What is the treatment protocol for diphtheria?

Diphtheria Treatment Protocol

The treatment of diphtheria requires immediate administration of diphtheria antitoxin (DAT) upon clinical suspicion, without waiting for laboratory confirmation, along with concurrent antimicrobial therapy such as erythromycin or penicillin. 1

Diagnosis and Initial Assessment

• Characteristic clinical presentation includes:

  • Upper respiratory tract illness with sore throat and low-grade fever
  • Adherent grayish membrane on the tonsils, pharynx, and/or nose
  • Possible presence of "bull neck" in severe cases
  • For cutaneous diphtheria: skin lesions with membrane formation

• Laboratory confirmation:

  • Throat cultures should be obtained before starting antimicrobial therapy
  • Serum specimen for antitoxin level testing (levels below 0.01 IU/mL support diagnosis)

Treatment Algorithm

Step 1: Diphtheria Antitoxin (DAT) Administration

• Administer DAT immediately upon clinical suspicion
• Critical timing: Delay increases mortality risk
• Caution: Test for sensitivity to equine serum before administration due to risk of allergic reactions (7% immediate hypersensitivity, 5% serum sickness) 2

Step 2: Antimicrobial Therapy (Start Concurrently with DAT)

• First-line options:
  • Erythromycin: 500 mg orally four times daily for 14 days 3
  • Alternative: Benzathine penicillin (single IM injection)
• For children:
  • Erythromycin: 40-50 mg/kg/day in divided doses for 14 days 3

Step 3: Supportive Care

• Monitor for complications:
  • Airway compromise (may require intubation)
  • Myocarditis
  • Neurological complications
  • Renal failure
• Cardiac monitoring for at least 2-3 weeks

Management of Close Contacts

• Identify close contacts:

  • Household members
  • Persons with habitual, close contact
  • Individuals directly exposed to oral secretions

• For all contacts:

  1. Obtain throat cultures before starting prophylaxis
  2. Monitor daily for 7 days for signs of disease
  3. Initiate antimicrobial prophylaxis immediately:
     • Benzathine penicillin (single IM injection): 600,000 units (<6 years), 1,200,000 units (≥6 years)
     • OR Erythromycin (oral for 7-10 days): 40 mg/kg/day for children, 1 g/day for adults 1
  4. Perform follow-up cultures after completion of antimicrobial therapy
  5. For persistent carriers: additional 10-day course of oral erythromycin

• Vaccination for contacts:

  • Unknown/incomplete vaccination (<3 doses): immediate dose of age-appropriate diphtheria toxoid-containing vaccine and complete primary series
  • Fully vaccinated (≥3 doses) but no booster in past 5 years: age-appropriate booster dose 1

Special Considerations

• Cutaneous diphtheria:

  • If toxigenic strain: manage contacts as for respiratory diphtheria
  • If non-toxigenic strain: routine investigation or prophylaxis of contacts not necessary 2, 1

• Pregnancy:

  • While no evidence of teratogenicity exists, waiting until second trimester for Td administration is reasonable 1

• Hypersensitivity concerns:

  • Persons with previous Arthus-type reactions or high fever (>103°F/39.4°C) following tetanus toxoid should not receive Td more frequently than every 10 years 1

Common Pitfalls to Avoid

1. Delaying DAT administration while waiting for laboratory confirmation
2. Inadequate contact tracing and prophylaxis
3. Overlooking vaccination status updates for contacts
4. Insufficient monitoring for cardiac complications
5. Failure to complete full antimicrobial course

The treatment protocol outlined above aligns with the most recent guidelines from the Centers for Disease Control and Prevention, emphasizing the critical importance of early intervention with both antitoxin and antimicrobials to reduce mortality and prevent complications of this potentially fatal disease 1, 4.