Comparison of strategies to reduce meticillin-resistant Staphylococcus aureus rates in surgical patients: a controlled multicentre intervention trial

Effect of contact precautions on preventing meticillin-resistant Staphylococcus aureus transmission in intensive care units: a review and modelling study of field trials

BACKGROUND

Contact precautions (CPs) have been widely implemented in hospitals, particularly in intensive care units (ICUs), as the standard approach for managing meticillin-resistant Staphylococcus aureus (MRSA). However, the effectiveness of CPs in preventing MRSA transmission remains a subject of debate.

AIM

To assess the effectiveness of CPs in reducing MRSA transmission within ICUs.

METHODS

A comprehensive analysis was conducted using data from 16 sets of parameters collected from 13 field studies investigating the effectiveness of CPs in ICUs, and an epidemiologic model was developed to simulate the dynamics of MRSA incidence in the hospital setting.

FINDINGS

The analysis demonstrated a mean reduction of 20.52% (95% confidence interval -30.52 to 71.60%) in the MRSA transmission rate associated with the implementation of CPs. Furthermore, reducing the time-delay of screening tests and increasing the percentage of patients identified with MRSA through screening at admission were found to contribute to the effectiveness of CPs.

CONCLUSION

Proper implementation of CPs, with a particular emphasis on early identification of MRSA-colonized/infected patients, demonstrated a strong association with reduced MRSA transmission within the hospital setting. However, further research is necessary to investigate the effectiveness and safety of decolonization and other interventions used in conjunction with CPs to mitigate the risk of infection among colonized patients.

Postoperative Staphylococcus aureus Infections in Patients With and Without Preoperative Colonization

Importance

Staphylococcus aureus surgical site infections (SSIs) and bloodstream infections (BSIs) are important complications of surgical procedures for which prevention remains suboptimal. Contemporary data on the incidence of and etiologic factors for these infections are needed to support the development of improved preventive strategies.

Objectives

To assess the occurrence of postoperative S aureus SSIs and BSIs and quantify its association with patient-related and contextual factors.

Design, Setting, and Participants

This multicenter cohort study assessed surgical patients at 33 hospitals in 10 European countries who were recruited between December 16, 2016, and September 30, 2019 (follow-up through December 30, 2019). Enrolled patients were actively followed up for up to 90 days after surgery to assess the occurrence of S aureus SSIs and BSIs. Data analysis was performed between November 20, 2020, and April 21, 2022. All patients were 18 years or older and had undergone 11 different types of surgical procedures. They were screened for S aureus colonization in the nose, throat, and perineum within 30 days before surgery (source population). Both S aureus carriers and noncarriers were subsequently enrolled in a 2:1 ratio.

Exposure

Preoperative S aureus colonization.

Main Outcomes and Measures

The main outcome was cumulative incidence of S aureus SSIs and BSIs estimated for the source population, using weighted incidence calculation. The independent association of candidate variables was estimated using multivariable Cox proportional hazards regression models.

Results

In total, 5004 patients (median [IQR] age, 66 [56-72] years; 2510 [50.2%] female) were enrolled in the study cohort; 3369 (67.3%) were S aureus carriers. One hundred patients developed S aureus SSIs or BSIs within 90 days after surgery. The weighted cumulative incidence of S aureus SSIs or BSIs was 2.55% (95% CI, 2.05%-3.12%) for carriers and 0.52% (95% CI, 0.22%-0.91%) for noncarriers. Preoperative S aureus colonization (adjusted hazard ratio [AHR], 4.38; 95% CI, 2.19-8.76), having nonremovable implants (AHR, 2.00; 95% CI, 1.15-3.49), undergoing mastectomy (AHR, 5.13; 95% CI, 1.87-14.08) or neurosurgery (AHR, 2.47; 95% CI, 1.09-5.61) (compared with orthopedic surgery), and body mass index (AHR, 1.05; 95% CI, 1.01-1.08 per unit increase) were independently associated with S aureus SSIs and BSIs.

Conclusions and Relevance

In this cohort study of surgical patients, S aureus carriage was associated with an increased risk of developing S aureus SSIs and BSIs. Both modifiable and nonmodifiable etiologic factors were associated with this risk and should be addressed in those at increased S aureus SSI and BSI risk.

SHEA/IDSA/APIC Practice Recommendation: Strategies to prevent methicillin-resistant Staphylococcus aureus transmission and infection in acute-care hospitals: 2022 Update

Previously published guidelines have provided comprehensive recommendations for detecting and preventing healthcare-associated infections (HAIs). The intent of this document is to highlight practical recommendations in a concise format designed to assist acute-care hospitals in implementing and prioritizing efforts to prevent methicillin-resistant Staphylococcus aureus (MRSA) transmission and infection. This document updates the "Strategies to Prevent Methicillin-Resistant Staphylococcus aureus Transmission and Infection in Acute Care Hospitals" published in 2014.1 This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA). It is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the Association for Professionals in Infection Control and Epidemiology (APIC), the American Hospital Association (AHA), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise.

Impact of patient safety climate on infection prevention practices and healthcare worker and patient outcomes

BACKGROUND

Standard precautions may prevent patient health care associated infections and provider occupational exposures but are not often used by health care workers. A positive patient safety climate might contribute to improved adherence. The aim of this study was to determine the relationships among patient safety climate, standard precaution adherence, and health care worker exposures and HAIs.

METHODS

This multi-site, cross-sectional study included survey data from nurses on patient safety climate, observational data on adherence, and existing health care worker exposure and health care associated infections data. Data were aggregated to hospital unit level for correlational and multivariable regression analyses.

RESULTS

A total of 5,285 standard precaution observations and 452 surveys were collected across 43 hospital units. Observed adherence to all categories of standard precautions was 64.4%; there were significant differences by provider role. Multivariable models identified key predictors explaining sizeable variance in methicillin-resistant Staphylococcus aureus (41%), catheter associated urinary tract infections (23%), mucotaneous exposures (43%) and needlestick and sharps injuries (38%).

DISCUSSION

This study produced findings not previously published thus advancing the state of the science in patient and occupational health safety. These include identifying modifiable features of the safety climate and key organizational characteristics associated better outcomes.

CONCLUSIONS

In this novel study we identified that a positive patient safety climate and adherence to standard precautions predict key HAI and occupational health outcomes.

Strategies to prevent surgical site infections in acute-care hospitals: 2022 Update

The intent of this document is to highlight practical recommendations in a concise format designed to assist acute-care hospitals in implementing and prioritizing their surgical-site infection (SSI) prevention efforts. This document updates the Strategies to Prevent Surgical Site Infections in Acute Care Hospitals published in 2014. This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA). It is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the Association for Professionals in Infection Control and Epidemiology (APIC), the American Hospital Association (AHA), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise.

