From the Guidelines
The antibiotic of choice for streptococcal pneumonia in the bloodstream (bacteremic pneumococcal pneumonia) is penicillin G or amoxicillin for penicillin-susceptible strains, with a third-generation cephalosporin like ceftriaxone (1-2g IV every 24 hours) recommended for empiric therapy before susceptibility results are available, often combined with a macrolide such as azithromycin (500mg daily) to cover atypical pathogens 1.
Key Considerations
- For penicillin-susceptible strains, penicillin G or amoxicillin are the preferred choices.
- For empiric therapy, a third-generation cephalosporin like ceftriaxone is recommended, often combined with a macrolide like azithromycin.
- In penicillin-allergic patients, respiratory fluoroquinolones like levofloxacin (750mg daily) or moxifloxacin (400mg daily) are appropriate alternatives.
- Treatment duration is typically 7-10 days, with transition to oral therapy once the patient shows clinical improvement and has been afebrile for 48-72 hours.
Resistance and Susceptibility
- Streptococcus pneumoniae can develop resistance to penicillins through alterations in penicillin-binding proteins, which is why broader coverage is often initiated until susceptibility is confirmed 1.
- The choice of antibiotic should be narrowed based on culture results and susceptibility testing, as resistance patterns vary geographically.
Supportive Care
- Blood cultures should be repeated to ensure clearance of bacteremia.
- Supportive care including oxygen therapy and fluid management is essential alongside antibiotic treatment.
Recent Guidelines
- The most recent guidelines from 2015 recommend four weeks of antimicrobial therapy with penicillin, cefazolin, or ceftriaxone for IE caused by S pneumoniae, with vancomycin as an alternative for patients intolerant of β-lactam therapy 1.
From the Research
Antibiotic of Choice for Streptococcal Pneumonia with Bacteremia
- The antibiotic of choice for Streptococcal pneumonia with bacteremia is ceftriaxone, as it has been shown to be effective against penicillin-susceptible and -resistant strains of Streptococcus pneumoniae 2, 3, 4.
- Ceftriaxone has been recommended as empirical treatment in adults hospitalized with community-acquired pneumonia, with the addition of a macrolide 2.
- A study found that ceftriaxone 1 g/d was associated with similar mortality rates as ceftriaxone 2 g/d, with a decreased rate of C. difficile infection and shorter length of stay 2.
- Another study found that shorter antibiotic courses (5-10 days) may be appropriate in patients with S pneumoniae bacteremia secondary to community-acquired pneumonia 5.
- The in vitro activity of ceftriaxone against penicillin-resistant Streptococcus pneumoniae has been demonstrated, with ceftriaxone being one of the most active agents tested 3.
- A mouse pneumonia model study found that ceftriaxone was effective against both penicillin-susceptible and -resistant strains of Streptococcus pneumoniae, with a marked and prolonged antibacterial effect in the lungs 4.
- A review of the literature found that there is only a single report of documented microbiologic failure of parenteral penicillin-class antibiotics, including ceftriaxone, in the treatment of pneumococcal pneumonia, suggesting that ceftriaxone is a reliable choice for treatment 6.