Pharyngitis

Etiology

Pharyngitis is defined as inflammation of the pharynx and surrounding structures.

Most cases are due to an infectious organism acquired from close contact with an infected individual.

• Viral:
  • Adenovirus (most common) 
  • Coxsackie A virus
  • Orthomyxoviridae family
  • Epstein-Barr virus (causes infectious mononucleosis)
  • Herpes simplex virus
  • Measles virus
  • Rhinovirus
  • Coronavirus
  • Respiratory syncytial virus
  • Parainfluenza virus
• Bacterial:
  • Streptococcus pyogenes (most frequent bacterial cause of infectious pharyngitis)
  • Streptococcus pneumoniae (beta-hemolytic Streptococcus infections are common in children aged 4–7 years)
  • Haemophilus influenzae
  • Bordetella pertussis
  • Bacillus anthracis
  • Corynebacterium diphtheriae
  • Neisseria gonorrhoeae
  • Chlamydophila pneumoniae
  • Mycoplasma pneumoniae
  • Fusobacterium necrophorum
• Fungal:
  • Candidiasis (oral thrush involving pharynx can occur in immunocompromised patients, with antibiotic and inhaled glucocorticoid use, and in patients receiving chemotherapy and/or radiation)
• Non-infectious causes:
  • Smoking
  • Snoring
  • Shouting
  • Tracheal intubation
  • Medications
  • Concomitant illness
  • Indoor and outdoor air pollutants
  • Temperature and humidity (e.g., dryness during winter months, forced-air heating)
  • Hazardous or occupational irritants
  • Foreign body (e.g., fishbone embedded in the pharynx)
  • Systemic inflammatory conditions: Kawasaki disease, Stevens-Johnson syndrome, Behçet’s syndrome, PFAPA (periodic fever, aphthous stomatitis, pharyngitis, adenitis) syndrome
  • Chemical exposure (e.g., paraquat, alkali)
  • Referred pain (e.g., otitis media, tooth abscess)
  • Psychogenic

Clinical Presentation

• Symptoms usually last 3–5 days
• Throat discomfort
• Odynophagia: painful swallowing
• Dry cough
• Cervical lymphadenopathy
• Pharyngeal exudate
• No cough or hoarseness (points toward laryngitis if these symptoms are present)
• Constitutional symptoms: body aches, headache, fever, myalgia, malaise, abrupt onset

Diagnosis

Centor score: estimates the probability that pharyngitis is streptococcal and suggests management course for adults

• Criteria:
  • Age 3–14 years: +1
  • Age 15–44 years: +0
  • Age ≥ 45 years: –1
  • Absence of cough: +1
  • Tonsillar exudates: +1
  • Fever: +1
  • Tender anterior cervical adenopathy: +1
• Scoring:
  • –1, 0, or 1 point: no further testing or antibiotics
  • 2 points: optional rapid strep testing and/or culture
  • 3 points: rapid strep test and/or culture recommended, antibiotics only if positive
  • 4 or 5 points: rapid strep testing and/or culture with empiric antibiotics recommended

Laboratory diagnosis:

• Rapid strep test: detects ribonuclease antigen
• Throat swab for culture 
• Serological testing

Identification of beta-hemolytic streptococcal infection is of paramount importance as it is associated with the development of rheumatic heart disease if left untreated.

To recall the Centor criteria, remember:

• C = cough 
• E = exudate
• N = nodes
• T = temperature (fever)
• OR = young OR old modifier

Management

• The mainstay of treatment is symptomatic and supportive:
  • Adequate fluid intake, avoidance of respiratory irritants such as smoke, avoidance of acidic foods and beverages, soft diet, adequate rest, systemic analgesia, medicated lozenges, and throat spray
• Some patients may require antibiotics for laboratory-documented bacterial pharyngitis:
  • Treat pharyngitis due to group A beta-hemolytic Streptococci with oral penicillin or amoxicillin for 10 days (cephalexin if penicillin causes rash; clindamycin or macrolide if penicillin causes anaphylaxis).
  • Timely treatment is crucial for the prevention of acute rheumatic fever.
• Viral pharyngitis is self-limiting and resolves spontaneously and steadily within a few days without worsening.
• If there is an underlying cause, identify and treat it (e.g., retroviral therapy for HIV, penicillin for Group A Streptococcus, nystatin for Candida, etc.).

Complications

Suppurative complications

• Sinusitis
• Otitis media
• Epiglottitis
• Mastoiditis
• Peritonsillar abscess
• Retropharyngeal abscess
• Suppurative cervical lymphadenitis
• Pneumonia
• Tonsillar cellulitis
• Necrotizing fasciitis
• Streptococcal bacteremia (rare)
• Meningitis or brain abscess (extremely rare)

Non-suppurative complications

• Airway obstruction
• Thrombocytopenia
• Myocarditis
• Pericarditis
• Encephalitis
• Meningitis
• Toxic shock syndrome
• Acute rheumatic fever
• Acute inflammatory demyelinating polyneuropathy
• Poststreptococcal reactive arthritis
• Acute glomerulonephritis
• PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections)

Differential Diagnosis

The following conditions are differential diagnoses of pharyngitis:

• Epiglottitis: an inflammation of the epiglottis caused by Haemophilus, streptococcal, or staphylococcal infections, which manifests with difficulty in breathing, stridor, and cyanosis ultimately leading to death due to obstruction of airways
• Laryngitis or laryngotracheitis: an inflammation of the larynx due to trauma or infection, among other causes. In this condition, the 2 folds of mucous membrane that make up the vocal cords become inflamed and irritated. 
• Peritonsillar abscess: a deep neck infection that commonly occurs in adolescents or young adults as a complication of acute tonsillitis. Presents with fever, sore throat, dysphagia, so-called “hot-potato” voice, and trismus
• Candidiasis: a fungal infection caused by Candida yeasts that can cause infections deep within the body, affecting internal organs such as the kidney, heart, or brain
• Diphtheria: a serious bacterial infection caused by Corynebacterium diphtheriae that affects the mucous membranes in the nose and throat, resulting in sore throat, fever, swollen glands (so much so that a “bull neck” is pathognomonic of this infection), and weakness
• Croup: also called laryngotracheobronchitis; caused most commonly by a viral infection or, rarely, by a bacterial infection that results in swelling of the trachea and interferes with normal breathing
• Gonorrhea: a sexually transmitted disease that affects both genders, manifesting on the genitals, rectum, and throat, commonly affecting teens (15–24 years) who engage in vaginal, anal, or oral sex
• Pneumonia: an acute or chronic inflammation of lung tissue, which includes infection with bacteria, viruses, or fungi