National surgical antibiotic prophylaxis guideline in Singapore

Introduction: Institutional surgical antibiotic prophylaxis (SAP) guidelines are in place at all public hospitals in Singapore, but variations exist and adherence to guidelines is not tracked consistently. A national point prevalence survey carried out in 2020 showed that about 60% of surgical prophylactic antibiotics were administered for more than 24 hours. This guideline aims to align best practices nationally and provides a framework for audit and surveillance. Method: This guideline was developed by the National Antimicrobial Stewardship Expert Panel’s National Surgical Antibiotic Prophylaxis Guideline Development Workgroup Panel, which comprises infectious diseases physicians, pharmacists, surgeons and anaesthesiologists. The Workgroup adopted the ADAPTE methodology framework with modifications for the development of the guideline. The recommended duration of antibiotic prophylaxis was graded according to the strength of consolidated evidence based on the scoring system of the Singapore Ministry of Health Clinical Practice Guidelines. Results: This National SAP Guideline provides evidence-based recommendations for the rational use of antibiotic prophylaxis. These include recommended agents, dose, timing and duration for patients undergoing common surgeries based on surgical disciplines. The Workgroup also provides antibiotic recommendations for special patient population groups (such as patients with β-lactam allergy and patients colonised with methicillin-resistant Staphylococcus aureus), as well as for monitoring and surveillance of SAP. Conclusion: This evidence-based National SAP Guideline for hospitals in Singapore aims to align practices and optimise the use of antibiotics for surgical prophylaxis for the prevention of surgical site infections while reducing adverse events from prolonged durations of SAP. Keywords: Antibiotic prophylaxis duration, antimicrobial resistance, antimicrobial stewardship, hospital-acquired infection, surgical site infections

Effectiveness of Extended Infection Control Measures on Methicillin-Resistant Staphylococcus aureus Infection Among Orthopaedic Patients

Purpose

The purpose of the study was to find the effectiveness of Extended Infection Control Measures (EICM) in reducing the rate of methicillin-resistant Staphylococcus aureus (MRSA) infection among orthopaedic surgery patients.

Methods

The study adopted a quasi-experimental design and was conducted in the orthopaedic units of a tertiary care hospital. This study recruited 168 orthopaedic patients and 154 healthcare professionals (HCPs). EICM included hand hygiene, decolonizing the patients and HCPS, staff education, feedback of surveillance data, treatment of high-risk and MRSA-infected patients, having separate equipment for MRSA-infected patients, and appropriate cleaning of patient's unit.

Results

The EICM effectively reduced MRSA infection from 21.2 to 6% (p < 0.001). It also resulted in improving the knowledge of HCPs in the prevention and management of MRSA infection (p < 0.001), and all colonized HCPs were successfully (100%) decolonized.

Conclusion

EICM is a promising intervention to combat MRSA infection among orthopaedic wards. Hence, it can be executed in orthopaedic wards, thereby improving the treatment quality and reducing the infection-related consequences.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43465-022-00713-5.

Surgical Antibiotic Prophylaxis in an Era of Antibiotic Resistance: Common Resistant Bacteria and Wider Considerations for Practice

The increasing incidence of antimicrobial resistance (AMR) presents a global crisis to healthcare, with longstanding antimicrobial agents becoming less effective at treating and preventing infection. In the surgical setting, antibiotic prophylaxis has long been established as routine standard of care to prevent surgical site infection (SSI), which remains one of the most common hospital-acquired infections. The growing incidence of AMR increases the risk of SSI complicated with resistant bacteria, resulting in poorer surgical outcomes (prolonged hospitalisation, extended durations of antibiotic therapy, higher rates of surgical revision and mortality). Despite these increasing challenges, more data are required on approaches at the institutional and patient level to optimise surgical antibiotic prophylaxis in the era of antibiotic resistance (AR). This review provides an overview of the common resistant bacteria encountered in the surgical setting and covers wider considerations for practice to optimise surgical antibiotic prophylaxis in the perioperative setting.

Methicillin-Resistant Staphylococcus aureus: An Update on Prevention and Control in Acute Care Settings

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of health-care-associated infections. Controversies regarding the effectiveness of various control strategies have contributed to varying approaches to MRSA control. However, new evidence from large-scale studies has emerged, particularly concerning screening and decolonization. Importantly, implementation and outcomes of control measures in practice are not only influenced by scientific evidence, but also economic, administrative, and political factors, as demonstrated by decreasing MRSA rates in a number of countries after concerted and coordinated efforts at a national level. Flexibility to adapt measures based on local epidemiology and resources is essential for successful MRSA control.

Applying thematic synthesis to interpretation and commentary in epidemiological studies: identifying what contributes to successful interventions to promote hand hygiene in patient care

OBJECTIVES

Hand hygiene is considered the most important preventive measure for healthcare-associated infections, but adherence is suboptimal. We previously undertook a Cochrane Review that demonstrated that interventions to improve adherence are moderately effective. Impact varied between organisations and sites with the same intervention and implementation approaches. This study seeks to explore these differences.

METHODS

A thematic synthesis was applied to the original authors' interpretation and commentary that offered explanations of how hand hygiene interventions exerted their effects and suggested reasons why success varied. The synthesis used a published Cochrane Review followed by three-stage synthesis.

RESULTS

Twenty-one papers were reviewed: 11 randomised, 1 non-randomised and 9 interrupted time series studies. Thirteen descriptive themes were identified. They reflected a range of factors perceived to influence effectiveness. Descriptive themes were synthesised into three analytical themes: methodological explanations for failure or success (eg, Hawthorne effect) and two related themes that address issues with implementing hand hygiene interventions: successful implementation needs leadership and cooperation throughout the organisation (eg, visible managerial support) and understanding the context and aligning the intervention with it drives implementation (eg, embedding the intervention into wider patient safety initiatives).

CONCLUSIONS

The analytical themes help to explain the original authors' perceptions of the degree to which interventions were effective and suggested new directions for research: exploring ways to avoid the Hawthorne effect; exploring the impact of components of multimodal interventions; the use of theoretical frameworks for behaviour change; potential to embed interventions into wider patient safety initiatives; adaptations to demonstrate sustainability; and the development of systematic approaches to implementation. Our findings corroborate studies exploring the success or failure of other clinical interventions: context and leadership are important.

Reducing transmission of methicillin-resistant Staphylococcus aureus in a surgical ward of a resource-limited hospital in Indonesia: an intervention study

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is endemic in healthcare settings in Indonesia.

