Streptococcus pneumoniae

Streptococcus pneumoniae is a topic covered in the Johns Hopkins ABX Guide.

To view the entire topic, please or .

Official website of the Johns Hopkins Antibiotic (ABX), HIV, Diabetes, and Psychiatry Guides, powered by Unbound Medicine. Johns Hopkins Guide App for iOS, iPhone, iPad, and Android included. Explore these free sample topics:

-- The first section of this topic is shown below --

MICROBIOLOGY

  • Aerobic, Gram-positive diplococcus [Fig 1] with a capsule.
  • Grows on blood agar.
  • Capsular swelling w/ application of Quelling antisera [Fig 2].
  • Serotypes: immunity is serotype-specific.
    • Abx resistance is often serotype-specific.
    • Serotypes 19A and 19F have emerged as predominant pathogen following increased immunization.
  • Minimum inhibitory concentration (MIC) to penicillin (mcg/mL) breakpoints for non-CNS specimens.
    • Susceptible: 2 mcg/mL
    • Intermediate: 4 mcg/mL
    • Resistant: 8 mcg/mL
    • Previously were determined solely on the basis of possible meningeal disease.
      • New breakpoints above are based on anticipated respiratory or non-CNS isolates.
      • Susceptible breakpoint for meningitis caused by S. pneumoniae remains unchanged
        • S= 0.06 mcg/mL
        • I = 0.12 - 1.0 mcg/mL
        • R ≥ 2 mcg/mL
      • This now means that >95% of strains are sensitive to penicillin, and penicillin is the preferred drug.
  • Penicillin resistance is increasing due to "replacement strains" associated with extensive use of Prevnar (PCV-7, now PCV-13) vaccine with the emergence of 19A strain and more recently serotypes 6C and 35. These serotypes are relatively nonsusceptible to penicillin.

-- To view the remaining sections of this topic, please or --

MICROBIOLOGY

  • Aerobic, Gram-positive diplococcus [Fig 1] with a capsule.
  • Grows on blood agar.
  • Capsular swelling w/ application of Quelling antisera [Fig 2].
  • Serotypes: immunity is serotype-specific.
    • Abx resistance is often serotype-specific.
    • Serotypes 19A and 19F have emerged as predominant pathogen following increased immunization.
  • Minimum inhibitory concentration (MIC) to penicillin (mcg/mL) breakpoints for non-CNS specimens.
    • Susceptible: 2 mcg/mL
    • Intermediate: 4 mcg/mL
    • Resistant: 8 mcg/mL
    • Previously were determined solely on the basis of possible meningeal disease.
      • New breakpoints above are based on anticipated respiratory or non-CNS isolates.
      • Susceptible breakpoint for meningitis caused by S. pneumoniae remains unchanged
        • S= 0.06 mcg/mL
        • I = 0.12 - 1.0 mcg/mL
        • R ≥ 2 mcg/mL
      • This now means that >95% of strains are sensitive to penicillin, and penicillin is the preferred drug.
  • Penicillin resistance is increasing due to "replacement strains" associated with extensive use of Prevnar (PCV-7, now PCV-13) vaccine with the emergence of 19A strain and more recently serotypes 6C and 35. These serotypes are relatively nonsusceptible to penicillin.

There's more to see -- the rest of this entry is available only to subscribers.