Meningitis/Bacterial CNS Infections Flashcards
1 cause of bacterial meningitis?
Strep pneumo b/c of the capsule
what does it mean when neutrophils predominate in CSF?
bacterial infection
gram (-) cocci
Strep pneumo
gram (-) diplococci
Neisseria meningitidis
gram (-) rod
Haemophilus
parasites that cause encephalitis
Tosoplasma
Cryptococcus
Plasmodia
bacteria that cause encephalitis
Borrelia
Legionella
most common mechanism of meningitis
infection of cells lining the BBB
gram + cocci
Step agalactiae
gram (-) rod
E. coli
Gram + rod
Listeria
most common causes of bacterial meningitis in neonates?
Group B strep (Strep agalactiae)
enterics (E. coli)
Listeria monocytogenes
most common causes of bacterial meningitis in infants and kids i.e. older than 4 weeks?
Strep pneumo
N. meningitides
H. flu b (vaccine now so very uncommon)
cause of bacterial meningitis in teens and adolescents?
N. meningitidis
cause of bacterial meningitis in elderly?
Strep pneumo
which bugs have capsules that cause bacterial meningitis?
N. meningitidis, H. flu, Strep pneumo, Strep agalactiae, E. coli
- the capsule is the virulence factor that helps bug cross BBB, survive/escape phagocytosis or opsonization
- capsule is in the H. flu vaccine
infant meningitidis
- nuchal rigidity, opisthotonos, bulging fontanelle, convulsions, photophobia, lethargy, irritability, seizures, coma
- will have cardinal signs = fever, vomiting (common but not specific), nuchal rigidity
what does a maculopapular or petechial rash tell you?
meningococcal meningitis = N. meningitidis
pneumococcal meningitis
- gram (+) diplococci
- meningitis after bacteremia, sinusitis, otitis media; primarily in peds; sickle cell, elderly, and asplenic pts at higher risk
- respiratory transmission; pts usually have pneumonia symptoms before it progresses to meningitis
- dx: culture and gram stain; increased PMNs in CSF
- tx: combo therapy; ceftriaxone + ampicillin
if more than 2% resistance = ceftriaxone + vancomycin - prevention: vaccine schedule; 1 from 2-23 months; 2nd one over age 5
Neisseria meningitidis
- gram (-) diplococci
- young healthy adults, teenager, military recruits, prisons, college dorms
- inhaled, goes to pharynx into blood into CSF; doesn’t go to lungs
N. meningitidis clinical disease
- headache, fever, stiff neck from inflammation of meninges
- LOS; cytokine storm, septic shock
- will have recurrent infections if deficient in C6-9 = can’t make MAC
- petechial/pupuric rash, DIC, shock
Waterhouse-Friedrichsen syndrome
- result of N. meningitidis
- hemorrhagic necrosis of adrenal glands, fever, septic shock, DIC
- very high mortality
N. meningitidis: dx and tx
- gram stain of CSF = increased WBCs
- culture of blood and CSF
- tx = ceftriaxone + ampicillin
use chloramphenicol if pt allergic to penicillin
give 2d rifampin prophylaxis to family members
H. flu b
- gram (-) coccobacilli
- has capsule; look for unvaccinated pt hx
- maternal antibody protects baby for 3-4 months; need to vaccinate babies early
H flu b: dx, tx, prevention
- dx: gram stain CSF, culture of blood and CSF
does NOT grow on MacConkey or blood agar; culture on chocolate agar - tx: cefotaxime or ceftriaxone; rifampin prophylaxis for patient contacts
- prevention w/ vaccine
neonate meningitis - pathogenesis
- acquired from vaginal tract via rupture of membranes = group b strep, E. coli, Listeria
- travels in blood to meninges = local host immune response
- can spread on respiratory equipment = Serratia marcescens, Pseudomonas, Proteus
- uncommon but high mortality = Citrobacter, Salmonella, Proteus; would see brain abscesses
