Snapshot A 6-year-old boy presents to his pediatrician for sore throat and a headache. His symptoms began approximately 2 days ago and have not improved. The mother reports that the patient appears uncomfortable and feels warm. She says that he was born at 39-weeks gestation via a normal spontaneous vaginal delivery with no complications. He has received all of his vaccinations appropriate for his age. He has no significant past medical history and only takes a daily multivitamin. He has no allergies to medications known to the mother. Physical examination is notable for perioral crusted lesions with tonsilar swelling with exudates. A rapid antigen detection test is positive for Streptococcal pyogenes infection. He is started on oral penicillin. Introduction Classification gram-positive cocci Microbiology reservoir properties Lacefield group A β-hemolytic bacitracin sensitive pyrrolidonyl arylamidase (PYR) positive hyaluronic acid capsule inhibits phagocytosis M protein major virulence factor that inhibits complement activation and protects against phagocytosis plasma cells create antibodies against this protein for opsonization via molecular mimicry, this can lead to acute rheumatic fever streptolysin O an oxygen labile enzyme that destroys both red and white blood cells, giving this organism its β-hemolytic property antibodies against streptolysin O (anti-ASO antibodies) allows checking ASO titers to determine if there was a recent Streptococcus pyogenes infection DNase B antibodies against DNase B (anti-DNase B) also indicate recent Streptococcus pyogenes infection pyogenic exotoxin (erythrogenic toxin) can result in scarlet fever can superstimulate T-cells, resulting in streptococcal toxic shock syndrome Associated conditions streptococcal pharyngitis streptococcal skin infections Scarlet fever delayed antibody-mediated reactions rheumatic fever poststreptococcal glomerulonephritis Presentation Diseases Associated with Streptococcal Pyogenes Disease Presentation Diagnostic Studies Treatment Streptococcal pharyngitis Symptoms sore throat headache Physical exam tonsillar enlargement without or with exudates fever lymphadenopathy Rapid antigen detection test (RADT) high specificity (~95%) Throat culture high sensitivity (90-95%) Penicillin prompt treatment prevents the development of rheumatic fever Skin infections Symptoms/physical exam folliculitis infection of the hair follicle cellulitis erythematous, edematous, and warm skin impetigo vesicular and blistered skin lesions that flakes typically found by the mouth Gram stain and culture Dicloxacillin covers both Streptococcus pyogenes and Staphylococcus aureus Scarlet fever Symptoms/physical exam scarlet red rash begins on the trunk and neck and then spreads to the extremities a sand paper-like rash strawberry tongue fever Gram stain and culture Penicillin Rheumatic fever Symptoms/physical exam fever chest pain (secondary to myocarditis) arthritis (acute migratory polyarthritis) chorea dance-like movements of the extremities (2-3 weeks post pharyngitis Note that many years after the myocarditis, patients can develop rheumatic valvular disease the mitral valve is most commonly affected and the aortic valve is the second most common Clinical diagnosis typically seen in untreated cases of streptococcal pharyngitis based on the Jones criteria having 2 major manifestations or 1 major manifestation plus 2 minor manifestations classifies the patient as having acute rheumatic fever Major manifestations carditis/valvulitis arthritis Sydenham chorea Minor manifestations arthralgia fever Antibiotic prophylaxis with penicillin the goal is to prevent recurrent streptococcal pharyngitis and acute rheumatic fever in order to decrease the risk of damaging the heart and its valves further Poststreptococcal glomerulonephritis Symptoms/physical exam generalized edema hematuria hypertension Based on both clinical and laboratory findings laboratory findings positive throat or skin culture positive anti-ASO antibodies or streptozyme test Penicillin if the streptococcal infection is still present Supportive therapy Rapid antigen detection test (RADT) high specificity (~95%) Throat culture high sensitivity (90-95%) Penicillin