Pharyngitis

BASICS

Definition: Acute or chronic inflammation of the pharyngeal mucosa and structures (synonyms: sore throat, tonsillitis, “strep throat”)
GAS (Group A Streptococcus) pharyngitis: Notable for preventable suppurative (abscess) and nonsuppurative (rheumatic) complications

~15 million cases annually in the US
1–2% of all outpatient visits; 6% of pediatric primary care visits
Most common cause: Viral (40–60%)
GAS: 15–30% pediatric, 5–15% adult cases; peak in ages 5–11 years
Rheumatic fever: Rare in US (<1/100,000), but serious; highest risk ages 5–18
Other bacterial causes: Fusobacterium necrophorum (young adults), group C/G Strep, Neisseria gonorrhoeae (sexually active), diphtheria (rare)

Group A β-hemolytic streptococcus (GAS)
N. gonorrhoeae, C. diphtheriae, H. influenzae, Moraxella, Chlamydia pneumoniae, F. necrophorum, Mycoplasma pneumoniae

Family history of rheumatic fever increases risk of complications if GAS is untreated

Exposure/epidemics, late fall–early spring, ages 5–15, close contact (household, daycare, barracks), immunosuppression, smoking, acid reflux, diabetes, oral sex, recent illness, chronic tonsillar/adenoid colonization

Sore throat, dysphagia/odynophagia, fever, malaise, headache, anorexia, chills, cough (rare in GAS), sick contacts, “hot potato” voice, dysuria/arthralgia (gonococcal)

Enlarged tonsils (± exudate), pharyngeal erythema, palatal petechiae, unilateral tonsil swelling or uvular deviation (abscess), trismus/stridor/drooling (abscess), cervical lymphadenopathy (anterior: GAS; posterior: mono), fever, ulcers (viral/autoimmune), scarlet fever rash (GAS), pseudomembrane (diphtheria/mono), vesicles (HSV/coxsackie), conjunctivitis (adenovirus)

Viral (HIV, EBV, CMV), Streptococcal, allergic rhinitis, GERD, malignancy, irritants, atypical bacteria (gonococcal, syphilis, diphtheria), oral candidiasis, thyroiditis, epiglottitis

Modified Centor Score (to guide testing/treatment):
+1: tonsillar exudate
+1: tender anterior cervical nodes
+1: absence of cough
+1: fever
+1: age <15; 0: 15–45; -1: age >45
Score 4+: treat empirically; 2–3: rapid strep; 0–1: no test/treat symptomatically
Testing:
Rapid antigen strep test (RAST) – high specificity
Throat culture (gold standard, especially in children if RAST negative)
Backup culture not needed in adults if RAST negative
ASO titer not recommended for routine diagnosis
Other:
NAAT for gonococcus if indicated, monospot for EBV, viral cultures (HSV), IgM for CMV, HIV viral load

Conservative therapy for most cases: salt water gargles, acetaminophen/NSAIDs, anesthetic lozenges, humidifier, hydration, viscous lidocaine for severe pain

First-line:
Penicillin V: Children <27kg: 250 mg PO TID; Adolescents/adults: 250 mg QID or 500 mg BID
Penicillin G benzathine: <27kg: 600,000u IM ×1; ≥27kg/adults: 1.2 million u IM ×1
Amoxicillin: 50 mg/kg PO QD (max 1g/dose) or 25 mg/kg PO BID (max 500mg/dose)
Caution: Amoxicillin with EBV may cause rash
Second-line:
Type IV PCN allergy: Cephalexin, cefadroxil
Type I (anaphylactic) PCN allergy: Azithromycin, clarithromycin, clindamycin

Consider for ≥7 infections in 1 year, ≥5/yr × 2 yrs, ≥3/yr × 3 yrs, or history of peritonsillar abscess, multiple antibiotic allergies

Suppurative: Peritonsillar abscess, retropharyngeal abscess, airway compromise
Nonsuppurative: Rheumatic fever (carditis, arthritis), post-strep glomerulonephritis
Chronic GAS carriage is low risk—no repeated antibiotics/testing