SARS-CoV-2 surface and air contamination in an acute healthcare setting during the first and second pandemic waves

BACKGROUND

Surfaces and air in healthcare facilities can be contaminated with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Previously, the authors identified SARS-CoV-2 RNA on surfaces and air in their hospital during the first wave of the coronavirus disease 2019 pandemic (April 2020).

AIM

To explore whether the profile of SARS-CoV-2 surface and air contamination had changed between April 2020 and January 2021.

METHODS

This was a prospective, cross-sectional, observational study in a multi-site London hospital. In January 2021, surface and air samples were collected from comparable areas to those sampled in April 2020, comprising six clinical areas and a public area. SARS-CoV-2 was detected using reverse transcription polymerase chain reaction and viral culture. Sampling was also undertaken in two wards with natural ventilation alone. The ability of the prevalent variants at the time of the study to survive on dry surfaces was evaluated.

FINDINGS

No viable virus was recovered from surfaces or air. Five percent (N=14) of 270 surface samples and 4% (N=1) of 27 air samples were positive for SARS-CoV-2, which was significantly lower than in April 2020 [52% (N=114) of 218 surface samples and 48% (N=13) of 27 air samples (P<0.001, Fisher's exact test)]. There was no clear difference in the proportion of surface and air samples positive for SARS-CoV-2 RNA based on the type of ventilation in the ward. All variants tested survived on dry surfaces for >72 h, with a <3-log10 reduction in viable count.

CONCLUSION

This study suggests that enhanced infection prevention measures have reduced the burden of SARS-CoV-2 RNA on surfaces and air in healthcare facilities.

Hospital-onset COVID-19 infection surveillance systems: a systematic review

Hospital-onset COVID-19 infections (HOCIs) are associated with excess morbidity and mortality in patients and healthcare workers. The aim of this review was to explore and describe the current literature in HOCI surveillance. Medline, EMBASE, the Cochrane Database of Systematic Reviews, the Cochrane Register of Controlled Trials, and MedRxiv were searched up to 30 November 2020 using broad search criteria. Articles of HOCI surveillance systems were included. Data describing HOCI definitions, HOCI incidence, types of HOCI identification surveillance systems, and level of system implementation were extracted. A total of 292 citations were identified. Nine studies on HOCI surveillance were included. Six studies reported on the proportion of HOCI among hospitalized COVID-19 patients, which ranged from 0 to 15.2%. Six studies provided HOCI case definitions. Standardized national definitions provided by the UK and US governments were identified. Four studies included healthcare workers in the surveillance. One study articulated a multimodal strategy of infection prevention and control practices including HOCI surveillance. All identified HOCI surveillance systems were implemented at institutional level, with eight studies focusing on all hospital inpatients and one study focusing on patients in the emergency department. Multiple types of surveillance were identified. Four studies reported automated surveillance, of which one included real-time analysis, and one included genomic data. Overall, the study quality was limited by the observational nature with short follow-up periods. In conclusion, HOCI case definitions and surveillance methods were developed pragmatically. Whilst standardized case definitions and surveillance systems are ideal for integration with existing routine surveillance activities and adoption in different settings, we acknowledged the difficulties in establishing such standards in the short-term.

The cost-effectiveness of temporary single-patient rooms to reduce risks of healthcare-associated infection

BACKGROUND

The use of single rooms for patient isolation often forms part of a wider bundle to prevent certain healthcare-associated infections (HAIs) in hospitals. Demand for single rooms often exceeds what is available and the use of temporary isolation rooms may help resolve this. Changes to infection prevention practice should be supported by evidence showing that cost-effectiveness is plausible and likely.

AIM

To perform a cost-effectiveness evaluation of adopting temporary single rooms into UK National Health Service (NHS) hospitals.

METHODS

The cost-effectiveness of a decision to adopt a temporary, single-patient, isolation room to the current infection prevention efforts of an NHS hospital was modelled. Primary outcomes are the expected change to total costs and life-years from an NHS perspective.

FINDINGS

The mean expected incremental cost per life-year gained (LYG) is £5,829. The probability that adoption is cost-effective against a £20,000 threshold per additional LYG is 93%, and for a £13,000 threshold the probability is 87%. The conclusions are robust to scenarios for key model parameters. If a temporary single-patient isolation room reduces risks of HAI by 16.5% then an adoption decision is more likely to be cost-effective than not. Our estimate of the effectiveness reflects guidelines and reasonable assumptions and the theoretical rationale is strong.

CONCLUSION

Despite uncertainties about the effectiveness of temporary isolation rooms for reducing risks of HAI, there is some evidence that an adoption decision is likely to be cost-effective for the NHS setting. Prospective studies will be useful to reduce this source of uncertainty.

