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Block 2 Neuro > Meningitis > Flashcards

Meningitis Flashcards

1
Q

Clinical symptoms of meningitis

A

Fever (not as likely in elderly), headache. Also: nuchal rigidity, photophobia, rash, upper respiratory symptoms, nausea, anorexia, vomiting, diarrhea, altered mental state

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2
Q

Location of meningitis

A

Subarachnoid space

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3
Q

What does the subarachnoid space lack?

A

Antibody and complement production needed for phagocytosis

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4
Q

Infectious agents associated with meningitis

A
  1. viral 2. bacteria 3. fungi 4. mycobacteria. 5. protozoa
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5
Q

Bacterial meningitis lumbar puncture findings

A

Increased intracranial pressure. Very increased WBC count. Mostly PMN. Very increased proteins. Decreased glucose.

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6
Q

Viral meningitis lumbar puncture findings

A

No increased intracranial pressure. Increased WBC count. Mostly lymphocytes, about 20% PMNs. Increased protein. Glucose levels about the same

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7
Q

Fungal meningitis lumbar puncture findings

A

Increased intracranial pressure. Increased WBC count (more than viral) Mostly lymphocytes. Increased protein. Glucose about the same

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8
Q

TB meningitis lumbar puncture findings

A

No increased intracranial pressure. Increased WBC count (less than bacterial). Mostly lymphocytes. Increased protein and decreased glucose.

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9
Q

Aseptic Meningitis syndrome

A
  • Often viral, could be noninfectious though.
  • Fever, headache, photophobia, less neck stiffness and altered mental state.
  • Slight increase in protein, glucose normal. Increase in lymphocytes and monocytes.
  • Highest incidence in 1st yr of life.
  • Supportive therapy. Recover on own
  • Can be fatal in neonates
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10
Q

What are more than 855 of viral meningitis types associated with?

A

Enteroviruses

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11
Q

Do enteroviruses include RNA or DNA viruses?

A

Usually RNA viruses

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12
Q

When are enteroviruses more common?

A

Summer and fall

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13
Q

Enterovirus/Picornavirus characteristics

A
  • Transmitted oral/fecal or respiratory.
  • ssRNA (+)
  • Icosahedral
  • No envelope
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14
Q

Bacterial (Septic) meningitis

A
  • Fever, stiff neck, irritability, neuro dysfunction.
  • Acute onset and progression
  • life-threatening
  • Need prompt empiric therapy BEFORE lumbar puncture
  • Inflammation associated with exudate in CSF
  • Increased PMN, increased protein, decreased glucose
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15
Q

Bacterial meningitis treatment

A

Immediate empiric treatment with 3rd gen. cephalosporin (Ceftriaxone). Risk of other agents: vanco (MRSA), acyclovir (HSV-2), cefepime (pseudomonas), ampicillin (listeria). Even 3 hr delay in treatment can increase risk of fatality within 3 months. Consider prophylactic treatment of household and others exposed to oral secretions.

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16
Q

Most common causes of bacterial meningitis?

A

Streptococcus pneumonia
Neisseria meningiditis
Haemophilus influenza type b

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17
Q

Most common bacterial meningitis in adults?

A

Streptococcus pneumonia

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18
Q

Most common bacterial meningitis in children ages 11-16

A

Neisseria meningiditis

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19
Q

What should all adults over 65 be getting to protect against pneumococcal form?

A

13 valent pneumococcal conjugate vaccine

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20
Q

Steps in development of bacterial meningitis?

A
  1. mucosal colonization at nasopharynx
  2. invasion and multiplication in bloodstream
  3. cross bbb
  4. egress into CSF
  5. Release inflammatory cytokines in CSF by astrocytes and microglia
  6. Increased permeability of bbb
  7. Diapedisis of leukocytes in CSF
  8. Edema and increased intracranial pressure.
  9. Neuronal injury including hearing loss (CN VIII)
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21
Q

Gram - organisms causing bacterial meningitis?

A

Neisseria meningitidis and Haemophilus influenzae

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22
Q

Gram + organism causing bacterial meningitis?

