{
 "topic": "Acute Pharyngitis",
 "slug": "acute-pharyngitis",
 "category_id": 15666,
 "summary": "Distinguishing viral from GAS pharyngitis, the diagnostic testing that matters, organism-specific treatment, and why confirming GAS still matters for preventing rheumatic fever.",
 "written_by": "claude-sonnet",
 "references": [
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 ],
 "short": [
  {
   "title": "In short",
   "content": "- Pharyngitis is inflammation of the pharynx (erythema, edema, exudate, or enanthem); over 90% of pediatric sore throat with fever is viral. Acute pharyngitis peaks between ages 4 and 7 years and is rare under age 1.\n- Group A Streptococcus (GAS, S. pyogenes) is the most common bacterial cause but accounts for only 15\u201330% of pediatric acute pharyngitis overall; other bacterial causes include groups C/G streptococcus (teens/young adults), Mycoplasma pneumoniae, Arcanobacterium haemolyticum, Neisseria gonorrhoeae (sexually active adolescents), and Corynebacterium diphtheriae (rare with universal immunization).\n- Viral clues (favor a non-antibiotic-treatable cause): concurrent coryza, cough, conjunctivitis, hoarseness, oral ulcers, rash, and/or diarrhea. Common viral causes include influenza, parainfluenza, rhinovirus, coronavirus, adenovirus, RSV, enteroviruses, HSV, and EBV (often with splenomegaly/generalized lymphadenopathy).\n- GAS pharyngitis clinical criteria (Centor-type): sore throat plus at least one of tender/large (>2 cm) cervical lymphadenopathy, tonsillar exudates, positive GAS culture, or fever >38.3\u00b0C \u2014 but the syndrome is nonspecific enough that laboratory testing is required for diagnosis; culture is the gold standard, rapid antigen tests are less sensitive than culture, and NAATs approach culture sensitivity/specificity.\n- GAS pharyngitis and acute rheumatic fever (ARF) both peak between ages 5 and 15; ARF is now rare in the US (well under 3% of confirmed strep pharyngitis cases), while asymptomatic GAS pharyngeal carriage (low ARF risk) occurs in 10\u201315% of children \u2014 this is why specific, tested diagnosis (not empiric treatment of every sore throat) matters.\n- Acute rheumatic fever typically develops 10\u201321 days after GAS pharyngitis, by which time pharyngitis symptoms have resolved and only 10\u201320% of patients still culture positive for GAS; a third of ARF patients recall no antecedent sore throat. Diagnosis relies on elevated/rising antistreptococcal antibody titers \u2014 a single titer (usually ASO) is elevated in only 80\u201385% of ARF cases, but measuring three titers (ASO, anti-DNase B, anti-hyaluronidase) together raises detection to 95\u2013100%.\n- Arcanobacterium haemolyticum pharyngitis often mimics GAS (fever, exudate, cervical adenopathy, rash) but lacks palatal petechiae and strawberry tongue; about half of cases develop a morbilliform/scarlatiniform rash starting on distal extensor surfaces, spreading centripetally, sparing face/palms/soles, typically 1\u20134 days after sore throat onset.\n- Treatment by organism: GAS \u2014 penicillin or amoxicillin (second-line azithromycin, erythromycin, or clindamycin); N. gonorrhoeae \u2014 ceftriaxone (add azithromycin/doxycycline if Chlamydia co-infection possible); C. pneumoniae \u2014 azithromycin 1 g single dose or doxycycline x7 days; C. diphtheriae \u2014 penicillin or erythromycin plus equine diphtheria antitoxin; A. haemolyticum \u2014 azithromycin/erythromycin or a cephalosporin; HSV \u2014 acyclovir or valacyclovir; influenza \u2014 oseltamivir/zanamivir or amantadine/rimantadine; Mycoplasma \u2014 azithromycin or doxycycline."
