Info
🌱 來自: Huppert’s Notes
Bloodstream Infections🚧 施工中
Bloodstream Infections
• Pathophysiology: A bloodstream infection can arise from:
- An endovascular source of infection (e.g., endocarditis or septic thrombophlebitis)
- As a complication of another organ infection (e.g., E. coli bacteremia due to pyelonephritis)
- As a result of direct blood stream innoculation (e.g., as a complication of a central line infection or intravenous drug use)
• Risk factors:
- Any risk factor for severe infection portends an increased risk for bacteremia
- The presence of any indwelling device increases the risk for bacteremia, such as indwelling central venous catheters (e.g., a central line) or hemodialysis catheters
- Certain infections carry an increased risk for bacteremia (e.g., pyelonephritis, cholangitis, pyogenic liver abscess, severe HAP or VAP, severe SSTI)
• Pathogens: Can be Gram-positive, Gram-negative, or fungal. Common organisms include:
- Gram-positive: S. aureus, S. pneumoniae (often as a complication of S. pneumoniae pneumonia), viridans streptococci, Enterococcus spp., S. lugdunensis
- Gram-negative: E. coli, K. pneumoniae, P. aeruginosa, Enterobacter spp.
- Fungi: Most often Candida spp., particularly common in immunocompromised or critically ill patients
• Clinical features: Rigors suggest a bloodstream infection. Other clinical features are non-specific (e.g., fevers, malaise, etc.)
• Diagnosis: Blood cultures ×2. Of note, the presence of a positive blood culture does not always mean that there is a clinically significant blood stream infection (See Table 8.22).
TABLE 8.22 • Interpretation of Positive Blood Cultures
• Treatment:
- Source control: Remove central venous catheters if possible, drain any fluid collection(s) if present, order a TTE in all cases of S. aureus bacteremia or if suspicion for endocarditis
- Empiric antibiotic therapy:
• Gram-positive cocci: Vancomycin
• Gram-negative rods: Ceftriaxone IV 2 g daily (or consider broader Gram-negative coverage if risk factors for P. aeruginosa or ESBL infection). For intra-abdominal infection, empyema, or necrotizing SSTI, ensure you have anaerobic coverage by adding metronidazole to ceftriaxone or cefepime or using piperacillin-tazobactam or a carbapenem.
• Candida spp.: An echinocandin
- Targeted antibiotic therapy and duration of treatment:
• Targeted antibiotic therapy will depend on the antimicrobial susceptibilities
• Duration of therapy depends on the source of the infection and the organism isolated
• Gram-positive organisms: Endocarditis and S. aureus bacteremia are often treated for 4–6 weeks. Other Gram-positive organisms such as S. pneumoniae or viridans streptococci are often treated for 10–14 days.
• Gram-negative rods are often treated for 7–14 days. Patients with uncomplicated Gram-negative rod bacteremia can be transitioned to oral therapy after initial clinical improvement if antibiotic susceptibilities allow. Most data is with an oral fluoroquinolone, although emerging data suggests oral beta lactams can also be used in certain clinical situations.
- Special considerations for bacteremia with certain organisms:
• S. aureus
- Consult ID for all cases due to improved mortality with ID involvement
- Obtain a TTE for all cases of S. aureus bacteremia. If TTE negative, TEE may be necessary depending on the clinical suspicion for endocarditis.
• S. lugdunensis
- Obtain a TTE and consult ID as this can cause a very aggressive infection with multiple metastatic foci (this organism should be treated similarly to S. aureus)
• Candida spp.
- Consult ID for all cases
- Consult ophthalmology to evaluate for endophthalmitis
- Remove any central venous catheters; it may be okay to leave a central venous catheter in place if there is a clear GI source of candidemia (e.g., chemotherapy induced mucositis), but this should be discussed with an infectious disease consultant discuss with ID