ACUTE BACTERIAL MENINGITIS

Question 1

Organisms most often responsible for community-acquired bacterial meningitis

Answer 1

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

Question 2

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

Answer 2

S. pneumoniae

Question 3

The most important condition that increases the risk of pneumococcal meningitis

Answer 3

Pneumonoccal pneumonia

Question 4

Important causes of meningitis that occurs following invasive neurosurgical procedures

Answer 4

S. aureus and coagulase-negative staphylococci

Question 5

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

Answer 5

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.

Question 6

The classic clinical triad of meningitis

Answer 6

fever, headache, and nuchal rigidity

Question 7

The preferred imaging modality for TB meningitis

Answer 7

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

Question 8

The typical CSF profile with viral CNS infections

Answer 8

lymphocytic pleocytosis with a normal glucose

Question 9

Most common etiologic agent for community-acquired bacterial meningitis

Answer 9

S. pneumoniae and N. meningitidis

Question 10

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

Answer 10

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

Question 11

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?

Answer 11

Ampicillin

Question 12

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

Answer 12

Staphylococci and gram-negative organisms including P. aeruginosa

Question 13

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

Answer 13

Ampicllin + Ceftazidime or Meropenem + Vancomycin

Question 14

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

Answer 14

Ampicillin + Cefotaxime, Ceftriaxone or Cefepime + Vancomycin

Question 15

Empirical regimen for adults < 55 years old

Answer 15

Cefotaxime, Ceftriaxone or Cefepime + Vancomycin

Question 16

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

Answer 16

Penicillin G

Question 17

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

Answer 17

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)

Question 18

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

Answer 18

TRUE

Question 19

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

Answer 19

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

Question 20

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

Answer 20

TRUE

Question 21

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

Answer 21

Cefotaxime or ceftriaxone should be substituted for penicillin.

• 7-day course of intravenous antibiotic therapy is adequate

Question 22

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

Answer 22

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.

Question 23

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

Answer 23

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.

Question 24

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

Answer 24

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.

Question 25

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

Answer 25

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

Question 26

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

Answer 26

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).

Question 27

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

Answer 27

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

Question 28

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

Answer 28

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.

Question 29

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

Answer 29

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

Question 30

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

Answer 30

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.

Question 31

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

Answer 31

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

Question 32

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

Answer 32

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.

Question 33

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

Answer 33

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.

Question 34

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

Answer 34

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.

Question 35

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

Answer 35

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

Question 36

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

Answer 36

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.

Question 37

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

Answer 37

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.

Question 38

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

Answer 38

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