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Neurology USMLE Step 3 > Section 6: CNS Infections > Flashcards

Section 6: CNS Infections Flashcards

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USMLE® Step 1 flashcards
1
Q

Indicatiosn for CT scan before LP

A
  • A history of central nervous system disease
  • Focal neurologic deficit
  • Presence of papilledema
  • Seizures
  • Altered consciousness
  • Significant delay in the ability to perform an LP

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7219-7220). . Kindle Edition.

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2
Q

A 45-year-old man comes to the emergency department with fever, headache, photophobia, and a stiff neck. What is the next best step in the management of this patient?

a. Lumbar puncture
b. Head CT scan
c. Ceftriaxone and vancomycin
d. Penicillin
e. Movement of patient to ICU

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7224-7234). . Kindle Edition.

A

A. When you suspect bacterial meningitis, administer antibiotics quickly. Further, do blood cultures stat simultaneously with a lumbar puncture (LP), or immediately prior. Penicillin can never be used as empiric therapy for meningitis; it is not

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7224-7234). . Kindle Edition.

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3
Q

Most accurate diagnosis for bacterial meningitis

A

Culture of CSF

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4
Q

Diagnosis:

Gram-positive diplococci

Gram-negative diplococci

Gram-negative pleomorphic, coccobacillary organisms

Gram-positive bacilli

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7241-7248). . Kindle Edition.

A

Pneumococcus

Neisseria

Haemophilus

Listeria

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7241-7248). . Kindle Edition.

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5
Q

True or False:

The Gram stain has poor sensitivity but good specificity for bacterial meningitis.

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7241-7248). . Kindle Edition.

A

True

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6
Q

Normal CSF findings

A
  • Protein = 10-45 mg/dL
  • Glucose = 40-80mg/dL
  • Pressure = 60-180mmH2O
  • Leukocyte, total = <5/mm3
    • Lymphocytes 60-75%
    • Monocytes 25-50%
    • Neutrophils 1-3%
  • Cell count 0-5 lymps/HPF
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7
Q

CSF findings in pyogenic meningitis

A
  • Cells/ml → 200-5,000
  • Cytology → PMN
  • Glucose → Low (below 60% of serum level)
  • Protein → High
  • Gram stain → Positive
  • CIE or LA → Positive
  • Pressure → High
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8
Q

CSF findings in meningitis that has been partially treated

A
  • Cells/ml → 200-5,000
  • Cytology → Mostly PMN
  • Glucose → Low
  • Protein → High
  • Gram stain → Variable
  • CIE or LA → Positive
  • Pressure → High
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9
Q

CSF findings in granulomatous disease e.g TB

A
  • Cells/ml → 200-500
  • Cytology → Lymphocytes
  • Glucose → Low
  • Protein → High
  • Gram stain → Negative
  • CIE or LA → Negative
  • Pressure → High
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10
Q

CSF findings in aseptic meningitis

A
  • Cells/ml → 100-700
  • Cytology → PML, Lymphocytes
  • Glucose → Normal
  • Protein → Slightly high
  • Gram stain → Negative
  • CIE or LA → Negative
  • Pressure → Normal
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11
Q

CSF findings in Neighborhood reaction

A
  • Cells/ml → 100-500
  • Cytology → Variable
  • Glucose → Normal
  • Protein → Variable
  • Gram stain → Negative
  • CIE or LA → Negative
  • Pressure → Variable
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12
Q

Best initial test for diagnosis of meningitis

A

Cell count

  • Although not as specific as a culture, it is available much sooner
  • Cell count with a differential is much more specific than an elevated CSF protein level
  • If thousands of neutrophils are present in the CSF, start IV ceftriaxone, vancomycin, and steroids. Steroids have been associated with a decrease in mortality in bacterial meningitis
  • CSF cell count is the most important criterion to determine the need to treat a patient. Thousands of polys (neutrophils) indicate bacterial meningitis until proven otherwise.

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7253-7260). . Kindle Edition.

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13
Q

An elderly man comes to the emergency department with fever, headache, a stiff neck, and photophobia. He is HIV positive with CSF shows 2,500 white cells that are all neutrophils; Gram stain is normal. What is the best initial therapy?

a. Ceftriaxone and metronidazole
b. Cefoxitin and mefloquine
c. Ceftriaxone, ampicillin, and vancomycin
d. Fluconazole
e. Amphotericin

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7294-7301). . Kindle Edition.

