the amount of virus-contaminated air that is exhaled into the hospital room. The McMonty isolation hood has been developed to trap and decontaminate the air around an infected patient. We tested the efficacy of the hood using a live virus model to mimic a COVID-19 patient in a hospital room. Using the McMonty hood reduced the amount of exhaled air particles in the room by over 109-times. In our tests, people working in the room were exposed to 374-times less infectious virus in the air, and room surfaces were 87-times less contaminated. Our study supports using devices like the McMonty hood in combination with PPE to keep healthcare workers safe from virus exposure at work.

BackgroundOutbreaks of respiratory pathogens on hospital wards present a major challenge for control of hospital-acquired infections. When illness presentation is mild or infection is asymptomatic, isolation of recognised cases may be insufficient to prevent outbreaks, as unrecognised cases may be common. In such scenarios, structural controls such as the design of wards with single-occupancy patient rooms, or routine precautions such as the use of N95 respirators by healthcare staff can play an important role in preventing and mitigating outbreaks. MethodsThis study applies an agent-based extension of the Wells-Riley model of airborne pathogen exposure to simulate COVID-19 outbreaks on hospital wards. We simulated the impact of single-vs. double-occupancy patient rooms on secondary attack rates and the sizes of outbreaks resulting from introduction of unrecognised cases. We further simulated the impact of N95 respirator use by nurses during patient care activities, assuming an efficacy of 90% for protection and source control. ResultsIn our simulations, the size of outbreaks recorded at day 14 was markedly lower in wards with only single-occupancy rooms, compared to double-occupancy rooms (with means of 15.2 and 25.1 infections, respectively). We found that nurses working on wards were more likely to acquire infection than patients. Higher patient room occupancy was associated with increased outbreak size, with a larger relative impact on patients than staff. N95 respirators were effective at mitigating outbreaks, with higher impacts in wards with single-occupancy patient rooms. ConclusionsSingle-occupancy rooms can greatly decrease the risk of hospital acquired airborne infection for patients. We show that single-occupancy hospital rooms can also reduce the number of healthcare workers infected during an outbreak of an airborne respiratory virus, but not to the same relative extent as patients. Due to the structural constraints limiting transmission between patients in different rooms, outbreaks were driven by transmission events involving nurses, which were effectively mitigated through the use of N95 respirators. Taken together, our results suggest that single-occupancy rooms are effective at reducing outbreak sizes. However, they are insufficient by themselves to prevent large outbreaks without mitigation efforts focused on limiting the potential for transmission involving healthcare workers, such as the use of N95 respirators.

First responders are at increased risk of occupational exposure to SARS-CoV-2 while providing frontline support to communities during the COVID-19 pandemic. In the District of Columbia (DC), first responders were among the first people exposed to and infected with SARS-CoV-2, with over 200 first responders diagnosed with COVID-19 by May 15, 2020. From June - July 2020, DC Health conducted a serologic survey to estimate SARS-CoV-2 seroprevalence and assess risk factors and occupational exposures among a convenience sample of first responders in DC. Of the 310 first responders tested, 3.5% (n = 11) had anti-SARS-CoV-2 antibodies. Seropositivity varied by occupation, with 4.8% (3/62) of firefighters; 3.6% (8/220) of police officers; and no paramedics (0/10) or administration and support staff (0/18) testing positive. Type and consistency of personal protective equipment (PPE) use also varied: all paramedics (n=10) reported wearing a N95 respirator all or most of the time, compared to 83.3% of firefighters, 38.8% of police officers, and 23.5% of administration and support staff (p<0.001). All paramedics reported wearing gloves all or most of the time, compared to 80.0% of firefighters, 27.8% of administration and support staff, and 24.3% of police (p<0.001). The relatively low seroprevalence among first responders highlights the benefits of continuous training on and reinforcement of the proper use of PPE while performing job duties to mitigate potential transmission within and between first responders and the community. SummaryUnderstanding occupational exposure to and infection with SARS-CoV-2 among first responders is important for workforce planning and emergency preparedness and response. Seroprevalence among first responders (3.5%; 11/310) who participated in a survey conducted by the District of Columbia Department of Health (DC Health) from May 28 - July 15 was 48% lower than reported in the DC community (6.7%; 876/12990). The lower prevalence of SARS-CoV-2 among first responders highlights the importance of continuous training on and reinforcement of the proper use of personal protective equipment (PPE). Proper use of PPE is a critical mitigation strategy to reduce transmission among and between first responders and the community.

