Guidelines for the control and prevention of meticillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities

The Control of Methicillin-Resistant Staphylococcus aureus Blood Stream Infections in England

Methicillin-resistant Staphylococcus aureus (MRSA) blood stream infection (BSI) is a major healthcare burden in some but not all healthcare settings, and it is associated with 10%-20% mortality. The introduction of mandatory reporting in England of MRSA BSI in 2001 was followed in 2004 by the setting of target reductions for all National Health Service hospitals. The original national target of a 50% reduction in MRSA BSI was considered by many experts to be unattainable, and yet this goal has been far exceeded (∼80% reduction with rates still declining). The transformation from endemic to sporadic MRSA BSI involved the implementation of serial national infection prevention directives, and the deployment of expert improvement teams in organizations failed to meet their improvement trajectory targets. We describe and appraise the components of the major public health infection prevention campaign that yielded major reductions in MRSA infection. There are important lessons and opportunities for other healthcare systems where MRSA infection remains endemic.

High prevalence of mupirocin resistance in Staphylococcus aureus isolates from a pediatric population

Topical mupirocin is used widely to treat skin and soft tissue infections and to eradicate nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA). Few studies to date have characterized the rates of S. aureus mupirocin resistance in pediatric populations. We retrospectively studied 358 unique S. aureus isolates obtained from 249 children seen in a predominantly outpatient setting by the Division of Pediatric Dermatology at a major academic center in New York City between 1 May 2012 and 17 September 2013. Mupirocin resistance rates and the associated risk factors were determined using a logistic regression analysis. In our patient population, 19.3% of patients had mupirocin-resistant S. aureus isolates at the time of their first culture, and 22.1% of patients with S. aureus infection had a mupirocin-resistant isolate at some time during the study period. Overall, 31.3% of all S. aureus isolates collected during the study period were resistant to mupirocin. Prior mupirocin use was strongly correlated (odds ratio [OR] = 26.5; P = <0.001) with mupirocin resistance. Additional risk factors for mupirocin resistance included methicillin resistance, atopic dermatitis (AD), epidermolysis bullosa (EB), immunosuppression, and residence in northern Manhattan and the Bronx. Resistance to mupirocin is widespread in children with dermatologic complaints in the New York City area, and given the strong association with mupirocin exposure, it is likely that mupirocin use contributes to the increased resistance. Routine mupirocin testing may be important for MRSA decolonization strategies or the treatment of minor skin infections in children.

Universal Screening and Decolonization for Control of MRSA in Nursing Homes: A Cluster Randomized Controlled Study

OBJECTIVE

The risk of carrying methicillin-resistant Staphylococcus aureus (MRSA) is higher among nursing home (NH) residents than in the general population. However, control strategies are not clearly defined in this setting. In this study, we compared the impact of standard precautions either alone (control) or combined with screening of residents and decolonization of carriers (intervention) to control MRSA in NHs.

DESIGN

Cluster randomized controlled trial

SETTING

NHs of the state of Vaud, Switzerland

PARTICIPANTS

Of 157 total NHs in Vaud, 104 (67%) participated in the study.

INTERVENTION

Standard precautions were enforced in all participating NHs, and residents underwent MRSA screening at baseline and 12 months thereafter. All carriers identified in intervention NHs, either at study entry or among newly admitted residents, underwent topical decolonization combined with environmental disinfection, except in cases of MRSA infection, MRSA bacteriuria, or deep skin ulcers.

RESULTS

NHs were randomly allocated to a control group (51 NHs, 2,412 residents) or an intervention group (53 NHs, 2,338 residents). Characteristics of NHs and residents were similar in both groups. The mean screening rates were 86% (range, 27%–100%) in control NHs and 87% (20%–100%) in intervention NHs. Prevalence of MRSA carriage averaged 8.9% in both control NHs (range, 0%–43%) and intervention NHs (range, 0%–38%) at baseline, and this rate significantly declined to 6.6% in control NHs and to 5.8% in intervention NHs after 12 months. However, the decline did not differ between groups (P=.66).

CONCLUSION

Universal screening followed by decolonization of carriers did not significantly reduce the prevalence of the MRSA carriage rate at 1 year compared with standard precautions.

Infect Control Hosp Epidemiol 2015;00(0): 1–8

Limitations of the Efficacy of Surface Disinfection in the Healthcare Setting

We examined the efficacy of 2 commercially available wipes to effectively remove, kill, and prevent the transfer of both methicillin-resistant and methicillin-susceptible Staphylococcus aureus from contaminated surfaces. Although wipes play a role in decreasing the number of pathogenic bacteria from contaminated surfaces, they can potentially transfer bacteria to other surfaces if they are reused.

Electronic Prediction Rules for Methicillin-ResistantStaphylococcus aureusColonization

Background.

Considerable hospital resources are dedicated to minimizing the number of methicillin-resistantStaphylococcus aureus(MRSA) infections. One tool that is commonly used to achieve this goal is surveillance for MRSA colonization. This process is costly, and false-positive test results lead to isolation of individuals who do not carry MRSA. The performance of this technique would improve if patients who are at high risk of colonization could be readily targeted.

Methods.

Five MRSA colonization prediction rules of varying complexity were derived in a population of 23,314 patients who were consecutively admitted to a US hospital and tested for colonization. Rules incorporated only prospectively collected, structured electronic data found in a patient's record within 1 day of hospital admission. These rules were tested in a validation cohort of 26,650 patients who were admitted to 2 other hospitals.

Results.

The prevalence of MRSA at hospital admission was 2.2% and 4.0% in the derivation and validation cohorts, respectively. Multivariable modeling identified predictors of MRSA colonization among demographic, admission-related, pharmacologic, laboratory, physiologic, and historical variables. Five prediction rules varied in their performance, but each could be used to identify the 30% of patients who accounted for greater than 60% of all cases of MRSA colonization and approximately 70% of all MRSA-associated patient-days. Most rules could also identify the 20% of patients with a greater than 8% chance of colonization and the 40% of patients among whom colonization prevalence was 2% or less.

Conclusions.

We report electronic prediction rules that can fully automate triage of patients for MRSA-related hospital admission testing and that offer significant improvements on previously reported rules. The efficiencies introduced may result in savings to infection control programs with little sacrifice in effectiveness.

