ACUTE BACTERIAL MENINGITIS Flashcards

1
Q

Organisms most often responsible for community-acquired bacterial meningitis

A

Streptococcus pneumoniae (~50%)
Neisseria meningitidis (~25%)
Group B streptococci (~15%)
Listeria monocytogenes (~10%)
Haemophilus influenzae type b (<10%)

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2
Q

The most common cause of meningitis in adults >20 years of age

A

S. pneumoniae

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3
Q

The most important condition that increases the risk of pneumococcal meningitis

A

Pneumonoccal pneumonia

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4
Q

Important causes of meningitis that occurs following invasive neurosurgical procedures

A

S. aureus and coagulase-negative staphylococci

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5
Q

TRUE OR FALSE: The neurologic manifestations and complications of bacterial meningitis result from the immune response to the invading pathogen

A

TRUE - The neurologic manifestations and complications of bacterial meningitis result from the immune response to the invading pathogen

* As a result, neurologic injury can progress even after the CSF has been sterilized by antibiotic therapy.
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6
Q

The classic clinical triad of meningitis

A

fever, headache, and nuchal rigidity

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7
Q

The preferred imaging modality for TB meningitis

A

MRI

  • MRI is preferred over CT because of its superiority in demonstrating areas of cerebral edema and ischemia
  • diffuse meningeal enhancement is often seen after the administration of gadolinium
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8
Q

The typical CSF profile with viral CNS infections

A

lymphocytic pleocytosis with a normal glucose

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9
Q

Most common etiologic agent for community-acquired bacterial meningitis

A

S. pneumoniae and N. meningitidis

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10
Q

Empirical therapy of community-acquired suspected bacterial meningitis in adults include what drugs

A

Dexamethasone
Third- or fourth-generation cephalosporin (e.g., ceftriaxone, cefotaxime, or cefepime)
Vancomycin
Acyclovir as HSV encephalitis is the leading disease in the differential diagnosis
Doxycycline during tick season to treat tickborne bacterial infections

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11
Q

What drug should be added to the empirical regimen for coverage of L. monocytogenes in individuals <3 months of age, those >55, or those with suspected impaired cell-mediated immunity?

A

Ampicillin

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12
Q

The most common etiologic organisms for hospital-acquired meningitis, and particularly meningitis following neurosurgical procedures

A

Staphylococci and gram-negative organisms including P. aeruginosa

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13
Q

Regimen for hospital acquired meningitis, post traumatic or post neurosurgery meningitis

A

Ampicllin + Ceftazidime or Meropenem + Vancomycin

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14
Q

Empirical regimen for age and adults of any age with alcoholism or other debilitating illnesses

A

Ampicillin + Cefotaxime, Ceftriaxone or Cefepime + Vancomycin

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15
Q

Empirical regimen for adults < 55 years old

A

Cefotaxime, Ceftriaxone or Cefepime + Vancomycin

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16
Q

This drug remains the antibiotic of choice for meningococcal meningitis caused by susceptible strains

A

Penicillin G

17
Q

In meningococcal meningitis, what is the chemoprophylaxis regimen for the index case and all close contacts?

A

2-day regimen of rifampin 600 mg every 12 h for 2 days in adults

  • Alternatively, adults can be treated with one dose of azithromycin (500 mg) or one intramuscular dose of ceftriaxone (250 mg)
18
Q

TRUE OR FALSE: Antimicrobial therapy of pneumococcal meningitis is initiated with a cephalosporin (ceftriaxone, cefotaxime, or cefepime) and vancomycin

A

TRUE

19
Q

When should repeat LP be performed in patients with S. pneumonia meningitis?

A

Repeat LP 24–36 h after the initiation of antimicrobial therapy to document sterilization of the CSF.

20
Q

TRUE OR FALSE: Failure to sterilize the CSF after 24–36h of antibiotic therapy should be considered presumptive evidence of antibiotic resistance.