Evaluation of a personal protective equipment support programme for staff during the COVID-19 pandemic in London

BACKGROUND

The coronavirus disease 2019 pandemic has presented an enormous challenge to healthcare providers worldwide. The appropriate use of personal protective equipment (PPE) has been essential to ensure staff and patient safety. The 'PPE Helper Programme' was developed at a large London hospital group to counteract suboptimal PPE practice. Based on a behaviour change model of capability, opportunity and motivation (COM-B), the programme provided PPE support, advice and education to ward staff.

AIM

Evaluation of the PPE Helper Programme.

METHODS

Clinical and non-clinical ward staff completed a questionnaire informed by the Theoretical Domains Framework and COM-B model. The questionnaire was available in paper and electronic versions. Quantitative responses were analysed using descriptive and non-parametric statistics, and free-text responses were analysed thematically.

FINDINGS

Over a 6-week period, PPE helpers made 268 ward visits. Overall, 261 questionnaires were available for analysis. Across the Trust, 68% of respondents reported having had contact with a PPE helper. Staff who had encountered a PPE helper responded significantly more positively to a range of statements about using PPE than staff who had not encountered a PPE helper. Black and minority ethnic staff were significantly more anxious regarding the adequacy of PPE. Non-clinical and redeployed staff (e.g. domestic staff) were most positive about the impact of PPE helpers. Free-text comments showed that staff found the PPE Helper Programme supportive and would have liked it earlier in the pandemic.

CONCLUSION

The PPE Helper Programme is a feasible and beneficial intervention for providing support, advice and education to ward staff during infectious disease outbreaks.

Development and Delivery of a Real-time Hospital-onset COVID-19 Surveillance System Using Network Analysis

Background

Understanding nosocomial acquisition, outbreaks, and transmission chains in real time will be fundamental to ensuring infection-prevention measures are effective in controlling coronavirus disease 2019 (COVID-19) in healthcare. We report the design and implementation of a hospital-onset COVID-19 infection (HOCI) surveillance system for an acute healthcare setting to target prevention interventions.

Methods

The study took place in a large teaching hospital group in London, United Kingdom. All patients tested for SARS-CoV-2 between 4 March and 14 April 2020 were included. Utilizing data routinely collected through electronic healthcare systems we developed a novel surveillance system for determining and reporting HOCI incidence and providing real-time network analysis. We provided daily reports on incidence and trends over time to support HOCI investigation and generated geotemporal reports using network analysis to interrogate admission pathways for common epidemiological links to infer transmission chains. By working with stakeholders the reports were co-designed for end users.

Results

Real-time surveillance reports revealed changing rates of HOCI throughout the course of the COVID-19 epidemic, key wards fueling probable transmission events, HOCIs overrepresented in particular specialties managing high-risk patients, the importance of integrating analysis of individual prior pathways, and the value of co-design in producing data visualization. Our surveillance system can effectively support national surveillance.

Conclusions

Through early analysis of the novel surveillance system we have provided a description of HOCI rates and trends over time using real-time shifting denominator data. We demonstrate the importance of including the analysis of patient pathways and networks in characterizing risk of transmission and targeting infection-control interventions.

How do surgeons feel about the 'Getting it Right First Time' national audit? Results from a qualitative assessment

The implementation of the national 'Getting It Right First Time' was assessed by interviewing six surgeons involved at various levels in surgical site infection (SSI) audit. The positive impacts were to create new professional collaboration, improve stakeholder engagement, and increase the profile of SSIs. One particular knowledge gap highlighted was that some participants had been unaware until that point of the criteria for diagnosing an SSI. The quality of data collected was felt to be poor due to methodological flaws. The audit was described as highly time-consuming and unsustainable if leaning on junior surgeons, without protected time and designated responsibility.

Individual- and community-level risk factors for ESBL Enterobacteriaceae colonization identified by universal admission screening in London

OBJECTIVES

We evaluated risk factors for gastrointestinal carriage of Enterobacteriaceae which produce extended-spectrum β-lactamases (ESBL-E), including individual-level variables such as antibiotic use and foreign travel, and community-level variables such as housing and deprivation.

METHODS

In an observational study in 2015, all patients admitted to a London hospital group were approached to be screened for ESBL-E carriage using rectal swabs for 4 months. Patients completed a risk factor questionnaire. Those with a residential postcode in the local catchment area were linked to a database containing community-level risk factor data. Risk factors for ESBL-E carriage were determined by binary logistic regression.