Real-Time Polymerase Chain Reaction Detection of Methicillin-ResistantStaphylococcus aureus:Impact on Nosocomial Transmission and Costs

Objectives.

To assess the impact of real-time polymerase chain reaction (PCR) detection of methicillin-resistantStaphylococcus aureus(MRSA) on nosocomial transmission and costs.

Design.

Monthly MRSA detection rates were measured from April 1, 2000, through December 31, 2005. Time series analysis was used to identify changes in MRSA detection rates, and decision analysis was used to compare the costs of detection by PCR and by culture.

Setting.

A 1,200-bed, tertiary care hospital in Canada.

Patients.

Admitted patients at high risk for MRSA colonization. MRSA detection using culture-based screening was compared with a commercial PCR assay.

Results.

The mean monthly incidence of nosocomial MRSA colonization or infection was 0.37 cases per 1,000 patient-days. The time-series model indicated an insignificant decrease of 0.14 cases per 1,000 patient-days per month (95% confidence interval, —0.18 to 0.46) after the introduction of PCR detection (P= .39). The mean interval from a reported positive result until contact precautions were initiated decreased from 3.8 to 1.6 days (P<.001). However, the cost of MRSA control increased from Can$605,034 to Can$771,609. Of 290 PCR-positive patients, 120 (41.4%) were placed under contact precautions unnecessarily because of low specificity of the PCR assay used in the study; these patients contributed 37% of the increased cost. The modeling study predicted that the cost per patient would be higher with detection by PCR (Can$96) than by culture (Can$67).

Conclusion.

Detection of MRSA by the PCR assay evaluated in this study was more costly than detection by culture for reducing MRSA transmission in our hospital. The cost benefit of screening by PCR varies according to incidences of MRSA colonization and infection, the predictive values of the assay used, and rates of compliance with infection control measures.

Evaluation of Real-Time Polymerase Chain Reaction for the Detection of Methicillin-ResistantStaphylococcus aureuson Environmental Surfaces

We compared real-time polymerase chain reaction (RT-PCR) with in vitro culture for detecting methicillin-resistantStaphylococcus aureusin samples from environmental surfaces. The sensitivity of RT-PCR, compared with culture, was 92.5%, and the specificity was 51.4%. Because of poor specificity, the RT-PCR kit tested is not suitable for the detection of MRSA on hospital surfaces.

Strategies to Prevent Transmission of Methicillin-ResistantStaphylococcus aureusin Acute Care Hospitals

Previously published guidelines are available that provide comprehensive recommendations for detecting and preventing healthcare-associated infections (HAIs). Our intent in this document is to highlight practical recommendations in a concise format to assist acute care hospitals in their efforts to prevent transmission of methicillin-resistantStaphylococcus aureus(MRSA). Refer to the Society for Healthcare Epidemiology of America/Infectious Diseases Society of America “Compendium of Strategies to Prevent Healthcare-Associated Infections” Executive Summary, Introduction, and accompanying editorial for additional discussion.

1. Burden of HAIs caused by MRSA in acute care facilities

a. In the United States, the proportion of hospital-associatedS. aureusinfections that are caused by strains resistant to methicillin has steadily increased. In 2004, MRSA accounted for 63% ofS. aureusinfections in hospitals.

b. Although the proportion ofS. aureus–associated HAIs among intensive care unit (ICU) patients that are due to methicillin-resistant strains has increased (a relative measure of the MRSA problem), recent data suggest that the incidence of central line–associated bloodstream infection caused by MRSA (an absolute measure of the problem) has decreased in several types of ICUs since 2001. Although these findings suggest that there has been some success in preventing nosocomial MRSA transmission and infection, many patient groups continue to be at risk for such transmission.

c. MRSA has also been documented in other areas of the hospital and in other types of healthcare facilities, including those that provide long-term care.

Methicillin-Resistant Staphylococcus aureus Infection in a College Football Team: Risk Factors Outside the Locker Room and Playing Field

We investigated a cluster of methicillin-resistant Staphylococcus aureus infections in college football players. Risk factors included a history of recurrent skin infections and contact with the skin lesions of persons outside college. The infections were controlled through treatment of carriers with topical mupirocin, chlorhexidine body washes, and enhancement of personal hygiene practices. Varsity and professional teams need to consider similar preventive measures.

Screening for Carriage of Methicillin-Resistant Staphylococcus aureus Shortly After Exposure May Lead to False-Negative Results

We evaluated a double screening strategy for carriage of methicillin-resistant Staphylococcus aureus (MRSA) in patients exposed to a newly detected MRSA carrier. If the first screening of the exposed patient yielded negative results, screening was repeated 4 days later. This strategy detected 12 (28%) of the 43 new MRSA carriers identified during the study period. The results suggest that there is an incubation period before MRSA carriage is detectable.

Endemic methicillin-resistant Staphylococcus aureus: Nurses' risk perceptions and attitudes

Dissemination of methicillin-resistant Staphylococcus aureus (MRSA) remains one of the most difficult challenges for prevention, control, and treatment of health care-associated infections. A survey and interviews were conducted on nurses from a hospital center. We found that most nurses' perceived risk of acquiring MRSA related to themselves (72%), other nurses (88.5%), and patients (97.8%). This perception influences attitudes, leading to compliance with the existing recommendations.

MRSA care in the community: why patient education matters

In primary care, patients are prescribed decolonisation treatment to eradicate meticillin-resistant Staphylococcus aureus (MRSA). This complex treatment process requires the patient to apply a topical antimicrobial treatment as well as adhering to rigorous cleaning regimens to ensure the environment is effectively managed. A pilot study was carried out that involved developing an enhanced, nurse-delivered education tool, training a community nurse to use it, then testing its use with a patient. Three interviews were carried out: one with a patient who received usual care, one with a patient who received the enhanced education and one with the community nurse who delivered the enhanced education tool. The patient who received the enhanced education reported better knowledge and understanding of the application of treatment than the patient who did not. These results are interesting and point the way forward for larger research studies to build on the learning from this limited exploration and develop more effective management of MRSA in primary care.

