Staph aureus bacteremia (SAB) includes both MRSA and MSSA bacteremia and carries an attributable mortality rate of up to 25%. As such, it is important to determine ways in which this mortality rate can be reduced.
The evidence base for SAB is summarized nicely in two reviews published in 2014 and 2015. Nine studies with a total of 4050 patients, use of transesophageal echocardiography was associated with higher rates of a diagnosis of endocarditis (14%-28%) compared with transthoracic echocardiography (2%-15%). This has guided standard of care that should be followed to this day and includes:
- All patients with SaB have an echocardiogram. Patients with a medium-to-high risk of endocarditis should undergo a TEE (given lower rate of false-negative studies), but at least a TTE should be performed.
- The option to forego a TEE in low-risk patients with the following: (1) patients had negative blood cultures within 4 days; (2) no haemodialysis dependence; (3) no secondary foci of infection; (4) no clinical signs of endocarditis.
- Vancomycin or daptomycin are first-line therapies for MRSA bacteremia
- The duration of therapy should default to 4–6 weeks unless the patient fulfils criteria for uncomplicated bacteremia (endocarditis excluded; no implanted prostheses; negative blood cultures in 3–4 days; afebrile within 3 days of therapy; no evidence of metastatic infection; no clinical signs of endocarditis).
- Uncomplicated Staph aureus bacteremia with no evidence of endocarditis requires a minimum of 2 weeks IV antibiotics
Most recently, a VA study published this year has defined three interventions in Staph aureus bacteremia that can decrease mortality: requesting infectious disease (ID) consultation; performing echocardiography to detect endocarditis; and choosing antibiotics to reflect the organism’s sensitivities. Overall risk-adjusted for mortality were OR = 0.61 for ID consultation, OR = 0.73 for echocardiography, and OR = 0.74 for suitable antibiotics. Risk-adjusted SAB-related mortality declined from 23.5% in 2003 to 18.2% in 2014. The investigators believe that most of this decline in mortality was due to the increased use of these three interventions.
