Author Christine Perry, MSc, PGDip, RN, is associate programme manager, MRSA/Cleaner Hospitals Team, Department of Health.
Christine Perry summarises current recommendations for MRSA screening and provides information on implementing them.
Screening is a component of an effective MRSA prevention programme and has been recommended in national guidelines for MRSA prevention and control since 1986 (Hospital Infection Society and British Society for Antimicrobial Chemotherapy, 1986). Recent guidance from the Department of Health in England (DH, 2006) and findings from a Health Technology Assessment in Scotland (NHS Health Quality Scotland, 2007) provide current evidence for MRSA screening practices.
Who should be screened for MRSA?
An assessment of the benefits of universal screening for MRSA suggested that the total cost for MRSA screening and associated activity of all patients admitted to a tertiary referral hospital (850 beds) would be £760,000 in the first year (NHS Health Quality Scotland, 2007). A pilot study of the effectiveness of all admission screening to inpatient units in a Scottish Health Board was also recommended in this assessment.
Plans have been announced to screen all elective admissions and all emergency admissions within the next three years in England (DH, 2007).
Certain patient groups should always be included in a screening programme, with others included if indicated by local risk assessment (DH 2006) (see Boxes 1 and 2). It is vital that a clearly agreed process is implemented to ensure patients receive timely results and topical decolonisation therapy.
Elective surgical procedures All patients who are undergoing elective surgical procedures in the orthopaedic, cardiothoracic and neurosurgery specialties should be screened before surgery. The overall risk of MRSA infection for these groups of patients is not high, but MRSA infection as a complication of this type of surgery can be serious, leading to removal of prosthetic implants and potentially death.
Trauma and orthopaedic emergencies All patients admitted as emergencies to trauma and orthopaedic wards should be considered for screening. This is particularly important if emergency patients are cared for in the same location as elective orthopaedic patients.
Critical care and high dependency The risk of MRSA to patients in critical care and high-dependency units is high. Being critically ill and having invasive devices in situ increases the risk of infection both from MRSA that may already be present in or on the body (colonisation/carriage) and from cross-infection from other patients. Patients admitted to intensive and critical care units should be screened on admission and then at weekly intervals while they remain on the unit.
Renal units Patients in renal units have a high risk of acquiring an MRSA bacteraemia. MRSA screening should be carried out when patients are admitted onto a renal dialysis programme and before undergoing fistula formation or insertion of peritoneal or haemodialysis access lines. An ongoing programme of screening should also be put in place for patients receiving haemodialysis and peritoneal dialysis. The frequency of this screening should be determined by local information on MRSA infection and colonisation rates in both renal patients and in the general patient population.
Other groups Screening for specific groups of patients (see Box 2) should be carried out following local risk assessment. This should be based on local knowledge of MRSA rates in specific populations and patient groups, practical aspects of screening and whether the patient is likely to need intensive or critical care.
Staff screening is controversial and mass screening of staff is not recommended (Coia et al, 2006). If staff are screened as part of an MRSA outbreak control initiative, it is important that the screening is not carried out while they are on duty. This is because transient carriage of MRSA that disappears once staff leave the clinical environment is common (Cookson et al, 1989).
Local risk assessments may classify hospital staff as ‘at risk’ if they require admission to hospital. This is because of their exposure to MRSA-positive patients. Other health-related staff may also warrant assessment for screening, for example veterinary personnel who have been found to have relatively high (18%) rates of MRSA carriage (Loeffler et al, 2005).
Obtaining MRSA screening samples The site most commonly sampled for MRSA screening swabs is the nose (DH, 2006). This can detect up to 80% of MRSA-positive patients (Rohr et al, 2004). Including samples from other sites, such as the groin and axilla, can increase the percentage of positive-patient detection to up to 100%. Samples may also be taken from other sites, for example wounds and skin lesions, as non-intact skin encourages MRSA carriage. Sampling the hairline can be used as an indicator of the extent to which an individual will shed MRSA and their risk to other patients.
Invasive devices, such as urinary catheters, can be a focus for MRSA colonisation. A sample may be collected from an invasive device, for example a catheter specimen of urine.
Moistening a swab with sterile saline or water prior to taking a sample from the nose, throat and intact skin can increase the number of micro-organisms collected.
The laboratory request form should clearly indicate that samples are for MRSA screening to ensure the correct laboratory techniques are used. This also avoids potentially wasteful additional processing of the specimens.