Bacteriophage as effective decolonising agent for elimination of MRSA from anterior nares of BALB/c mice

BACKGROUND

Nasal carriers not only pose serious threat to themselves but also to the community by playing an active role in the dissemination of serious and life threatening S. aureus especially MRSA strains. The present study focuses on the use of broad spectrum lytic phage as decolonising agent. In addition, the combined use of lytic phage with mupirocin has also been investigated as an effective decolonising regimen. The effect of phage on the adherence, invasion and cytotoxic effect of MRSA strains on nasal epithelial cells was studied in an ex-vivo model of cultured murine nasal epithelial cells. This was followed by demonstration of therapeutic potential of phage along with mupirocin in decolonising the nares of BALB/c mice using a nasal model of MRSA colonisation.

RESULTS

Phage was able to significantly reduce the in vitro adherence, invasion and cytotoxicity of MRSA 43300 as well as other clinical MRSA strains on murine nasal epithelial cells as compared to untreated control. Also, the frequency of emergence of spontaneous mutants decreased to negligible levels when both the agents (phage and mupirocin) were used together.

CONCLUSION

Phage MR-10, given along with mupirocin showed an additive effect and the combination was able to effectively eradicate the colonising MRSA population from the nares of mice by day 5.

MRSA carriage among healthcare workers in non-outbreak settings in Europe and the United States: a systematic review

Abstarct

Staphylococcus aureus: Screening for Nasal Carriers in a Community Setting with Special Reference to MRSA

Introduction. Emergence of MRSA infections among previously healthy persons in community settings (without exposure to health care facilities) has been noted recently. MRSA infections are now classified as health care-associated MRSA (HA-MRSA) and community-associated MRSA (CA-MRSA) infections. Its colonization is an important risk factor for subsequent MRSA infection. Aims and Objectives. The aim was to screen patients and health care workers for staphylococcal carriage, identify risk factors for MRSA colonization, and determine the sensitivity pattern. Materials and Methods. A total of 200 subjects were screened for nasal carriage after obtaining verbal consent. These were both healthy subjects attending various outpatient departments and health care workers. Specimens were collected from the anterior nares using premoistened sterile cotton swabs and inoculated onto blood agar and mannitol salt agar and incubated at 37°C for 24-48 h. Results. Staphylococcus aureus colonisation was found to be 12% (n = 24). MRSA was identified in 5% (n = 10) which represents 41.66% of SA. A total of 10 strains of MRSA were isolated from 200 subjects, giving an overall positivity rate of 5%. Discussion. Staphylococcal colonization was found to be 12% (MRSA 5%). Fluoroquinolone resistance was remarkable whereas all strains were sensitive to vancomycin, teicoplanin, linezolid, quinupristin-dalfopristin.

Multidrug-resistant bacterial infections after liver transplantation: An ever-growing challenge

Bacterial infections are a leading cause of morbidity and mortality among solid organ transplant recipients. Over the last two decades, various multidrug-resistant (MDR) pathogens have emerged as relevant causes of infection in this population. Although this fact reflects the spread of MDR pathogens in health care facilities worldwide, several factors relating to the care of transplant donor candidates and recipients render these patients particularly prone to the acquisition of MDR bacteria and increase the likelihood of MDR infectious outbreaks in transplant units. The awareness of this high vulnerability of transplant recipients to infection leads to the more frequent use of broad-spectrum empiric antibiotic therapy, which further contributes to the selection of drug resistance. This vicious cycle is difficult to avoid and leads to a scenario of increased complexity and narrowed therapeutic options. Infection by MDR pathogens is more frequently associated with a failure to start appropriate empiric antimicrobial therapy. The lack of appropriate treatment may contribute to the high mortality occurring in transplant recipients with MDR infections. Furthermore, high therapeutic failure rates have been observed in patients infected with extensively-resistant pathogens, such as carbapenem-resistant Enterobacteriaceae, for which optimal treatment remains undefined. In such a context, the careful implementation of preventive strategies is of utmost importance to minimize the negative impact that MDR infections may have on the outcome of liver transplant recipients. This article reviews the current literature regarding the incidence and outcome of MDR infections in liver transplant recipients, and summarizes current preventive and therapeutic recommendations.

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.

Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases)

BACKGROUND

Superficial bacterial folliculitis (SBF) is usually caused by Staphylococcus pseudintermedius and routinely treated with systemic antimicrobial agents. Infection is a consequence of reduced immunity associated with alterations of the skin barrier and underlying diseases that may be difficult to diagnose and resolve; thus, SBF is frequently recurrent and repeated treatment is necessary. The emergence of multiresistant bacteria, particularly meticillin-resistant S. pseudintermedius (MRSP), has focused attention on the need for optimal management of SBF.

OBJECTIVES

Provision of an internationally available resource guiding practitioners in the diagnosis, treatment and prevention of SBF.

DEVELOPMENT OF THE GUIDELINES

The guidelines were developed by the Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases, with consultation and advice from diplomates of the American and European Colleges of Veterinary Dermatology. They describe optimal methods for the diagnosis and management of SBF, including isolation of the causative organism, antimicrobial susceptibility testing, selection of antimicrobial drugs, therapeutic protocols and advice on infection control. Guidance is given for topical and systemic modalities, including approaches suitable for MRSP. Systemic drugs are classified in three tiers. Tier one drugs are used when diagnosis is clear cut and risk factors for antimicrobial drug resistance are not present. Otherwise, tier two drugs are used and antimicrobial susceptibility tests are mandatory. Tier three includes drugs reserved for highly resistant infections; their use is strongly discouraged and, when necessary, they should be used in consultation with specialists.

CONCLUSIONS AND CLINICAL IMPORTANCE

Optimal management of SBF will improve antimicrobial use and reduce selection of MRSP and other multidrug-resistant bacteria affecting animal and human health.

Occurrence of nosocomial methicillin-resistant Staphylococcus aureus as a marker for transmission in a surgical intensive care unit in China

In 2008, an intensive care unit (ICU) in a large Chinese hospital was moved from a 6-bed old ward to a 20-bed new ward. After the move, the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in patients and environmental sites decreased significantly, but the number of ICU-acquired cases per imported MRSA case increased from 1.4 to 4.1. This study suggests that the nurse cohorting level and hand hygiene compliance are strong predicators of MRSA transmission in ICUs.