ImportanceThis study addresses the pressing clinical question of how variations in physician and nursing staffing levels influence methicillin-resistant Staphylococcus aureus (MRSA) rates, providing essential insights for optimizing staff allocation and improving patient outcomes in critical care settings. ObjectiveThe main objective is to assess whether variations in staffing ratios and workload conceptualization significantly alter the rates of MRSA acquisitions in the ICU setting. DesignThis simulation-based study utilizes stochastic compartmental mathematical modeling to explore the impact of staffing ratios and workload conceptualization on MRSA acquisitions in ICUs. Derived from a previously published model, the analysis involves running year-long stochastic simulations for each scenario 1000 times, varying nurse-to-patient ratios and intensivist staffing levels under infinite and finite workload conceptualizations. Our baseline model was a 3:1 nurse ratio with one intensivist. Main OutcomeMRSA acquisitions in ICUs, measured as median acquisitions per 1000 person-years. ResultsUnder baseline conditions, our model had a median of 8.2 MRSA acquisitions per 1000 person-years. Varying patient-to-nurse ratios and intensivist numbers showed substantial impacts. For infinite models, a 2:1 nurse ratio resulted in a 21% decrease, while a 1:1 nurse ratio led to a 65% reduction. Finite models demonstrated even larger effects, with a 48% decrease when having a 2:1 ratio, and an 83% reduction with a 1:1 nurse ratio. Reducing patient-to-nurse ratios in finite models increased acquisitions exponentially with a 348% increase for a 6:1 ratio. Intensivist variations had modest impacts. Conclusions and RelevanceOur study highlights the crucial role of optimizing staffing levels in ICUs for effective MRSA infection control. While intensivist variations have modest effects, bolstering nursing ratios significantly reduces MRSA acquisitions, underscoring the need for tailored staffing strategies, and recognizing the nuanced impact of workload conceptualization. Our findings offer practical insights for refining staffing protocols, emphasizing the dynamic nature of healthcare-associated infection outcomes. Key PointsO_ST_ABSQuestionC_ST_ABSHow does the conceptualization of ICU healthcare worker tasks in models--whether infinite or finite-- impact the results of changes in staffing ratios affecting methicillin-resistant Staphylococcus aureus (MRSA) acquisition? FindingsIn this compartmental mathematical model approach that included 15 different models, the trends of the impact of staffing ratios were consistent between the Infinite and Finite tasks models. However, both the absolute and relative values were markedly different, with the infinite task models having a much more linear effect on MRSA acquisitions while the number of MRSA cases in the finite model continued to rise exponentially as the number of nurses decreased. MeaningIt is essential when considering model generalizability, to state the assumptions made about how workload and contact patterns within a hospital work, and to ensure these are appropriately tailored for the specific setting being modeled.

Although hydrogen peroxide (H2O2) nebulization has shown promise for reducing SARS-CoV-2 loads in healthcare settings, its precise kinetics and real-world efficacy remain incompletely understood. In this prospective environmental sampling study, we collected air and surface samples from COVID-19 patient rooms before and after automated H2O2 nebulization, quantifying viral RNA by RT-qPCR and viral antigens by indirect ELISA, while assessing infectivity via Vero E6 cell cultures. A piecewise exponential model characterized the kinetics of viral load reduction, capturing both initial delays and subsequent decay phases. Results revealed a marked decrease in RT-qPCR positivity rates, higher cycle threshold values indicative of lower viral loads, and substantially reduced cytopathic effects, suggesting that residual viral RNA was largely non-viable. These findings underscore the non-linear nature of H2O2-mediated decontamination and the influence of environmental variables such as airflow, humidity, and surface composition. By integrating molecular diagnostics, infectivity assays, and mathematical modeling, our study offers a comprehensive framework for refining decontamination protocols. Future investigations should explore larger, multi-institutional cohorts and evaluate the applicability of these insights to emerging viral threats in diverse clinical environments. ImportanceThis study represents a significant advance in environmental decontamination by demonstrating that automated hydrogen peroxide (H2O2) nebulization markedly reduces SARS-CoV-2 contamination in hospital settings. By integrating rigorous molecular diagnostics with infectivity assays and sophisticated kinetic modeling, the research delineates the non-linear decay of viral loads, providing robust evidence that residual viral RNA post-treatment is largely non-infectious. Such insights are invaluable for refining disinfection protocols, ensuring patient and healthcare worker safety, and mitigating nosocomial transmission. Incorporating advanced machine learning techniques further improves the predictive accuracy of decontamination outcomes. Ultimately, this work lays a strong foundation for future studies to optimize and personalize disinfection strategies across diverse clinical environments, thereby bolstering public health efforts to combat current and emerging infectious diseases.

