Non-bullous impetigo is the most common form of impetigo. Lesions begin as papules that progress to vesicles surrounded by erythema. Subsequently they become pustules that enlarge and rapidly break down to form thick, adherent crusts with a characteristic golden appearance; this evolution usually occurs over about one week. Lesions usually involve the face and extremities. Systemic symptoms are usually absent. Regional lymphadenitis may occur.
Most infections begin as a streptococcal infection, but staphylococci replace the streptococci over time. S aureus produces bacteriotoxins toxic to streptococci. These bacteriotoxins may be the reason that only S aureus is isolated in lesions that are caused predominantly by streptococci.
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