RESULTS

Of 4006 patients, 360 (9.0%) carried ESBL-E. Escherichia coli was the most common organism (77.8%), and CTX-M-type ESBLs were the most common genes (57.9% CTX-M-15 and 20.7% CTX-M-9). In multivariable analysis, risk factors for phenotypic ESBL-E among the 1633 patients with a residential postcode within the local catchment area were: travel to Asia (OR 4.4, CI 2.5-7.6) or Africa (OR 2.4, CI 1.2-4.8) in the 12 months prior to admission, two or more courses of antibiotics in the 6 months prior to admission (OR 2.0, CI 1.3-3.0), and residence in a district with a higher-than-average prevalence of overcrowded households (OR 1.5, CI 1.05-2.2). .

CONCLUSIONS

Both individual and community variables were associated with ESBL-E carriage at hospital admission. The novel observation that household overcrowding is associated with ESBL-E carriage requires confirmation, but raises the possibility that targeted interventions in the community could help prevent transmission of antibiotic-resistant Gram-negative bacteria.

Planning to halve Gram-negative bloodstream infection: getting to grips with healthcare-associated Escherichia coli bloodstream infection sources

BACKGROUND

A thorough understanding of the local sources, risks, and antibiotic resistance for Escherichia coli bloodstream infection (BSI) is required to focus prevention initiatives and therapy.

AIM

To review the sources and antibiotic resistance of healthcare-associated E. coli BSI.

METHODS

Sources and antibiotic resistance profiles of all 250 healthcare-associated (post 48 h) E. coli BSIs that occurred within our secondary and tertiary care hospital group from April 2014 to March 2017 were reviewed. Epidemiological associations with urinary source, gastrointestinal source, and febrile neutropenia-related BSIs were analysed using univariable and multivariable binary logistic regression models.

FINDINGS

E. coli BSIs increased 9% from 4.0 to 4.4 per 10,000 admissions comparing the 2014/15 and 2016/17 financial years. Eighty-nine cases (36%) had a urinary source; 30 (34%) of these were classified as urinary catheter-associated urinary tract infections (UTIs). Forty-five (18%) were related to febrile neutropenia, and 38 (15%) had a gastrointestinal source. Cases were rarely associated with surgical procedures (11, 4%) or indwelling vascular devices (seven, 3%). Female gender (odds ratio: 2.3; 95% confidence interval: 1.2-4.6) and older age (1.02; 1.00-1.05) were significantly associated with a urinary source. No significant associations were identified for gastrointestinal source or febrile neutropenia-related BSIs. Forty-seven percent of the isolates were resistant to ciprofloxacin, 37% to third-generation cephalosporins, and 22% to gentamicin.

CONCLUSION

The gastrointestinal tract and febrile neutropenia together accounted for one-third of E. coli BSI locally but were rare associations nationally. These sources need to be targeted locally to reduce an increasing trend of E. coli BSIs.

Comparison of national strategies to reduce meticillin-resistant Staphylococcus aureus infections in Japan and England

BACKGROUND

National responses to healthcare-associated infections vary between high-income countries, but, when analysed for contextual comparability, interventions can be assessed for transferability.

AIM

To identify learning from country-level approaches to addressing meticillin-resistant Staphylococcus aureus (MRSA) in Japan and England.

METHODS

A longitudinal analysis (2000-2017), comparing epidemiological trends and policy interventions. Data from 441 textual sources concerning infection prevention and control (IPC), surveillance, and antimicrobial stewardship interventions were systematically coded for: (a) type: mandatory requirements, recommendations, or national campaigns; (b) method: restrictive, persuasive, structural in nature; (c) level of implementation: macro (national), meso (organizational), micro (individual) levels. Healthcare organizational structures and role of media were also assessed.

FINDINGS

In England significant reduction has been achieved in number of reported MRSA bloodstream infections. In Japan, in spite of reductions, MRSA remains a predominant infection. Both countries face new threats in the emergence of drug-resistant Escherichia coli. England has focused on national mandatory and structural interventions, supported by a combination of outcomes-based incentives and punitive mechanisms, and multi-disciplinary IPC hospital teams. Japan has focused on (non-mandatory) recommendations and primarily persuasive interventions, supported by process-based incentives, with voluntary surveillance. Areas for development in Japan include resourcing of dedicated data management support and implementation of national campaigns for healthcare professionals and the public.

CONCLUSION

Policy interventions need to be relevant to local epidemiological trends, while acceptable within the health system, culture, and public expectations. Cross-national learning can help inform the right mix of interventions to create sustainable and resilient systems for future infection and economic challenges.

Efficacy and acceptability of rectal and perineal sampling for identifying gastrointestinal colonization with extended spectrum β-lactamase Enterobacteriaceae

OBJECTIVES

We evaluated 'pre-laboratory' factors associated with the detection of extended spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) colonization including anatomical site, and staff and patient factors.