Synergistic activity of biocides and antibiotics on resistant bacteria from organically produced foods

Synergism between biocides and antibiotics was investigated in 20 biocide and antibiotic-resistant bacterial strains that were previously isolated from organically produced foods, according to their antimicrobial resistance profiles. Most of the antibiotic/biocide combinations yielded synergistic interactions, reducing the inhibitory concentrations of biocides and antibiotics by 4- to 16-fold. Among enterococci, synergism with biocides was detected for amoxicillin (AM), cefuroxime (CX), erythromycin (EM), ciprofloxacin (CP), and trimethoprim/sulphametoxazol (T/S). Among staphylococci, interactions were synergistic (AM) and either synergistic or indifferent (CX and EM, depending on biocide). Among the three methicillin-resistant Staphylococcus aureus clinical strains included in the study, the combinations of methicillin and triclosan or hexachlorophene acted synergistically in all strains, but interactions were either synergistic or indifferent for the other biocides, depending on the strain. All combinations tested were synergistic for Lactobacillus (AM, CX, EM, and CP) and Micrococcus (AM, EM). In Salmonella, interactions were indifferent (AM, CX, EM, and CP) or synergistic (T/S). Synergism with biocides was also detected in Klebsiella isolates (AM, CX, and T/S), Enterobacter sp. (AM, CX, EM, and T/S), Pantoea (AM, CX, EM, CP, and T/S), and Chryseobacterium sp. (EM). These results suggest that combinations of biocides and antibiotics may open new possibilities to combat antimicrobial resistance.

Survey of policy for MRSA screening in English cataract surgical units and changes to practice after updated National guidelines

Background

National guidelines on MRSA (methicillin-resistant Staphylococcus aureus) screening policy in England have changed on a number of occasions, but there is limited data on its influence at a local level. The aim of this study was to determine if changes in National policy influenced preoperative screening of cataract patients for MRSA.

Methods

A structured telephone survey was conducted on all 133 ophthalmology units in England in 2004 and again in 2007 for the initial responders, after a change in national policy.

Results

A total of 74 units (56%) responded in 2004 and 71 units (96% of initial respondents) in 2007. In 2004, 57% of units screened for MRSA. They screened groups at high risk of carriage, including patients with previous MRSA (93%) and patients from Nursing homes (21%). Swab sites included the nose (100%), eyes (31%) and perineum (62%). In 2007, there was no significant change in the number of units that screened for MRSA (57% vs 66%; p = 0.118; McNemar test). However, more units screened for MRSA in patients from nursing/residential homes (21% vs 51%; p = 0.004, McNemar test), and in patients who had recent admission to hospital (12% vs 36%; p = 0.003). In the second survey, 3 units (6%) now screened patients who were close relatives of MRSA carriers.

Conclusion

This survey has highlighted inconsistences in MRSA screening practice of day-case cataract surgery patients across England after 2 major national policy changes. A change in DoH policy only led to more units screening patients for MRSA from high risk groups.

Whole-genome sequencing shows that patient-to-patient transmission rarely accounts for acquisition of Staphylococcus aureus in an intensive care unit

An assessment of Staphylococcus aureus acquisition among intensive care patients using serial sampling and whole-genome sequencing found less than a fifth of acquisitions resulted from patient-to-patient transmission. Whole-genome sequencing identified transmission more accurately than spa-typing and patient stay data.

Background. Strategies to prevent Staphylococcus aureus infection in hospitals focus on patient-to-patient transmission. We used whole-genome sequencing to investigate the role of colonized patients as the source of new S. aureus acquisitions, and the reliability of identifying patient-to-patient transmission using the conventional approach of spa typing and overlapping patient stay.

Methods. Over 14 months, all unselected patients admitted to an adult intensive care unit (ICU) were serially screened for S. aureus. All available isolates (n = 275) were spa typed and underwent whole-genome sequencing to investigate their relatedness at high resolution.

Results. Staphylococcus aureus was carried by 185 of 1109 patients sampled within 24 hours of ICU admission (16.7%); 59 (5.3%) patients carried methicillin-resistant S. aureus (MRSA). Forty-four S. aureus (22 MRSA) acquisitions while on ICU were detected. Isolates were available for genetic analysis from 37 acquisitions. Whole-genome sequencing indicated that 7 of these 37 (18.9%) were transmissions from other colonized patients. Conventional methods (spa typing combined with overlapping patient stay) falsely identified 3 patient-to-patient transmissions (all MRSA) and failed to detect 2 acquisitions and 4 transmissions (2 MRSA).

Conclusions. Only a minority of S. aureus acquisitions can be explained by patient-to-patient transmission. Whole-genome sequencing provides the resolution to disprove transmission events indicated by conventional methods and also to reveal otherwise unsuspected transmission events. Whole-genome sequencing should replace conventional methods for detection of nosocomial S. aureus transmission.

Infection control strategies for preventing the transmission of meticillin-resistant Staphylococcus aureus (MRSA) in nursing homes for older people

BACKGROUND

Nursing homes for older people provide an environment likely to promote the acquisition and spread of meticillin-resistant Staphylococcus aureus (MRSA), putting residents at increased risk of colonisation and infection. It is recognised that infection prevention and control strategies are important in preventing and controlling MRSA transmission.

OBJECTIVES

To determine the effects of infection prevention and control strategies for preventing the transmission of MRSA in nursing homes for older people.

SEARCH METHODS

In August 2013, for this third update, we searched the Cochrane Wounds Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), Database of Abstracts of Reviews of Effects (DARE, The Cochrane Library), Ovid MEDLINE, OVID MEDLINE (In-process and Other Non-Indexed Citations), Ovid EMBASE, EBSCO CINAHL, Web of Science and the Health Technology Assessment (HTA) website. Research in progress was sought through Current Clinical Trials, Gateway to Reseach, and HSRProj (Health Services Research Projects in Progress).

SELECTION CRITERIA

All randomised and controlled clinical trials, controlled before and after studies and interrupted time series studies of infection prevention and control interventions in nursing homes for older people were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed the results of the searches. Another review author appraised identified papers and undertook data extraction which was checked by a second review author.

MAIN RESULTS

For this third update only one study was identified, therefore it was not possible to undertake a meta-analysis. A cluster randomised controlled trial in 32 nursing homes evaluated the effect of an infection control education and training programme on MRSA prevalence. The primary outcome was MRSA prevalence in residents and staff, and a change in infection control audit scores which measured adherence to infection control standards. At the end of the 12 month study, there was no change in MRSA prevalence between intervention and control sites, while mean infection control audit scores were significantly higher in the intervention homes compared with control homes.

