What Is the Best Treatment for an Adult Patient with Staphylococcus aureus Bacteremia?

Key Points

  • Staphylococcus aureus bacteremia (SAB) is a common cause of morbidity and mortality.
  • The treatment of SAB is twofold, requiring both the removal of the nidus of infection if present, such as a catheter or a prosthetic device, and appropriate antimicrobial therapy.
  • The duration of antibiotics varies depending on several factors including presence of metastatic infection, clinical response to antimicrobial therapy, and comorbid conditions.
  • Per IDSA, echocardiography is recommended in all patients with bacteremia, with preference of transesophageal echocardiography (TEE) over transthoracic echocardiography (TTE), although recent studies suggest that TEE might not be necessary in a subset of low-risk SAB patients.
  • Routine infectious-disease consult should be considered in patients with SAB, especially those with severe illness and multiple comorbid conditions, as it improves clinical outcomes.
In a recent prospective cohort study in a tertiary-care center, even after adjusting for pre-existing comorbidities and severity of disease, an ID consult was associated with a 56% reduction in 28-day mortality.

Case

An 82-year-old man with non-Hodgkin’s lymphoma in remission and a history of congestive heart failure and hypertension presents with one week of generalized malaise and intermittent fevers. Vitals show a temperature of 101oF, blood pressure of 130/60 mmHg, and heart rate of 100. His exam is notable for an erythematous and tender chest port site, with no murmurs. Blood cultures drawn upon presentation show gram-positive cocci speciated to Staphylococcus aureus. What are the next steps in management of this patient?

Overview

S. aureus bacteremia (SAB) is a common infectious cause of morbidity and mortality worldwide, causing both community-acquired and hospital-acquired bacteremia. In the U.S. alone, it accounts for 23% of all bloodstream infections and is the bacterial pathogen most strongly associated with death.1 Mortality rates are approximately 42% in those with methicillin-resistant S. aureus (MRSA) bacteremia and 28% in those with methicillin-sensitive S. aureus (MSSA) bacteremia.2

Recognizing the severity of SAB, the Infectious Disease Society of America (IDSA) published treatment guidelines in 2011 to help direct the clinical care of this disease process.3 However, the majority of the recommendations are based on observational studies and expert opinion, as less than 1,500 patients have been enrolled in randomized controlled trials specifically targeted to investigate the treatment of SAB.4

Review of the Data

A clinically significant SAB usually is defined as the isolation of S. aureus from a venous blood culture with associated symptoms and signs of systemic infection.5 As SAB contamination is rare and can be associated with multiple complications, including metastatic infections, embolic stroke, recurrent infection, and death, any finding of a positive blood culture must be taken seriously.4

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