9.3 Common Upper Respiratory ENT Infections

Upper Respiratory Tract ENT Infections

Acute upper respiratory infections are among the most common reasons patients seek primary care. Distinguishing viral infections from bacterial processes that benefit from antibiotic therapy is crucial for patient safety and stewardship.

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Acute Pharyngitis & Tonsillitis: Centor Criteria and Treatment

Pharyngitis is inflammation of the pharynx, with viral pathogens (e.g., rhinovirus, adenovirus, Epstein-Barr virus) accounting for the vast majority of cases. The most common bacterial cause is Group A Beta-Hemolytic Streptococcus (GABHS), also known as Streptococcus pyogenes. Treating GABHS is essential to prevent acute rheumatic fever, which can lead to permanent rheumatic heart disease.

The Centor Criteria (Modified McIsaac Score)

Clinicians use the Centor criteria to estimate the probability of GABHS pharyngitis and guide management. The elements are:

• Fever: History of or documented fever >38°C (100.4°F) (+1 point)
• Tonsillar Exudates: Presence of tonsillar swelling or exudate (+1 point)
• Cervical Lymphadenopathy: Tender anterior cervical lymph nodes (+1 point)
• Absence of Cough (+1 point)
• Age Modifier:
  • Age 3 to 14 years (+1 point)
  • Age 15 to 44 years (0 points)
  • Age 45 years and older (-1 point)

Management Guidelines Based on Score

• Score 0–1: Very low risk of GABHS (<10%). No diagnostic testing or antibiotic treatment is indicated.
• Score 2–3: Intermediate risk (15–30%). Perform a Rapid Antigen Detection Test (RADT). If positive, treat with antibiotics. If negative, supportive care. In children, a negative RADT must be confirmed with a throat culture (the gold standard); in adults, throat culture backup is not routinely recommended due to low risk of rheumatic fever.
• Score 4 or higher: High risk (>50%). Perform RADT. Empirical antibiotic therapy can be considered if testing is unavailable.

Pharmacotherapy for GABHS Pharyngitis

• First-line: Penicillin V potassium (500mg orally two to three times daily for 10 days), or amoxicillin (50 mg/kg up to 1000mg once daily for 10 days). Alternatively, a single dose of intramuscular benzathine penicillin G (1.2 million units) can be given if adherence is a concern.
• Penicillin Allergy: For patients with non-anaphylactic penicillin allergies, first-generation cephalosporins (e.g., cephalexin for 10 days) are appropriate. For severe Type I hypersensitivity (anaphylaxis), use macrolides (e.g., azithromycin for 5 days) or clindamycin for 10 days.

Acute Sinusitis (Rhinosinusitis)

Acute rhinosinusitis is inflammation of the nasal cavity and paranasal sinuses lasting less than 4 weeks. Most cases are viral (viral rhinosinusitis) and resolve within 7–10 days. Less than 2% of cases develop into acute bacterial rhinosinusitis (ABRS).

Clinical Distinction: Viral vs. Bacterial

ABRS should only be diagnosed, and antibiotics prescribed, when a patient meets one of the following three clinical criteria:

1. Persistent Symptoms: Symptoms of congestion, nasal discharge, or facial pain/pressure that last for 10 or more days without any evidence of clinical improvement.
2. "Double Sickening": The patient begins to improve after a typical viral prodrome, but then develops sudden worsening of symptoms (new-onset fever, headache, increased nasal discharge, or facial pain) around day 5 or 6 of the illness.
3. Severe Onset: High fever (>39°C or 102.2°F) accompanied by purulent nasal discharge and severe facial pain lasting for at least 3–4 consecutive days at the very beginning of the illness.

Treatment Guidelines

• Viral Rhinosinusitis: Managed supportively. Therapy includes saline nasal irrigation, intranasal corticosteroids (e.g., fluticasone), and short-term topical decongestants (e.g., oxymetazoline for no more than 3 consecutive days to avoid rebound congestion, known as rhinitis medicamentosa).
• Acute Bacterial Rhinosinusitis (ABRS):
  • First-line: Amoxicillin-clavulanate (500 mg/125 mg three times daily, or 875 mg/125 mg twice daily for 5–7 days) is preferred over amoxicillin alone to overcome beta-lactamase resistance in H. influenzae and M. catarrhalis.
  • Penicillin Allergy: Doxycycline (100mg twice daily) or a respiratory fluoroquinolone (e.g., levofloxacin 500mg daily). Macrolides and trimethoprim-sulfamethoxazole are not recommended due to high rates of streptococcal resistance.

Peritonsillar Abscess (Quinsy)

A peritonsillar abscess is a localized accumulation of pus in the peritonsillar space, situated between the tonsillar capsule and the superior pharyngeal constrictor muscle. It typically develops as a complication of acute tonsillitis.

Clinical Presentation

Patients are usually young adults presenting with:

• Severe, progressive unilateral sore throat and painful swallowing (odynophagia).
• Trismus (inability to open the mouth fully) caused by spasm of the internal pterygoid muscle.
• A muffled "hot potato" voice.
• Uvular deviation to the contralateral side due to marked unilateral swelling of the soft palate and palatopharyngeal arch.
• Drooling, fever, and ipsilateral referred ear pain (otalgia).

Management

• Airway Assessment: The primary clinical focus must be verifying airway patency. Stridor, accessory muscle use, or inability to manage secretions require immediate airway stabilization.
• Drainage: The gold standard of treatment is surgical drainage. This can be accomplished via:
  1. Needle Aspiration: Under local anesthesia, a large-bore needle is used to aspirate pus from the area of maximal fluctuance. Highly effective and well-tolerated.
  2. Incision and Drainage (I&D): A small scalpel incision is made, followed by blunt dissection using hemostats to disrupt loculations.
  3. Acute Tonsillectomy: Reserved for patients with recurrent tonsillitis, airway compromise, or failure of needle/I&D drainage.
• Antibiotic Therapy: Intravenous therapy is initiated with ampicillin-sulbactam or clindamycin, followed by a 10–14 day course of oral antibiotics (e.g., amoxicillin-clavulanate or oral clindamycin).
• Corticosteroids: A single dose of intravenous dexamethasone is often administered to decrease edema, reduce pain, and speed recovery.