AUTHORS' CONCLUSIONS

There is a lack of research evaluating the effects on MRSA transmission of infection prevention and control strategies in nursing homes. Rigorous studies should be conducted in nursing homes, involving residents and staff to test interventions that have been specifically designed for this unique environment.

Methicillin-resistant Staphylococcus aureus screening as a patient safety initiative: using patients' experiences to improve the quality of screening practices

AIMS AND OBJECTIVES

To explore the patient experience and acceptability of methicillin-resistant Staphylococcus aureus screening of inpatient admissions to acute hospital settings.

BACKGROUND

Prevention of healthcare-associated infections such as methicillin-resistant Staphylococcus aureus is a major patient safety concern internationally. Screening of patients for methicillin-resistant Staphylococcus aureus colonisation is becoming a routine aspect of hospital admission; however, evidence of the patient experience and acceptability of methicillin-resistant Staphylococcus aureus screening is limited.

DESIGN

A mixed-methods study set in six acute care hospitals in three Scottish regions.

METHODS

Data collection involved postdischarge self-report survey of patients who had been screened (n = 54) and qualitative patient interviews (n = 10). Theoretical constructs derived from the Health Belief Model and Theory of Planned Behaviour used in analysis.

RESULTS

Findings indicated that methicillin-resistant Staphylococcus aureus screening was broadly acceptable to patients. The experience of screening did not appear to be problematic; responses demonstrate that screening provided reassurance and generated confidence that health organisations were tackling healthcare-associated infections. Patients were less positive regarding the provision of information, the possibility of refusing a screen and the consequences of a positive test result. Furthermore, there were indications that patients wanted to be told the results of the screen and strong support for screening of hospital staff.

CONCLUSIONS

Analysis of constructs from our theoretical frameworks provides evidence that attitudes were largely positive; responses indicate a belief in the beneficial impact of methicillin-resistant Staphylococcus aureus screening for patients and the wider community. However, it is important that health professionals continually assess the patient experience of 'routine' aspects of health care such as MRSA screening.

RELEVANCE TO CLINICAL PRACTICE

The findings from this study suggest that while methicillin-resistant Staphylococcus aureus screening is generally acceptable to patients as a regular patient safety initiative, to enhance the quality of the patient experience, clinicians should consider the timing, content and effectiveness of information provision.

The national one week prevalence audit of universal meticillin-resistant Staphylococcus aureus (MRSA) admission screening 2012

Introduction

The English Department of Health introduced universal MRSA screening of admissions to English hospitals in 2010. It commissioned a national audit to review implementation, impact on patient management, admission prevalence and extra yield of MRSA identified compared to “high-risk” specialty or “checklist-activated” screening (CLAS) of patients with MRSA risk factors.

Methods

National audit May 2011. Questionnaires to infection control teams in all English NHS acute trusts, requesting number patients admitted and screened, new or previously known MRSA; MRSA point prevalence; screening and isolation policies; individual risk factors and patient management for all new MRSA patients and random sample of negatives.

Results

144/167 (86.2%) trusts responded. Individual patient data for 760 new MRSA patients and 951 negatives. 61% of emergency admissions (median 67.3%), 81% (median 59.4%) electives and 47% (median 41.4%) day-cases were screened. MRSA admission prevalence: 1% (median 0.9%) emergencies, 0.6% (median 0.4%) electives, 0.4% (median 0%) day-cases. Approximately 50% all MRSA identified was new. Inpatient MRSA point prevalence: 3.3% (median 2.9%). 104 (77%) trusts pre-emptively isolated patients with previous MRSA, 63 (35%) pre-emptively isolated admissions to “high-risk” specialties; 7 (5%) used PCR routinely. Mean time to MRSA positive result: 2.87 days (±1.33); 37% (219/596) newly identified MRSA patients discharged before result available; 55% remainder (205/376) isolated post-result. In an average trust, CLAS would reduce screening by 50%, identifying 81% of all MRSA. “High risk” specialty screening would reduce screening by 89%, identifying 9% of MRSA.

Conclusions

Implementation of universal screening was poor. Admission prevalence (new cases) was low. CLAS reduced screening effort for minor decreases in identification, but implementation may prove difficult. Cost effectiveness of this and other policies, awaits evaluation by transmission dynamic economic modelling, using data from this audit. Until then trusts should seek to improve implementation of current policy and use of isolation facilities.

A selected screening programme was less effective in the detection of methicillin-resistant Staphylococcus aureus colonisation in an orthopaedic unit

PURPOSE

Our unit has used a selective screening policy for methicillin-resistant Staphylococcus aureus (MRSA) colonisation using standard chromogenic growth media, based upon risk stratification. The aim of this study was to examine the effectiveness of this selective screening policy.

METHODS

A cohort of 429 patients was assessed for their risk status for MRSA colonisation using both rapid polymerase chain reaction (PCR) swabs and traditional culture and sensitivity analysis. The sensitivity, specificity, positive predictive values and negative predictive values of the traditional selective approach were calculated compared to universal rapid screening.

RESULTS

One hundred eighteen patients were considered high risk and would traditionally be further screened with standard culture of swabs. The prevalence of MRSA was 15/429 (3.5%). The sensitivity of selective screening was 53% identifying eight of 15 cases. The false-negative rate was therefore 47% and seven would have been missed. PCR results were available within four to six hours, whereas culture results were only available at 24 hours for the media showing no growth and not until 72 hours for positive MRSA cases.

CONCLUSIONS

We now advocate universal screening prior to, or on admission, using this rapid PCR test, as we consider this identifies MRSA colonisation more effectively and facilitates "ring-fencing" of orthopaedic beds.

A systematic literature review and meta-analysis of factors associated with methicillin-resistant Staphylococcus aureus colonization at time of hospital or intensive care unit admission

OBJECTIVE

Screening for methicillin-resistant Staphylococcus aureus (MRSA) in high-risk patients is a legislative mandate in 9 US states and has been adopted by many hospitals. Definitions of high risk differ among hospitals and state laws. A systematic evaluation of factors associated with colonization is lacking. We performed a systematic review of the literature to assess factors associated with MRSA colonization at hospital admission.

DESIGN

We searched MEDLINE from 1966 to 2012 for articles comparing MRSA colonized and noncolonized patients on hospital or intensive care unit (ICU) admission. Data were extracted using a standardized instrument. Meta-analyses were performed to identify factors associated with MRSA colonization.

