Laboratory-confirmed cases of Staphylococcus aureus bacteraemia detected by blood culture confirmed resistant to any of:
- Meticillin
- Oxacillin
- Cefoxitin
- Flucloxacillin
Rationale
A long running voluntary surveillance scheme of laboratory reported cases of Staphylococcus aureus bacteraemia showed increasing incidence of meticillin resistant S. aureus (MRSA) infections in England, Wales and Northern Ireland in the 1990s. This generated both media and public interest. In response, the Department of Health (DH) in England introduced a mandatory surveillance scheme for S. aureus bacteraemias in April 2001, which included data on the number of cases that were due to MRSA. In October 2005 the mandatory surveillance scheme for MRSA bacteraemias was enhanced to collect patient-level data.
Additionally, all NHS organisations reporting cases of MRSA bacteraemia from the 1 April 2013, are required to complete a Post Infection Review (PIR). This process was commenced to support the delivery of zero tolerance on MRSA bacteraemia, as set out by NHS England in the Planning Guidance Everyone counts: Planning for Patients 2013/14. A PIR is undertaken after all MRSA bacteraemias with the purpose of identifying how a case occurred, to identify actions by local healthcare teams which will prevent a reoccurrence and to identify the organisation best placed to ensure improvements are made (this is known as “assigning” a case to an organisation). A low value is indicative of a low count of MRSA.
Definition of numerator
All cases of MSSA meeting the 'Definition' section above occurring for the past 11 months are summed with the current month to give a rolling 12-month total. For the calculation of rates, the past 11 months are summed with the current month and the denominator is the sum of the bed-days (for trusts) or population (for SICBLs) for the current month and preceding 11 months.
The rate for a month is then calculated by dividing the numerator by the denominator and multiplying by 100,000 to give a manageable value.
Definition of denominator
Denominator values are calculated as an annual rolling sum. For any given month, the denominator includes the value for the defined geography in the given month and the 11 preceding months.
Caveats
These data do not provide a basis for decisions on the clinical effectiveness of infection control interventions in individual Trusts: further investigations considering potential confounders would need to be undertaken before this could be done. Nor do these data provide a basis for comparisons between acute Trust or SICBLs. Rate information, using rate calculations as currently defined, is not appropriate for comparison. The counts of infections have not been adjusted to give a standardised rate considering factors such as organisational demographics or case mix. Rate information is of use for comparison of an individual organisation over time.
‘All reported cases’ refers to all MRSA-positive blood cultures reported by the Trust whose laboratory processes the specimen. It is important to note that this does not necessarily imply that the infection was acquired there. Cases that the UKHSA's HCAI Data Capture System attributes to a commissioning hub (such as the national commissioning hub, 13Q, or one of the regional Health & Justice commissioning hubs) are not featured in sub ICB Location dashboards but they do still contribute to the highest spatial level—the England national total. This means the England case total may be slightly higher than the sum of all sub ICB Location cases.