A 6-year-old child presents with honey-coloured crusted lesions around the nose and mouth that started as vesicles 3 days ago. Gram staining of the exudate shows Gram-positive cocci in chains. Culture confirms the causative organism. Which organism and complication should the treating physician be most vigilant about?
- A Streptococcus pyogenes (Group A Streptococcus); post-streptococcal glomerulonephritis ✓
- B Staphylococcus aureus; toxic shock syndrome
- C Streptococcus pyogenes; acute rheumatic fever
- D Staphylococcus aureus; scalded skin syndrome
Explanation
Impetigo most commonly involves Staphylococcus aureus (bullous impetigo) or Streptococcus pyogenes (non-bullous/crusted impetigo). Non-bullous impetigo with honey-coloured crusts and Gram-positive cocci in chains indicates streptococcal origin. The critical non-suppurative complication is post-streptococcal acute glomerulonephritis (nephritogenic strains such as M-types 2, 49, 55, 57, 60). Importantly, unlike pharyngeal streptococcal infection, cutaneous impetigo does NOT cause acute rheumatic fever, as the skin lacks the necessary streptococcal M-protein antigen expression for cardiac cross-reactivity.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.