A

C. Listeria monocytogenes is a cause of meningitis that is not adequately treated by any form of cephalosporin. Ampicillin is added to the usual regimen of ceftriaxone and vancomycin to cover Listeria. This cannot be fungal meningitis, because the CSF is characterized exclusively by a high number of neutrophils; neutrophils are not consistent with fungal meningitis.

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7302-7316). . Kindle Edition.

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14
Q

A 17-year-old male is brought to the emergency department with fever, headache, stiff neck, and photophobia. He has a petechial rash. CSF shows 2,499 neutrophils. Ceftriaxone and vancomycin are started. What should be done next?

a. Test for HIV
b. Wait for results of culture
c. Add ampicillin
d. Enforce respiratory isolation
e. Enforce respiratory isolation and prescribe rifampin for close contacts

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7302-7316). . Kindle Edition.

A

E. When an adolescent presents with a petechial rash and increased neutrophils on CSF, it is suggestive of Neisseria meningitidis. These patients should be placed on respiratory isolation, and close contacts should receive prophylaxis.

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7302-7316). . Kindle Edition.

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15
Q

List those susceptible to listeria meningitis

A

Elderly

Neonates

HIV-positive patients

Asplenic patients

Those on steroids

Immunocompromised with leukemia or lymphoma

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16
Q

Rx for listeria meningitis

A

Ampicillin

17
Q

Susceptible for Neisseria meningitides

A

Adolescents

Military personnel

Asplenic patients

Terminal complement deficiency

18
Q

Apart from antibiotics, what other measures should be taken for those with meningitis due to Neisseria meningitides?

A
  • Patient: Begin respiratory isolation
  • Close contacts: Start prophylaxis with rifampin, ciprofloxacin, or ceftriaxone for close contacts, such as household members and those who share utensils, cups, or kisses
  • Routine contacts: Routine school and work contacts do not need to receive prophylaxis.

The nurse or medical student taking care of a patient with Neisseria does not need prophylaxis. Those with kissing and other saliva-type contact do need prophylaxis.

Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 7323-7327). . Kindle Edition.

19
Q
  1. Fever + confusion
  2. Main cause of (1) above in the US
  3. Best initial test for above diagnosis
  4. Most accurate test for above diagnosis
  5. Best initial Rx
  6. For resistance to initial Rx
A
  1. Encephalitis
  2. Herpes
  3. Head CT scan
  4. PCR of the CSF (Brain BIOPSY is not correct)
  5. Acyclovir
  6. Foscarnet
20
Q

HIV-positive patient with CD4 count less than 100, and features of meningitis

  1. Diagnosis
  2. Best initial test
  3. Most accurate test
  4. Best initial Rx
  5. Additional Rx
A
  1. Cryptococcus
  2. India ink stain
  3. Cryptococcal antigen
  4. Amphotericin B
  5. Add oral fluconazole. If patients CD4 does not rise Rx for life. If it increases above 100 fluconazole can be stopped
21
Q

Rx for TB meningitis

A
  • Rifampicin
  • Isoniazid (INH)
  • Pyrizinamide
  • Ethambutol
  • Steroids

Use the mneumonic RIPE(S)

Rx is usually longer than in pulmonary TB

22
Q

CF of brain abscess

A
  • Fever
  • Headache
  • Focal neurological deficits
  • Contrast enhancing lesion on CT scan of the head
23
Q
  1. Diagnosis:
  • Patient is immigrant from Mexico
  • Seizure
  • Head CT with multiple 1 cm cystic lesions; possible calcification of lesions
  1. Confirmatory diagnostic test
  2. Rx of above diagnosis
A
  1. Neurocysticercosis
  2. Serology
  3. Albendazole + Steroids
24
Q

Empiric antibiotic choice for meningitis in the neonate

A
  • 0-7 days: ampicillin plus gentamicin
  • >7 days: (and gram negative suspected), add cefotaxime
25
Q

Empiric antibiotic choice for meningitis in the adolescent

A

IV ceftriaxone plus vancomycin

26
Q

Empiric antibiotic choice for meningitis in the adult

A

IV ceftriaxone plus vancomycin and steroids

27
Q

Empiric antibiotic choice for meningitis in the immunocompromised (HIV, leukemia and lymphoma patients) and >50 years

A

Add ampicillin to empiric Rx for adult

Neurology USMLE Step 3 (10 decks)

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