Which pathogens are most commonly involved in impetigo?

• A. Staphylococcus aureus is most common; GAS 2nd MC
• B. Candida species
• C. Pseudomonas aeruginosa
• D. Mycobacterium leprae

Answer: (B)

Impetigo is a superficial skin infection most often caused by Staphylococcus aureus and Streptococcus pyogenes (group A beta-hemolytic Streptococcus). These bacteria can invade through breaks in the skin and spread by direct contact, producing the classic honey-colored crusted lesions. The nonbullous form is typically due to either organism, while the bullous form is more specifically linked to S. aureus that produces exfoliative toxins. Candida species cause mucocutaneous candidiasis, not impetigo. Pseudomonas aeruginosa is linked to other skin infections such as hot tub folliculitis or burn wound infections, and Mycobacterium leprae causes leprosy. So the best answer is the combination of Staphylococcus aureus and Streptococcus pyogenes as the common pathogens in impetigo.