Aim

To evaluate the effect of a bundle of preventive measures on the transmission and acquisition of MRSA in a surgical ward of a resource-limited hospital in Indonesia.

Methods

The study consisted of a pre-intervention (7 months), intervention (2 months), and post-intervention phase (5 months) and included screening for MRSA among eligible patients, healthcare workers (HCWs), and the hospital environment. In the intervention phase, a bundle of preventive actions was introduced, comprising: a hand hygiene educational program, cohorting of MRSA-positive patients, decolonization therapy for all MRSA-positive patients and HCWs, and cleaning and disinfection of the ward's innate environment. Hand hygiene compliance was assessed throughout the study period. The primary outcome was the acquisition rate of MRSA among patients per 1,000 patient-days at risk. Clonality of MRSA isolates was determined by Raman spectroscopy and multilocus sequence typing.

Findings

In total, 1,120 patients were included. Hand hygiene compliance rate rose from 15% pre-intervention to 65% post-intervention (P<0.001). The MRSA acquisition decreased from 9/1,000 patient-days at risk pre-intervention to 3/1,000 patient-days at risk post-intervention, but this difference did not reach statistical significance (P=0.08). Raman type 9 which belonged to ST239 was the single dominant MRSA clone.

Conclusion

The introduction of a bundle of preventive measures may reduce MRSA transmission and acquisition among surgery patients in a resource-limited hospital in Indonesia, but additional efforts are needed.

Nation-wide survey of screening practices to detect carriers of multi-drug resistant organisms upon admission to Swiss healthcare institutions

As emergence and spread of multi-drug resistant organisms (MDRO) requires a standardized preventive approach, we aimed to evaluate current MDRO admission screening practices in Swiss hospitals and to identify potential barriers impeding their implementation. In early 2018, all Swiss public and private healthcare institutions providing inpatient care were contacted with a 34-item questionnaire to investigate current MDRO admission screening policies. Among 139 respondents representing 180 institutions (response rate, 79%), 83% (149) of institutions implemented MDRO admission screening, while 28% of private and 9% of public institutions did not perform any screening. Targeted high-risk screening included carbapenemase producers, extended-spectrum beta-lactamase producers and methicillin-resistant Staphylococcus aureus at the institutional level for respectively 78% (115), 81% (118) and 98% (145) of screening institutions. Vancomycin-resistant enterococci (44% of institutions), multi-resistant Acinetobacter baumanii (41%) and Pseudomonas aeruginosa (37%) were systematically searched only by a minority of screening institutions. A large diversity of risk factors for targeted screening and some heterogeneity in body sites screened were also observed. Admission-screening practices were mostly impeded by a difficulty to identify high-risk patients (44%) and non-compliance of healthcare workers (35%). Heterogeneous practices and gaps in small and privately-owned institutions, as well as a mismatch between current epidemiologic MDRO trends and screening practices were noticed. These results highlight the need for uniform national MDRO screening standards.

Methicillin-resistant Staphylococcus aureus

Since the 1960s, methicillin-resistant Staphylococcus aureus (MRSA) has emerged, disseminated globally and become a leading cause of bacterial infections in both health-care and community settings. However, there is marked geographical variation in MRSA burden owing to several factors, including differences in local infection control practices and pathogen-specific characteristics of the circulating clones. Different MRSA clones have resulted from the independent acquisition of staphylococcal cassette chromosome mec (SCCmec), which contains genes encoding proteins that render the bacterium resistant to most β-lactam antibiotics (such as methicillin), by several S. aureus clones. The success of MRSA is a consequence of the extensive arsenal of virulence factors produced by S. aureus combined with β-lactam resistance and, for most clones, resistance to other antibiotic classes. Clinical manifestations of MRSA range from asymptomatic colonization of the nasal mucosa to mild skin and soft tissue infections to fulminant invasive disease with high mortality. Although treatment options for MRSA are limited, several new antimicrobials are under development. An understanding of colonization dynamics, routes of transmission, risk factors for progression to infection and conditions that promote the emergence of resistance will enable optimization of strategies to effectively control MRSA. Vaccine candidates are also under development and could become an effective prevention measure.

Control of healthcare- and community-associated MRSA: recent progress and persisting challenges

BACKGROUND

Healthcare adapted meticillin-resistant Staphylococcus aureus (MRSA) has spread to hospitals around the world over 50 years. More recently, other strains of MRSA have emerged with the ability to spread in the community and infect otherwise healthy individuals. Morbidity and mortality associated with MRSA remains high and its control in both the healthcare and community setting has proven challenging.

SOURCES OF DATA

Pubmed (Medline).

AREAS OF AGREEMENT

The use of targeted screening and decolonization, hand hygiene and antimicrobial stewardship is supported by the most robust studies, though many studies have implemented bundles for effective healthcare-associated (HA)-MRSA control.

AREAS OF CONTENTION

Universal screening, universal decolonization and contact precautions for HA-MRSA control are supported by less evidence. Some interventions may not be cost-effective. Contact precautions may be associated with potential for patient harm. Evidence for effective control community acquired (CA)-MRSA is largely lacking.

GROWING POINTS

Programmes that focus on implementing bundles of interventions aimed at targeting HA-MRSA are more likely to be effective, with an emphasis on hand hygiene as a key component. Control of CA-MRSA is likely to be more difficult to achieve and relies on prevalence, risk factors and community healthcare interactions on a broader scale.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further research in the area of CA-MRSA in particular is required. Antimicrobial stewardship for both CA and HA-MRSA is promising, as is the role of whole genome sequencing in characterizing transmission. However, further work is required to assess their long-term roles in controlling MRSA. With many institutions applying widespread use of chlorhexidine washes, monitoring for chlorhexidine resistance is paramount to sustaining efforts at controlling MRSA.

Interventions to improve hand hygiene compliance in patient care: Reflections on three systematic reviews for the Cochrane Collaboration 2007-2017

This article presents highlights from a recently updated systematic Cochrane review evaluating the effectiveness of interventions to improve hand hygiene compliance in patient care. It is an advance on the two earlier reviews we undertook on the same topic as it has, for the first time, provided very rigorous synthesis of evidence that such interventions can improve practice. In this article, we provide highlights from a recently updated Cochrane systematic review. We identify omissions in the information reported and point out important aspects of hand hygiene intervention studies that were beyond the scope of the review. A full report of the review is available free of charge on the Cochrane website.

Interventions to improve hand hygiene compliance in patient care

BACKGROUND

Health care-associated infection is a major cause of morbidity and mortality. Hand hygiene is regarded as an effective preventive measure. This is an update of a previously published review.

