CNS Infections Flashcards
types of aseptic meningitis (neg bacterial cultures)
viral meningitis, fungal infections, bacterial infections
clinical signs and symptoms - meningitis
petechiae rash first 3 days; purpuric lesions; severe headache, fever, pos Brudzinski’s sign (cervical rigidity), hamstring spasm, pos blood culture may be seen
describe Brudzinski’s sign and Kernig’s sign
Brudzinski’s: cervical rigidity causing knees to pop up; Kernig’s sign: unable to straighten leg in 90 degree angle without pain
signs and symptoms of bacteremia
upper RTI, pos blood culture but not much replication, transient with fever, resolves in 1-2 days
signs and symptoms of meningococcemia
pos blood culture, replication in the blood, malaise, rash, may resolve or proceed
*signs and symptoms of meningitis
sudden onset fever, nausea, vomiting, headache, decreased ability to concentrate, myalgias; may have disseminated intravascular coagulation, shock; will have pos Brudzinski’s and Kernig’s signs
what causes disseminated intravascular coagulation?
activation of extrinsic and intrinsic clotting cascade by macrophage production of procoagulant tissue factor
what are the symptoms and signs of DIC?
widespread ischemic changes and bleeding due to using up of clotting factors; septic shock; increased vascular permeability, fluid loss
what is Waterhouse-Friderichsen syndrome?
adrenal infarction leading to acute adrenal insufficiency (associated with DIC, not meningitis)
highest incidence of meningitis in this age group
children 6-12 months
morphology of Neisseria meningitidis
gram-neg, diplococcic, lipooligosaccharide to form effective capsule, has serogroups
metabolism of Neisseria meningitidis
aerobic but can grow anaerobic, cyt c oxidase positive, ideally grown in increased CO2, grows on blood agar, choc agar
Neisseria meningitides pathogenesis- function of capsule, pili, and LOS
capsule resistance to phagocytosis, pili for adherence, LOS production of cytokines esp. TNF (may result in septic shock)
major cause of N. meningitides pathology
LOS (TNF, inflammation)- activates macrophages through the Toll pathway, which leads to production of procoagulant TF, subsequent bleeding
physical findings on path slides for N. meningitidis
PMN’s, gram neg diplococcic on gram stain of CSF
diagnosis procedures for N. meningitidis
culture of CSF on blood and choc agars (gold standard), blood cultures when meningococcemia suspected.
treatment of suspected meningitis needs to cover..// what ABs should be used?
meningococcus, pneumococcus, hemophilus (cefotaxime, vancomycin); rif and ciprofloxacin for contacts
methods of immunity to meningitis
antibodies directed against the CAPSULE, vaccines available
life cycle of toxoplasma gondii
oocyst in cat feces, ingested, sporozoites hatch into tachyzoites in the gut of the animal, goes through asexual repro, infects primarily macrophages (liver, lungs)
the definitive host (cat) houses which stages of the organism?
sexual and asexual stages (psuedocysts form containing bradyzoites)
toxo is asymptomatic in what percentage of cases?
80-90%
picture of toxo resembles..
infectious mono or CMV infection
how severe toxo manigefests
CNS disease: encephalopathy, meningoencephalitis
describe infection of congenital toxo
newly acquired in mother during pregnancy; systemic spread to the fetus
what is the outcome of toxo infection during 1st trimester?
spontaneous abortion, stillbirth, severe disease
what is the outcome/signs of toxo infection in 2nd/3rd trimester?
chorioretinitis (25% of cases), epilepsy, encephalitis, hydrocephaly, retardation
diagnosis of toxo
serology: determination of 4-fold increase in titer essential to diagnosis of acute infection (1/3 of pop. is seropositive); brain imaging
treatment for HIV-associated toxo
sulfadiazine and pyrimethamine; maintain to prevent recurrence
bugs that cause primary amoebic meningoencephalitis
Naegleria fowleri, Acanthamoeba sp.
where Naegleria fowleri is found
amoeba-flagellate in soil, water; found in 50% of fresh (WARM) water
how is Naegleria fowleri acquired by humans?
getting water in nose; amoeba penetrates the cribriform plate
signs of meningoencephalitis caused by Naegleria fowleri
headache, stiff neck, fever, lethargy, rapid progression to confusion, convulsions, coma
naegleria fowleri infection is fatal in how much time?
6-`7 days (mean=10)
blood work picture for diagnosis of meningitis
high protein, low glucose, a few WBC’s; gram stain is NEGATIVE (why?)
describe the detection methods of amoeba in purulent CSF
wet mount; gram stain is difficult to recognize, use Wright stain because its distinctive
treatment of meningitis caused by naegleria fowleri
all: amphotericin (IV and intrathecally), fluconazole, azithromycin, rifampin, miltefosine, dexamethasone
Acanthamoeba is acquired by
water in nose, penetration of cribriform plate
infections associated with Acanthamoeba
CNS infection (longer, chronic granulomatoud encephalitis); ocular infection (bruised eye contaminated with dirt, contaminated contacts, results in keratitis)
