What is the further workup for a patient presenting with a sore throat?

Further Workup for Sore Throat

Use the Centor criteria to risk-stratify patients, then test only those with 2 or more criteria using a rapid antigen detection test (RADT) or throat culture for Group A Streptococcus—patients with fewer than 2 criteria do not need testing. 1

Clinical Risk Stratification Algorithm

Apply the Centor criteria to determine likelihood of Group A Streptococcal (GAS) pharyngitis and guide testing decisions 1:

The four Centor criteria are:

• Fever (temperature ≥38.0°C or history of fever) 1
• Tonsillar exudates or pharyngeal exudates 1, 2
• Tender anterior cervical lymphadenopathy 1, 2
• Absence of cough 1, 2

Testing strategy based on Centor score:

• 0-1 criteria: No testing needed—viral etiology most likely, provide symptomatic treatment only 1
• 2 criteria: Consider testing with RADT or throat culture 1
• 3-4 criteria: Perform RADT or throat culture before prescribing antibiotics 1

Laboratory Testing Approach

For patients meeting testing criteria (≥2 Centor criteria):

• Rapid Antigen Detection Test (RADT) is the preferred initial test and does not require confirmatory throat culture after a negative result in both adults and children 1
• Throat culture is not necessary for routine diagnosis but can be used as an alternative to RADT 1
• Do NOT routinely use biomarkers (C-reactive protein, procalcitonin) in the assessment of acute sore throat 1

The positive predictive value of Centor criteria alone is low, which is why microbiological confirmation is essential before prescribing antibiotics 1.

Red Flags Requiring Urgent Evaluation

Immediately evaluate for life-threatening conditions if the patient presents with:

• Difficulty swallowing, drooling, or neck swelling—suggests peritonsillar abscess, parapharyngeal abscess, or epiglottitis 1
• Severe unilateral throat pain with trismus and uvular deviation—indicates peritonsillar abscess (quinsy) 3
• Persistent fever with neck pain in adolescents/young adults with severe pharyngitis—consider Lemierre syndrome (suppurative thrombophlebitis of internal jugular vein) 1, 3

Routine testing for Fusobacterium necrophorum is not recommended, but maintain high clinical suspicion for Lemierre syndrome in adolescents and young adults with severe presentations 1.

Features Suggesting Viral Etiology (No Testing Needed)

Strong indicators of viral pharyngitis that make GAS unlikely:

• Conjunctivitis, cough, hoarseness, or coryza (runny nose) 3
• Diarrhea or viral exanthem 3
• Anterior stomatitis or discrete ulcerative lesions 3

When these features are present, testing for GAS is not indicated regardless of Centor score 3.

Special Considerations

Chronic GAS carriers (10.9% in children ≤14 years, 2.3% in adults):

• Extremely difficult to differentiate from acute infection when they develop intercurrent viral pharyngitis 3
• Show extremely low risk of post-streptococcal complications and low transmission likelihood 3
• Antimicrobial therapy is NOT indicated for most chronic carriers 3

Infectious mononucleosis (Epstein-Barr virus):

• Consider when pharyngitis is accompanied by generalized lymphadenopathy (especially posterior cervical) and splenomegaly 3
• This requires different management than bacterial pharyngitis 3

Common Pitfalls to Avoid

• Do not test patients with clear viral symptoms (cough, rhinorrhea, conjunctivitis)—this leads to false-positive results in carriers and unnecessary antibiotic use 1, 3
• Do not prescribe antibiotics based on clinical features alone without microbiological confirmation—clinical features cannot reliably distinguish GAS from viral pharyngitis 3
• Do not misinterpret lymphadenopathy as bacterial infection—swollen lymph nodes commonly occur with viral pharyngitis 4
• Do not overlook life-threatening complications in patients with unusually severe presentations—maintain high suspicion for peritonsillar abscess and Lemierre syndrome 1, 3