The coronavirus disease 2019 crisis is creating a shortage of personal protective equipment (PPE), most critically, N95 respirators for healthcare personnel. Our group was interested in the feasibility of ozone disinfection of N95 respirators as an alternative for healthcare professionals and organizations that might not have access to other disinfection devices. We tested the effectiveness of ozone on killing Pseudomonas aeruginosa (PsA) on three different N95 respirators: 3M 1860, 3M 1870, and 3M 8000. We used an ozone chamber that consisted of: an airtight chamber, an ozone generator, an ozone destruct unit, and an ozone UV analyzer. The chamber was capable of concentrating ozone up to 500 parts per million (ppm) from ambient air, creating an airtight seal, and precisely measuring ozone levels within the chamber. Exposure to ozone at 400 ppm with 80% humidity for two hours effectively killed bacteria on N95 respirators, types 1860, 1870, and 8000. There were no significant changes in filtration efficiency of the 1860 and 1870 type respirators for up to ten cycles of ozone exposure at similar conditions. There was no change in fit observed in the 1870 type respirator after ozone exposure. There was no significant change in the strap integrity of the 1870 type respirator after ozone exposure. Tests for filtration efficiency were not performed on the 8000 type respirator. Tests for fit or strap integrity were not performed on the 8000 or 1860 type respirators. This study demonstrates that an ozone application achieves a high level of disinfection against PsA, a vegetative bacteria that the CDC identifies as more difficult to kill than medium sized viruses such as SARS-CoV-2 (Covid-19). Furthermore, conditions shown to kill these bacteria did not damage or degrade respirator filtration. This is the first report of successful disinfection of N95 PPE with ozone of which the authors are aware. It is also the first report, to the authors knowledge, to identify necessary conditions for ozone to kill organisms on N95 masks without degrading the function of N95 filters.

ObjectiveTo determine the prevalence of SARS-CoV-2 infection among asymptomatic COVID-19 facing and non-COVID-19 facing Healthcare Workers (HCWs), with varying job categories across different hospitals. DesignCross-sectional analysis of a healthcare system surveillance program that included asymptomatic clinical (COVID-19 facing and non-COVID-19 facing), and non-clinical HCWs. A convenience sample of asymptomatic community residents (CR) was also tested. Proportions and 95% confidence Intervals (CI) of SARS-CoV-2 positive HCWs are reported. Proportional trend across HCW categories was tested using Chi Square trend test. Logistic regression model-based likelihood estimates of SARS-CoV-2 prevalence among HCWs with varying job functions and across different hospitals are reported as adjusted odds ratios (aOR) and CI. SettingHealthcare system comprising one tertiary care academic medical center and six large community hospitals across Greater Houston and a community sample. Participants2,872 self-reported asymptomatic adult (> 18 years) HCWs and CRs. ExposureClinical HCWs in COVID-19 and non-COVID-19 units, non-Clinical HCWs, and CRs. Job categories of Nursing, Providers, Allied Health, Support, and Administration / Research. Seven hospitals in the healthcare system. Main OutcomesPositive reverse transcriptase polymerized chain reaction (RT-PCR) test for SARS-CoV-2 ResultsAmong 2,872 asymptomatic HCWs and CRs, 3.9% (CI: 3.2 - 4.7) tested positive for SARS-CoV-2. Mean (SD) age was 40.9 (11.7) years and 73% were females. Among COVID-19 facing HCWs 5.4% (CI: 4.5 - 6.5) were positive, whereas 0.6% (CI: 0.2 - 1.7%) of non COVID-19 facing HCWs and none of the non-clinical HCWs or CRs were positive (Ptrend < 0.001). Among COVID-19 facing HCWs, SARS-CoV-2 positivity was similar for all job categories (p = 0.74). However, significant differences in positivity were observed across hospitals. Conclusions and RelevanceAsymptomatic HCWs with COVID-19 patient exposure had a higher rate of SARS-CoV-2 positive testing than those not routinely exposed to COVID-19 patients and those not engaged in patient care. Among HCWs with routine COVID-19 exposure, all job types had relatively similar infection rates. These data can inform hospital surveillance and infection control practices for patient-facing job classifications and suggest that general environmental exposure within hospitals is not a significant source of asymptomatic SARS-CoV-2 infection. What is already known on this topicO_LIA sizeable proportion of individuals who contract the novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) can remain largely asymptomatic. C_LIO_LIThough such individuals may not develop symptoms, they continue to shed enough viral particles to trigger positive reverse transcriptase polymerized chain reaction (RT PCR) test for SARS-CoV-2 C_LIO_LIPrior reports on proportion of asymptomatic SARS-CoV-2 individuals are highly variable with positivity ranging across < 1% to 36% C_LIO_LIAsymptomatic SARS-CoV-2 infection among healthcare workers is specifically critical to understand C_LI What this study addsO_LIThis study demonstrates that overall rate of SARS-CoV-2 infection among asymptomatic healthcare workers in a large healthcare system of a metropolitan city in the United States was 3.9% C_LIO_LIThe rate of SARS-CoV-2 infection among healthcare workers who provided direct care to COVID-19 patients was 5.4% whereas it was 0.6% among those healthcare workers who did not provide direct care to COVID-19 patients C_LIO_LIThere was no difference in SARS-CoV-2 positivity rate for different job categories of healthcare workers who provided direct care to COVID-19 patients C_LI