RESULTS

We reviewed 4,381 abstracts; 29 articles met inclusion criteria (n = 76,913 patients). MRSA colonization at hospital admission was associated with recent prior hospitalization (odds ratio [OR], 2.4 [95% confidence interval (CI), 1.3-4.7]; P < .01), nursing home exposure (OR, 3.8 [95% CI, 2.3-6.3]; P < .01), and history of exposure to healthcare-associated pathogens (MRSA carriage: OR, 8.0 [95% CI, 4.2-15.1]; Clostridium difficile infection: OR, 3.4 [95% CI, 2.2-5.3]; vancomycin-resistant Enterococci carriage: OR, 3.1 [95% CI, 2.5-4.0]; P < .01 for all). Select comorbidities were associated with MRSA colonization (congestive heart failure, diabetes, pulmonary disease, immunosuppression, and renal failure; P < .01 for all), while others were not (human immunodeficiency virus, cirrhosis, and malignancy). ICU admission was not associated with an increased risk of MRSA colonization (OR, 1.1 [95% CI, 0.6-1.8]; P = .87).

CONCLUSIONS

MRSA colonization on hospital admission was associated with healthcare contact, previous healthcare-associated pathogens, and select comorbid conditions. ICU admission was not associated with MRSA colonization, although this is commonly used in state mandates for MRSA screening. Infection prevention programs utilizing targeted MRSA screening may consider our results to define patients likely to have MRSA colonization.

Surveillance and management of multidrug-resistant microorganisms

Multidrug-resistant organisms are an established and growing worldwide public health problem and few therapeutic options remain available. The traditional antimicrobials (glycopeptides) for multidrug-resistant Gram-positive infections are declining in efficacy. New drugs that are presently available are linezolid, daptomicin and tigecycline, which have well-defined indications for severe infections, and talavancin, which is under Phase III trial for hospital-acquired pneumonia. Unfortunately the therapies available for multidrug-resistant Gram-negatives, including carbapenem-resistant Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacteriaceae, are limited to only colistin and tigecycline. Both of these drugs are still not registered for severe infections, such as hospital acquired pneumonia. Consequently, as confirmed by scientific evidence, a multidisciplinary approach is needed. Surveillance, infection control procedures, isolation and antimicrobial stewardship should be implemented to reduce multidrug-resistant organism diffusion.

Limited value of routine spa typing: a cross-sectional study of methicillin-resistant Staphylococcus aureus-positive patients in an Austrian hospital

BACKGROUND

We investigated whether spa typing is useful for indicating the setting of methicillin-resistant Staphylococcus aureus (MRSA) acquisition (community or health care acquired), the clinical relevance (colonization or infection), the type of infection (invasive or noninvasive), and the clinical outcome.

METHODS

Between August 2006 and December 2009, 381 routinely diagnosed culture-confirmed MRSA-positive patients were included into a cross-sectional study at an 800-bed hospital.

RESULTS

Out of 159 patients with colonization, 27 (17%) acquired MRSA in the community (CA-MRSA) and 123 (77.4%) in health care settings (HA-MRSA), and, of the 222 patients with infections, 119 (53.6%) had HA-MRSA and 103 (46.4%) had CA-MRSA. The 10 most frequent spa types accounted for 68.2% of the 346 typed MRSA isolates: t190 (28.3%), t032 (16.5%), t041 (9.4%), t008 (8.4%), t001 (3.4%), t002 (2.9%), t044 (3.1%), t223 (2.1%), t015 (2.1%), t127 (1.3%).

CONCLUSION

Spa typing of routinely identified MRSA isolates is unsuitable to predict the likeliness of an infection, of an invasive infection, and the clinical outcome. Molecular criteria such as spa type or Panton-Valentine leukocidin positivity used for classifying MRSA as either belonging to a community or hospital clone are of limited value to indicate the setting, where the MRSA strain was actually acquired according to epidemiologic criteria.

Molecular epidemiological analysis of methicillin-resistant Staphylococcus aureus isolates from a medical intensive care unit: a comparison of nasal and clinical isolates

BACKGROUND

The control of nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) represents a significant challenge to infection control professionals. Nasal carriage colonization by MRSA plays a crucial role in the epidemiology and pathogenesis of this infection.

METHODS

Patients in the medical intensive care unit (ICU) between November 2010 and March 2011 were swabbed when hospitalized, reswabbed 1 week later and for a third time, when they were discharged from the ICU. All swabs were examined within 2 hours of collection using ChromID MRSA-Select agar plates to detect MRSA. Positive specimens were determined to have the mecA and femB gene through amplification with duplex polymerase chain reaction. Repetitive element sequence-based polymerase chain reaction was used to investigate the epidemiological types of MRSA isolates in the third screening and clinical isolates obtained from 2007 to 2010 in West China Hospital. A comparison of molecular types was performed to investigate the genetic relationship between nasal and clinical isolates.

RESULTS

After the third screening, 16 nasal MRSA isolates were identified. Epidemiological analysis revealed that 16 nasal MRSA isolates and 37 clinical MRSA isolates differentiated into 2 clusters, comprising 9 subclusters. Of the 16 nasal strains, 11 (68.8%) belonged to subcluster I of cluster I; 3 of 9 subclusters consisted of both nasal and clinical isolates, while 4 of 9 subclusters consisted of clinical isolates and only 2 of 9 consisted of nasal isolates.

CONCLUSIONS

Our study indicated a high degree of genetic relatedness between nasal and clinical MRSA isolates. The molecular typing of MRSA is critical for controlling the nosocomial transmission of this pathogen in ICU setting and defining a nosocomial infection control policy.

Impact of an enhanced antibiotic stewardship on reducing methicillin-resistant Staphylococcus aureus in primary and secondary healthcare settings

The objective of this study was to evaluate the impact of restricting high-risk antibiotics on methicillin-resistant Staphylococcus aureus (MRSA) incidence rates in a hospital setting. A secondary objective was to assess the impact of reducing fluoroquinolone use in the primary-care setting on MRSA incidence in the community. This was an interventional, retrospective, ecological investigation in both hospital and community (January 2006 to June 2010). Segmented regression analysis of interrupted time-series was employed to evaluate the intervention. The restriction of high-risk antibiotics was associated with a significant change in hospital MRSA incidence trend (coefficient=-0·00561, P=0·0057). Analysis showed that the intervention relating to reducing fluoroquinolone use in the community was associated with a significant trend change in MRSA incidence in community (coefficient=-0·00004, P=0·0299). The reduction in high-risk antibiotic use and fluoroquinolone use contributed to both a reduction in incidence rates of MRSA in hospital and community (primary-care) settings.

