CNS Infections- S. pneumoniae Flashcards
Etiologic agent predominately seen in infants to elderly people
Streptococcus pneumoniae - PNEUMOCOCCAL MENINGITIS
Peaks in the young (infants & child
Streptococcus pneumoniae description
- Gram-positive, lancet-shaped diplococcus.
- Not fastidious, grows on blod agar – alpha hemolytic
- aerotolerant anaerobe; catalse negative
Virulence factors of S. pneumoniae
- Encapsulated (90 serotypes)
1. antiphagocytic (capsule)
2. little or no crossreactivity among capsular types relates to possibility of multiple infections.
3. coagulase negative
S. pneumoniae is the most common infectious agent associated with _____________
patients with recurrent meningeal infections
Of the 7 major agents of bacterial meningitis, the highest case fatality rate occurs with ________
pneumococcal meningitis
Seasonality of S. pneumo
Peaks in the late fall and winter but generally all year round
Risk Factor: patients may have pneumococcal pneumonia or antecedent RT infections that lead to
pneumonoccal pulmonary infections
Risk Factor: CSF leaks lea to recurrent meningeal infections; CSF leaks occur in patients with:
- history of head trauma
- congenital defects
Note: it is not uncommon to observe CSF leakage through ear or nose; If the fluid contains β2-transferrin, you know it’s CSF`
Risk Factor: Invasive Pneumococcal Disease (IPD) (describe it)
Disease in which agent has been isolated from a normally sterile site (blood, CSF)
Pathogenesis-
Primary site of damage is the ______ due to neuronal injury/loss via induced apoptosis.
If pneumococcal bacteremia occurs, may produce __________ but NO organisms are present in the lesion. Indistinguishable in appearance from ________ caused by N. meningitidis, except that the pneumococcus is NOT in the lesion.
hippocampus
petechial-purpuric skin lesions (aka- symmetrical peripheral gangrene, SPG)
purpura fulminans
Treatment for children (and adults) with pneumococcal meningitis
- intravenous cefotaxime (an extended-spectrum cephalosporin, 200 mg/kg/d) AND continuous infusion vancomycin (60mg/kg/d after a loading dose of 15mg/kg)
- adjunctive therapy with dexamethasone (10 mg every 6 hours) until strain is proven penicillin-sensitive
-Penicillin susceptible (PenicillinS) S. pneumoniae is treated with Penicillin
Penicillin nonsusceptible S. pneumoniae (PNSP) means its resistant to
- intermediately resistance to penicillin
- full resistance to penicillin.
- resistance to other antibiotics also appeared along with penicillin resistance: Trimethoprim-Sulfamethoxazole, Macrolides like Erythromycin, Fluoroquinolones)
Drug-resistance S. pneumoniae (DRSP) is resistant to penicillin is due to __________.
Resistance to ________ is also increasing, but may be effective. Strains resistant to penicillin are often resistant to at least one other antibiotic, thus penicillin (the drug) resistance is a marker for __________.
mutations in PBPs (AKA transpeptidases)
cephalosporins
resistance to several drugs
Multiply drug resistant (MDR) S. pneumoniae (MDRSP) are resistant to ___________.
> 3 classes of antibiotics
Vancomycin tolerance (antibiotic is now ________), is first seen occurring in some community-circulating strains. Vancomycin tolerance occurs with ___________. Clinically important because its related to relapses, esp. in ___________.
static, no longer cidal
penicillin, aminoglycoside and quinolone tolerance
pediatric cases of pneumococcal meningitis
