Streptococcal pharyngitis

Background

Anatomy of the posterior pharynx.

• Peak in 5-15yr old
• Rare in <2yr of age
• Accounts for only 15-30% of pharyngitis
• Caused by S. pyogenes (Group A strep)
• Peak season is late winter / early spring
• Transmission is respiratory secretions
• Incubation period is 24-72 hours
• Antibiotics shorten symptoms by 16 hours

Clinical Features

culture positive strep pharyngitis with typical tonsillar exudate

• Sore throat
• Painful swallowing
• Fever
• Nausea and vomiting
• Tonsillar exudate
• Palatal petechiae

Should NOT have a rash; if have scarlatiniform rash consider scarlet fever

Modified Centor Criteria

One point is given for each of the criteria:

1. Absence of a cough
2. Swollen and tender cervical lymph nodes
3. Temperature >38.0 °C (100.4 °F)
4. Tonsillar exudate or swelling
5. Age less than 15^
   • Subtract a point if age >44

Modified Centor score

Points	Probability of Streptococcal pharyngitis
1 or fewer	<10%
2	11–17%
3	28–35%
4 or 5	52%

Differential Diagnosis

• Acute rheumatic fever
• Scarlet fever
• Suppurative complications
  • Peritonsillar abscess
  • Mastoiditis

Acute Sore Throat

Bacterial infections

• Streptococcal pharyngitis (Strep Throat)
• Neisseria gonorrhoeae
• Diphtheria (C. diptheriae)
• Bacterial Tracheitis

Viral infections

• Infectious mononucleosis (EBV)
  • Patients with peritonsillar abscess have a 20% incidence of mononucleosis
• Laryngitis
• Acute Bronchitis
• Rhinovirus
• Coronavirus
• Adenovirus
• Herpesvirus
• Influenza virus
• Coxsackie virus
  • Herpangina
  • Hand-foot-and-mouth disease
• HIV (Acute Retroviral Syndrome)

Noninfectious

• Stevens-Johnson Syndrome
• Pemphigus
• Angioedema

Other

• Deep neck space infection
  • Retropharyngeal abscess
  • Ludwig's angina
  • Parapharyngeal space infection
• Peritonsillar Abscess (PTA)
• Epiglottitis
• Kawasaki disease
• Penetrating injury
• Caustic ingestion
• Lemierre's syndrome
• Peritonsillar cellulitis
• Lymphoma
• Internal carotid artery aneurysm
• Oral Thrush
• Parotitis
• Post-tonsillectomy hemorrhage
• Vincent's angina
• Acute necrotizing ulcerative gingivitis

Oral rashes and lesions

• Angioedema
• Aphthous stomatitis
• Herpes gingivostomatitis
• Herpes labialis
• Measles (Koplik's spots)
• Perioral dermatitis
• Oral thrush
• Steven Johnson syndrome
• Streptococcal pharyngitis
• Tongue diagnoses
• Vincent's angina

Evaluation

• Per a 2016 Cochrane Review of rapid strep tests in children, tests on average had a specificity of 95% and sensitivity of 86%, regardless of type of rapid strep test used (enzyme immunoassays or optical immunoassays).

Rapid Antigen Detection Test Algorithm for Acute Pharyngitis

Category	Testing and Treatment
Clinical features strongly suggesting viral etiology (eg. cough, rhinorrhea, hoarseness, oral ulcers)	None
<3 years old	None because immature immune system not mature enough to develop anti-streptolysin O (ASO) antibodies and acute rheumatic fever. Unless they have a special risk factor (e.g. older sibling with GAS infection)
CENTOR = 1	None
None of the above with CENTOR ≥2	Send rapid antigen detection test Positive = treat Negative Children and adolescents Send back up throat culture (treat later, if positive) Adults None (no need for back up throat culture)

Diagnostic testing or empiric treatment of asymptomatic household contacts of patients with acute streptococcal pharyngitis is not routinely recommended

Management

Antibiotics

Treatment can be delayed for up to 9 days and still prevent major sequelae

Penicillin Options:

• Penicillin V 250mg PO BID x 10d (child) or 500mg BID x 10d (adolescent or adult)
• Bicillin L-A <27 kg: 0.6 million units; ≥27 kg: 1.2 million units IM x 1
• Amoxicillin 50 mg/kg once daily (maximum = 1000 mg) for 10 days

Penicillin allergic (mild):

• Cephalexin 20 mg per kg PO BID (maximum 500 mg per dose) x 10 days
• Cefadroxil 30 mg per kg PO QD (maximum 1 g daily) x 10 days

Penicillin allergic (anaphylaxis):

• Clindamycin 7 mg/kg/dose TID (maximum = 300 mg/dose) x 10 days
• Azithromycin 12 mg/kg PO once (maximum = 500 mg), then 6 mg/kg (max=250 mg) once daily for the next 4 days
• Clarithromycin 7.5 mg/kg/dose PO BID (maximum = 250 mg/dose) x 10 days

Steroids

• Consider single dose of dexamethasone 0.6mg/kg PO (Max = 10mg)

Disposition

• Discharge

Complications

• Acute rheumatic fever
• Scarlet fever
• Toxic shock syndrome
• Post-streptococcal glomerular nephritis
• PANDAS syndrome
• Peritonsillar abscess
• Cervical lymphadenitis
• Mastoiditis

See Also

• Sore Throat