A

Streptococcus pneumoniae

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23
Q

Lipopolysaccharide (LPS)/endotoxin

A

Endotoxin shed from gram - bacteria. Activates macrophages and causes release of NO (hypotension and shock) and IL-1 (fever).

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24
Q

Lipooligosacchride (LOS)

A

Neisseria meningitides structure (similar to LPS). Mimics brain sphingolipids so it is recognized as self

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25
Q

If skin rash present what forms of bacterial meningitis should you be leaning toward?

A

Neisseria meningitidis or haemophilus influenzae

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26
Q

When does meningitis occur?

A

When pathogen virulence factors overwhelm host defense mechanisms

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27
Q

Other virulence factors involved in bacterial meningitis?

A

Pili, IgA protease, Capsule composed of acidic polysaccharides

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28
Q

Pili virulence factor function

A

Colonization of the nasopharynx

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29
Q

IgA protease virulence factor function

A

Cleaves IgA allowing for colonization of mucosa

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30
Q

Capsule virulence factor function

A

Protects from phagocytosis of polymorphonuclear granulocytes

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31
Q

Neisseria meningiditis

A

Gram negative. Diplococcus.

32
Q

Meningococcal meningitis (neisseria meningiditis) vaccine

A

covers 4 of the 13 serogroups

33
Q

Meningococcal meningitis (neisseria meningiditis) virulence factors

A

pili, IgA protease, capsule, endotoxin

34
Q

Meningococcal meningitis (neisseria meningiditis) outbreaks

A

More common in the winter and early spring (overcrowding). Transmitted through respiratory droplets

35
Q

Meningococcal meningitis (neisseria meningiditis) treatment

A

Definitive and prophylactic treatment with ceftriaxone

36
Q

Meningococcal meningitis (neisseria meningiditis) LOS virulence factor causes what symtms

A

Leads to thrombocytopenia. Disseminate intravascular coagulation–>hemorrhagic skin rash.

37
Q

Streptococcus pneumonia–Pneumococcal meningitis

A

Gram + diplococci, lancet shape. Not in long chains

38
Q

Streptococcus pneumonia–Pneumococcal meningitis transmission

A

Respiratory droplets. Meningitis is secondary to otitis media or paranasal sinusitis

39
Q

Streptococcus pneumonia–Pneumococcal meningitis most common cases

A

Indivduals over 2 mths

40
Q

Streptococcus pneumonia–Pneumococcal meningitis. What is used to identify the serotype?

A

Quellung (capsula swelling in response to specific anticapsular antiserum

41
Q

Streptococcus pneumonia–Pneumococcal meningitis. Risks if on previous antibiotic?

A

Higher chance of resistant strain (can predict based on serotype). 19A esp. resistant. Would treat with vanco

42
Q

Streptococcus pneumonia–Pneumococcal meningitis vaccine

A

Hepatovalent protein-conjugate

43
Q

Haemophilis influenzae type B

A

Gram -, coccoid rod. Separate from the influenza virus

44
Q

Haemophilis influenzae type B virulence factors

A

pili, outer membrane proteins, IgA protease and endotoxin

45
Q

Haemophilis influenzae type B infection can be followed by what?

A

Hearing loss

46
Q

Haemophilis influenzae type B most common age group?

A

Unvaccinated infants and young children

47
Q

Haemophilis influenzae type B prevention

A

Hib vaccine–B capsular polysaccharide

48
Q

Haemophilis influenzae type B growth support needed?

A

Chocolate agar with factors V (NAD+) and X (Hematin)

49
Q

Torch infections (perinatal)

A
  • mild maternal morbidity, can have major fetal consequences.
  • meningitis, group B strep, E. coli, listeria.
  • TORCH includes: toxoplasmosis, syphilis, varicella-zoster, parvo, rubella, CMV, HSV-2
50
Q

Group B streptococcus (Streptococcus agalactiae)

A
  • Normal part of GI and GU tract
  • Vertical transmission to infant can occur
  • Adult disease in immunocompromised increasing
  • Sepsis, pneumonia, meningitis
  • 2x as common in African American infants
  • Pregnant women screened. Given penicillin G if carriers.
51
Q