We conducted a systematic review of hygiene intervention effectiveness against SARS-CoV-2, including developing inclusion criteria, conducting the search, selecting articles for inclusion, and summarizing included articles. We reviewed 104,735 articles, and 109 articles meeting inclusion criteria were identified, with 33 additional articles identified from reference chaining. Herein, we describe results from 58 mask disinfection and reuse studies, where the majority of data were collected using N95 masks. Please note, no disinfection method consistently removed >3 log of virus irrespective of concentration, contact time, temperature, and humidity. However, results show it is possible to achieve >3 log reduction of SARS-CoV-2 using appropriate concentrations and contact times of chemical (ethanol, hydrogen peroxide, peracetic acid), radiation (PX-UV, UVGI), and thermal (autoclaving, heat) disinfection on N95 masks. N95 mask reuse and failure data indicate that hydrogen peroxide, heat, and UV-GI are promising for mask reuse, peracetic acid and PX-UV need more data, and autoclaving and ethanol lead to mask durability failures. Data on other mask types is limited. We thus recommend focusing guidelines and further research on the use of heat, hydrogen peroxide, and UVGI for N95 mask disinfection/reuse. All of these disinfection options could be investigated for use in LMIC and humanitarian contexts. TOC Art O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=106 SRC="FIGDIR/small/20229880v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@154383borg.highwire.dtl.DTLVardef@37b888org.highwire.dtl.DTLVardef@33eae1org.highwire.dtl.DTLVardef@818e32_HPS_FORMAT_FIGEXP M_FIG C_FIG SynopsisIn resource-limited contexts, N95s are reused. We recommend using heat, hydrogen peroxide, or UVGI to disinfect and reuse N95 masks.

Decontamination of N95 respirators has become critical to alleviate PPE shortages for healthcare workers in the current COVID-19 emergency. The factors that are considered for the effective reuse of these masks are the fit, filter efficiency and decontamination/disinfection level both for SARS-CoV-2, which is the causative virus for COVID-19, and for other organisms of concern in the hospital environment such as Staphylococcus aureus or Clostridium difficile. In its guidance entitled Recommendations for Sponsors Requesting EUAs for Decontamination and Bioburden Reduction Systems for Surgical Masks and Respirators During the Coronavirus Disease 2019 (COVID19) Public Health Emergency (May 2020)[1], the FDA recommends a 6-log10 reduction in either the most resistant bacterial spores for the system or in a mycobacterium species to authorize the use of a decontamination method of N95 respirators for single or multiple users. While the goal is primarily inactivation against SARS-CoV-2, testing of decontamination methods against the virus may not always be available. For decontamination methods considered for only single users, the recommendation is a 6-log10 reduction in the infective virus concentration of 3 non-enveloped viruses or in the concentration of two Gram (+) and two Gram (-) bacteria. Based on these recommendations, we explored the efficacy of vaporized H2O2 (VHP) treatment of N95 respirators against surrogate viruses covering a wide range of disinfection resistance for emergency decontamination and reuse to alleviate PPE shortages for healthcare workers in the COVID-19 emergency.

