infectious diseases
Pneumococcal Infections
Treatment of Pneumococcal Infections
A beta-lactam, macrolide, respiratory fluoroquinolone (eg,levofloxacin,moxifloxacin),tetracycline(eg,doxycycline,omadacycline), or pleuromutilin (eg,lefamulin) If pneumococcal infection is suspected, initial therapy pending susceptibility studies should be determined by local resistance patterns. Although preferred treatment for pneumococcal infections is a beta-lactam or macrolide antibiotic, treatment has become more challenging because resistant strains have emerged. Strains highly resistant to penicillin,ampicillin, and other beta-lactams are common worldwide. The most common predisposing factor to beta-lactam resistance is use of these antibiotics within the past several months. Resistance to macrolide antibiotics has also increased significantly; these antibiotics are not recommended as monotherapy for hospitalized patients with community-acquired pneumonia. Susceptibility or resistance to beta-lactam antibiotics (penicillin and the extended-spectrum cephalosporinsceftriaxoneandcefotaxime) depends on the site of infection and minimal inhibitory concentration (MIC) breakpoints. Susceptible organisms have MICs below the breakpoint, and resistant organisms have MICs above the breakpoint. MIC breakpoints typically are higher for nonmeningeal pneumococcal infection than for meningeal infection. MIC breakpoints for patients with meningeal pneumococcal infection: Penicillin-susceptible strains: MIC ≤ 0.06 mcg/mL Penicillin-resistant strains: MIC ≥ 0.12 mcg/mL Cefotaxime- andceftriaxone-susceptible strains: MIC ≤ 0.5 mcg/mL Cefotaxime- andceftriaxone-intermediate strains: MIC > 0.5 to ≤ 1.0 mcg/mL Cefotaxime- andceftriaxone-resistant strains: MIC > 1.0 mcg/mL If the penicillin MIC is ≤ 0.06 mcg/mL, treatment of meningeal pneumococcal infection may be with IV penicillin; however,ceftriaxoneorcefotaximeis preferable. If the penicillin MIC is ≥ 0.12 mcg/mL and theceftriaxoneorcefotaximeMIC is ≤ 0.5 mcg/mL, treatment is withceftriaxoneorcefotaxime. If theceftriaxoneorcefotaximeMIC is ≥ 1.0 mcg/mL, treatment is withceftriaxoneorcefotaximeplusvancomycin. MIC breakpoints for patients with nonmeningeal pneumococcal infection: Penicillin-susceptible strains: MIC ≤ 2 mcg/mL Penicillin-intermediate strains: MIC > 2.0 to ≤ 4.0 mcg/mL Penicillin-resistant strains: MIC > 4.0 mcg/mL Cefotaxime- andceftriaxone-susceptible strains: MIC ≤ 1 mcg/mL Cefotaxime- andceftriaxone-intermediate strains: MIC > 1.0 to ≤ 2.0 mcg/mL Cefotaxime- andceftriaxone-resistant strains: MIC > 2.0 mcg/mL Seriously ill patients with nonmeningeal infections caused by organisms that are resistant to penicillin can often be treated withceftriaxoneorcefotaxime. Very high doses of parenteralpenicillin G(20 to 40 million units/day IV for adults) also work, unless the MIC of the isolate is very high, indicating resistance. Fluoroquinolones (eg,moxifloxacin,levofloxacin),omadacycline, andlefamulinare effective for respiratory infections with highly penicillin-resistant pneumococci in adults. Evidence suggests that the mortality rate for bacteremic pneumococcal pneumonia is lower when combination therapy (eg, macrolide plus beta-lactam) is used. All penicillin-resistant isolates have been susceptible tovancomycinso far, but parenteralvancomycindoes not always produce concentrations in cerebrospinal fluid adequate for treatment of meningitis (especially if corticosteroids are also being used). Therefore, in patients with meningitis,ceftriaxoneorcefotaximeis commonly used withvancomycin. 