Staphylococcus aureus bacteremia
From IDWiki
Classification
- Community-onset: positive blood culture obtained within 48 hours of presentation
- Nosocomial: positive blood culture obtained after 48 hours of presentation
Etiology
- IVDU
- Poor dentition
- Dental work
Clinical Presentation
- Often non-specific fevers and chills, diagnosed on blood cultures
- May have back pain unrelated to spinal osteomyelitis
- May present with focus of metastatic disease
Investigations
- Repeat blood cultures every 24 to 48 hours until negative
- Transthoracic echo (TTE) or transesophageal echo (TEE)
- A modern TTE that is good-quality and shows normal valves is quite good, though TEE is still better
Management
- Infectious diseases consultation
- Must rule out endocarditis! TTE, followed by TEE if suspicion remains high
- Low risk for endocarditis (no TEE) if all of the following:
- No intracardiac device
- Sterile follow-up blood cultures within 4 days from the initial set
- No hemodialysis
- Nosocomial acquisition of S. aureus
- Absence of secondary foci
- No clinical signs of endocarditis
- Uncomplicated if
- Endocarditis is excluded
- No implanted prostheses
- Blood cultures clear by 2-4 days
- Defervesces within 72 hours
- No evidence of metastases
- +/- identified source has been removed
- Two-week course acceptable if uncomplicated, otherwise 4-6 weeks
- MSSA: cloxacillin 2g IV q4h for 2 weeks (cefazolin as an alternative)
- MRSA: vancomycin 1g IV q12h for 2 weeks
- Adjust based on serum trough before every fourth dose
- Target trough 15-20
Prognosis
- Mortality 20-50% at 30 days, 60% at 1 year
- Mortality halved by ID consult
- Prognosis worse with
- Increased age
- Female sex
- Pneumonia or source unknown
- Dementia
- Increasing comorbidities
- Shock at time of presentation
- Institutionalized patient