BackgroundHealthcare-associated carbapenemase-producing Enterobacterales (CPE) outbreaks are a major healthcare challenge. Epidemiological studies have identified patient-level risk factors for CPE transmission, and genomic studies have highlighted high-risk lineages or mobile genetic elements (MGEs); however, a unified dissemination risk-prediction framework is lacking. ObjectivesTo synthesise available data on epidemiological, microbiological and genomic risk factors to quantify healthcare-associated CPE outbreak potential. MethodsO_ST_ABSDataC_ST_ABSSix bibliographic databases and other sources were searched ( carbapenemase AND outbreak AND MGE; [&le;]31/01/24). Data were extracted on primary (patients infected/colonised) and secondary (outbreak duration/resolution, mortality) outcomes, and risk/protective factors including epidemiological, microbiological/genomic and infection control measures. Study eligibilityStudies reporting healthcare-associated CPE outbreaks involving MGE-associated IMP/KPC/NDM/OXA-48-like/VIM carbapenemases confirmed by whole-genome sequencing. Study qualityReporting quality was assessed against the ORION checklist (random subset). Data synthesisAfter descriptive summaries, multivariable linear mixed effect modelling was used to estimate associations between risk/protective factors and outbreak size. Results179 records (272 outbreaks) were included from 3,188 screened (41 countries, 2004-2023), affecting median 10 patients (IQR=5-27, range=2-223), and lasting 12 months (IQR=5-30, range=1 day-16 years). Data on outbreak size (primary outcome) was 99.6% complete (271/272) but more limited for secondary outcomes (29-97% complete) and risk/protective factors (70/91 factors had [&ge;]10% missingness). 39% (107/272) of outbreaks involved MGE-mediated transmission, which is a potential underestimate as 66% (104/157) of reports used clonal outbreak definitions. The involvement of more institutions (adjusted relative outbreak size: 1.10 per institution [95% CI: 1.04-1.16];p=0.001), and more Enterobacterales sequence types (1.04 per sequence type [1.01-1.08];p=0.011), were associated with larger outbreaks. Reporting quality assessment (n=98 studies) revealed adequate reporting on median 11/19 relevant ORION items (IQR=8-13; range=1-18). ConclusionsHeterogenous/incomplete reporting of CPE outbreaks precludes integrated risk evaluation based on epidemiological, microbiological, and genomic factors. Systematic sampling, sequencing and epidemiological metadata reporting may strengthen data quality for quantifying healthcare-associated CPE dissemination risk.

BackgroundCurrent methods are insufficient alone for outbreak detection in hospitals. Real-time genomic surveillance using offers the potential to detect otherwise unidentified outbreaks. We initiated and evaluated the Enhanced Detection System for Healthcare-associated Transmission (EDS-HAT), a real-time genomic surveillance program for outbreak detection and mitigation. MethodsThis study was conducted at UPMC Presbyterian Hospital from November 2021 to October 2023. Whole genome sequencing (WGS) was performed weekly on healthcare-associated clinical bacterial isolates to identify otherwise undetected outbreaks. Interventions were implemented in real-time based on identified transmission. A clinical and economic impact analysis was conducted to estimate infections averted and net cost savings. ResultsThere were 3,921 bacterial isolates from patient healthcare-associated infections that underwent WGS, of which 476 (12.1%) clustered into 172 outbreaks (size range 2-16 patients). Of the outbreak isolates, 292 (61.3%) had an identified epidemiological link. Among the outbreaks with interventions, 95.6% showed no further transmission on the intervened transmission route. The impact analysis estimated that, over the two-year period, 62 infections were averted, with gross cost savings of $1,011,146, and net savings of $695,706, which translates to a 3.2-fold return on investment. Probabilistic sensitivity analysis showed EDS-HAT was cost-saving and more effective in 98% of simulations. ConclusionReal-time genomic surveillance enabled the rapid detection and control of outbreaks in our hospital and resulted in economic benefits and improvement in patient safety. This study demonstrates the feasibility and effectiveness of integrating genomic surveillance into routine infection prevention practice, offering a paradigm shift in healthcare outbreak detection and control.

