explain pharangitis

Reading File

Finding Sources

Searching PubMed

pharyngitis diagnosis treatment

Reading File

Loading Image

I now have comprehensive information from authoritative sources. Let me compile the full explanation.

Pharyngitis

Pharyngitis is inflammation of the pharynx (the back of the throat), most commonly presenting as a sore throat. It is one of the most frequent reasons for medical visits - accounting for over 7 million pediatric primary care visits annually in the US alone.

Clinical Appearance

Streptococcal pharyngitis showing inflamed, erythematous tonsils with white/yellow exudates bilaterally

Typical appearance of bacterial (streptococcal) pharyngitis: erythematous, swollen tonsils with confluent white exudates.

Etiology (Causes)

Viral (50-80% of cases)

Viral causes dominate, especially in children. Common culprits include:

Virus	Notes
Adenovirus	Very common
Epstein-Barr virus (EBV)	Causes infectious mononucleosis
Rhinovirus	Most frequent URI agent
Influenza A & B	Seasonal
Enterovirus (Coxsackievirus)	Hand-foot-mouth disease
Coronavirus, RSV, Parainfluenza	Various respiratory illnesses
Herpes simplex virus 1 & 2	Can cause ulcerative pharyngitis
HIV	Acute retroviral syndrome
Cytomegalovirus	Mimics EBV mono

Bacterial (20-40% in children, 5-15% in adults)

Group A beta-hemolytic Streptococcus (GABHS) / Streptococcus pyogenes - the most important and most common bacterial cause
Neisseria gonorrhoeae (in sexually active individuals)
Corynebacterium diphtheriae (rare, but serious - diphtheria)
Mycoplasma pneumoniae, Chlamydophila pneumoniae
Fusobacterium necrophorum (can cause Lemierre's syndrome)

Symptoms

Sore throat (dominant complaint)
Odynophagia (pain on swallowing)
Fever
Headache
Nausea, vomiting, abdominal pain (more common in children)
Cough, hoarseness, coryza (suggest viral etiology)
Myalgias, arthralgias, lethargy
Chilliness (frank rigors are unusual in strep)

Physical Examination Findings

Tonsillopharyngeal erythema and/or exudates
Soft palate petechiae
Uvular edema
Hypertrophied tonsils
Anterior cervical lymphadenopathy (submandibular)
Rash (in scarlet fever)
Conjunctivitis (suggests viral/adenovirus)
Discrete oral ulcers/vesicles (suggest viral)

Key point: Tonsillar exudate does NOT reliably distinguish bacterial from viral etiology. Cough, rhinorrhea, oral ulcers, and conjunctivitis point strongly toward a viral cause.

Streptococcal Pharyngitis - the Clinically Most Important Type

S. pyogenes pharyngitis peaks in children aged 5-15 years, typically in winter and early spring. Classic presentation: abrupt onset of fever, sore throat, and submandibular adenopathy WITHOUT cough.

The infection triggers antibodies against M protein, streptolysin O, DNase, hyaluronidase, and pyrogenic exotoxins.

Even without treatment, symptoms typically resolve in 3-6 days - but untreated strep carries risks of serious complications.

The Centor/McIsaac Score (Modified Centor Score)

Used to predict likelihood of GABHS and guide testing/treatment:

Criterion	Points
Tonsillar exudates	+1
Tender anterior cervical lymphadenopathy	+1
Absence of cough	+1
Fever (>38°C)	+1
Age 3-14 years	+1
Age 15-44 years	0
Age ≥45 years	-1

Score 0-1: GABHS unlikely - no testing or antibiotics needed
Score 2-3: Test with rapid antigen or culture
Score 4-5: High likelihood; consider empiric treatment

Diagnosis

Gold Standard

Throat culture - sensitivity 90-95%, but requires 18-48 hours for results.

Rapid Tests

Rapid antigen detection test (RADT): sensitivity 80-90%, results in minutes
Rapid nucleic acid test: sensitivity 97.5%, specificity 95% - preferred over antigen tests
If RADT is negative in children/adolescents, a follow-up culture is recommended
In adults, backup culture is usually not needed given the low incidence of GABHS and low rheumatic fever risk

Infectious Mononucleosis (EBV)

Monospot (heterophile antibody) test - relatively insensitive in young children (only 25% positive in 10-24 months age)
EBV IgM/IgG is more sensitive and specific but slower
Atypical lymphocytes on CBC
A telltale sign: amoxicillin or ampicillin given for presumed bacterial pharyngitis triggers a characteristic pruritic maculopapular rash

Complications of Untreated Streptococcal Pharyngitis

These are the main reason to diagnose and treat GABHS:

Suppurative complications: peritonsillar abscess, retropharyngeal abscess, mastoiditis, otitis media, sinusitis
Scarlet fever: strep infection + fever + characteristic sandpaper rash from pyrogenic exotoxins
Acute rheumatic fever (ARF): autoimmune sequel affecting heart, joints, CNS; prevented by antibiotics
Post-streptococcal glomerulonephritis (PSGN): immune complex nephritis; antibiotics do NOT prevent this
Bacteremia
Streptococcal toxic shock syndrome (uncommon)

Treatment

Viral Pharyngitis

Supportive care only: analgesics (acetaminophen, NSAIDs), hydration, throat lozenges, warm saltwater gargles
85% resolve spontaneously within 1 week
No antibiotics indicated
For EBV/mono with severe tonsillar enlargement: a short course of corticosteroids may be considered to reduce swelling (though evidence is limited)
EBV patients with splenomegaly: avoid contact sports until cleared by a physician

Bacterial (GABHS) Pharyngitis

Antibiotic of choice:

Penicillin V (oral) or Amoxicillin - 10 days - first line
Benzathine penicillin G - single IM injection - for compliance concerns
Penicillin allergy: Azithromycin or clindamycin

Key points:

Antibiotics shorten illness duration by ~1 day and prevent rheumatic fever
Antibiotics do NOT prevent PSGN regardless of timing
Delaying treatment by a few days is acceptable - still achieves the goal of preventing rheumatic fever while reducing unnecessary antibiotic use
Patient satisfaction is most influenced by physician concern and reassurance - not antibiotic prescription

Special Considerations

Immunocompromised Patients

Consider opportunistic organisms: Candida albicans (thrush/pharyngitis), Mycobacterium avium.

Adolescents with Pharyngitis + High-Risk Behaviors

Acute HIV (acute retroviral syndrome) can mimic EBV pharyngitis in 50-70% of patients. Distinguishing features: no prominent exudates or tonsillar hypertrophy, mucocutaneous ulceration, rash.

Children Under 3 Years

Routine streptococcal testing is not recommended - low rates of strep and very low complication risk in this age group.

Summary Table

Feature	Viral	Streptococcal (GABHS)
Cough	Common	Absent
Rhinorrhea	Present	Absent
Exudate	Possible	Common
Fever	Variable	Abrupt, high
Adenopathy	Posterior > anterior	Anterior cervical
Treatment	Supportive	Penicillin/Amoxicillin
Complications	Usually none	ARF, abscess, scarlet fever

Sources:

Goldman-Cecil Medicine, International Edition (Block 44)
Tintinalli's Emergency Medicine: A Comprehensive Study (Block 10)
Goldman-Cecil Medicine - S. pyogenes section

This is a shared conversation. Sign in to Orris to start your own chat.