METHODS

All admissions to a large London hospital over 3 months were approached to provide rectal and perineal swabs, which were cultured for ESBL-E using chromogenic media. ESBL-E detection rates for patient- or staff-collected rectal or perineal swabs were compared using McNemar tests. Binary logistic regression was used to explore factors associated with patients declining to provide a rectal swab. The impact of simplifying the verbal study description to patients to improve the participation rate was evaluated.

RESULTS

Carriage of ESBL-E was significantly higher in rectal swabs than perineal swabs (7.8% of 4006 versus 3.8% of 4006, p <0.001), whether collected by staff or patients; 31.9% of 869 patients did not provide a rectal swab before the change in study description compared with 7.6% of 3690 patients afterwards (p <0.001). In multivariable analysis, factors associated with patients declining to provide a rectal swab were younger age (OR 0.99, 95% CI 0.99-1.00), female gender (OR 1.26, 95% CI 1.04-1.52), transfers from other hospitals (OR 1.77, 95% CI 1.07-2.93) or an unknown admission route (OR 1.61, 95% CI 1.09-2.37), being admitted before the change in study description (OR 0.39, 95% CI 0.31-0.48), and the staff member who consented the patient (p <0.001); ethnicity was not a significant factor.

CONCLUSIONS

Rectal swabs are recommended for the detection of ESBL-E colonization. Staff and patient factors influence whether patients participate in prevalence studies, which may skew their findings.

ID: 98: EFFECTIVENESS OF DAILY CHLORHEXIDINE BATHING FOR REDUCING GRAM NEGATIVE INFECTIONS: A META-ANALYSIS

Background

Multiple studies have demonstrated that daily chlorhexidine gluconate (CHG) bathing is associated with a significant reduction in infections caused by Gram positive pathogens. However, there is limited data on the effectiveness of daily CHG bathing on gram negative infections. The aim of this study was to determine if daily CHG bathing is effective in controlling and preventing gram negative infections in adult ICU patients.

Methods

We searched MEDLINE and 3 other databases for original studies comparing daily CHG bathing to soap and water bathing. All studies investigating the effectiveness of daily CHG bathing on gram negative infections were eligible. Two investigators extracted data independently on baseline characteristics, study design, form and concentration of CHG, incidence and outcomes related to gram negative infections. Data were combined by means of a random-effects model and pooled relative risk ratios (RRs) and 95% confidence intervals (CIs) were derived for overall gram negative infections and individual gram negative pathogens.

Results

Eleven studies (n=27,793 patients) met the inclusion criteria. Of these, 13,852 patients received daily CHG bathing, and 13,941 patients daily bathing with soap and water. Daily CHG bathing was not associated with a lower risk of gram negative infections (2.03% vs. 2.38%; RR 0.84; 95%CI: 0.64–1.09, P=.19). Subgroup analysis demonstrated that daily CHG bathing significantly reduced the risk of gram negative infections caused by Acinetobacter (RR, 0.33; 95% CI: 0.17–0.66, P<.00001) but was not effective for E. coli, Klebsiella, Enterobacter and Pseudomonas associated gram negative infections.

Conclusions

In a meta-analysis of 11 studies, the use of daily CHG was not associated with a lower risk of gram negative infections. However, daily CHG bathing appears to be effective for Acinetobacter associated gram negative infections. There is a need for larger and better designed trials with adequate power with gram negative infections as the primary endpoint to determine the effectiveness of daily CHG bathing.

Abstract ID: 98 Figure 1

Transmission of SARS and MERS coronaviruses and influenza virus in healthcare settings: the possible role of dry surface contamination

Viruses with pandemic potential including H1N1, H5N1, and H5N7 influenza viruses, and severe acute respiratory syndrome (SARS)/Middle East respiratory syndrome (MERS) coronaviruses (CoV) have emerged in recent years. SARS-CoV, MERS-CoV, and influenza virus can survive on surfaces for extended periods, sometimes up to months. Factors influencing the survival of these viruses on surfaces include: strain variation, titre, surface type, suspending medium, mode of deposition, temperature and relative humidity, and the method used to determine the viability of the virus. Environmental sampling has identified contamination in field-settings with SARS-CoV and influenza virus, although the frequent use of molecular detection methods may not necessarily represent the presence of viable virus. The importance of indirect contact transmission (involving contamination of inanimate surfaces) is uncertain compared with other transmission routes, principally direct contact transmission (independent of surface contamination), droplet, and airborne routes. However, influenza virus and SARS-CoV may be shed into the environment and be transferred from environmental surfaces to hands of patients and healthcare providers. Emerging data suggest that MERS-CoV also shares these properties. Once contaminated from the environment, hands can then initiate self-inoculation of mucous membranes of the nose, eyes or mouth. Mathematical and animal models, and intervention studies suggest that contact transmission is the most important route in some scenarios. Infection prevention and control implications include the need for hand hygiene and personal protective equipment to minimize self-contamination and to protect against inoculation of mucosal surfaces and the respiratory tract, and enhanced surface cleaning and disinfection in healthcare settings.