Methicillin-resistant Staphylococcus aureus (MRSA) is a strain of Staphylococcus aureus that poses significant challenges in treatment and infection control within healthcare settings. Recent research suggests that the incidence of healthcare-associated MRSA (HA-MRSA) is higher among patients treated in safety-net hospitals compared to those in non-safety-net hospitals. This study aimed to identify HA-MRSA transmission patterns across various nursing units of a safety-net hospital to improve to enhance patient outcomes and facilitate the implementation of targeted infection control measures. A retrospective analysis was conducted using surveillance data from 2019 to 2023. A compartmental disease model was applied to estimate MRSA transmission rates and basic reproduction number (R0) for each nursing unit of an urban, multicenter safety-net hospital before and during the COVID-19 pandemic. Posterior probability distributions for transmission, isolation, and hospital discharge rates were computed using the Delayed Rejection Adaptive Metropolis (DRAM) Bayesian algorithm. Analysis of 187,040 patient records revealed that inpatient nursing units exhibited the highest MRSA transmission rates in three out of the five years studied. Notable transmission rates were observed in certain inpatient and progressive care units (0.55 per individual per month; 0.018 per individual per day) and the surgical ICU (0.44 per individual per month; 0.015 per individual per day). In contrast, the Nursery NICU and Medical ICU had the lowest transmission rates. Although MRSA transmission rates significantly declined across all units in 2021, these rates rebounded to pre-pandemic levels in subsequent years. Notably, outbreaks emerged in units such as ICUs and progressive care units that had not experienced prior MRSA outbreaks since 2019. While MRSA transmission significantly declined during the initial phase of the pandemic, the pathogen reestablished itself in later years. These findings highlight the need for sustained resources and adaptive infection control strategies to reduce the incidence of HA-MRSA in safety-net hospitals.

BackgroundRecently the US CDC acknowledged by that the COVID-19 crisis is facilitated at least in part by aerosolized virus exhaled by symptomatic, asymptomatic, or pre-symptomatic infected individuals. Disposable N95 masks remain in short supply due to their use in healthcare settings during the Coronavirus pandemic, whereas NIOSH-approved elastomeric N95 (eN95) masks remain immediately available for use by essential workers and the general public. New reusable N95 mask options with symmetric filtration efficiency can be anticipated to be NIOSH approved in the coming months, todays eN95 masks have asymmetric filtration efficiency upon inhalation (95%) and exhalation (well under 95%) but are available now during the Fall and Winter when Coronavirus cases are expected to peak. MethodsBased on the Wells-Riley model of infection risk, we examine how the rate of transmission of the virus from one infected person in a closed, congested room with poor ventilation to several other susceptible individuals is impacted by the filtration efficiency of the masks they are wearing. Three scenarios are modeled - a room (6 people, 12 x 20 x 10), a bar (18 people, 20 x 40 x 10), and a classroom (26 people, 20 x 30 x 10) with one infectious individual and remaining susceptibles. By dynamically estimating the accumulation of virus in aerosols exhaled by the infected person in these congested spaces for four hours using a "box model," we compare the transmission risk (probability) when susceptible people based on a realistic hypothesis of face mask protection during inhaling and exhaling e.g. using cloth masks or N95 respirators. ResultsAcross all three scenarios, cloth masks modeled with 30% symmetric filtration efficiency alone were insufficient to stop the spread (18% to 40% infection risk), whereas eN95 masks (modeled as 95% filtration efficiency on inhalation, 30% on exhalation) reduced the infection risk to 1.5% to 3.6%. Symmetric filtration of 80% reduces the risk to 1.7% to 4.1% and symmetric filtration of 95% would further reduce the risk to 0.11% to 0.26%. ConclusionThis modeling of mask filtration efficiency suggests that the pandemic could be readily controlled within several weeks if (in conjunction with sensible hygiene) a sufficiently large majority of people wear asymmetric but higher-filtration masks (e.g. eN95) that also block aerosols whenever exposed to anyone else outside their household in order to completely stop inter-household spread.

BackgroundThere is a significant transmission of contaminants in the healthcare setting. Daily disinfection utilizing ammonium and chlorine-based products can lead to adverse health effects such as asthma, cancer, and other serious health issues. MethodsThis study evaluated the effectiveness of eraDOCator-60 in a health care facility. This randomized trial took place at Copley Hospital in Morristown, Vermont. Separate areas of the hospital were cleaned and disinfected in one step with eraDOCator-60. A Charm analyzer was utilized to evaluate the efficacy of disinfection before and after 1 minute application of eraDOCator-60. The Charm analyzer detects Adenosine Triphosphate (ATP) presence measured in Relative Light Units (RLUs). ResultsThe median number of RLUs decreased from 52,874 s to 0 RLUs after one-minute eraDOCator-60 dwell time in the emergency room; 18.611 RLUs to 0 RLUs in the medical-surgical unit, 41,507 RLUs to 0 RLUs in the cafeteria; 24,932 RLUs to 0 RLUs in the birthing center. ConclusionsEraDOCator-60 reduced contamination levels on all surfaces in the acute care setting down to a value of zero following a 1-minute dwell time in less than 5% soil load.