OBJECTIVES

To assess the short- and long-term success of strategies to improve compliance to recommendations for hand hygiene, and to determine whether an increase in hand hygiene compliance can reduce rates of health care-associated infection.

SEARCH METHODS

We conducted electronic searches of the Cochrane Register of Controlled Trials, PubMed, Embase, and CINAHL. We conducted the searches from November 2009 to October 2016.

SELECTION CRITERIA

We included randomised trials, non-randomised trials, controlled before-after studies, and interrupted time series analyses (ITS) that evaluated any intervention to improve compliance with hand hygiene using soap and water or alcohol-based hand rub (ABHR), or both.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened citations for inclusion, extracted data, and assessed risks of bias for each included study. Meta-analysis was not possible, as there was substantial heterogeneity across studies. We assessed the certainty of evidence using the GRADE approach and present the results narratively in a 'Summary of findings' table.

MAIN RESULTS

This review includes 26 studies: 14 randomised trials, two non-randomised trials and 10 ITS studies. Most studies were conducted in hospitals or long-term care facilities in different countries, and collected data from a variety of healthcare workers. Fourteen studies assessed the success of different combinations of strategies recommended by the World Health Organization (WHO) to improve hand hygiene compliance. Strategies consisted of the following: increasing the availability of ABHR, different types of education for staff, reminders (written and verbal), different types of performance feedback, administrative support, and staff involvement. Six studies assessed different types of performance feedback, two studies evaluated education, three studies evaluated cues such as signs or scent, and one study assessed placement of ABHR. Observed hand hygiene compliance was measured in all but three studies which reported product usage. Eight studies also reported either infection or colonisation rates. All studies had two or more sources of high or unclear risks of bias, most often associated with blinding or independence of the intervention.Multimodal interventions that include some but not all strategies recommended in the WHO guidelines may slightly improve hand hygiene compliance (five studies; 56 centres) and may slightly reduce infection rates (three studies; 34 centres), low certainty of evidence for both outcomes.Multimodal interventions that include all strategies recommended in the WHO guidelines may slightly reduce colonisation rates (one study; 167 centres; low certainty of evidence). It is unclear whether the intervention improves hand hygiene compliance (five studies; 184 centres) or reduces infection (two studies; 16 centres) because the certainty of this evidence is very low.Multimodal interventions that contain all strategies recommended in the WHO guidelines plus additional strategies may slightly improve hand hygiene compliance (six studies; 15 centres; low certainty of evidence). It is unclear whether this intervention reduces infection rates (one study; one centre; very low certainty of evidence).Performance feedback may improve hand hygiene compliance (six studies; 21 centres; low certainty of evidence). This intervention probably slightly reduces infection (one study; one centre) and colonisation rates (one study; one centre) based on moderate certainty of evidence.Education may improve hand hygiene compliance (two studies; two centres), low certainty of evidence.Cues such as signs or scent may slightly improve hand hygiene compliance (three studies; three centres), low certainty of evidence.Placement of ABHR close to point of use probably slightly improves hand hygiene compliance (one study; one centre), moderate certainty of evidence.

AUTHORS' CONCLUSIONS

With the identified variability in certainty of evidence, interventions, and methods, there remains an urgent need to undertake methodologically robust research to explore the effectiveness of multimodal versus simpler interventions to increase hand hygiene compliance, and to identify which components of multimodal interventions or combinations of strategies are most effective in a particular context.

Prevention and Control of Methicillin-Resistant Staphylococcus aureus in Acute Care Settings

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of health care-associated infections worldwide. Controversies with regard to the effectiveness of various MRSA control strategies have contributed to varying approaches to the control of this pathogen in different settings. However, new evidence from large-scale studies has emerged, particularly with regards to MRSA screening and decolonization strategies, which will inform future control practices. The implementation as well as outcomes of control measures in the real world is not only influenced by scientific evidence but also depends on economic, administrative, governmental, and political influences.

Methicillin-Resistant Staphylococcus aureus Control in the 21st Century: Laboratory Involvement Affecting Disease Impact and Economic Benefit from Large Population Studies

Methicillin-resistant Staphylococcus aureus (MRSA) infection is a global health care problem. Large studies (e.g., >25,000 patients) show that active surveillance testing (AST) followed by contact precautions for positive patients is an effective approach for MRSA disease control. With this approach, the clinical laboratory will be asked to select what AST method(s) to use and to provide data monitoring outcomes of the infection prevention interventions. This minireview summarizes evidence for MRSA disease control, reviews the involvement of the laboratory, and provides examples of how to undertake a program cost analysis. Health care organizations with total MRSA clinical infections of >0.3/1,000 patient days or bloodstream infections of >0.03/1,000 patient days should implement a MRSA control plan.

Research Methods in Healthcare Epidemiology and Antimicrobial Stewardship-Quasi-Experimental Designs

Quasi-experimental studies evaluate the association between an intervention and an outcome using experiments in which the intervention is not randomly assigned. Quasi-experimental studies are often used to evaluate rapid responses to outbreaks or other patient safety problems requiring prompt, nonrandomized interventions. Quasi-experimental studies can be categorized into 3 major types: interrupted time-series designs, designs with control groups, and designs without control groups. This methods paper highlights key considerations for quasi-experimental studies in healthcare epidemiology and antimicrobial stewardship, including study design and analytic approaches to avoid selection bias and other common pitfalls of quasi-experimental studies. Infect Control Hosp Epidemiol 2016;1-6.

Infection Risk in Sterile Operative Procedures

BACKGROUND

The main objective of hospital hygiene and infection prevention is to protect patients from preventable nosocomial infections. It was recently stated that the proper goal should be for zero infection rates in sterile surgical procedures. In this article, we attempt to determine whether this demand is supported by the available literature.

METHODS

We systematically searched the Medline and EMBASE databases for studies published in the last 10 years on the efficacy of infection control measures and carried out a meta-analysis according to the PRISMA tool. We used the following search terms: "aseptic surgery," "intervention," "surgical site infection," "nosocomial infection," "intervention," and "prevention."

RESULTS

2277 articles were retrieved, of which 204 were acquired in full text and analyzed. The quantitative analysis included 7 prospective cohort studies on the reduction of nosocomial infection rates after aseptic surgery. The measures used included training sessions, antibiotic prophylaxis, and operative-site disinfection and cleaning techniques. These interventions succeeded in reducing postoperative wound infections (relative risk (RR] 0.99 [0.98; 1.00]). Subgroup analyses on antibiotic prophylaxis (RR 0.99 [0.98; 1.01]) and noncontrolled trials (RR 0.97 [0.92; 1.02]) revealed small, insignificant effects.