Controversies in guidelines for the control of multidrug-resistant Gram-negative bacteria in EU countries

The various guidelines that are available for multidrug-resistant Gram-negative bacteria are useful, and contain broad areas of agreement. However, there are also important areas of controversy between the guidelines in terms of the details of applying contact precautions, single-room isolation and active surveillance cultures, differences in the approach to environmental cleaning and disinfection, and whether or not to perform staff and patient cohorting, healthcare worker screening or patient decolonization. The evidence-base is extremely limited and further research is urgently required to inform an evidence-based approach to multidrug-resistant Gram-negative bacteria prevention and control.

What's trending in the infection prevention and control literature? From HIS 2012 to HIS 2014, and beyond

This is an informal review of some of the trends in the infection prevention and control literature since the last Healthcare Infection Society (HIS) conference in late 2012. Google Trends was used to investigate how the volume of interest in various infection control topics had changed over time. Ebola trumped all the others in Google searches, reflecting a surge of publications in the literature. Aside from Ebola, other trends in the infection prevention and control literature covered in this article include Middle East Respiratory Syndrome (MERS) coronavirus, universal versus targeted interventions, faecal microbiota transplantation, whole genome sequencing, carbapenem-resistant Enterobacteriaceae, and some aspects of environmental science. The review ends with an attempt to predict some of the trends in the infection prevention and control literature between now and the next HIS conference in 2016.

Aqueous oxygen peroxide treatment of VLUs in a primary care-based randomised, double-blind, placebo-controlled trial

OBJECTIVE

To evaluate a novel aqueous oxygen peroxide (AOP) wound therapy (BioxyQuell) in a multi-centre, primary care-based, randomised, double-blind, placebo-controlled, parallel-group trial, monitoring long-term healing outcomes over 12 months.

METHOD

Sixty-one patients with chronic, stable venous leg ulceration were treated with either AOP solution or sterile water placebo applied as a lavage over 2 weeks. The patients' wounds were dressed weekly and assessed fortnightly over the following 6 weeks. Patients who completed the initial 8-week trial were invited into a 10-month follow-up trial. The primary endpoints of the study were wound healing at 8 weeks, 12 weeks, 6 months and 12 months, and wound size reduction during the treatment phase. Secondary endpoints were reductions in wound bioburden and pain.

RESULTS

Patients treated with AOP were more likely to heal at 6 months (p=0.014) and 12 months (p=0.006), but not at 8 weeks (p=0.979) or 12 weeks (p=0.263). Patients treated with AOP had greater wound area reduction (p=0.015), reductions in pain measured on a 100-point scale (p=0.001) and wound bioburden reduction (p=0.005) during the treatment phase.

CONCLUSION

The addition of AOP treatment provides substantial benefits to patients with chronic venous leg ulceration compared with current best practice.

Implications of targeted versus universal admission screening for meticillin-resistant Staphylococcus aureus carriage in a London hospital

Universal admission screening for meticillin-resistant Staphylococcus aureus (MRSA) has been performed in England since 2010. We evaluated the predictive performance of a regression model derived from the first year of universal screening for detecting MRSA at hospital admission. If we had used our previous targeted screening policy, 75% fewer patients (21,699 per year) would have been screened. However, this would have identified only ~55% of all MRSA carriers, 65% of healthcare-associated MRSA strains, and 40% of community-associated strains. Failing to identify ~45% of patients (262 per year) carrying MRSA at hospital admission may have implications for MRSA control.

Evaluating the virucidal efficacy of hydrogen peroxide vapour

BACKGROUND

Surface contamination has been implicated in the transmission of certain viruses, and surface disinfection can be an effective measure to interrupt the spread of these agents.

AIM

To evaluate the in-vitro efficacy of hydrogen peroxide vapour (HPV), a vapour-phase disinfection method, for the inactivation of a number of structurally distinct viruses of importance in the healthcare, veterinary and public sectors. The viruses studied were: feline calicivirus (FCV, a norovirus surrogate); human adenovirus type 1; transmissible gastroenteritis coronavirus of pigs (TGEV, a severe acute respiratory syndrome coronavirus [SARS-CoV] surrogate); avian influenza virus (AIV); and swine influenza virus (SwIV).

