Pharyngitis

Pharyngitis: Definition & Etiology - Sore Throat Origins

Pharyngitis: Inflammation of the pharynx, presenting as sore throat.

• Etiology (Causes):
  • Infectious Agents (Predominant):
    • Viral: Most common (~80% adults). E.g., Rhinovirus, Adenovirus, Influenza, Coronavirus, EBV, HSV.
    • Bacterial: GABHS / S. pyogenes (main bacterial; esp. children 5-15 yrs). Others: M. pneumoniae, C. pneumoniae, N. gonorrhoeae, C. diphtheriae.
    • Fungal: Candida albicans (immunocompromised).
  • Non-Infectious Causes:
    • Irritants (smoke, pollutants), GERD, allergies, trauma, vocal strain.

⭐ Most cases of acute pharyngitis in adults are caused by viruses.

Pharyngitis: Clinical Features - Throat's Tale

• Common Presentation: Sore throat (often severe, odynophagia), dysphagia, fever, pharyngeal erythema.

• Distinguishing Features: Viral vs. Bacterial (GAS)

  Feature	Viral Pharyngitis	Bacterial (GAS) Pharyngitis
  Onset & Fever	Gradual; fever typically low-grade	Sudden; high fever (>38°C or 100.4°F)
  Cough & Coryza	Usually present	Typically absent (important diagnostic clue)
  Tonsils/Pharynx	Mild to moderate erythema; exudate rare	Marked erythema; tonsillar swelling & exudates
  Cervical Nodes	Diffuse, small, often non-tender	Tender, enlarged anterior cervical lymph nodes
  Systemic	Myalgia, fatigue, hoarseness, conjunctivitis	Headache, nausea, vomiting, abdominal pain (esp. children)

⭐ Palatal petechiae (petechial lesions on the soft palate or uvula) are highly suggestive of Group A Streptococcal pharyngitis.

• Suspicion for GAS ↑ with: Absence of cough, tonsillar exudates, history of fever, tender anterior cervical lymphadenopathy.

Pharyngitis: Diagnosis & DDx - The Whodunit

• Clinical Diagnosis: Sore throat, fever, odynophagia, tonsillar erythema/exudates, cervical lymphadenopathy.
• 📌 CENTOR Criteria (modified by McIsaac for age):
  • Cough absent (+1)
  • Exudates (tonsillar) (+1)
  • Nodes (tender anterior cervical) (+1)
  • Temperature (>38°C / 100.4°F) (+1)
  • Age: 3-14 yrs (+1), 15-44 yrs (0), ≥45 yrs (-1)
• Interpretation:
  • Score 0-1: Low GABHS risk; symptomatic treatment, no test/antibiotics.
  • Score 2: Consider RADT or throat culture.
  • Score ≥3: Perform RADT. If (+), treat for GABHS.

⭐ A negative Rapid Antigen Detection Test (RADT) in children and adolescents should be backed up by a throat culture.

• Differential Diagnosis (DDx):
  • Viral (most common): Adenovirus, EBV (mononucleosis), Influenza.
  • Bacterial: GABHS (key target!), Diphtheria (greyish pseudomembrane).
  • Fungal: Candida (immunocompromised).
  • Non-infectious: GERD, Kawasaki disease, Lemierre's syndrome.

Pharyngitis: Management & Complications - Healing Hurdle

• Symptomatic Management:

  • Analgesia (paracetamol, ibuprofen), lozenges, warm saline gargles, adequate hydration, rest.

• GABHS Pharyngitis Management:

  ⭐ The primary goal of antibiotic treatment for GABHS pharyngitis is to prevent acute rheumatic fever.

  • Antibiotic Regimens for GABHS Pharyngitis:

    Drug	Child Dose	Adult Dose	Duration	Notes
    Penicillin V	250mg BID-TID	500mg BID-QID	10 days	Gold Std
    Amoxicillin	50mg/kg OD (max 1g)	1g OD / 500mg TID	10 days	Palatable
    Benzathine Pen G	0.6MU (<27kg); 1.2MU (≥27kg) IM	Single Dose		Compliance
    Pen-Allergy:
    Cephalexin	20mg/kg/dose BID (max 500mg/dose)	500mg BID	10 days	Non-anaphyl.
    Clindamycin	7mg/kg/dose TID (max 300mg/dose)	300mg TID	10 days
    Azithromycin	12mg/kg OD (max 500mg)	500mg OD	5 days

• Management Algorithm:

• Complications:

  • Suppurative: Peritonsillar abscess (quinsy), retropharyngeal abscess, otitis media, sinusitis, cervical lymphadenitis.
  • Non-suppurative: Acute Rheumatic Fever (ARF), Post-Streptococcal Glomerulonephritis (PSGN), PANDAS.

• Referral Criteria (Red Flags):

  • Airway compromise (stridor, drooling), severe dysphagia/dehydration, toxic appearance, neck stiffness/swelling, failure to improve in 48-72 hrs, suspected suppurative complications (e.g., quinsy).

High‑Yield Points - ⚡ Biggest Takeaways

• Viral infections are the most frequent cause of pharyngitis.
• Group A Streptococcus (GAS) is the primary bacterial pathogen, potentially causing rheumatic fever and PSGN.
• Centor criteria (fever, exudates, tender anterior cervical nodes, absence of cough) suggest GAS.
• Penicillin (or amoxicillin) is crucial for GAS pharyngitis to prevent complications.
• Diphtheria features a greyish-white pseudomembrane and "bull neck".
• Infectious Mononucleosis (EBV) presents with posterior cervical lymphadenopathy, splenomegaly, and atypical lymphocytes.