CONCLUSION

A multimodal approach with the participation of specialists from various disciplines can further reduce the rate of postoperative infection. A reduction to zero is not realistic and is not supported by available evidence.

Evidence for Community Transmission of Community-Associated but Not Health-Care-Associated Methicillin-Resistant Staphylococcus Aureus Strains Linked to Social and Material Deprivation: Spatial Analysis of Cross-sectional Data

BACKGROUND

Identifying and tackling the social determinants of infectious diseases has become a public health priority following the recognition that individuals with lower socioeconomic status are disproportionately affected by infectious diseases. In many parts of the world, epidemiologically and genotypically defined community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) strains have emerged to become frequent causes of hospital infection. The aim of this study was to use spatial models with adjustment for area-level hospital attendance to determine the transmission niche of genotypically defined CA- and health-care-associated (HA)-MRSA strains across a diverse region of South East London and to explore a potential link between MRSA carriage and markers of social and material deprivation.

METHODS AND FINDINGS

This study involved spatial analysis of cross-sectional data linked with all MRSA isolates identified by three National Health Service (NHS) microbiology laboratories between 1 November 2011 and 29 February 2012. The cohort of hospital-based NHS microbiology diagnostic services serves 867,254 usual residents in the Lambeth, Southwark, and Lewisham boroughs in South East London, United Kingdom (UK). Isolates were classified as HA- or CA-MRSA based on whole genome sequencing. All MRSA cases identified over 4 mo within the three-borough catchment area (n = 471) were mapped to small geographies and linked to area-level aggregated socioeconomic and demographic data. Disease mapping and ecological regression models were used to infer the most likely transmission niches for each MRSA genetic classification and to describe the spatial epidemiology of MRSA in relation to social determinants. Specifically, we aimed to identify demographic and socioeconomic population traits that explain cross-area extra variation in HA- and CA-MRSA relative risks following adjustment for hospital attendance data. We explored the potential for associations with the English Indices of Deprivation 2010 (including the Index of Multiple Deprivation and several deprivation domains and subdomains) and the 2011 England and Wales census demographic and socioeconomic indicators (including numbers of households by deprivation dimension) and indicators of population health. Both CA-and HA-MRSA were associated with household deprivation (CA-MRSA relative risk [RR]: 1.72 [1.03-2.94]; HA-MRSA RR: 1.57 [1.06-2.33]), which was correlated with hospital attendance (Pearson correlation coefficient [PCC] = 0.76). HA-MRSA was also associated with poor health (RR: 1.10 [1.01-1.19]) and residence in communal care homes (RR: 1.24 [1.12-1.37]), whereas CA-MRSA was linked with household overcrowding (RR: 1.58 [1.04-2.41]) and wider barriers, which represent a combined score for household overcrowding, low income, and homelessness (RR: 1.76 [1.16-2.70]). CA-MRSA was also associated with recent immigration to the UK (RR: 1.77 [1.19-2.66]). For the area-level variation in RR for CA-MRSA, 28.67% was attributable to the spatial arrangement of target geographies, compared with only 0.09% for HA-MRSA. An advantage to our study is that it provided a representative sample of usual residents receiving care in the catchment areas. A limitation is that relationships apparent in aggregated data analyses cannot be assumed to operate at the individual level.

CONCLUSIONS

There was no evidence of community transmission of HA-MRSA strains, implying that HA-MRSA cases identified in the community originate from the hospital reservoir and are maintained by frequent attendance at health care facilities. In contrast, there was a high risk of CA-MRSA in deprived areas linked with overcrowding, homelessness, low income, and recent immigration to the UK, which was not explainable by health care exposure. Furthermore, areas adjacent to these deprived areas were themselves at greater risk of CA-MRSA, indicating community transmission of CA-MRSA. This ongoing community transmission could lead to CA-MRSA becoming the dominant strain types carried by patients admitted to hospital, particularly if successful hospital-based MRSA infection control programmes are maintained. These results suggest that community infection control programmes targeting transmission of CA-MRSA will be required to control MRSA in both the community and hospital. These epidemiological changes will also have implications for effectiveness of risk-factor-based hospital admission MRSA screening programmes.

Randomized, placebo-controlled, double-blind clinical trial to evaluate the efficacy of polyhexanide for topical decolonization of MRSA carriers

OBJECTIVES

The objective of this study was to evaluate the efficacy of polyhexanide (Prontoderm(®)) in eliminating MRSA carriage.

METHODS

In a 1900 bed teaching hospital, MRSA-colonized patients were randomized into a double-blind, placebo-controlled superiority trial between January 2011 and July 2014. Patients were treated with either polyhexanide or placebo applied to the anterior nares (thrice daily) and skin (once daily) for 10 days. The primary outcome was MRSA decolonization at day 28 (D28) after the end of treatment assessed by ITT responder and PP analyses (microbiological follow-up ± 7 days and topical treatment ≥ 5 days). Secondary outcomes included safety, emergence of resistance and MRSA genotype changes. Registered trial number ISRCTN02288276.

RESULTS

Of 2590 patients screened, 146 (polyhexanide group, 71; placebo group, 75) were included. ITT analysis showed that 24/71 (33.8%) patients in the polyhexanide group versus 22/75 (29.3%) in the placebo group were MRSA-free at D28 (risk difference, 4.5%; 95% CI, -10.6% to 19.5%; P = 0.56). PP analysis confirmed the results with 19/53 (35.8%) decolonized polyhexanide-treated patients versus 17/56 (30.4%) in the placebo arm (risk difference, 5.5%; 95% CI, -12.2% to 23%; P = 0.54). Nine serious adverse events occurred in the polyhexanide group versus 12 in the placebo group; none was attributable to study medication. Emergence of polyhexanide resistance or cross-resistance between polyhexanide and chlorhexidine was not observed. No case of exogenous recolonization by a genotypically different MRSA strain was documented.

CONCLUSIONS

This study suggests that under real-life conditions, a single polyhexanide decolonization course is not effective in eradicating MRSA carriage.

Back to basics: hand hygiene and isolation

Purpose of review

Hand hygiene and isolation are basic, but very effective, means of preventing the spread of pathogens in healthcare. Although the principle may be straightforward, this review highlights some of the controversies regarding the implementation and efficacy of these interventions.

