Nelson Chapter 409 (Pharyngitis)

Question 1

1. Which scoring system is commonly used in children to assess likelihood of Group A Streptococcal (GAS) pharyngitis?
   A. Centor score
   B. McIsaac score
   C. Wells score
   D. Pediatric Early Warning Score

Answer 1

Answer: B — The McIsaac score modifies the Centor criteria for children, adding age 3–14 yr as a criterion and subtracting a point for age ≥45 yr.

Question 2

4. Which antibiotic is first-line for GAS pharyngitis in a non-allergic child?
   A. Azithromycin
   B. Amoxicillin
   C. Clindamycin
   D. Cephalexin

Answer 2

Answer: B — Amoxicillin is preferred in children due to taste, availability as liquid/chewable tablets, and once-daily dosing.

Question 3

3. What is the PRIMARY reason for treating GAS pharyngitis with antibiotics?
   A. Prevent acute poststreptococcal glomerulonephritis
   B. Reduce symptom duration by 3–5 days
   C. Prevent acute rheumatic fever
   D. Reduce spread to household contacts

Answer 3

Answer: C — The primary intent is prevention of acute rheumatic fever (ARF). Antibiotics do NOT prevent APSGN.

Question 3

2. Which virus is most commonly responsible for pharyngoconjunctival fever?
   A. Influenza virus
   B. Epstein-Barr virus
   C. Adenovirus
   D. Rhinovirus

Answer 3

Answer: C — Adenovirus causes pharyngoconjunctival fever (pharyngitis + conjunctivitis). Outbreaks are linked to swimming pools.

Question 4

5. Fusobacterium necrophorum pharyngitis is most concerning because of its association with which complication?
   A. Peritonsillar abscess
   B. Lemierre syndrome
   C. Acute rheumatic fever
   D. Ludwig’s angina

Answer 4

Answer: B — F. necrophorum causes Lemierre syndrome (septic thrombophlebitis of the internal jugular vein) in approximately 80% of cases.

Question 5

6. Which finding is most suggestive of a VIRAL etiology of pharyngitis rather than GAS?
   A. Tonsillar exudates
   B. Palatal petechiae
   C. Hoarseness and coryza
   D. Tender anterior cervical lymphadenopathy

Answer 5

Answer: C — Hoarseness, coryza, cough, diarrhea, and conjunctivitis all point toward viral pharyngitis.

Question 5

7. What is the gold standard diagnostic test for streptococcal pharyngitis?
   A. Rapid antigen detection test (RADT)
   B. Throat culture on blood agar
   C. Molecular PCR test
   D. Streptococcal antibody test

Answer 5

Answer: B — Throat culture on blood agar remains the gold standard. Negative RADTs should be confirmed with culture due to lower sensitivity.

Question 6

8. A child with GAS pharyngitis develops a sandpaper-like rash. Which toxin is most commonly responsible?
   A. Streptococcal pyrogenic exotoxin B
   B. Streptococcal pyrogenic exotoxin A
   C. M protein
   D. Streptolysin O

Answer 6

Answer: B — Streptococcal pyrogenic exotoxin A (encoded by speA) is most commonly associated with scarlet fever.

Question 6

10. Which organism is incorrectly listed as having an established role in CAUSING pharyngitis?
    A. Group C streptococcus
    B. Arcanobacterium haemolyticum
    C. Haemophilus influenzae
    D. Fusobacterium necrophorum

Answer 6

Answer: C — H. influenzae may be cultured from the throat but its role in causing pharyngitis has NOT been established.

Question 7

9. A child has repeated positive GAS tests during illnesses that appear viral. What is the most likely explanation?
   A. Macrolide resistance
   B. Penicillin resistance
   C. Chronic GAS carriage
   D. Immunodeficiency

Answer 7

Answer: C — Chronic GAS carriage gives a positive test even when the illness is viral. It generally poses little risk and usually doesn’t require eradication.