BackgroundClinical research focused on the burden and impact of Clostridioides difficile infection (CDI) often relies upon accurate identification of cases using existing health record data. Use of diagnosis codes alone can lead to misclassification of cases. Our goal was to develop and validate a multi-component algorithm to identify hospital-associated CDI (HA-CDI) cases using electronic health record (EHR) data. MethodsWe performed a validation study using a random sample of adult inpatients at a large academic hospital setting in Portland, Oregon from January 2018 to March 2020. We excluded patients with CDI on admission and those with short lengths of stay (< 4 days). We tested a multi-component algorithm to identify HA-CDI; case patients were required to have received an inpatient course of metronidazole, oral vancomycin, or fidaxomicin and have at least one of the following: a positive C. difficile laboratory test or the International Classification of Diseases, Tenth Revision (ICD-10) code for non-recurrent CDI. For a random sample of 80 algorithm-identified HA-CDI cases and 80 non-cases, we performed manual EHR review to identify gold standard of HA-CDI diagnosis. We then calculated overall percent accuracy, sensitivity, specificity, and positive and negative predictive value for the algorithm overall and for the individual components. ResultsOur case definition algorithm identified HA-CDI cases with 94% accuracy (95% Confidence Interval (CI): 88% to 97%). We achieved 100% sensitivity (94% to 100%), 89% specificity (81% to 95%), 88% positive predictive value (78% to 94%), and 100% negative predictive value (95% to 100%). Requiring a positive C. difficile test as our gold standard further improved diagnostic performance (97% accuracy [93% to 99%], 93% PPV [85% to 98%]). ConclusionsOur algorithm accurately detected true HA-CDI cases from EHR data in our patient population. A multi-component algorithm performs better than any isolated component. Requiring a positive laboratory test for C. difficile strengthens diagnostic performance even further. Accurate detection could have important implications for CDI tracking and research.

ObjectivesThe aim of this observational study was to demonstrate the behaviour and trajectory of exhaled material from an individual wearing an FFP3 mask. Valves allow material release, but we theorised that valve design may direct material downwards towards patient and surrounding environment. Limiting transmission of diseases with aerosolised spread is a current and serious concern within healthcare worldwide. Filtering face piece masks (FFP) are an essential piece of protective equipment when treating patients with ongoing infection. However, valved masks in other settings such as elective theatre and by the general public may have unforeseen negative effects. DesignA heating coil-based vaporiser was used to produce visible water vapour. A healthy test subject was filmed wearing a variety of different masks and exhaling the water vapour. ResultsFlexible pleated and solid-shell FFP masks direct exhaled material downwards in plumes exceeding 25 cm. Duckbill-shaped masks appear to direct exhaled vapour laterally, with a smaller plume. The effect is influenced by mask design and type of valve. Fluid repellent surgical masks reduce material directed downwards, and when used in conjunction with an FFP3 mask, appear to reduce the size and density of the exhaled vapour plume. The use of a visor was ineffective in reducing plume expulsion. InterpretationA properly fit-tested FFP3-rated protective mask may only moderately limit expulsion of aerosolised particles from asymptomatic healthcare workers to patients, particularly in cases where procedures are being performed in close proximity to patients or in cases where mucosal surfaces are exposed. Further research in this area is needed.