Recent findings

Hand hygiene compliance is an accepted measure of quality and safety in many countries. The evidence for the efficacy of hand hygiene in directly reducing rates of hospital-acquired infections has strengthened in recent years, particularly in terms of reduced rates of staphylococcal sepsis. Defining the key components of effective implementation strategies and the ideal method(s) of assessing hand hygiene compliance are dependent on a range of factors associated with the healthcare system. Although patient isolation continues to be an important strategy, particularly in outbreaks, it also has some limitations and can be associated with negative effects. Recent detailed molecular epidemiology studies of key healthcare-acquired pathogens have questioned the true efficacy of isolation, alone as an effective method for the routine prevention of disease transmission.

Summary

Hand hygiene and isolation are key components of basic infection control. Recent insights into the benefits, limitations and even adverse effects of these interventions are important for their optimal implementation.

Screening for methicillin-resistant Staphylococcus aureus … all doors closed?

PURPOSE OF REVIEW

To describe the latest evidence for methicillin-resistant Staphylococcus aureus (MRSA) infection control strategies, with particular emphasis on active surveillance cultures with contact precautions and targeted decolonization, and their impact.

RECENT FINDINGS

Several major trials published last year questioned the effectiveness of universal screening and contact precautions in controlling MRSA. These trials generally recommend universal decolonization as part of bundles to control MRSA, especially in ICUs, with some even concluding that universal decolonization should replace active screening and contact precautions. However, emerging resistance to agents used for decolonization, such as mupirocin and chlorhexidine, is a major concern. Several other studies confirmed a combination of hand hygiene enhancement, screening, contact precaution and targeted decolonization as a more viable MRSA infection control strategy for specific population groups.

SUMMARY

Universal decolonization is an acceptable MRSA control strategy for intensive care units; however, close monitoring of chlorhexidine and mupirocin resistance is warranted. As a strategy, screening and contact precautions are suitable for hospital-wide MRSA control. Targeted decolonization is a proven measure for patients undergoing clean surgery. Enhancement of hand hygiene is a core measure regardless of the strategy.

Comparative efficacy of interventions to promote hand hygiene in hospital: systematic review and network meta-analysis

OBJECTIVE

To evaluate the relative efficacy of the World Health Organization 2005 campaign (WHO-5) and other interventions to promote hand hygiene among healthcare workers in hospital settings and to summarize associated information on use of resources.

DESIGN

Systematic review and network meta-analysis.

DATA SOURCES

Medline, Embase, CINAHL, NHS Economic Evaluation Database, NHS Centre for Reviews and Dissemination, Cochrane Library, and the EPOC register (December 2009 to February 2014); studies selected by the same search terms in previous systematic reviews (1980-2009).

REVIEW METHODS

Included studies were randomised controlled trials, non-randomised trials, controlled before-after trials, and interrupted time series studies implementing an intervention to improve compliance with hand hygiene among healthcare workers in hospital settings and measuring compliance or appropriate proxies that met predefined quality inclusion criteria. When studies had not used appropriate analytical methods, primary data were re-analysed. Random effects and network meta-analyses were performed on studies reporting directly observed compliance with hand hygiene when they were considered sufficiently homogeneous with regard to interventions and participants. Information on resources required for interventions was extracted and graded into three levels.

RESULTS

Of 3639 studies retrieved, 41 met the inclusion criteria (six randomised controlled trials, 32 interrupted time series, one non-randomised trial, and two controlled before-after studies). Meta-analysis of two randomised controlled trials showed the addition of goal setting to WHO-5 was associated with improved compliance (pooled odds ratio 1.35, 95% confidence interval 1.04 to 1.76; I(2)=81%). Of 22 pairwise comparisons from interrupted time series, 18 showed stepwise increases in compliance with hand hygiene, and all but four showed a trend for increasing compliance after the intervention. Network meta-analysis indicated considerable uncertainty in the relative effectiveness of interventions, but nonetheless provided evidence that WHO-5 is effective and that compliance can be further improved by adding interventions including goal setting, reward incentives, and accountability. Nineteen studies reported clinical outcomes; data from these were consistent with clinically important reductions in rates of infection resulting from improved hand hygiene for some but not all important hospital pathogens. Reported costs of interventions ranged from $225 to $4669 (£146-£3035; €204-€4229) per 1000 bed days.

CONCLUSION

Promotion of hand hygiene with WHO-5 is effective at increasing compliance in healthcare workers. Addition of goal setting, reward incentives, and accountability strategies can lead to further improvements. Reporting of resources required for such interventions remains inadequate.

Combined interventions are effective in MRSA control

BACKGROUND

A large healthcare-associated epidemic mainly caused by one methicillin-resistant Staphylococcus aureus (MRSA) strain broke out in Pirkanmaa County, Finland, in 2001. This study describes the impact of infection control and screening practices on the epidemic.

METHODS

The number of hospital-acquired (HA)-MRSA findings obtained from clinical and screening samples during the epidemic was calculated. Strains were typed by pulsed-field electrophoresis (PFGE) or spa typing. Strain type distribution was studied in relation to sample type, year of the epidemic and site of transmission. Several infection control interventions were launched stepwise and screening protocols were expanded.

RESULTS

A total of 4118 cases were identified during 2001-2014, of which 3527 were classified as HA. One strain (spa t067) dominated in the epidemic. HA-MRSA cases decreased constantly from the year 2011. The number of new HA-MRSA cases was 57% less in the year 2014 (n = 171) as compared with the year 2011 (n = 399). The proportion of the epidemic strain declined significantly over the years. Screening samples comprised 71% (2439/3527) and clinical samples 29% (1034/3527) of HA-MRSA findings. The number of HA-MRSA cases found from clinical samples started to decrease when screening was expanded. An increase in hand-rub consumption was associated with a decrease in transmissions in Tampere University Hospital (TAUH).

CONCLUSION

Implementation of universal screening together with several other interventions is effective in containing an MRSA epidemic. The proportion of other than Pirkanmaa epidemic (PE)-MRSA strain findings increased throughout the period, indicating the changing epidemiology of MRSA.

Evaluation of multiple real-time PCR tests on nasal samples in a large MRSA surveillance program

OBJECTIVES

We evaluated the LightCycler MRSA Advanced Test (Roche Molecular Diagnostics, Pleasanton, CA), the BD MAX MRSA assay (Becton Dickinson, Franklin Lakes, NJ), and the Xpert MRSA assay (Cepheid, Sunnyvale, CA) on nasal samples using the same population.

METHODS

Admission and discharge nasal swabs were collected from inpatients using a double-headed swab. One swab was plated onto CHROMagar MRSA (CMA; Becton Dickinson, Sparks, MD) and then broken off into tryptic soy broth (TSB) for enrichment. TSB was incubated for 24 hours and then plated to CMA. The molecular tests were performed on the second swab. We analyzed the cost benefit of testing to evaluate what parameters affect hospital resources.

