Bacterial Infections of the CNS Flashcards
Meningitis: most common cause of infection:
Meningitis is an inflammation of the meninges. The most common cause of infection is BACTERIA
Acute Bacterial Meningitis 1) Routes of Entry 2) Clinical Manifestations 3) Most common bacterial agents -neonates-3 mo, >3 mo, Elderly
Acute Bacterial meningitis has three routes of entry into the CNS: Hematogenous (through the blood after colonization- must break down the BBB), direct inoculation (usually present after trauma), and Penetration at the choroid plexus Common clinical manifestations of bacterial meningitis are fever, headache, and skin rash (sign of septecemia)
What are the most common bacterial agents of meningitis? -neonates-3 mo - >3 mo -Elderly
The most common bacterial agents of meningitis -neonates: Strep agalactica (Group B strep) ->3 months: streptococcus pneumoniae, Neisseria meningitidis, Hib -Elderly: strep pneumoniae **consider meningitis caused by Hib in a patient with unknown immunization status and a headache plus nunchal rigidity
What are possible abnormal lab findings associated with acute bacterial meningitis?
Possible abnormal lab findings of the CSF include: -elevated % of neutrophils (>80%) -elevated oppening pressure -very high white blood cell count -gram stain for bacteria -low glucose level -elevated protein
Haemophilus influenzae
shape:
motility:
oxygen use:
virulence factor:
growth media for culture:
vaccine availability:
treatment:
Haemophilus influenzae:
shape: small, gram-negative coccobacilli
motility: nonmotile
oxygen use: facultative anaerobe
virulence factor: PRP capsule, virulent strains also produce IgA protease and neuraminidase
growth media for culture: requires X factor (hemin) and V factor
vaccine availability: yes! vaccines center on CONJUGATE CAPSULAR POLYSACCHARIDES
treatment: ceftotaxime, and Ceftazidime (cephalosporins)
Nisseria meningitidis
transmission:
shape:
oxygen usage:
virulence factor:
growth media for culture:
vaccine availability:
pili:
treatment:
Neisseria meningitidis
*Humans are the only natural host
susceptible populations include children <5, institutionalized individuals, military barracks, jails, etc. any patient with a late complement deficiency
transmission: person to person transmission through respiratory secretions
shape: small, gram-negative, diplocci
oxygen usage: aerobic, oxidase positive
virulence factor: Polysaccharide capsule (also used for serotyping) produces lipooligosaccharide (LOS) endotoxin
growth media for culture: fastidious growth requirements utilizing glucose and maltose
vaccine availability: yes! polysaccharide vaccine. Some combo preps available with Hib
type IV pilus
treatment: cephalosporin or penicillin G
Meningococcemia:
clinical manifestation:
complications:
Meningococcemia:
the clinical presentation of meningococcemia is a purpuric rash on the hands. It may or may not be associated iwth clinical evidence of meningitis
a complication of meningococcemia is DIC with shock
this reflects the high blood content of the LOS endotoxin
Waterhouse Friderichsen Syndrome
Waterhouse Friderichsen Syndrome is acute primary adrenal insufficiency due to hemorrhage of adrenal glands associated with Neisseria meningitidis infection
Streptococcus agalactiae
shape:
hemolysis type:
treatment:
Streptococcus agalactiae-
*the most common cause of meningitis in newborns
shape: Gram-postitive cocci arranged in pairs or chains
Hemolysis type: Beta hemolytic (incomplete hemolysis- turns green on blood agar)
Treatment: penicillin G, ampicillin
Streptococcus pneumoniae
shape:
Transmission:
oxygen usage:
virulence factor:
growth media for culture:
vaccine availability:
treatment:
Streptococcus pneumoniae
*colonized humans are the reservoir
shape: Gram positive, lancet shaped, diploocci
transmission: person to person, aerosols of respiratory secretions
oxygen usage: faculative anaerobe
virulence factor: Polysaccharide capsule (C polysaccharide). sIgA protease (helps to escape host mucin binding)
growth media for culture: blood agar
vaccine availability:
treatment: Penicillin G
Listeria monocytogens
shape:
motility:
cell attachment factors:
oxygen usage:
treatment:
hemolysins:
Lysteria monocytogens
*outbreaks associated with contaminated food. can grow in high salt environments (loose meat, and at cold temperatures)
shape: Gram-positive bacillus
motility: actin- directed intracellular motility (cell to cell) also spread through macrophage-mediated dissemination
cell attachment factors: internalins
oxygen usage: facultative anaerobe
treatment:
hemolysins: Listerolysin O (LLO) pore forming cytolysin and phospholipase C
Brain Abscess
bacterial causes:
spread:
symptoms caused by:
Brain Abscesses are a direct extension from a contiguous focus of infection
bacterial causes: mixed facultative and anaerobic bacteria (Actinomyces, Peptostreptococci, fusobcteria, Prevotella)
Spread through the blood: after surgery/trauma the most common cause is staph aureus
Symptoms are a result of increased intracranial pressure and tissue destruction at specific locations