A

TRUE

21
Q

If the CSF isolate of N. meningitidis is resistant to penicillin and ampicillin, what alternative drug(s) should be given to the patient?

A

Cefotaxime or ceftriaxone should be substituted for penicillin.

  • 7-day course of intravenous antibiotic therapy is adequate
22
Q

Which of the following is the most common cause of bacterial meningitis in adults over 20 years of age?
A) Neisseria meningitidis
B) Streptococcus pneumoniae
C) Listeria monocytogenes
D) Haemophilus influenzae

A

Answer: B) Streptococcus pneumoniae
Rationale: S. pneumoniae accounts for approximately 50% of cases and is the most common cause of bacterial meningitis in adults over 20 years old.

23
Q

Which of the following tests is positive when passive flexion of the neck results in spontaneous flexion of the hips and knees?
A) Brudzinski’s sign
B) Kernig’s sign
C) Cushing’s reflex
D) Babinski’s sign

A

Answer: A) Brudzinski’s sign
Rationale: Brudzinski’s sign is a clinical sign of meningeal irritation where passive neck flexion leads to hip and knee flexion.

24
Q

Which of the following is a hallmark sign of increased intracranial pressure (ICP)?
A) Bradycardia, hypertension, and irregular respirations
B) Tachycardia and hypotension
C) Hyperreflexia and clonus
D) Muscle atrophy

A

Answer: A) Bradycardia, hypertension, and irregular respirations
Rationale: The Cushing reflex (bradycardia, hypertension, and irregular respirations) is a classic sign of increased ICP, which is a severe complication of bacterial meningitis.

25
Q

Which imaging modality is preferred for evaluating bacterial meningitis due to its ability to show cerebral edema and ischemia?
A) CT scan
B) MRI
C) X-ray
D) Ultrasound

A

Answer: B) MRI
Rationale: MRI is superior to CT in detecting cerebral edema, ischemia, and diffuse meningeal enhancement in bacterial meningitis.

26
Q

Which empirical antibiotic regimen is recommended for community-acquired bacterial meningitis in adults?
A) Ceftriaxone + Vancomycin + Dexamethasone + Acyclovir
B) Amoxicillin + Clavulanic acid
C) Metronidazole + Ciprofloxacin
D) Rifampin + Isoniazid

A

Answer: A) Ceftriaxone + Vancomycin + Dexamethasone + Acyclovir
Rationale: Empirical treatment includes a third- or fourth-generation cephalosporin (e.g., ceftriaxone), vancomycin, dexamethasone, and acyclovir (for potential HSV encephalitis).

27
Q

In patients >55 years or those with suspected impaired immunity, which additional antibiotic should be added to the regimen for coverage of Listeria monocytogenes?
A) Ampicillin
B) Azithromycin
C) Doxycycline
D) Clindamycin

A

Answer: A) Ampicillin
Rationale: L. monocytogenes requires ampicillin for adequate coverage, especially in neonates, pregnant women, elderly (>55), and immunocompromised patients.

28
Q

In hospital-acquired bacterial meningitis following neurosurgical procedures, which of the following pathogens is most likely?
A) Escherichia coli
B) Mycobacterium tuberculosis
C) Staphylococcus aureus
D) Treponema pallidum

A

Answer: C) Staphylococcus aureus
Rationale: Hospital-acquired meningitis is commonly caused by staphylococci (e.g., S. aureus) and gram-negative bacilli (e.g., Pseudomonas aeruginosa), particularly after neurosurgical interventions.

29
Q

Which antimicrobial agent should be included in the empirical treatment of hospital-acquired meningitis to cover Pseudomonas aeruginosa?
A) Vancomycin
B) Meropenem
C) Amoxicillin
D) Clindamycin

A

Answer: B) Meropenem
Rationale: Meropenem (or ceftazidime) is used to cover Pseudomonas aeruginosa, a common pathogen in hospital-acquired meningitis, especially post-neurosurgery.