RESULTS

A total of 27,647 specimens were enrolled. The sensitivity/specificity was 98.3%/98.9% for the LightCycler MRSA Advanced Test and 95.7%/98.8% for the Xpert MRSA assay, but the difference was not significant. The positive predictive value was 86.7% for the LightCycler MRSA Advanced Test, 82.7% for the Xpert MRSA assay (P > .1), and 72.2% and for the BD MAX MRSA test (P < .001 compared with the LightCycler MRSA Advanced Test). All three assays were cost-effective, with the LightCycler MRSA Advanced Test having the highest economic return.

CONCLUSIONS

Our results suggest that the performance of the three commercial assays is similar. When assessing economic cost benefit of methicillin-resistant Staphylococcus aureus screening, the two measures with the most impact are the cost of the test and the specificity of the assay results.

Preoperative skin antiseptics for preventing surgical wound infections after clean surgery

BACKGROUND

Surgical site infection rates in the month following clean surgery vary from 0.6% (knee prosthesis) to 5% (limb amputation). Due to the large number of clean surgical procedures conducted annually the costs of these surgical site infections (SSIs) can be considerable in financial and social terms. Preoperative skin antisepsis using antiseptics is performed to reduce the risk of SSIs by removing soil and transient organisms from the skin where a surgical incision will be made. Antiseptics are thought to be toxic to bacteria and therefore aid their mechanical removal. The effectiveness of preoperative skin preparation is thought to be dependent on both the antiseptic used and the method of application, however, it is unclear whether preoperative skin antisepsis actually reduces postoperative wound infection, and, if so, which antiseptic is most effective.

OBJECTIVES

To determine whether preoperative skin antisepsis immediately prior to surgical incision for clean surgery prevents SSI and to determine the comparative effectiveness of alternative antiseptics.

SEARCH METHODS

For this third update we searched just the Cochrane Wounds Group Specialised Register (searched 27 January 2015); The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 12).

SELECTION CRITERIA

Randomised controlled trials evaluating the use of preoperative skin antiseptics applied immediately prior to incision in clean surgery. There was no restriction on the inclusion of reports based on language of publication, date or publication status.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of risk of bias were undertaken independently by two review authors.

MAIN RESULTS

There were no new studies added to the review in the third updateThirteen studies were included in this review (2,623 participants). These evaluated several different types of skin antiseptics - leading to 11 different comparisons being made. Although the antiseptics evaluated differed between studies, all trials involved some form of iodine. Iodine in alcohol was compared to alcohol alone in one trial; one trial compared povidone iodine paint (solution type not reported) with soap and alcohol. Six studies compared different types of iodine-containing products with each other and five compared iodine-containing products with chlorhexidine-containing products.There was evidence from one study suggesting that preoperative skin preparation with 0.5% chlorhexidine in methylated spirits led to a reduced risk of SSI compared with an alcohol based povidone iodine solution: RR 0.47 (95% CI 0.27 to 0.82). However, it is important to note that the trial does not report important details regarding the interventions (such as the concentration of povidone iodine paint used) and trial conduct, such that risk of bias was unclear.There were no other statistically significant differences in SSI rates in the other comparisons of skin antisepsis. Overall the risk of bias in included studies was unclear.A mixed treatment comparison meta-analysis was conducted and this suggested that alcohol-containing products had the highest probability of being effective - however, again the quality of this evidence was low.

AUTHORS' CONCLUSIONS

A comprehensive review of current evidence found some evidence that preoperative skin preparation with 0.5% chlorhexidine in methylated spirits was associated with lower rates of SSIs following clean surgery than alcohol-based povidone iodine paint. However this single study was poorly reported. Practitioners may therefore elect to consider other characteristics such as costs and potential side effects when choosing between alternatives.The design of future trials should be driven by the questions of high priority to decision makers. It may be that investment in at least one large trial (in terms of participants) is warranted in order to add definitive and hopefully conclusive data to the current evidence base. Ideally any future trial would evaluate the iodine-containing and chlorhexidine-containing solutions relevant to current practice as well as the type of solution used (alcohol vs. aqueous).

Variable performance of models for predicting methicillin-resistant Staphylococcus aureus carriage in European surgical wards

Background

Predictive models to identify unknown methicillin-resistant Staphylococcus aureus (MRSA) carriage on admission may optimise targeted MRSA screening and efficient use of resources. However, common approaches to model selection can result in overconfident estimates and poor predictive performance. We aimed to compare the performance of various models to predict previously unknown MRSA carriage on admission to surgical wards.

Methods

The study analysed data collected during a prospective cohort study which enrolled consecutive adult patients admitted to 13 surgical wards in 4 European hospitals. The participating hospitals were located in Athens (Greece), Barcelona (Spain), Cremona (Italy) and Paris (France). Universal admission MRSA screening was performed in the surgical wards. Data regarding demographic characteristics and potential risk factors for MRSA carriage were prospectively collected during the study period. Four logistic regression models were used to predict probabilities of unknown MRSA carriage using risk factor data: “Stepwise” (variables selected by backward elimination); “Best BMA” (model with highest posterior probability using Bayesian model averaging which accounts for uncertainty in model choice); “BMA” (average of all models selected with BMA); and “Simple” (model including variables selected >50% of the time by both Stepwise and BMA approaches applied to repeated random sub-samples of 50% of the data). To assess model performance, cross-validation against data not used for model fitting was conducted and net reclassification improvement (NRI) was calculated.

Results

Of 2,901 patients enrolled, 111 (3.8%) were newly identified MRSA carriers. Recent hospitalisation and presence of a wound/ulcer were significantly associated with MRSA carriage in all models. While all models demonstrated limited predictive ability (mean c-statistics <0.7) the Simple model consistently detected more MRSA-positive individuals despite screening fewer patients than the Stepwise model. Moreover, the Simple model improved reclassification of patients into appropriate risk strata compared with the Stepwise model (NRI 6.6%, P = .07).

Conclusions

Though commonly used, models developed using stepwise variable selection can have relatively poor predictive value. When developing MRSA risk indices, simpler models, which account for uncertainty in model selection, may better stratify patients’ risk of unknown MRSA carriage.