METHODS

The viruses were dried on stainless steel discs in 20- or 40-μL aliquots and exposed to HPV produced by a Clarus L generator (Bioquell, Horsham, PA, USA) in a 0.2-m(3) environmental chamber. Three vaporized volumes of hydrogen peroxide were tested in triplicate for each virus: 25, 27 and 33 mL.

FINDINGS

No viable viruses were identified after HPV exposure at any of the vaporized volumes tested. HPV was virucidal (>4-log reduction) against FCV, adenovirus, TGEV and AIV at the lowest vaporized volume tested (25 mL). For SwIV, due to low virus titre on the control discs, >3.8-log reduction was shown for the 25-mL vaporized volume and >4-log reduction was shown for the 27-mL and 33-mL vaporized volumes.

CONCLUSION

HPV was virucidal for structurally distinct viruses dried on surfaces, suggesting that HPV can be considered for the disinfection of virus-contaminated surfaces.

Low prevalence of meticillin-resistant Staphylococcus aureus carriage at hospital admission: implications for risk-factor-based vs universal screening

BACKGROUND

There is debate over the optimal policy for detecting meticillin-resistant Staphylococcus aureus (MRSA) colonization at hospital admission. The emergence of community-associated (CA)-MRSA may compromise targeted screening strategies based on risk factors for healthcare-associated (HA)-MRSA.

AIM

To determine the prevalence of MRSA colonization at admission, and the genotype and molecular epidemiology of the strains involved.

METHODS

A 12-month observational study was performed at a 1200-bed London tertiary referral hospital from 1 April 2008 to 1 March 2009. All available MRSA isolates were genotyped by spa and staphylococcal cassette chromosome mec (SCCmec) typing.

FINDINGS

The overall MRSA colonization rate was 2.0% of 28,892 admissions (range 6.6% in critical care to 0.8% in obstetrics/gynaecology/neonatology). The overall frequency of previously unknown carriage of MRSA on admission was 1.4%. Most colonizing strains were epidemic HA-MRSA-15 and -16. However, heterogeneous CA strains accounted for 18% of recovered isolates, including 37.5% of MRSA from accident and emergency and 23.1% of MRSA from surgery. The CA-MRSA strain types had significantly different epidemiological associations from the HA-MRSA strains, so risk factors used for the identification of HA-MRSA may not detect CA-MRSA reliably.

CONCLUSION

The low rate of HA-MRSA in the UK increases the relative proportion due to CA-MRSA, for which conventional risk-factor-based screening strategies may be less effective. Cost-benefit analyses of universal MRSA admission screening will need to take account of this new epidemiology.

The role of 'no-touch' automated room disinfection systems in infection prevention and control

BACKGROUND

Surface contamination in hospitals is involved in the transmission of pathogens in a proportion of healthcare-associated infections. Admission to a room previously occupied by a patient colonized or infected with certain nosocomial pathogens increases the risk of acquisition by subsequent occupants; thus, there is a need to improve terminal disinfection of these patient rooms. Conventional disinfection methods may be limited by reliance on the operator to ensure appropriate selection, formulation, distribution and contact time of the agent. These problems can be reduced by the use of 'no-touch' automated room disinfection (NTD) systems.

AIM

To summarize published data related to NTD systems.

METHODS

Pubmed searches for relevant articles.

FINDINGS

A number of NTD systems have emerged, which remove or reduce reliance on the operator to ensure distribution, contact time and process repeatability, and aim to improve the level of disinfection and thus mitigate the increased risk from the prior room occupant. Available NTD systems include hydrogen peroxide (H(2)O(2)) vapour systems, aerosolized hydrogen peroxide (aHP) and ultraviolet radiation. These systems have important differences in their active agent, delivery mechanism, efficacy, process time and ease of use. Typically, there is a trade-off between time and effectiveness among NTD systems. The choice of NTD system should be influenced by the intended application, the evidence base for effectiveness, practicalities of implementation and cost constraints.

CONCLUSION

NTD systems are gaining acceptance as a useful tool for infection prevention and control.

