Management of Staphylococcus aureus bacteremia in adults
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* Anthony D. Bai
* Andrew M. Morris

## Cases in which a blood culture grows *Staphylococcus aureus *should always be treated as a true bloodstream infection

*Staphylococcus aureus *bacteremia is associated with substantial mortality and complications, including endocarditis and metastatic infection requiring specific investigations and treatment.1 Given the potential for substantial mortality and morbidity, patients with growth of *S. aureus *in blood culture should always be treated.1

## Expert consultation is suggested for all patients with *S. aureus *bacteremia

In observational and quasi-experimental studies, consultation with infectious disease specialists improved the quality of care in patients with *S. aureus *bacteremia, including early source control, follow-up blood culture, echocardiography, and appropriate choice and duration of antibiotic therapy.1 These measures decrease mortality and facilitate earlier discharge.1

## Initial antibiotic therapy for *S. aureus *bacteremia should be intravenous and tailored to susceptibility once known

Vancomycin can be used as empiric therapy before susceptibility is known and as definitive therapy for methicillin-resistant *S. aureus*.2 Definitive therapy for methicillin-susceptible *S. aureus *should be cefazolin or an antistaphylococcal penicillin.2,3 Evidence supporting oral antibiotic therapy is currently limited.

## All patients with *S. aureus *bacteremia should undergo thorough evaluation for infectious source and secondary infectious foci

About 10%–20% of patients with *S. aureus *bacteremia have infective endocarditis.4 All patients with *S. aureus *bacteremia should undergo echocardiography, because the presence of endocarditis has therapeutic and diagnostic implications including consideration for surgery.4,5 Patients at high risk (i.e., those with embolic events, pacemakers, prior endocarditis, prosthetic valves or intravenous drug use) need transesophageal echocardiography to exclude endocarditis.4

## Patients with *S. aureus *bacteremia should be treated with at least 2 weeks of antibiotic therapy

According to consensus guidelines, patients with uncomplicated *S. aureus *bacteremia (Box 1) may be treated with 2 weeks of antibiotic therapy.5 All other patients should be treated with at least 4 weeks of antibiotic therapy.5

Box 1: 
### **Criteria for uncomplicated bacteremia5**

Patients have uncomplicated bacteremia if they satisfy all of the following:

*   Exclusion of endocarditis

*   No implanted prostheses

*   Repeat blood cultures (2–4 d after initial set) give negative results

*   Defervescence within 72 hours of appropriate antibiotic therapy

*   No evidence of metastatic infectious foci

## Footnotes

*   **Competing interests: **None declared.

*   This article has been peer reviewed.

## References

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4.  Bai AD, Agarwal A, Steinberg M, et al. Clinical predictors and clinical prediction rules to estimate initial patient risk for infective endocarditis in *Staphylococcus aureus* bacteraemia: a systematic review and meta-analysis. Clin Microbiol Infect 2017;23:900–6
    
    

5.  Liu C, Bayer A, Cosgrove SE, et al.Infectious Diseases Society of America. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant *Staphylococcus aureus* infections in adults and children. Clin Infect Dis 2011;52:e18–55.
    
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