Scarlet fever. Scarlet fever, although uncommon today, typically presents with fever, a generalized maculopapular rash, and Pastia's lines on the neck or antecubital skin folds (dark red lines in the skinfolds). A, Cervical adenopathy is evident in a 5-year-old girl, as are the characteristic Pastia's lines on her neck. B, Red swollen tonsils and petechiae on her palate are noted. Penicillin therapy for 10 days brought prompt improvement. C, Diagnosis is confirmed by a throat culture positive for group A b-hemolytic streptococci. Blood agar plates show Staphylococcus aureus (left panel) and group A b-hemolytic streptococcus (right panel). Inhibition of bacterial growth around the bacitracin taxose A disk confirms a group A streptococcal etiology.