ObjectivesThe United States Environmental Protection Agency has determined that formaldehyde presents an "unreasonable risk of injury to human health." Occupational inhalation exposure is associated with short- and long-term damage to the respiratory, female reproductive, and nervous systems, and is also carcinogenic. The European Union (EU) has recently introduced formaldehyde workplace exposure limits (WELs) that are lower (long-term: 0.3ppm; short-term: 0.6ppm) than those currently applied in the United Kingdom (UK) (long-term: 2ppm; short-term: 2ppm). UK regulation additionally requires exposure to carcinogens to be reduced to as low as is reasonably practicable. We evaluated formaldehyde airborne concentrations in National Health Service (NHS) cell pathology departments to assess the adequacy of exposure controls. MethodsUsing the Freedom of Information Act (2000), we requested 12 months (2024-2025) of formaldehyde airborne monitoring data collected by cell pathology departments across n=122 NHS Trusts in England (n=102), Scotland (n=10), Wales (n=6), and Northern Ireland (n=4). Results were evaluated empirically and using EN 689:2018 statistical methods to assess exposure variability, estimate upper-bound concentrations, and determine the likelihood of adequate exposure control when benchmarked against EU WELs. ResultsA total of 1,715,516 formaldehyde airborne monitoring results were disclosed by n=117 cell pathology departments. Monitoring was infrequent, with 73% of sites measuring formaldehyde airborne concentrations once weekly or less. EU long-term WELs were exceeded regularly at 70% of sites (95th percentile >0.3 ppm), and EU short-term WELs were exceeded regularly at 43% of sites (95th percentile >0.6 ppm). The 95th percentile upper tolerance limit (UTL95,70) exceeded the EU short-term WEL at 68% of sites. Only 11% and 17% of departments demonstrated frequent (once daily or more) formaldehyde airborne monitoring with 95th percentiles below the EU long- and short-term WELs, respectively. ConclusionsFormaldehyde exposure is infrequently monitored and inadequately controlled in NHS cell pathology departments. What is already knownA substantial body of occupational exposure data shows that formaldehyde inhalation is associated with myriad short- and long-term deleterious health effects on the respiratory, female reproductive, and nervous systems. It is also a human carcinogen. Pathology departments are amongst the riskiest occupational environments for formaldehyde inhalation exposure and therefore require a high standard of governance and infrastructure to adequately protect staff. What this study addsWe show that formaldehyde airborne concentrations in most NHS cell pathology departments are monitored infrequently and regularly exceed EU WELs. Our data raises concern for the health of thousands of NHS employees working in these environments. How this study might affect research, practice, or policyUrgent national regulatory intervention is now warranted to improve the occupational hygiene of NHS cell pathology departments. This will require a combination of upgraded infrastructure, more regular personal exposure monitoring, better employee education on basic lab practice and occupational health risks, improved access to appropriate personal protective equipment, management accountability for occupational health, and external oversight by the Health and Safety Executive.

BackgroundHealthcare-associated infections (HAIs) constitute a significant financial strain on healthcare systems across the world, with surgical site infections (SSIs) being the costliest form. Despite the existence of diverse sources of infection in the operating room (OR), current literature focuses on human and procedural sources of contamination that could lead to an infection. Comparatively, the OR built environment is understudied as a potential disease transmission interface between the environment, patients, and surgical staff. This systematic literature review aims to investigate how the physical characteristics and components of the built environment impact airflow, infection risk, aerosols, particle counts, contamination, and pathogens in operating rooms. Methods and FindingsLiterature searches were conducted in the PubMed and Web of Science Core Collection databases on December 21, 2020, ultimately retrieving 2,965 articles after duplicates were removed. During abstract screening, all abstracts were independently reviewed by two authors and conflicts were resolved by a third author. All articles published since January 1, 2010, that reported primary data investigating an aspect of the built environment inside an OR in relation to airflow, contamination, and/or infection for which the full text in English was available were included. This resulted in the inclusion of 138 articles, which includes studies conducted in ORs during active surgeries, computer modeling studies, and simulations in which a real OR was used for a mock surgical procedure. Six major built environment categories were identified based on the collected literature: OR layout, disinfection systems, surgical lights, doors, ventilation, and portable airflow devices. A survey created on Qualtrics software was used to record the aspect of the built environment and the outcome of each study, as well as the relationship between the two. ConclusionsWhile OR ventilation has been studied extensively, the OR built environment as a whole is understudied in relation to airflow, contamination, and infection. The current literature is inconsistent in both its findings and subsequent recommendations, making it difficult to inform hospital design in the context of SSIs. No articles were identified that discussed respiratory infection transmission in the OR, and very few addressed healthcare worker (HCW) safety in relation to the OR built environment. The significant discrepancies in the literature identified in this review highlight the need for future studies that assess the quality and bias of these studies before firm recommendations can be made. Future work should also focus on addressing the lack information regarding respiratory infection transmission in the OR, especially in the context of HCW safety.