Question 8

11. For how many days should oral penicillin or amoxicillin be given for GAS pharyngitis?
    A. 5 days
    B. 7 days
    C. 10 days
    D. 14 days

Answer 8

Answer: C — 10 days is the recommended duration to ensure eradication and prevent ARF.

Question 8

13. What is the clinical significance of the M protein in GAS?
    A. It is the target of penicillin
    B. It facilitates resistance to phagocytosis and determines type-specific immunity
    C. It produces scarlet fever toxin
    D. It causes hemolysis on blood agar

Answer 8

Answer: B — The M protein (emm gene) resists phagocytosis. Immunity is M type–specific, allowing repeated infections with different M types.

Question 8

15. Herpangina (posterior oropharyngeal papulovesicular lesions) is caused by which organism?
    A. Herpes simplex virus type 1
    B. Various enteroviruses
    C. Adenovirus
    D. Epstein-Barr virus

Answer 8

Answer: B — Herpangina is caused by enteroviruses (e.g., Coxsackie viruses), producing lesions in the posterior oropharynx.

Question 9

12. Which feature best differentiates primary HSV pharyngitis from other causes?
    A. Posterior oropharyngeal vesicles only
    B. Ulcerating vesicles in the anterior pharynx, lips, and perioral skin
    C. Palatal petechiae with exudates
    D. Pseudomembrane on the tonsils

Answer 9

Answer: B — Primary oral HSV causes gingivostomatitis with vesicles in the anterior pharynx AND on the lips and perioral skin, often lasting 14 days.

Question 10

14. Which statement about macrolide resistance in GAS is correct?
    A. All GAS are macrolide-resistant
    B. Macrolide resistance precludes clindamycin resistance
    C. Macrolide-resistant strains may also be clindamycin-resistant
    D. Macrolide resistance is unrelated to antibiotic use patterns

Answer 10

Answer: C — Some macrolide-resistant GAS are also clindamycin-resistant, which matters in invasive GAS infections.

Question 10

16. Which regimen is appropriate for eradicating GAS carriage in a child with ping-pong family spread?
    A. Azithromycin 5-day course
    B. Clindamycin 20 mg/kg/day for 10 days
    C. Penicillin V 10-day course
    D. Amoxicillin 7-day course

Answer 10

Answer: B — Clindamycin orally for 10 days effectively eradicates chronic GAS carriage. Amoxicillin-clavulanate is an alternative.

Question 11

17. Hand-foot-mouth disease is most commonly caused by which virus?
    A. Enterovirus 71
    B. Coxsackie A16
    C. Coxsackie A6
    D. Herpes simplex virus

Answer 11

Answer: B — Coxsackie A16 is the most common cause, though Enterovirus 71 and Coxsackie A6 can also cause this syndrome.

Question 11

18. Which antibiotic class should NOT be used to treat GAS pharyngitis?
    A. Beta-lactams
    B. First-generation cephalosporins
    C. Fluoroquinolones
    D. Clindamycin

Answer 11

Answer: C — Tetracyclines, fluoroquinolones, and sulfonamides should not be used for GAS pharyngitis.

Question 12

19. What is the recommended tonsillectomy threshold per the Paradise criteria?
    A. 3 episodes per year for 1 year
    B. ≥7 episodes in 1 year, OR ≥5 per year for 2 years, OR ≥3 per year for 3 years
    C. 10 episodes in 1 year
    D. Any recurrent GAS with positive cultures

Answer 12

Answer: B — Paradise criteria require ≥7 episodes in the past year, ≥5 per year in each of 2 preceding years, or ≥3 per year in each of 3 preceding years.

Question 13

20. A 16-year-old has exudative tonsillitis, splenomegaly, and lymphadenopathy. Which test best confirms the diagnosis?
    A. Throat culture for GAS
    B. RADT for GAS
    C. Mononucleosis slide agglutination test and atypical lymphocytes on CBC
    D. Blood culture

Answer 13

Answer: C — EBV mononucleosis is suggested by splenomegaly and exudative tonsillitis in an adolescent. A positive monospot and atypical lymphocytes confirm it.