The prevalence of methicillin resistant Staphylococus aureus in orthopaedics in a non-selective screening policy

Can we reduce the number of MRSA screening site swabs in elective orthopedic patients?

BACKGROUND

Deep infection after routine elective orthopedic procedures can be catastrophic, leading to further surgery, loss of limb, disability, and risk of mortality. Ring-fencing elective orthopedic ward has been shown to significantly reduce the incidence of all postoperative infections especially with methicillin-resistant Staphylococcus aureus (MRSA). Our hospital's current MRSA screening is a four-site MRSA swabs.

OBJECTIVES

This study evaluates the possibility of reducing the number of MRSA swab sites as part of a quality improvement project.

STUDY DESIGN AND METHODS

Patients on the waiting list for elective orthopedic procedure in our trust who had an MRSA-positive swab from either four sites were analyzed over the time period from January 2012 to December 2014. Those without swabs from all four areas (nose, throat, axilla, and groin) were excluded. Positive swabs of different regions were recorded and compared.

RESULTS

There were 138 MRSA-positive patients, giving an incidence of 31 per 10,000 screen/year over that time period. Some patients ( n = 31, 22.5%) had a positive swab in more than one site. The positive sites were as follows: nose (69.60%, n = 96), groin (26.10%, n = 36), throat (25.30%, n = 35), and axilla (8.70%, n = 12). In our cohort, we would miss a significant proportion of positive patients if we change it to a two swab screening policy (26.8% for nose and axilla combination; 18.10% for nose and groin combination; and 15.20% for nose and throat). However, we would only miss 2.2% of cases for a nose, groin, and throat three-swab policy. There were also 11 instances, where a previously negative site become positive in the next swab.

CONCLUSION

A three-swab combination of nasal, throat, and groin swabs improves pickup rate of MRSA significantly compared to a two-swab policy and misses only 2.2% compared to a four-swab policy. Axilla swabbing does not make a significant difference to the results. Based on this study, the policy has now been changed from a four-swab to three-swab screening in our trust. This has now been audited four times and they were all negative. This has helped to reduce cost in terms of staff time and resources. We would not recommend screening only the previous positive site for the next repeat screening swabs as there is an 8% chance of missing MRSA carrier status.

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.

MRSA prevalence in European healthcare settings: a review

BACKGROUND

During the past two decades, methicillin-resistant Staphylococcus aureus (MRSA) has become increasingly common as a source of nosocomial infections. Most studies of MRSA surveillance were performed during outbreaks, so that results are not applicable to settings in which MRSA is endemic. This paper gives an overview of MRSA prevalence in hospitals and other healthcare institutions in non-outbreak situations in Western Europe.

METHODS

A keyword search was conducted in the Medline database (2000 through June 2010). Titles and abstracts were screened to identify studies on MRSA prevalence in patients in non-outbreak situations in European healthcare facilities. Each study was assessed using seven quality criteria (outcome definition, time unit, target population, participants, observer bias, screening procedure, swabbing sites) and categorized as 'good', 'fair', or 'poor'.

RESULTS

31 observational studies were included in the review. Four of the studies were of good quality. Surveillance screening of MRSA was performed in long-term care (11 studies) and acute care (20 studies). Prevalence rates varied over a wide range, from less than 1% to greater than 20%. Prevalence in the acute care and long-term care settings was comparable. The prevalence of MRSA was expressed in various ways - the percentage of MRSA among patients (range between 1% and 24%), the percentage of MRSA among S. aureus isolates (range between 5% and 54%), and as the prevalence density (range between 0.4 and 4 MRSA cases per 1,000 patient days). The screening policy differed with respect to time points (on admission or during hospital stay), selection criteria (all admissions or patients at high risk for MRSA) and anatomical sampling sites.

CONCLUSIONS

This review underlines the methodological differences between studies of MRSA surveillance. For comparisons between different healthcare settings, surveillance methods and outcome calculations should be standardized.

MRSA in dermatology - Prospective epidemiological study in employees and patients of a dermatological department of a university hospital

BACKGROUND

In recent years, the prevalence of MRSA has increased worldwide. There is a lack of systematic epidemiological studies evaluating the prevalence of MRSA in dermatology in Germany.

OBJECTIVE

What is the prevalence of MRSA in the employees and hospitalized patients in a dermatological department? What dermatological diagnoses have the highest risk for MRSA?

PATIENTS AND METHODS

Nasal swabs taken twice (at admission and discharge) from all consenting hospitalized patients and once from all consenting employees were analyzed for MRSA.

RESULTS

Analysis von 798 swabs (715 patients, 83 employees). Detection of MRSA in 31 swabs (MRSA rates: all = 4.3 %, patients = 3.7 %, employees = 4.8 %). Patients with a chronic leg ulcer had a significantly increased risk for MRSA (p = 0.03). Increased MRSA rates without statistical significance were found for men, patients with at least one hospitalization during the last 12 weeks and a hospitalization of at least 5 days. None of the patients with psoriasis had MRSA.

CONCLUSIONS

In comparison to international studies, the prevalence of MRSA in the current study is in the lower third. In dermatology, patients with a chronic leg ulcer have an increased risk for MRSA and should be screened at admission. A general screening for MRSA seems to be not reasonable in view of the low MRSA rates in the investigated department.