Bacteriology: post-streptococcal sequelae: practice question

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Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Impetigo can lead to post-streptococcal glomerulonephritis, but rheumatic fever classically follows only pharyngeal group A streptococcal infection

Nephritogenic strains of group A streptococci can cause glomerulonephritis after either pharyngitis or pyoderma, with a longer latent period after skin infection. Rheumatic fever classically follows pharyngeal infection by rheumatogenic strains. Early antibiotic treatment does not reliably prevent glomerulonephritis, but penicillin for pharyngitis prevents rheumatic fever.

Option by option

• A. Neither complication can follow a group A streptococcal infection of the skin

  This child already shows that a skin infection can precede glomerulonephritis.

• B. Rheumatic fever follows skin infection as often as it follows pharyngitis

  Rheumatic fever is not a classic sequel of impetigo, so this reverses the distinction.

• C. Impetigo can lead to post-streptococcal glomerulonephritis, but rheumatic fever classically follows only pharyngeal group A streptococcal infection (correct)

  Correct. Glomerulonephritis follows both sites, but rheumatic fever is a sequel of pharyngitis.

• D. Post-streptococcal glomerulonephritis follows only pharyngitis and never skin infection

  Glomerulonephritis follows pyoderma commonly, as in this child.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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