Involvement of occupational physicians in the management of MRSA-colonised healthcare workers in Germany - a survey

Background

Colonisation of healthcare workers (HCWs) with methicillin-resistant Staphylococcus aureus strains (MRSA) is a challenge for any healthcare facility. Persistent carriage of MRSA among HCWs causes special problems, particularly in occupational-medical care. German occupational physicians responsible for healthcare facilities were therefore asked about their experience in managing MRSA-colonised HCWs.

Methods

In May 2012, 549 occupational physicians were asked in writing about in-house management of MRSA-colonised HCWs. The semi-standardised survey form contained questions about collaboration between the infection control team and the occupational physician, the involvement of the occupational physician in in-house management of MRSA carriers and the number of persistently colonised HCWs in 2011. The answers were intended to apply to the largest facility cared for by the occupational physician.

Results

207 occupational physicians took part in the survey (response rate 38%). In 2011, 73 (35%) occupational physicians were responsible for the occupational-medical management of an average of four MRSA-colonised HCWs. Eleven doctors (5.3% of 207) managed a total of 17 persistently colonised HCWs. One of these 17 employees was dismissed. In the case of MRSA carriage among HCWs, most occupational physicians cooperated with the infection control team (77%) and 39% of occupational physicians were responsible for the occupational-medical management of the affected carrier. 65% of facilities had specified policies for the management of MRSA-colonised HCWs. After the first MRSA-positive screening result, 79% of facilities attempt to decolonise the affected employee. In 6% of facilities, the colonised HCWs were excluded from work while receiving decolonisation treatment. In 54% of facilities, infection control policies demand the removal of MRSA carriers from patient care.

Conclusions

Not all facilities have policies for the management of MRSA-colonised HCWs and there are major differences in occupational consequences for the affected HCWs. In order to protect both the employees and the patients, standards for the in-house management of MRSA colonisation in HCWs should be developed.

Effect of a disinfection strategy on the methicillin-resistant Staphylococcus aureus CC398 prevalence of sows, their piglets and the barn environment

AIMS

To assess, in a cleaned and disinfected barn environment, the efficacy of an animal disinfection strategy to reduce the livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) prevalence in sows, their offspring and the barn environment.

METHODS AND RESULTS

On each farm, six sow rounds were sampled; sows were divided into either a test or control group. Per round, 20 sows and 40 of their piglets were sampled at different time points together with the barn environment. The disinfection strategy of the test groups consisted of washing the sows with a shampoo followed by disinfection of the skin with a solution containing chlorhexidine digluconate and isopropanol. On the first day of disinfection and 6 days after stopping the disinfection, a significant decrease (P < 0·01) of on average 68 and 66% in sow MRSA prevalence was observed on both farms, whereas no decrease was seen in the control groups. Just before weaning, 21-28 days after the end of the disinfection strategy, the difference in MRSA prevalence between both groups was reduced to 4% and no longer significant (P = 0·20). The MRSA prevalence of the piglets in the test groups was significantly lower (26%; P < 0·01) 6 days after the end of disinfection. Just before weaning, this difference was reduced to 5% but still significant (P < 0·01). In the swine nursery unit, no significant difference (P = 0·99) was seen between both groups. Based on semi-quantitative counts, a relationship (r(2)  > 0·6; P < 0·01) was seen between MRSA contamination in the barn environment and the MRSA prevalence in pigs.

CONCLUSION

Results show that the tested disinfection strategy reduces temporarily the sow and piglet MRSA status, but does not result in a final reduction in MRSA at weaning or in the nursery unit.

SIGNIFICANCE AND IMPACT OF THE STUDY

First report on the efficacy of an animal disinfection strategy to reduce LA-MRSA prevalence in sows, their offspring and the barn environment.

EsxA might as a virulence factor induce antibodies in patients with Staphylococcus aureus infection

Staphylococcus aureus (S. aureus) is an important human pathogen, which commonly causes the acquired infectious diseases in the hospital and community. Effective and simple antibiotic treatment against S. aureus-related disease becomes increasingly difficult. Developing a safe and effective vaccine against S. aureus has become one of the world’s hot spots once again. The key issue of developing the vaccine of S. aureus is how to find an ideal key pathogenic gene of S. aureus. It was previously suggested that EsxA might be a very important factor in S. aureus abscess formation in mice, but clinical experimental evidence was lacking. We therefore expressed EsxA protein through prokaryotic expression system and purified EsxA protein by Ni-affinity chromatography. ELISA was used to detect the anti-EsxA antibodies in sera of 78 patients with S. aureus infection and results showed that the anti-EsxA antibodies were positive in the sera of 19 patients. We further analyzed the EsxA positive antibodies related strains by antimicrobial susceptibility assay and found that all of the corresponding strains were multi-drug resistant. Among those multi-drug resistant strains, 73.7% were resistant to MRSA. The results indicated EsxA is very important in the pathogenesis of S. aureus. We suggested that the EsxA is very valuable as vaccine candidate target antigens for prevention and control of S. aureus infection.

An effective active surveillance method for controlling nosocomial MRSA transmission in a Japanese hospital

Hospital-wide active surveillance for methicillin-resistant Staphylococcus aureus (MRSA) targeted to adult patients with a history of MRSA carriage within the past 5 years was performed in Juntendo University Hospital (JUH) over a 2-year period. In the first year, MRSA screening culture was ordered by physicians in charge. In the second year, infection-control practitioners (ICPs) took samples for active surveillance culture. The average monthly transmission rate of MRSA in JUH was 0.35 per 1,000 bed-days in the first year and decreased significantly to 0.26 per 1,000 bed-days in the second year (P < 0.05). In the second year, more active commitment of ICPs to MRSA screening was effective in improving the performance rate of screening, shortening turn-around time of screening results, and decreasing transmission rate. Increasing compliance with active MRSA surveillance by involvement of ICPs, targeting patients with a previous history of MRSA carriage in the previous 5 years, was effective to control nosocomial MRSA transmission.

