NHS Greater Glasgow & Clyde Area Drug and Therapeutics Committee
Greater Glasgow and Clyde Medicines
Medicines Update Acute

Management of Staphylococcus aureus Bacteraemia (SAB) in NHSGG&C

Staphylococcus aureus Bacteraemia (SAB) is a serious, life-threatening blood stream infection that is often related to hospitalisation and in many cases may be preventable. When S. aureus is isolated in blood it is seldom a contaminant and should always be treated as significant.


Risk Factors for SAB and prevention of SAB

 
Intravascular and other invasive devices, skin & soft tissue infections, surgical site infections and intravenous drug use are risk factors for SAB.


The following measures may prevent the development of SAB:
1) Follow the correct procedure for the insertion and maintenance of the following invasive devices: - central venous catheterperipheral venous cathetersurinary catheters and devices for vascular access for haemodialysis.       .       
2) Ensure patients who do not require intravenous (IV) therapy/fluids have their intravascular devices removed promptly.
3) Follow IV to oral switch antibiotic guidelines to minimise prolonged IV antibiotic therapy.


Treatment of SAB

 
The Scottish Antimicrobial Prescribing Group (SAPG) developed guidance to optimise the management of SAB in adults and the key points are summarised below.
• Undertake a clinical review to identify the source of infection e.g. vascular device, skin, bone/joint, endocarditis, prosthesis/implant.  Remove the source where possible.
• Prescribe empirical treatment with IV flucloxacillin 2 grams 6 hourly (unless renal function is impaired). For patients with true penicillin allergy or MRSA, prescribe vancomycin (target trough level is 15-20mg/L).
• Continue IV therapy for a minimum of 2 weeks to reduce the risk of relapse.
• Discuss all patients with an infection specialist.
• SAB is an important indication for echocardiogram.  Unless overwhelming evidence against endocarditis (e.g. acute peripheral cannula-related infection with no signs of endocarditis or ongoing sepsis), all patients should undergo echocardiography.
• Repeat blood cultures after 48-96 hours of effective antibiotic therapy.


National targets and local audits

 
The Scottish Government target is to reduce healthcare-associated SABs to  ≤ 24 patients per 100,000 acute occupied bed days;  the target for NHSGGC is therefore ≤ 25 cases per month. In January 2015 there were 32 SAB cases (of note, only one patient had MRSA bacteraemia), representing a rate of 26 per 100,000 acute occupied bed days.  This is just above the government target but the graph demonstrates an improvement over the past 10 years.

 

Key findings from July-Sept 2013 audit (n= 61)

• Only 43% (n=26) of patients with SAB received a minimum of 14 days of IV antibiotic therapy, although in 38% (n=23) of patients a valid reason for shortened therapy was recorded.
• In 20% (n=12) of patients no valid reason was recorded for shortened therapy and one patient from this group experienced a relapse in infection at 9 months.
• Overall 41% (n=35) of patients did not undergo echocardiography (clinical portal was accessed to determine if the scan had been carried out).
• Overall mortality at 6 months was 31% (n=19) irrespective of duration of therapy; 8 of these patients (42%) received ≥ 14 days of IV antibiotics and 11 patients (58%) received < 14 days therapy.


Key messages for managing SAB

 
1. Prevent SAB by correct insertion and maintenance of catheters, removing catheters promptly when no longer  required and switching IV antibiotics to oral therapy as appropriate.
2. Always treat if S. aureus is isolated in blood.
3. Investigate for and remove source of SAB.
4. Discuss all patients with an infection specialist.
5. Unless overwhelming evidence against endocarditis, all patients should undergo echocardiography.
6. Ensure that all patients with SAB receive at least 14 days IV antibiotic therapy.