  }
 ],
 "long": [
  {
   "title": "Definition",
   "content": "Pharyngitis refers to inflammation of the pharynx, manifesting as erythema, edema, exudates, or an enanthem (ulcers or vesicles). Inflammation can arise from environmental exposures (tobacco smoke, air pollutants, allergens), contact with caustic substances or hot food/liquids, infectious agents, or as part of broader noninfectious inflammatory syndromes (PFAPA, Kawasaki disease, MIS-C, inflammatory bowel disease, Stevens-Johnson syndrome, SLE) \u2014 the latter group is usually distinguishable by history and exam, whereas differentiating among the numerous infectious causes is often the harder clinical task."
  },
  {
   "title": "Epidemiology",
   "content": "Acute infections of the upper respiratory tract, frequently featuring pharyngitis, account for a substantial share of pediatric visits. Acute pharyngitis peaks between ages 4 and 7 years and is rare in children under 1 year old. Over 90% of pediatric sore throat with fever is viral in origin. Among bacterial causes, GAS is by far the most common, but accounts for only 15\u201330% of all pediatric acute pharyngitis cases (a lower proportion in adults); groups C and G beta-hemolytic streptococcus typically cause pharyngitis in teens and young adults. GAS pharyngitis and its complication, acute rheumatic fever, share a peak age range of 5\u201315 years; in the United States, ARF is now rare, occurring in well under 3% of confirmed streptococcal pharyngitis cases, while asymptomatic GAS pharyngeal carriage (which carries minimal ARF risk) is found in roughly 10\u201315% of children \u2014 a distinction central to why accurate, tested diagnosis matters more than empiric treatment of every sore throat."
  },
  {
   "title": "Etiology",
   "content": "Viruses are the most common cause of acute pharyngitis in children, including the common respiratory viruses (influenza, parainfluenza, rhinovirus, coronavirus, adenovirus, RSV), enteroviruses, herpes simplex virus, and Epstein-Barr virus (often accompanied by other mononucleosis findings such as splenomegaly and generalized lymphadenopathy); systemic infections with cytomegalovirus, rubella, measles, and HIV may also present with pharyngitis. Among bacteria, GAS (Streptococcus pyogenes) predominates; other causes include groups C and G streptococcus, Mycoplasma pneumoniae, Arcanobacterium haemolyticum, Fusobacterium necrophorum, Neisseria gonorrhoeae (in sexually active adolescents), Chlamydia pneumoniae, and, rarely, Corynebacterium diphtheriae (now uncommon where immunization is universal), Francisella tularensis, and Yersinia enterocolitica, as well as mixed anaerobic infection (Vincent angina)."
  },
  {
   "title": "Clinical features",
   "content": "Clinical features overlap substantially regardless of cause: pharyngeal erythema, petechiae, and/or exudates can occur with either viral or bacterial pharyngitis. Features favoring a viral etiology include concurrent coryza, cough, conjunctivitis, hoarseness, oral ulcers, rash, and/or diarrhea. Clinical criteria suggestive of GAS pharyngitis include sore throat plus at least one of: tender or enlarged (>2 cm) cervical lymphadenopathy, tonsillar exudates, a positive GAS culture, or fever above 38.3\u00b0C \u2014 though the overall streptococcal pharyngitis syndrome (abrupt sore throat, cervical adenopathy, fever, headache, often abdominal pain and rash) remains nonspecific enough that laboratory confirmation is required. Arcanobacterium haemolyticum pharyngitis often closely mimics GAS \u2014 fever, pharyngeal exudate, lymphadenopathy, and rash are common \u2014 but classically lacks the palatal petechiae and strawberry tongue seen with GAS; about half of A. haemolyticum cases develop a morbilliform or scarlatiniform exanthem beginning on the extensor surfaces of the distal extremities, spreading centripetally to the trunk while sparing the face, palms, and soles, typically appearing 1\u20134 days after sore throat onset (occasionally preceding it). Distinct viral pharyngitis syndromes include acute lymphonodular pharyngitis (coxsackievirus A10, with nonulcerative yellow-white posterior pharyngeal papules, lasting 1\u20132 weeks) and acute febrile pharyngitis with headache, myalgia, and abdominal discomfort lasting 3\u20134 days, more common in older children."