Molecular identification and antimicrobial susceptibility of Staphylococcus aureus nasal isolates from medical students in Cartagena, Colombia

Staphylococcus aureus (SA) remains a major cause of nosocomial and community-acquired infections worldwide. Nasal carriage of this bacterium among hospital personnel constitutes an important source for nosocomial infections. A cross-sectional study enrolling the whole medical student population (n=387) of the School of Medicine at the Universidad de Cartagena, Colombia, was conducted to evaluate the carriage rates of both methicillin sensitive- and methicillin resistant-SA, the frequency of Panton-Valentine leukocidin genes in the isolates, and risk factors associated with carriage in this selected population. After signing an informed consent, participants completed a survey related to possible risk factors for colonization, and nasal swabs were collected from anterior nares. Staphylococcus aureus strains isolated from carriers were subjected to DNA extraction and PCR assays to determine the presence of MecA and Panton-Valentine leukocidin genes. Typing of the staphylococcal chromosomal cassette was performed for methicillin resistant strains. Molecular analysis was performed for only one strain per carrier. Prevalence of carriage for methicillin sensitive- and methicillin resistant-SA was 25% and 1.6% respectively. Most of the methicillin resistant isolates carried the staphylococcal chromosomal cassette type IV and the genes for Panton-Valentine leukocidin. To determine carrier types among medical students, each participant was subjected to four additional swabs, each taken two weeks apart. 9.8% persistent carriers, 53.1% intermittent carriers, and 37.1% non-carriers of SA were found. There was no association between risk factors analyzed and carriage of the bacterium. The study was conducted from April to September 2009 and found a persistent carriage of methicillin resistant-SA strains bearing the genes for Panton-Valentine leukocidin among medical students, evidencing the potential contribution of this portion of healthcare personnel either to the spread or introduction of these strains into the healthcare environment.

A survey of methicillin-resistant Staphylococcus aureus control strategies in Italy

PURPOSE

Data regarding the implementation of state-of-the-art methicillin-resistant Staphylococcus aureus (MRSA) control procedures in Italy are lacking. There is a need to evaluate compliance with MRSA recommendations (CR) in Italian hospitals.

METHODS

A 67-question closed-answer survey was sent to all Italian hospitals, in order to analyze and evaluate program consistency with CR [hand hygiene (HH), contact precautions, screening of high-risk patients, decolonization, feedback on surveillance data, and antimicrobial guidelines and education programs].

RESULTS

205 hospitals, which account for 42 % of national admissions, returned questionnaires. 131 hospitals (64 %) did not have written MRSA control guidelines. Hospitals reported the following levels of compliance with CR: (1) HH: 67 hospitals (33 %); (2) contact precautions: 33 (16 %); (3) MRSA screening: 66 (32 %); (4) MRSA decolonization: 42 (20 %); (5) surveillance data feedback: 87 (43 %); and (6) antimicrobial guidelines and education programs: 41 (20 %). One hospital (0.5 % of responses) had implemented all recommendations and 28 hospitals (14 %) had implemented four or five recommendations. 31 % of hospitals surveyed had implemented none. Multivariate analysis showed that the only factor identified as being associated with the implementation of MRSA control recommendations was the number of meetings/year of the infection control team (ICT) (p = 0.004).

CONCLUSIONS

Written MRSA control guidelines are available in only one-third of Italian facilities. An organized system, with ≥4 interventions, has been implemented in just 1 out of 7 hospitals. HH programs and ICT activity are related to better MRSA control. In Italy, there is significant opportunity for improvement in MRSA control.

Relationship and susceptibility profile of Staphylococcus aureus infection diabetic foot ulcers with Staphylococcus aureus nasal carriage

BACKGROUND

Staphylococcus aureus is the main cause of diabetic foot infection with the patient's endogenous flora as the principal source. Nasal carriage of S. aureus has been identified as an important risk factor for the acquisition of diabetic foot infections.

OBJECTIVES

The study assessment the associations of S. aureus with methicillin resistant S. aureus were isolation from diabetic foot infection and nasal carriage of the same patients and their antibiotic susceptibility profile.

METHODS

Diagnosis of S. aureus and methicillin resistant S. aureus were carried out by using standard procedures. Antibiotic sensitivity profiles were determent by breakpoint dilution method.

RESULTS

Out of 222 S. aureus isolation, 139 (62.61%) were isolated from the diabetic foot and 83 (37.39%) from the nasal carriage. Seventy one (30.87%) of the patients were S. aureus infection diabetic foot with nasal carriage. Among diabetic foot infection and nasal carriage patients, 40.85% of S. aureus were considered as methicillin resistant S. aureus. Rifampicin (96.40%) and Levofloxacin (91.44%) were active against S. aureus.

CONCLUSION

Patients at strong risk for methicillin resistant S. aureus nasal carriage and subsequent diabetic foot infection with high resistance to antibiotics.

Prolonged outbreak of meticillin-resistant Staphylococcus aureus in a cardiac surgery unit linked to a single colonized healthcare worker

BACKGROUND

In low- as well as in high-prevalence settings, healthcare workers (HCWs) may be a substantial, under-recognized, reservoir of meticillin-resistant Staphylococcus aureus (MRSA) and an important potential source of transmission to patients.

AIM

To report an outbreak of MRSA in a cardiac surgery unit in England over a 10-month period.

METHODS

Cases were defined as patients and staff on the cardiac surgery unit from whom the outbreak strain was newly isolated between 20 May 2011 and 16 March 2012. Representative isolates from all cases were characterized by spa-typing, pulsed-field gel electrophoresis and multi-locus variable-number tandem-repeat analysis (MLVA).

FINDINGS

Four patients appeared to acquire MRSA during their inpatient stay on the cardiac surgery unit. All four patients and one HCW were found to be carrying an identical epidemic (E)MRSA-15 strain (spa t032, pulsotype A, MLVA profile 16-6-3-1-1-17-1-4). No other members of staff were found to be colonized with MRSA. The colonized HCW was thought to be the source of the outbreak and was decolonized using a combination of nasal mupirocin, chlorhexidine body wash and oral rifampicin and doxycycline.

CONCLUSIONS

This report highlights recent changes in the epidemiology of MRSA in England and suggests an important role for colonized HCWs in the transmission of MRSA to patients. Screening HCWs may provide an increasingly valuable strategy in managing linked hospital acquisitions and well-defined outbreaks where initial investigation does not reveal a source.

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.