What are the plans for diagnosing and managing Streptococcal (Strep) Pharyngitis?

Diagnosis and Management of Streptococcal Pharyngitis (Strep Throat)

Throat swabbing with rapid antigen detection test (RADT) and/or culture is essential for diagnosing Group A Streptococcal (GAS) pharyngitis, as clinical features alone cannot reliably distinguish between GAS and viral pharyngitis. 1

Diagnostic Approach

When to Test

• Test patients with acute pharyngitis when:

  • No overt viral features are present (absence of cough, rhinorrhea, hoarseness, oral ulcers) 1
  • Patient presents with abrupt onset of sore throat, fever, headache, tender/enlarged anterior cervical lymph nodes, and pharyngeal/tonsillar exudate 2

• Do NOT test when:

  • Clinical features strongly suggest viral etiology (cough, rhinorrhea, hoarseness, oral ulcers) 1
  • Children under 3 years of age (unless they have specific risk factors like an older sibling with GAS infection) 1

Diagnostic Methods

1. Rapid Antigen Detection Test (RADT):

   • First-line diagnostic tool
   • Provides results within minutes
   • High specificity (positive results are reliable) 1
   • For children and adolescents: negative RADT results must be backed up with throat culture 1
   • For adults: backup throat culture not routinely necessary due to lower incidence of GAS and minimal risk of acute rheumatic fever 1

2. Throat Culture:

   • Gold standard for diagnosis 2
   • Required to confirm negative RADT in children/adolescents
   • Results available in 24-48 hours

3. Clinical Scoring Systems:

   • Modified Centor score can help assess risk of GAS infection 2
   • Criteria include: absence of cough, presence of tonsillar exudates, tender anterior cervical lymphadenopathy, history of fever, and age

4. NOT Recommended:

   • Anti-streptococcal antibody titers (reflect past, not current infection) 1
   • Post-treatment throat cultures in asymptomatic patients 1
   • Testing of asymptomatic household contacts 1

Treatment Plan

Antibiotic Therapy

1. First-line treatment:

   • Penicillin or amoxicillin for 10 days 1
   • Preferred due to narrow spectrum, low adverse reaction rate, and modest cost

2. For penicillin-allergic patients:

   • First-generation cephalosporins for 10 days (if not anaphylactically sensitive) 1
   • Clindamycin or clarithromycin for 10 days 1
   • Azithromycin for 5 days 1

Adjunctive Therapy

• For symptom relief:
  • Acetaminophen or NSAIDs for moderate to severe symptoms or fever control 1
  • Avoid aspirin in children due to risk of Reye's syndrome 1
  • Corticosteroids are NOT recommended 1

Patient Education

Key Points for Patients

• Importance of completing the full course of antibiotics:

  • Even if feeling better, complete the entire prescribed course (usually 10 days) to:
    • Eradicate the organism from the pharynx
    • Prevent complications like rheumatic fever
    • Reduce risk of developing antibiotic resistance 3

• Expected course:

  • Symptoms typically improve within 24-48 hours of starting antibiotics
  • Patients are no longer contagious after 24 hours of antibiotic therapy

• Warning signs requiring follow-up:

  • Worsening symptoms despite treatment
  • Development of new symptoms (rash, joint pain, difficulty breathing)
  • Persistent symptoms after completing antibiotics

• Prevention measures:

  • Avoid sharing utensils, food, or drinks
  • Practice good hand hygiene
  • Replace toothbrush after starting antibiotics

Special Considerations

Recurrent Streptococcal Pharyngitis

• Consider two possibilities: 1

  • Multiple episodes of true GAS infections
  • Chronic GAS carrier experiencing viral infections

• For true recurrences:

  • Consider intramuscular benzathine penicillin G if compliance with oral therapy is questionable 1
  • Alternative agents like clindamycin or amoxicillin-clavulanate may be beneficial in eradicating pharyngeal streptococci 1

Common Pitfalls to Avoid

1. Over-reliance on clinical features alone for diagnosis

   • Clinical features cannot reliably distinguish between viral and GAS pharyngitis 1

2. Unnecessary antibiotic treatment

   • Only 5-15% of adults and 15-35% of children with pharyngitis have GAS infection 4
   • Prescribing antibiotics without confirming GAS increases risk of antibiotic resistance 3

3. Inadequate follow-up for treatment failures

   • While routine post-treatment cultures are not needed, patients with persistent symptoms should be re-evaluated 1

4. Failure to consider complications

   • Monitor for suppurative complications (peritonsillar abscess, cervical lymphadenitis) and non-suppurative complications (acute rheumatic fever, post-streptococcal glomerulonephritis) 2

By following this systematic approach to diagnosis and management, clinicians can effectively identify and treat patients with GAS pharyngitis while minimizing unnecessary antibiotic use and preventing complications.