Community-associated meticillin-resistant Staphylococcus aureus strains as a cause of healthcare-associated infection

Community-associated meticillin-resistant Staphylococcus aureus (CA-MRSA) was first noticed as a cause of infection in community-based individuals without healthcare contact. As the global epidemic of CA-MRSA has continued, CA-MRSA strain types have begun to emerge as a cause of healthcare-associated infections (HAIs) and hospital outbreaks have occurred worldwide. In areas where CA-MRSA clones have become established with high prevalence, for example USA300 (ST8-IV) in the USA, CA-MRSA are beginning to supplant or overtake traditional healthcare-associated MRSA strains as causes of HAI. The emergence of CA-MRSA as a cause of HAI puts a wider group of hospitalised patients, healthcare workers and their community contacts potentially at risk of MRSA infection. It also exposes CA-MRSA strains to the selective pressure of antibiotic use in hospitals, potentially resulting in increased antibiotic resistance, challenges traditional definitions of CA-MRSA and hampers control efforts due to the constant re-introduction of MRSA from an emerging community reservoir. There is thus an urgent need to clarify the definitions, prevalence and epidemiology of CA-MRSA and to develop systems for the identification and control of these organisms in the community, in hospitals and other healthcare facilities, and at the community-hospital interface.

Utility of antimicrobial susceptibility-based algorithms for the presumptive identification of genotypically-defined community-associated methicillin-resistant Staphylococcus aureus at a London teaching hospital

PURPOSE

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains are classically characterised by susceptibility to most non-β-lactam antimicrobial agents. We sought to determine whether antimicrobial susceptibility (AMS)-based algorithms could be used to presumptively identify CA-MRSA in a hospital MRSA collection.

METHODS

Over a three-month period, all MRSA were tested for AMS, staphylococcal cassette chromosome mec (SCCmec) type, presence of the Panton-Valentine leukocidin (PVL) genes and spa type. CA-MRSA isolates were defined genotypically using a combination of spa and SCCmec type. AMS based algorithms were developed and tested for their sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

RESULTS

Ciprofloxacin susceptibility (p < 0.001) and fusidic acid resistance (p  = 0.044) were independent predictors of CA-MRSA in a multivariate model. Although 98.5% of HA-MRSA were ciprofloxacin resistant, so too were 36.6% of CA-MRSA. Algorithms based on ciprofloxacin-susceptibility and fusidic acid resistance performed best, with specificity and NPV >90% and sensitivity and PPV >70%.

CONCLUSIONS

Our data indicate that while ciprofloxacin-susceptible isolates are likely to be CA-MRSA, the use of ciprofloxacin-susceptibility as a marker of CA-MRSA would miss approximately one third of CA-MRSA isolates. Therefore, AMS patterns have limited utility for the identification of genetically-defined CA-MRSA in our setting.

The emergence of community-associated methicillin-resistant Staphylococcus aureus at a London teaching hospital, 2000-2006

We used ciprofloxacin susceptibility as a phenotypic marker of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in a London hospital collection of MRSA isolates from inpatients, outpatients and primary-care clinics during 2000-2006. Four-hundred and fifty-eight ciprofloxacin-susceptible (Cip-S) MRSA isolates were reported; antimicrobial susceptibility, staphylococcal cassette chromosome mec (SCCmec) type, spa type and the presence of Panton-Valentine leukocidin (PVL) genes were determined for all 194 surviving Cip-S MRSA isolates. Multilocus sequence typing and pulsed-field gel electrophoresis were performed on representative isolates. Clinical and epidemiological features of Cip-S MRSA infections were consistent with CA-MRSA, the incidence of which increased markedly during the study period from 49 in 2000 to 102 in 2006. Most (82.0%) of the surviving Cip-S MRSA isolates were SCCmec IV and 25.3% were PVL-positive. Considerable clonal heterogeneity was noted among the recovered isolates, including the t044/ST80-IV European clone and the PVL-negative t127/ST1-IV clone; PVL-positive t008/ST8-IV (USA300) isolates were rare. Ciprofloxacin susceptibility is a useful screening marker of CA-MRSA strains in London, which are more frequent than previously thought and whose incidence is increasing.

Identification and control of an outbreak of ciprofloxacin-susceptible EMRSA-15 on a neonatal unit

We report the identification and control of an outbreak of a ciprofloxacin-susceptible strain of UK epidemic meticillin-resistant Staphylococcus aureus (EMRSA)-15 on a neonatal unit (NNU). All babies were screened for MRSA on admission using ciprofloxacin-containing media which did not detect the outbreak strain. The first identified case was a premature baby who developed MRSA bacteraemia with associated tibial osteomyelitis and multiple subcutaneous abscesses. The outbreak strain was subsequently identified in the nasopharyngeal secretions of a second child who was not clinically infected. Screening of all patients on the NNU using non-ciprofloxacin-media identified two other colonised babies. All four patient isolates were EMRSA-15, spa type t022, SCCmec IV, Panton-Valentine leucocidin (PVL) negative, indistinguishable by pulsed-field gel electrophoresis and susceptible to all non-beta-lactam antimicrobials tested. The outbreak strain was cultured from four of 48 environmental sites in a communal milk-expressing room. Unsupervised movement of mothers to and from the milk-expressing room may have contributed to the outbreak. Control measures included cohort isolation of affected babies, improved environmental cleaning, increased emphasis on hand hygiene and education of mothers. Ciprofloxacin-containing media should be used with caution for MRSA screening in settings where ciprofloxacin-susceptible strains (including community-associated MRSA) are increasing in prevalence.

