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MICN201 2025 Infection & Immunity > Meningitis > Flashcards

Meningitis Flashcards

1
Q

What are the three main lecture objectives regarding meningitis?

A
  1. Different classifications of meningitis
  2. Aetiology of bacterial meningitis
  3. Laboratory diagnosis & treatment
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2
Q

What is the clinical presentation of meningitis?

A

Varies; symptoms include fever, stiff neck, headache, altered mental state, vomiting, diarrhea, photophobia, muscle pain, seizures.

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3
Q

What is the significance of finding any organism in the CSF?

A

It is significant because the meninges & CSF are normally sterile sites.

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4
Q

What are the infective and non-infective causes of meningitis?

A

Infective: bacteria, viruses, fungi; Non-infective: lymphoma, leukaemia, subarachnoid haemorrhage, drug reactions, autoimmunity, trauma.

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5
Q

Which microorganism is most important for causing meningitis in individuals aged 3 months to 50 years?

A

Neisseria meningitidis

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6
Q

What is the classic triad of symptoms indicative of meningitis?

A

Fever, stiff neck, headache

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7
Q

True or False: Viral meningitis is usually severe and requires aggressive treatment.

A

False

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8
Q

What are common symptoms of meningitis in infants?

A

Lethargy, irritability, poor feeding, high-pitched cry, bulging fontanelle.

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9
Q

Fill in the blank: The most common cause of viral meningitis is _______.

A

Enteroviruses

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10
Q

What are the routes through which microorganisms can enter the CNS?

A
  • Haematogenous spread
  • Direct inoculation
  • Contiguous spread
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11
Q

What are the key virulence factors of Neisseria meningitidis?

A
  • Pili/Opa & Opc for attachment
  • Outer membrane porins (PorA/PorB) for translocation
  • Capsule to inhibit phagocytosis
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12
Q

What are the treatment options for suspected bacterial meningitis?

A

IM ceftriaxone or penicillin pre-hospital; IV ceftriaxone at the hospital.

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13
Q

What is the most common symptom in acute bacterial meningitis cases?

A

High fever (>39˚C)

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14
Q

What are the complications associated with meningitis?

A
  • Death
  • Amputation
  • Hearing loss/blindness
  • Epilepsy/cerebral palsy
  • Cognitive issues/developmental delay
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15
Q

True or False: The presence of a rash is always indicative of meningitis.

A

False

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16
Q

What is the significance of a haemorrhagic rash in meningitis?

A

It is associated with the sepsis stage of Neisseria meningitidis infection.

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17
Q

What is the age group most at risk for Neisseria meningitidis infection?

A

Infants (3 months - 1 year) and adolescents (>20 years)

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18
Q

What are the clinical features of meningitis?

A
  • Fever
  • Neck stiffness
  • Photophobia
  • Neurological symptoms (headache, altered mental state)
  • Rash
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19
Q

Which organisms are common causes of meningitis in neonates?

A
  • E. coli
  • Streptococcus agalactiae
  • Listeria monocytogenes
  • HSV
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20
Q

What is the typical age range for significant Neisseria meningitidis infections?

A

3 months to 50 years

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21
Q

Fill in the blank: The outer layer of the meninges is called the _______.

A

Dura

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22
Q

What is the role of the capsule in Neisseria meningitidis?

A

Inhibits phagocytosis and complement action.

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23
Q

What are the common laboratory diagnostic methods for bacterial meningitis?

A

CSF analysis, culture, and sensitivity tests.

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24
Q

What is the danger of delayed treatment in bacterial meningitis?

A

High morbidity and mortality rates.

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25
Q

True or False: Meningitis can only be caused by infectious agents.

A

False

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26
Q

What are the two main classifications of meningitis based on duration?

A

Acute (<4 weeks) and chronic (>4 weeks)

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27
Q

What percentage of cases present with the classic triad of meningitis symptoms?

A

20-66%

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28
Q

Fill in the blank: Meningitis is inflammation of the _______ and _______.

A

meninges; cerebrospinal fluid (CSF)

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29
Q

What are the common complications of bacterial meningitis?

A

Death, amputation, hearing loss, epilepsy, cognitive issues.

30
Q

What is the role of sialic acid in preventing C’ activation/opsonisation?

A

Prevents C’ activation/opsonisation

Sialic acid is a component that helps bacteria evade the immune system.

31
Q

What is the significance of sIgA protease?

A

It cleaves secretory IgA, aiding bacterial evasion of the immune response

Secretory IgA is an important antibody in mucosal immunity.

32
Q

What does catalase do in the context of bacterial infections?

A

Breaks down hydrogen peroxide, protecting bacteria from oxidative stress

Catalase is an enzyme that helps bacteria survive in hostile environments.

33
Q

What is LOS and its role in proinflammatory response?

A

Lipooligosaccharide, contributes to proinflammatory response

LOS is a component of the outer membrane of some bacteria, like Neisseria.

34
Q

How many cases of Neisseria meningitidis were notified in NZ in 2024?

A

43 cases notified

This reflects a decrease from 59 cases in 2023.

35
Q

What age groups had the highest incidence of Neisseria meningitidis in NZ?

A

Infants (<1 yr) and young adults (15-19 yrs)

B strain was the most common cause of infection in these groups.

36
Q

What was the peak number of meningococcal disease cases in NZ and when did it occur?

A

648 cases in 2001

This corresponds to an incidence rate of 17.4 per 100,000.

37
Q

What percentage of meningococcal cases in 2023 were caused by B strains?

