Pharyngitis

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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. Inflamed pharynx cross-section in pharyngitis

⭐ 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)

    FeatureViral PharyngitisBacterial (GAS) Pharyngitis
    Onset & FeverGradual; fever typically low-gradeSudden; high fever (>38°C or 100.4°F)
    Cough & CoryzaUsually presentTypically absent (important diagnostic clue)
    Tonsils/PharynxMild to moderate erythema; exudate rareMarked erythema; tonsillar swelling & exudates
    Cervical NodesDiffuse, small, often non-tenderTender, enlarged anterior cervical lymph nodes
    SystemicMyalgia, fatigue, hoarseness, conjunctivitisHeadache, 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 with exudates and petechiae

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:

      DrugChild DoseAdult DoseDurationNotes
      Penicillin V250mg BID-TID500mg BID-QID10 daysGold Std
      Amoxicillin50mg/kg OD (max 1g)1g OD / 500mg TID10 daysPalatable
      Benzathine Pen G0.6MU (<27kg); 1.2MU (≥27kg) IMSingle DoseCompliance
      Pen-Allergy:
      Cephalexin20mg/kg/dose BID (max 500mg/dose)500mg BID10 daysNon-anaphyl.
      Clindamycin7mg/kg/dose TID (max 300mg/dose)300mg TID10 days
      Azithromycin12mg/kg OD (max 500mg)500mg OD5 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.

Practice Questions: Pharyngitis

Test your understanding with these related questions

A patient presents with fever and dysphagia. An image shows a tonsil that is pushed medially. What is the most likely diagnosis?

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Flashcards: Pharyngitis

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_____styloid compartment involvement in parapharyngeal abscess will present as prolapse of tonsil and trismus

TAP TO REVEAL ANSWER

_____styloid compartment involvement in parapharyngeal abscess will present as prolapse of tonsil and trismus

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