Laboratory testing for MRSA
The traditional method for laboratory detection of MRSA involves culturing the sample, often on agar jelly plates that are specifically designed for the identification of MRSA. Recent developments in agar culture plates (chromogenic agar) have reduced the time that laboratories take to identify a possible MRSA-positive patient to 24 hours.
More rapid tests are in development. These include polymerase-chain reaction (PCR) rapid testing that can produce a result in two hours. PCR testing is a biochemical and molecular biology technique that can detect specific genetic material in micro-organisms and detects the gene in Staphylococcus aureus that renders it methicillin resistant. PCR techniques are licensed only for nose swabs in the UK (DH, 2006).
Introducing a policy for MRSA screening
The introduction of a new or amended policy on MRSA screening requires more than just the publication of the document. Staff education and training on the implications of the new policy are required, as well as new procedures to manage the screening, results, patient notification, patient isolation, decolonisation treatment prescription and follow-up screening processes.
It is preferable that the screening of patients undergoing elective surgery is done as part of the pre-operative screening process. Decolonisation treatments can be given before surgery. A care pathway or protocol should ensure that patients identified as MRSA positive receive the appropriate treatment and follow-up screening without delay to their surgical procedure.
It is important to agree responsibilities for checking results and prescribing topical decolonisation treatments and to develop a clear patient pathway and process. Collaboration with nurses and GPs in primary care is essential. Patient group directions for the dispensing of topical treatments may be useful in streamlining the process for patients to obtain treatments.
Elective surgical patients can play an active part in MRSA screening and treatment. The use of patient-held records of MRSA treatment and screening has been used successfully. Providing adequate information is important as patients often find MRSA screening processes complicated (Criddle and Potter, 2006). For an example of a patient-held screening and treatment record, see www.clean-safe-care.nhs.uk
Recommendations for patients who shouldbe screened (DH, 2006)
- Pre-operative patients in the following specialties:
- Elective orthopaedics;
- Cardiothoracic surgery;
- Emergency orthopaedic and trauma admissions.
- Patients requiring critical care (including intensive care and high-dependency units). -patients should be screened on admission to the unit and then weekly.
- Patients who have dialysis on renal units. Patients should be screened on admission and regularly during treatment.
Groups that should be considered for MRSA screening by local risk assessment (DH, 2006)
- All patients known to have been
- All elective surgical patients;
- Oncology/chemotherapy inpatients;
- Patients admitted from high-risk settings;
- All emergency admissions.
It is vital that nurses have sufficient knowledge of MRSA screening, MRSA topical decolonisation therapy and patient implications. Nurses will be at the front line in managing these processes and providing explanation to patients and relatives.
Coia, J.E. et al (2006) Guidelines for the control and prevention of methicillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities. Journal of Hospital Infection; 63: Suppl 1, S1–44.
Cookson, B. et al (1989) Staff carriage of epidemic methicillin-resistant Staphylococcus aureus. Journal of Clinical Microbiology; 27: 7, 1471–1476.
Criddle, P., Potter, J. (2006) Exploring patients’ views on colonisation with methicillin-resistant Staphylococcus aureus. British Journal of Infection Control; 7: 2, 24–28.
Department of Health (2007) Our NHS Our Future: NHS Next Stage Review Interim Report. www.dh.gov.uk/en/
Department of Health (2006) Screening for Methicillin-Resistant Staphylococcus Aureus (MRSA) Colonisation. www.clean-safe-care.nhs.uk
Hospital Infection Society and British Society for Antimicrobial Chemotherapy (1986) Guidelines for the control of methicillin-resistant Staphylococcus aureus. Journal of Hospital Infection; 7: 2, 193–201.
Loeffler, A. et al (2005) Prevalence of methicillin-resistant Staphylococcus aureus among staff and pets in a small animal referral hospital in the UK. Journal of Antimicrobial Chemotherapy; 56: 4, 692–697.
NHS Health Quality Scotland (2007) Health Technology Assessment Advice 9: The Clinical and Cost Effectiveness of Screening for MRSA.
Rohr, U. et al (2004) Qualitative and (semi) quantitative characterization of nasal and skin methicillin-resistant Staphylococcus aureus carriage of hospitalized patients. International Journal of Hygiene and Environmental Health; 207: 1, 51–55.