Group B streptococcus (Streptococcus agalactiae) classifcation

A

Bacitracin resistant, catalase negative, CAMP reaction (hemolysis of RBCs by phospholipase of GBS and B-hemolysin of S. aureus

52
Q

E. coli K1 strains

A
  • Gram negative rod
  • enteric organism, bacteremia, and transcellular permeation of BBB
  • LPS
  • capsular polysaccharide prevents lysosome fusion
  • May need to add carbapenem with ceftriaxone for empiric coverage
53
Q

Most common chronic meningitis causes

A

Spriochetes (sypillis leptospira, borrelia burgdoreferi, treponema pallidium). Mycobacterium tuberculosis. Fungi (Cryptococcus neoformans, coccidioides and candida. More common in immunocompromised

54
Q

Mycobacterium tuberculosis

A
  • 25% cases have meningeal involvement.
  • Gradual onset. Starts with generalized illness
  • mostly 0-4 yr olds effected if in areas with high TB.
  • In areas with low TB rates, mostly adults
  • Acid-fast bacilli stain needed
55
Q

Mycobacterium tuberculosis treatment

A

Rifampin, Isoniazid, pyrazinamide, ethambutol. BCG vaccine

56
Q

Rifampin mechanism of action

A

Inhibits DNA dependent RNA polymerase. Induces formation of drug-metabolizing enzyme (including cytochrome P450)

57
Q

Isoniazid mechanism

A

Inhibits mycolic acid (component of the mycobacterial cell wall).

58
Q

Pyrazinamide mechanism

A

Unknown

59
Q

Ethambutol mechanism

A

Inhibits cell wall synthesis by binding arabinosyl transferase

60
Q

Cryptococcus neoformans

A

Inhaled as spores, can disseminate hematogenously to CNS in immunocompromised.

61
Q

Cryptococcus neoformans treatment

A

Liposomal amphotericin B + flucytosine until culture negative, followed by fluconazole for 3-12 mths, sometimes for life

62
Q

Amphotericin B Mechanism

A

Binds ergosterol creating holes in fungi membrane allowing leakage of electrolytes

63
Q

Amphotericin B Spectrum

A

Broad. Invasive systemic fungal infections in immunocompromised. Active against yeast and molds

64
Q

Amphotericin B distribution

A

Liposomal form can cross BBB

65
Q

Amphotericin B adverse effects

A

TOXIC. Binds cholesterol. Decreases renal blood flow and can cause permanent destruction of the basement membrane

66
Q

Amphotericin B resistance

A

Rare, decrease ergosterol in membrane

67
Q

Flucytosine (5-FC) mechanism

A

Nucleic acid synthesis inhibitor. Antimetabolite selectively taken up and converted to 5-FU in fungi. Interferes with DNA and RNA synthesis

68
Q

Flucytosine (5-FC) spectrum

A

Narrow. Only yeast! Not molds or dimorphic. Candida albicans and cryptococcus

69
Q

Flucytosine (5-FC) distribution

A

Oral. Penetrates CNS

70
Q

Flucytosine (5-FC) toxicity

A

Bone marrow suppression

71
Q

Flucytosine (5-FC) Resistance

A

Loss of converting enzymes or transporters, cotreat with amphotericin B to min. development of resistance and increase uptake

72
Q

Azoles (fluconazole (CNS), Itraconazole, voriconazole (CNS)) mechanism

A

Binds fungal P-450 enzyme and blocks production of ergosterol

73
Q

Azoles (fluconazole (CNS), Itraconazole, voriconazole (CNS)) spectrum

A

Systemic mycoses (dimorphic fungi) and yeast

74
Q

Azoles (fluconazole (CNS), Itraconazole, voriconazole (CNS)) distribution

A

Orally available, substrate for efflux pump in brain

75
Q

Azoles (fluconazole (CNS), Itraconazole, voriconazole (CNS)) toxicity

A

Drug-drug interaction, hepatotoxicity, neurotoxicity, alters hormone synthesis. Avoid during pregnancy

76
Q

Azoles (fluconazole (CNS), Itraconazole, voriconazole (CNS)) resistance

A

Altered cytochrome p450, upregulation of efflux transporters

Block 2 Neuro (3 decks)

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