  },
  {
   "title": "Diagnostics",
   "content": "Because the clinical syndrome of streptococcal pharyngitis is variable and nonspecific, laboratory testing is necessary to confirm GAS infection rather than treating empirically. Throat culture remains the gold standard; rapid antigen detection tests are generally less sensitive than culture, while nucleic acid amplification tests (NAATs) approach culture-level sensitivity and specificity. For suspected acute rheumatic fever, diagnosis requires supporting evidence of a recent GAS infection \u2014 since ARF typically develops 10\u201321 days after the acute pharyngitis episode, by which point only 10\u201320% of patients still culture positive and about a third recall no antecedent sore throat at all, evidence instead relies on elevated or rising antistreptococcal antibody titers. A single titer (typically anti-streptolysin O) is elevated in only 80\u201385% of confirmed ARF cases, but measuring three different antibodies together (anti-streptolysin O, anti-DNase B, anti-hyaluronidase) raises detection to 95\u2013100%, so multiple antibody tests should be obtained whenever ARF is suspected clinically."
  },
  {
   "title": "Treatment",
   "content": "Treatment is targeted to the confirmed or strongly suspected organism. For GAS, penicillin or amoxicillin is first-line, with azithromycin, erythromycin, or clindamycin as second-line options; groups C/G streptococcal pharyngitis is treated with penicillin, typically for a shorter duration than GAS treatment. Neisseria gonorrhoeae pharyngitis is treated with ceftriaxone, adding azithromycin or doxycycline if chlamydial co-infection is a concern. Chlamydia pneumoniae is treated with azithromycin (1 g single dose) or doxycycline for 7 days, and Mycoplasma pneumoniae with azithromycin or doxycycline. Corynebacterium diphtheriae requires penicillin or erythromycin together with equine hyperimmune diphtheria antitoxin. Arcanobacterium haemolyticum is treated with azithromycin, erythromycin, or a cephalosporin. Among viral causes, HSV pharyngitis is treated with acyclovir or valacyclovir, influenza with oseltamivir/zanamivir or amantadine/rimantadine, and HIV with antiretroviral therapy; most other viral pharyngitis is managed with supportive care alone."
  }
 ],
 "clinical": [
  {
   "title": "Approach to the sore throat",
   "content": "Given that over 90% of pediatric sore throat with fever is viral, the central clinical task is identifying the minority of patients who have GAS pharyngitis and would benefit from antibiotics, while avoiding unnecessary antibiotic use in the rest. Use the clinical picture to decide who to test: sore throat plus tender/enlarged cervical nodes, tonsillar exudates, or fever above 38.3\u00b0C raises suspicion for GAS, while concurrent coryza, cough, conjunctivitis, hoarseness, oral ulcers, rash, or diarrhea argues for a viral cause and against testing or treating for GAS. Confirm suspected GAS with culture (gold standard) or a NAAT before treating; a rapid antigen test can be used but has lower sensitivity than culture, so a negative rapid test in a high-suspicion patient may warrant backup culture depending on local practice.\n\nTreat confirmed GAS pharyngitis with penicillin or amoxicillin (azithromycin, erythromycin, or clindamycin as second-line alternatives) both to shorten the clinical course and to prevent acute rheumatic fever, which remains the reason GAS diagnosis matters even though it is now rare in the US. If a patient presents weeks after a sore throat with new joint, cardiac, neurologic (chorea), or skin findings suggestive of ARF, do not rely on throat culture (likely negative by then) \u2014 send multiple antistreptococcal antibody titers (ASO, anti-DNase B, anti-hyaluronidase) to maximize the chance of confirming antecedent GAS infection, since a third of ARF patients will not even recall having had a sore throat. Consider less common bacterial causes based on context: N. gonorrhoeae in a sexually active adolescent (treat with ceftriaxone, covering for Chlamydia co-infection), and C. diphtheriae in an unimmunized or under-immunized child with a membranous pharyngitis (treat with antibiotics plus diphtheria antitoxin, and notify public health)."
  }
 ]
}