Streptococcus pneumoniae
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 had emerged as predominant pathogens following increased immunization.
- Serotype 24F, with the advent of PCV-13, is now problematic and often with multi-drug resistance[6].
- 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, MICs were determined solely based on possible meningeal disease.
- The breakpoints above are based on anticipated respiratory or non-CNS isolates.
- The 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 means that >95% of strains are sensitive to penicillin, the preferred drug.
- Penicillin resistance is increasing due to "replacement strains" associated with the extensive use of conjugated pneumococcal vaccines, although PCV-15 and PCV-20 are now on the scene. Replacement serotypes tend to be relatively nonsusceptible to penicillin.
There's more to see -- the rest of this topic is available only to subscribers.
Last updated: February 10, 2024
Citation
Auwaerter, Paul G. "Streptococcus Pneumoniae." Johns Hopkins ABX Guide, The Johns Hopkins University, 2024. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540523/all/Streptococcus_pneumoniae.
Auwaerter PG. Streptococcus pneumoniae. Johns Hopkins ABX Guide. The Johns Hopkins University; 2024. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540523/all/Streptococcus_pneumoniae. Accessed October 13, 2024.
Auwaerter, P. G. (2024). Streptococcus pneumoniae. In Johns Hopkins ABX Guide. The Johns Hopkins University. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540523/all/Streptococcus_pneumoniae
Auwaerter PG. Streptococcus Pneumoniae [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2024. [cited 2024 October 13]. Available from: https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540523/all/Streptococcus_pneumoniae.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC
T1 - Streptococcus pneumoniae
ID - 540523
A1 - Auwaerter,Paul,M.D.
Y1 - 2024/02/10/
BT - Johns Hopkins ABX Guide
UR - https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540523/all/Streptococcus_pneumoniae
PB - The Johns Hopkins University
DB - Pediatrics Central
DP - Unbound Medicine
ER -