clinical symptoms of neonate meningitis
- will not have the “cardinal signs” usually
- lethargy, irritability, fever or hypothermia, seizures, jaundice, shock
- BULGING FONTANELLE = inc. ICP
Group B strep
- Strep agalactiae = gram + cocci in short chains
- dx w/ gram stain, culture
CAMP test = beta-hemolytic; bacitracin resistant; Group B strep antigen in CSF - tx = penicillin G or ampicillin; vanco if allergic to penicillin
- prevention: no vaccine; can do chemoprophylaxis in neonates
E. coli
- gram (-) rods
- at time of birth or shortly after
- beta hemolytic on blood agar; K1 capsule
- dx w/ LP and CSF culture: lactose + on MacConkey; indole +
- tx w/ ceftriaxone
Listeria monocytogenes
- gram + rods in pairs/short chains
- mom gets it from cold cuts, baby exposed during birth
- in adults = IC pts
- neonates = bulging fontanelle, PMNs in CSF, could have seizures
- dx w/ blood culture, LP - CSF culture; will grow in cold; CAMP test
- tx w/ ampicillin (+ gentamicin); TMP-SMX if allergic to penicillin
neurotoxins: 2 of them + general info
- Clostridium botulinum and C. tetani
- anaerobic, gram + rods, spore-forming
- GI (botulinum) and wound infections (tetani)
C. botulinum
- adult = home canning food; baby = honey
- heat-labile toxin that inhibits ACh
- adults: blurred vision, dry mouth, dilated pupils, abd pain, no fever, CONSTIPATION
- infant: floppy baby syndrome = flaccid paralysis, constipation, “failure to thrive”
- dx: H&P; culture food source or fecal sample (baby)
- tx: antitoxin ASAP, then antibiotics
C. tetani
- toxin blocks glycine and GABA release
- lock jaw in most cases, drooling, dysphagia, hydrophobia
- CSF usually normal so dx by H&P
- descending spastic paralysis
- tx = supportive care, wound debridement; antimicrobial therapy = metronidazole, penicillin; tetanus immunoglobulin to bind toxin
aseptic meningitis
- caused by bacteria and viruses (usually viruses) = no bugs in CSF
- inflammation of meninges, headache and fever, increased lymphocytes
neurosyphilis
- primary = painless ulcer; secondary = copper colored rash; tertiary = neurosyphilis
- also affects heart and causes gummas
- can detect w/ VDRL
- CSF = inc WBCs, inc protein, dec glucose
- increased risk in AIDS pts
- tx w/ penicillin G
Lyme disease
- CN palsies, meningitis, chronic meningoencephalitis
- stage 1 = bulls eye rash; stage 2 = can get into CSF
- will have negative VDRL, some neutrophils in CSF, hx of tick bite
- tx w/ ceftriaxone
Leptospira
- obligate aerobic spirochetes
- causes aseptic meningitis during second phase of disease
- risk factors = hx, Hawaii, jet skis (bug you get from rat poop contaminating water)
- tx = IV penicillin G (severe) or for mild you can use doxycycline, ampicillin, amoxicillin
Brucellosis
- intracellular bacteria
- headache, depression, fatigue, acute meningoencephalitis
- common risk factors = being a vet, farmer; but found in aborted sheep/cow fetuses
- dx w/ serology or blood cultures
- tx = doxycycline w/ rifampin and/or TMP-SMX
Mycobacterium tuberculosis
- acid-fast bacilli, gram +
- usually pulmonary; associated w/ military TB
- gradual onset of apathy, anorexia, malaise; photophobia, nuchal rigidity, impaired consciousness
- tx = isoniazid, rifampin, pyrazinamide, streptomycin
Nocardia
- gram +, catalase + (filamentous) rods
- dx w/ CT or MRI; CSF will have inc leukocytes and protein, dec glucose
- tx = surgery for lesions; sulfonamides for CNS penetration
other bacteria in CNS infections
- bartonella henselae
- rickettsia ricketsii
- mycoplasma
