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Essentials of Diagnosis
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General Considerations
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Group A β-hemolytic streptococci (Streptococcus pyogenes) are the most common bacterial cause of exudative pharyngitis
The main concern is to determine whether the cause is group A β-hemolytic streptococcal infection (GABHS), because of the complications of rheumatic fever and glomerulonephritis
A second public health policy concern is to reduce the extraordinary cost (in both dollars and development of antibiotic-resistant Streptococcus pneumoniae in the United States associated with unnecessary antibiotic use)
About one-third of patients with infectious mononucleosis have secondary streptococcal tonsillitis, requiring treatment
Ampicillin should routinely be avoided if mononucleosis is suspected because it induces a rash
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Centor diagnostic criteria
Sore throat may be severe, with odynophagia, tender adenopathy, and a scarlatiniform rash
Hoarseness, cough, and coryza are not suggestive of this disease
Marked lymphadenopathy and a shaggy white-purple tonsillar exudate, often extending into the nasopharynx, suggest mononucleosis, especially if present in a young adult
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Differential Diagnosis
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Viral pharyngitis
Epstein-Barr virus (EBV)/infectious mononucleosis
Primary HIV infection
Candidiasis
Necrotizing ulcerative gingivostomatitis (Vincent fusospirochetal disease)
Retropharyngeal abscess
Diphtheria
Neisseria gonorrhoeae
Mycoplasma
Anaerobic streptococci
Corynebacterium haemolyticum
Epiglottitis
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The presence of the four Centor diagnostic criteria strongly suggests GABHS
When two or three of the four are present, there is an intermediate likelihood of GABHS
When zero or one Centor criterion is present, GABHS is unlikely; throat culture or rapid antigen detection testing of throat swab is not necessary
With about 90% sensitivity, lymphocyte to white blood cell ratios of > 35% suggest EBV infection and not tonsillitis
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Patients with zero or one Centor criteria should not receive antibiotics
Patients with two or three Centor criteria whose throat cultures or rapid antigen detection testing show positive results should receive antibiotic treatment
Patients who have four Centor criteria can receive empiric therapy without throat culture or rapid antigen detection testing
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Benzathine penicillin intramuscular injection
Analgesic, anti-inflammatory drugs (aspirin, acetaminophen, corticosteroids)
Oral antibiotics