Viewpoint: a response to "Screening and isolation to control methicillin-resistant Staphylococcus aureus: sense, nonsense, and evidence"

Surveillance and isolation for the prevention of methicillin-resistant Staphylococcus aureus (MRSA) has become a controversial topic, one that causes heated debate and appears to be surrounded by both politics and industrial conflicts-of-interest. There have been calls from numerous authors for a movement away from rigid mandates and toward an evidence-based medicine approach. However, much of the evidence can be viewed with an entirely different interpretation. Two major studies with negative findings have had an adverse impact on recommendations regarding active detection and isolation (ADI) for MRSA. However the negative findings in these studies can be explained by shortcomings in study implementation rather than the ineffectiveness of ADI. The use of daily chlorhexidine bathing has also been proposed as an alternative to ADI in ICU settings. There are shortcomings regarding the evidence in the literature concerning the effectiveness of daily chlorhexidine bathing. One of the major concerns with universal daily chlorhexidine bathing is the development of bacterial resistance. The use of surveillance and isolation to address epidemics and common dangerous pathogens should solely depend upon surveillance and isolation's ability to prevent further spread to and infection of other patients through indirect contact. At present, there is a preponderance of evidence in the literature to support continuing use of surveillance and isolation to prevent the spread of MRSA.

The relationship between hand hygiene and health care-associated infection: it's complicated

The reasoning that improved hand hygiene compliance contributes to the prevention of health care-associated infections is widely accepted. It is also accepted that high hand hygiene alone cannot impact formidable risk factors, such as older age, immunosuppression, admission to the intensive care unit, longer length of stay, and indwelling devices. When hand hygiene interventions are concurrently undertaken with other routine or special preventive strategies, there is a potential for these concurrent strategies to confound the effect of the hand hygiene program. The result may be an overestimation of the hand hygiene intervention unless the design of the intervention or analysis controls the effect of the potential confounders. Other epidemiologic principles that may also impact the result of a hand hygiene program include failure to consider measurement error of the content of the hand hygiene program and the measurement error of compliance. Some epidemiological errors in hand hygiene programs aimed at reducing health care-associated infections are inherent and not easily controlled. Nevertheless, the inadvertent omission by authors to report these common epidemiological errors, including concurrent infection prevention strategies, suggests to readers that the effect of hand hygiene is greater than the sum of all infection prevention strategies. Worse still, this omission does not assist evidence-based practice.

The effect of improved hand hygiene on nosocomial MRSA control

The purpose of this review is to examine studies that have assessed the association between hand hygiene enhancement and methicillin-resistant Staphylococcus aureus (MRSA) rates and to explore controversies surrounding this association. Many studies have been published confirming the link between improved hand hygiene compliance and reduction in MRSA acquisition and infections, including bacteremia. These studies have also shown the cost-beneficial nature of these programmes. Despite considerable research some issues remain unanswered still, including the temporal relationship between hand hygiene enhancement strategies and decrease in MRSA rates, association between hand hygiene enhancement and MRSA-related surgical site infections, diminishing effect of hand hygiene compliance on MRSA rates after reaching a threshold and the role of instituting contact precautions in the setting of low MRSA rates and sufficient hand hygiene compliance. In conclusion, enhancement of hand hygiene compliance has been shown to reduce MRSA rates; however, some open issues warrant further investigation.

The use of surveillance and preventative measures for methicillin-resistant staphylococcus aureus infections in surgical patients

The Agency for Healthcare Research & Quality (AHRQ) found that Methicillin-resistant Staphylococcus aureus (MRSA) is associated with up to 375,000 infections and 23,000 deaths in the United States. It is a major cause of surgical site infections, with a higher mortality and longer duration of care than Methicillin-sensitive Staphylococcus aureus. A multifactorial bundled approach is needed to control this epidemic, with single interventions unlikely to have a significant impact on attenuating MRSA infection rates. Active surveillance has been studied in a wide range of surgical patients, including surgical intensive care and non-intensive care units; cardiac, vascular, orthopedic, obstetric, head and neck cancer and gastrostomy patients. There is sufficient evidence demonstrating a beneficial effect of surveillance and eradication prior to surgery to recommend its use on an expanded basis. Studies on MRSA surveillance in surgical patients that were published over the last 10 years were reviewed. In at least five of these studies, the MRSA colonization status of patients was reported to be a factor in preoperative antibiotic selection, with the modification of treatment regiments including the switching to vancomycin or teicoplanin in MRSA positive preoperative patients. Several authors also used decolonization protocols on all preoperative patients but used surveillance to determine the duration of the decolonization. Universal decolonization of all patients, regardless of MRSA status has been advocated as an alternative prevention protocol in which surveillance is not utilized. Concern exists regarding antimicrobial stewardship. The daily and universal use of intranasal antibiotics and/or antiseptic washes may encourage the promotion of bacterial resistance and provide a competitive advantage to other more lethal organisms. Decolonization protocols which indiscriminately neutralize all bacteria may not be the best approach. If a patient's microbiome is markedly challenged with antimicrobials, rebuilding it with replacement commensal bacteria may become a future therapy. Preoperative MRSA surveillance allows the selection of appropriate prophylactic antibiotics, the use of extended decolonization protocols in positive patients, and provides needed data for epidemiological studies.

Risk factors for community-associated methicillin-resistant Staphylococcus aureus colonisation in a large metropolitan area in Greece: An epidemiological study using two case definitions

The aim of this study was to evaluate the epidemiology and characteristics and to identify modifiable risk factors for community-associated (CA) MRSA colonisation in a region with high prevalence. A large patient population (n=2280) from two tertiary care centres in Athens (Greece) was evaluated. Demographics and potential risk factors for CA-MRSA colonisation were recorded prospectively. Presence of the Panton-Valentine Leukocidin (PVL) toxin and mecA gene was determined in all MRSA isolates. Two definitions for CA-MRSA were applied. Univariate and multivariate analyses to identify predictors of previously unknown CA-MRSA colonisation were performed. In total, 120 (5.3%) MRSA carriers were identified; in 67 the isolates were classified as CA-MRSA using criteria based on the CDC definition, compared with 35 based on a definition including PVL toxin positivity. Factors significantly associated with previously unknown CA-MRSA carriage (CDC definition) included being a child or adolescent (OR=3.6, 95% CI 1.5-8.6), belonging to the family of an index case (OR=2.4, 95% CI 1.2-4.8), and presence of any co-morbidity (OR=1.7, 95% CI 1.04-2.8) or chronic skin disease (OR=3.6, 95% CI=2.2-6.1). In multivariate analysis, presence of any co-morbidity was the only significant predictor (OR=4.9, 95% CI 1.07-22.5; P=0.04). No easily modifiable risk factor for previously unknown CA-MRSA colonisation was identified. The CDC-based epidemiological definition for CA-MRSA appears to be more sensitive in detection of CA-MRSA colonisation than a purely molecular definition based on presence of the PVL gene.