Group A Streptococcal Pharyngitis vs Peritonsillar Abscess

Why Acute rheumatic fever with carditis is correct

• This child has confirmed group A streptococcal (GAS) pharyngitis: a positive rapid antigen test plus classic non-viral features (sudden onset, exudates, tender anterior cervical adenopathy, palatal petechiae, and no cough, rhinorrhea, or hoarseness). He is also in the peak age band for both GAS pharyngitis and acute rheumatic fever (5-15 years).
• Acute rheumatic fever (ARF) is the classic nonsuppurative sequela of untreated GAS pharyngitis. It follows the infection by about 2-4 weeks and results from molecular mimicry between streptococcal M protein and host tissues.
• Carditis, a pancarditis that most often scars the mitral valve, develops in roughly half or more of first ARF attacks and is the only manifestation that causes lasting damage (rheumatic heart disease).
• The declined prescription is the point of the question: antibiotics started within 9 days of symptom onset prevent ARF, so leaving GAS pharyngitis untreated is what creates this risk.

Why the others are wrong

• Splenic rupture with hemoperitoneum - This is a complication of Epstein-Barr virus infectious mononucleosis, which can also cause exudative tonsillitis and palatal petechiae. Mononucleosis, however, typically brings posterior or diffuse cervical adenopathy, marked fatigue, splenomegaly, and atypical lymphocytes, and the vignette reports none of these. The positive rapid antigen test and tender anterior nodes point to GAS, and GAS does not enlarge or rupture the spleen. Even in mononucleosis, rupture is rare (about 0.1-0.5%) (the trap is treating palatal petechiae as specific for mono).
• Internal jugular vein thrombophlebitis - This defines Lemierre syndrome, caused mainly by the anaerobe Fusobacterium necrophorum. It classically affects adolescents and young adults and presents with persistent fever, unilateral neck pain or swelling, and septic pulmonary emboli. It can follow a sore throat, but it is not a sequela of GAS infection, and it is far rarer than ARF after untreated streptococcal pharyngitis.
• Coronary artery aneurysm formation - This is the feared complication of Kawasaki disease, which mostly affects children under 5. Classic Kawasaki disease requires 5 or more days of fever plus at least 4 of 5 principal features: bilateral nonexudative conjunctival injection, oral changes without exudate (strawberry tongue, cracked lips), polymorphous rash, extremity changes, and cervical adenopathy. This 9-year-old has 2 days of fever with exudative pharyngitis. Rheumatic carditis damages the valves, not the coronary arteries (the trap is linking any childhood fever-plus-carditis picture to Kawasaki).

Additional high-yield points

• Poststreptococcal glomerulonephritis (PSGN) is the other nonsuppurative GAS sequela, appearing 1-2 weeks after pharyngitis or 3-6 weeks after skin infection. Unlike ARF, it is NOT prevented by antibiotic treatment of the preceding infection.
• First-line treatment for GAS pharyngitis is oral penicillin V or amoxicillin for 10 days, or a single IM dose of benzathine penicillin G when adherence is uncertain. With a non-anaphylactic penicillin allergy, a first-generation cephalosporin is appropriate.
• ARF is diagnosed with the revised Jones criteria (AHA 2015) and evidence of preceding GAS infection. The major criteria are carditis (clinical or subclinical on echocardiography), arthritis, Sydenham chorea, erythema marginatum, and subcutaneous nodules.
• In children and adolescents, a negative rapid antigen test should be backed up by a throat culture. A positive rapid test needs no confirmation because its specificity is high.
• Amoxicillin given to a patient who actually has EBV mononucleosis often causes a diffuse maculopapular rash. This is a classic reason to consider mono when exudative pharyngitis comes with posterior adenopathy and splenomegaly.
• Suppurative complications of GAS pharyngitis include peritonsillar abscess (muffled "hot potato" voice, trismus, uvular deviation), retropharyngeal abscess, and cervical lymphadenitis.

Why Deviation of the uvula toward the left with trismus is correct

• Peritonsillar abscess is the most common deep neck space infection in adolescents and young adults and typically develops as a suppurative complication of tonsillitis that fails to improve on oral antibiotics.
• Pus collects between the tonsillar capsule and the superior constrictor muscle, so the affected tonsil and soft palate are pushed medially and downward and the uvula is displaced toward the opposite side.
• Irritation of the adjacent internal pterygoid muscle produces trismus, and the swollen soft palate gives the characteristic muffled hot potato voice with referred otalgia and drooling.
• Treatment is drainage by needle aspiration or incision plus antibiotics covering group A streptococcus and oral anaerobes, with airway assessment first.
• Deviation of the uvula toward the left with trismus — correct, contralateral uvular displacement with limited mouth opening localizes a right peritonsillar collection.

Why the others are wrong

• Tender induration beneath the jaw with a raised tongue — Ludwig angina, a bilateral cellulitis of the submandibular and sublingual spaces that usually spreads from an infected lower molar; it produces woody floor-of-mouth swelling that elevates the tongue in the midline rather than a unilateral tonsillar bulge following a sore throat.
• Grey tonsillar exudate with posterior cervical adenopathy — infectious mononucleosis, a near-miss because it does not respond to amoxicillin (which often provokes a maculopapular rash), but its tonsillar enlargement is bilateral, with posterior cervical adenopathy, fatigue, and often splenomegaly, and it does not explain pain lateralized to the right with referred otalgia; persistent or worsening unilateral symptoms call for reassessment for a suppurative complication whatever antibiotic has been given.
• A bulging posterior pharyngeal wall with neck stiffness — retropharyngeal abscess, which mainly affects children under 6 and presents with neck extension, torticollis, and midline posterior swelling rather than asymmetric tonsillar bulging.