30
Q

Which antibiotic is the drug of choice for Neisseria meningitidis meningitis caused by susceptible strains?
A) Ceftriaxone
B) Vancomycin
C) Penicillin G
D) Rifampin

A

Answer: C) Penicillin G
Rationale: Penicillin G remains the antibiotic of choice for meningococcal meningitis caused by susceptible strains. However, if resistance is found, cefotaxime or ceftriaxone is recommended.

31
Q

If a Neisseria meningitidis strain is resistant to penicillin, which of the following should be used instead?
A) Ampicillin
B) Cefotaxime or Ceftriaxone
C) Meropenem
D) Doxycycline

A

Answer: B) Cefotaxime or Ceftriaxone
Rationale: If N. meningitidis is resistant to penicillin, cefotaxime or ceftriaxone should be substituted.

32
Q

Which of the following drugs is used for chemoprophylaxis of close contacts of a patient with N. meningitidis meningitis?
A) Rifampin
B) Acyclovir
C) Doxycycline
D) Linezolid

A

Answer: A) Rifampin
Rationale: Rifampin is used for chemoprophylaxis (600 mg every 12 hours for 2 days). However, rifampin is not recommended for pregnant women.

33
Q

Which of the following is an alternative prophylactic regimen for meningococcal meningitis in adults?
A) A single dose of azithromycin (500 mg)
B) A 3-day course of metronidazole
C) A weekly dose of doxycycline
D) A 5-day course of amoxicillin

A

Answer: A) A single dose of azithromycin (500 mg)
Rationale: Azithromycin (500 mg, single dose) or one intramuscular dose of ceftriaxone (250 mg) are alternative prophylactic options.

34
Q

What is the initial empirical antibiotic regimen for pneumococcal meningitis?
A) Vancomycin + Cephalosporin (Ceftriaxone, Cefotaxime, or Cefepime)
B) Penicillin G + Rifampin
C) Ampicillin + Metronidazole
D) Doxycycline + Ciprofloxacin

A

Answer: A) Vancomycin + Cephalosporin (Ceftriaxone, Cefotaxime, or Cefepime)
Rationale: Pneumococcal meningitis is initially treated with a combination of vancomycin and a third- or fourth-generation cephalosporin.

35
Q

For pneumococcal meningitis, how long should IV antibiotic therapy be continued?
A) 7 days
B) 10 days
C) 14 days
D) 21 days

A

Answer: C) 14 days
Rationale: A 2-week (14-day) course of IV antimicrobial therapy is recommended for pneumococcal meningitis.

36
Q

Why is a repeat lumbar puncture (LP) performed 24–36 hours after initiating antibiotic therapy in pneumococcal meningitis?
A) To monitor glucose levels
B) To confirm CSF sterilization
C) To check for increased ICP
D) To measure protein concentration

A

Answer: B) To confirm CSF sterilization
Rationale: In pneumococcal meningitis, a repeat LP is performed 24–36 hours after starting antibiotics to confirm CSF sterilization. If CSF remains positive, antibiotic resistance should be suspected.

37
Q

What is the role of dexamethasone in bacterial meningitis?
A) It directly kills bacteria
B) It enhances the effect of antibiotics
C) It reduces inflammation by inhibiting TNF-α production
D) It increases CSF penetration of antibiotics

A

Answer: C) It reduces inflammation by inhibiting TNF-α production
Rationale: Dexamethasone is given before antibiotics because it inhibits TNF-α production by macrophages and microglia, reducing inflammation and neurologic damage.

38
Q

Which age groups have the highest mortality risk in bacterial meningitis?
A) 5–10 years
B) 20–40 years
C) <1 year and >50 years
D) 30–50 years

A

Answer: C) <1 year and >50 years
Rationale: Infants (<1 year) and older adults (>50 years) have higher mortality due to weaker immune defenses.