A

74% identified isolates

B strains have been the most common cause of infection.

38
Q

What is the normal appearance of cerebrospinal fluid (CSF)?

A

Clear, colourless, watery

Any turbidity or discoloration can indicate infection.

39
Q

What does visible turbidity in CSF suggest?

A

Suggestive of bacterial meningitis

Turbidity typically indicates the presence of cells or infection.

40
Q

What is the clinical triad of symptoms for acute bacterial meningitis?

A

Fever, headache, neck stiffness

This triad is not always present in all cases.

41
Q

What is the recommended initial treatment for acute bacterial meningitis?

A

Prompt empiric antimicrobials

Delayed treatment can lead to significant mortality and complications.

42
Q

What specific antibiotic is recommended for Neisseria meningitidis?

A

IV ceftriaxone

This is the empiric and targeted treatment for N. meningitidis.

43
Q

What is the role of dexamethasone in the treatment of meningitis?

A

May be beneficial in decreasing complications/mortality

Dexamethasone can affect the transport of antimicrobials across the blood-brain barrier.

44
Q

What are the common causes of meningitis in neonates?

A
  • E. coli
  • S. agalactiae
  • S. epidermidis
  • Listeria monocytogenes
  • HSV

Neonates have an immature immune system, making them vulnerable.

45
Q

What is the most common cause of meningitis in adolescents?

A

Neisseria meningitidis

Viral infections are also common in this demographic.

46
Q

What is the typical CSF finding in acute bacterial meningitis?

A

Increased WBC (neutrophils), decreased glucose, increased protein

This is indicative of a bacterial infection.

47
Q

True or False: Prior antimicrobial treatment affects the sensitivity of Gram stain and culture in diagnosing meningitis.

A

True

Prior treatment can lead to false negatives in laboratory tests.

48
Q

What is the vaccination recommendation for meningitis?

A
  • S. pneumoniae
  • H. influenzae b
  • N. meningitidis (A, C, Y, W and B strains)

Vaccination is recommended for risk groups, especially infants and young adults.

49
Q

What is the difference between purulent and aseptic meningitis?

A

Purulent is bacterial; aseptic is viral

Aseptic meningitis typically has a better prognosis.

50
Q

What is the classic triad of symptoms for meningitis?

A

Fever, neck stiffness, headache

Not always present in every case (20-66% of cases).

51
Q

What is the most common symptom of acute bacterial meningitis?

A

Fever (95% of cases)

Typically ranges from 39-40˚C.

52
Q

What are some general symptoms of meningitis in infants?

A

Lethargy, irritability, poor feeding, high-pitched cry, bulging fontanelle

Symptoms can vary significantly.

53
Q

What type of rash is associated with N. meningitidis?

A

Petechiae (early) and purpuric (late)

Non-blanching rash tested with the glass test.

54
Q

What are Kernig’s and Brudzinski’s signs indicative of?

A

Meningeal irritation

Low sensitivity; <50% positive.

55
Q

List some complications of meningitis.

A
  • Death
  • Amputation
  • Hearing loss/blindness
  • Epilepsy/cerebral palsy
  • Cognitive issues/developmental delay
56
Q

Who are at risk groups for developing meningitis?

A
  • Infants
  • Elderly
  • Adolescents
  • Immunosuppressed individuals
  • Those with trauma or infections (e.g., otitis media, sinusitis)
57
Q

What is Neisseria meningitidis commonly referred to as?

A

Meningococcus

It is a Gram-negative diplococcus.

58
Q

How is N. meningitidis transmitted?

A

By respiratory aerosols

Carriers can transmit to non-immune individuals.

59
Q

What is a significant characteristic of N. meningitidis virulence?

A

Capsule

13 types, with A, B, C, W, Y causing >90% infections.

60
Q

What is the most common cause of meningococcal infections in New Zealand?

A

B strain

Responsible for 74% of identified isolates.

61
Q

What is the initial method for diagnosing meningitis?

A

CSF via lumbar puncture

Ideally before antimicrobials are given.

62
Q

What does visible turbidity in CSF indicate?

A

Possible bacterial meningitis

Normal CSF is clear, colorless, and watery.

63
Q

What is the typical WBC count in acute bacterial meningitis?

A

Increased WBC (neutrophils), decreased glucose, increased protein

Aseptic (viral) shows increased lymphocytes, normal glucose.

64
Q

What is the role of Gram stain in diagnosing meningitis?

A

Direct initial antimicrobial therapy

Affected by prior antimicrobial treatment.

65
Q

What is the recommended empiric treatment for N. meningitidis?

A

IV ceftriaxone

Resistance to penicillin is possible.

66
Q

What additional treatment may be beneficial for certain bacterial meningitis?

A

Dexamethasone

May decrease complications/mortality.

67
Q

What vaccinations are recommended for risk groups against meningitis?

A
  • S. pneumoniae
  • H. influenzae b
  • N. meningitidis (A, C, Y, W)

B strain is now part of the vaccine schedule.

68
Q

What is the mortality risk associated with sepsis from N. meningitidis?

A

> 50% mortality

Sepsis can lead to circulatory collapse and multiple organ dysfunction syndrome (MODS).

69
Q

What is a potential outcome of untreated bacterial meningitis?

A

Significant mortality and complications

Prompt antimicrobial therapy is crucial for better outcomes.

70
Q

True or False: All symptoms of meningitis are always present.

A

False

Symptoms can vary and overlap with other CNS conditions.

MICN201 2025 Infection & Immunity (6 decks)

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