Assessing the biological efficacy and rate of recontamination following hydrogen peroxide vapour decontamination

The inanimate hospital environment can become contaminated with nosocomial pathogens. Hydrogen peroxide vapour (HPV) decontamination has proven effective for the eradication of persistent environmental contamination. We investigated the extent of meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and gentamicin-resistant Gram-negative rod (GNR) contamination in a ward side-room occupied by a patient with a history of MRSA, VRE and GNR infection and colonisation and investigated the impact of HPV decontamination. Fifteen standardised sites in the room were sampled using a selective broth enrichment protocol to culture MRSA, VRE and GNR. Sampling was performed before cleaning, after cleaning, after HPV decontamination and at intervals over the subsequent 19 days on two separate occasions. Environmental contamination was identified before cleaning on 60, 30 and 6.7% of sites for MRSA, GNR and VRE, respectively, and 40, 10 and 6.7% of sites after cleaning. Only one site (3.3%) was contaminated with MRSA after HPV decontamination. No recontamination with VRE was identified and no recontamination with MRSA and GNR was identified during the two days following HPV decontamination. Substantial recontamination was identified approximately one week after HPV decontamination towards post-cleaning levels for GNR and towards pre-cleaning levels for MRSA. HPV is more effective than standard terminal cleaning for the eradication of nosocomial pathogens. Recontamination was not immediate for MRSA and GNR but contamination returned within a week in a room occupied by a patient colonised with MRSA and GNR. This finding has important implications for the optimal deployment of HPV decontamination in hospitals.

Tackling contamination of the hospital environment by methicillin-resistant Staphylococcus aureus (MRSA): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination

The hospital environment can sometimes harbour methicillin-resistant Staphylococcus aureus (MRSA) but is not generally regarded as a major source of MRSA infection. We conducted a prospective study in surgical wards of a London teaching hospital affected by MRSA, and compared the effectiveness of standard cleaning with a new method of hydrogen peroxide vapour decontamination. MRSA contamination, measured by surface swabbing was compared before and after terminal cleaning that complied with UK national standards, or hydrogen peroxide vapour decontamination. All isolation rooms, ward bays and bathrooms tested were contaminated with MRSA and several antibiogram types were identified. MRSA was common in sites that might transfer organisms to the hands of staff and was isolated from areas and bed frames used by non-MRSA patients. Seventy-four percent of 359 swabs taken before cleaning yielded MRSA, 70% by direct plating. After cleaning, all areas remained contaminated, with 66% of 124 swabs yielding MRSA, 74% by direct plating. In contrast, after exposing six rooms to hydrogen peroxide vapour, only one of 85 (1.2%) swabs yielded MRSA, by enrichment culture only. The hospital environment can become extensively contaminated with MRSA that is not eliminated by standard cleaning methods. In contrast, hydrogen peroxide vapour decontamination is a highly effective method of eradicating MRSA from rooms, furniture and equipment. Further work is needed to determine the importance of environmental contamination with MRSA and the effect on hospital infection rates of effective decontamination.

Evaluation of hydrogen peroxide vapour as a method for the decontamination of surfaces contaminated with Clostridium botulinum spores

The aim of this study was to evaluate the efficacy of hydrogen peroxide vapour (HPV) against spores of Clostridium botulinum, for use as a method for decontaminating environments where this pathogen has been handled. Spores were dried onto stainless steel slides and exposed to HPV in a sealed glovebox enclosure, transferred to a quenching agent at timed intervals during the exposure period, before survivors were cultured and enumerated. D-values were calculated from graphs of log10 survivors plotted against time and were found to range from 1.41 to 4.38 min. HPV was found to be effective at deactivating spores of toxigenic Cl. botulinum, non-toxigenic Clostridium spp. and Geobacillus stearothermophilus dried onto stainless steel surfaces. HPV could be used to decontaminate cabinets and rooms where Cl. botulinum has been handled. The cycle parameters should be based on studies carried out with relevant spores of this organism, rather than based on inactivation data for G. stearothermophilus spores, which have been used in the past as a standard biological challenge for disinfection and sterilisation procedures. HPV could provide an attractive alternative to other decontamination methods, as it was rapid, residue-free and did not give rise to the health and safety concerns associated with other gaseous decontamination systems.