What is the treatment for diphtheria?

Treatment of Diphtheria

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

Clinical Presentation and Diagnosis

Diphtheria typically presents as:

• Upper respiratory tract illness with sore throat and low-grade fever
• Adherent grayish pseudomembrane on the tonsils, pharynx, and/or nose
• Possible "bull neck" appearance in severe cases
• Respiratory symptoms including dyspnea
• Cutaneous manifestations in cutaneous diphtheria

Diagnostic steps:

• Obtain throat swabs or membrane samples before starting antibiotics
• Isolation of Corynebacterium diphtheriae from clinical specimens
• Toxigenicity testing to determine if the strain produces toxin
• Serology testing to check for protective antibody levels

Treatment Algorithm

1. Immediate Interventions

• Administer diphtheria antitoxin (DAT) immediately upon clinical suspicion
  • Do not wait for laboratory confirmation as delay increases mortality risk 2, 1
  • DAT can be obtained by contacting CDC's Emergency Operations Center at 770-488-7100 2
  • Administer with caution due to risk of allergic reactions (7% immediate hypersensitivity, 5% serum sickness) 2, 1

2. Antimicrobial Therapy (to be started concurrently with DAT)

• Erythromycin:
  • Children: 40 mg/kg/day orally for 7-10 days
  • Adults: 1 g/day orally for 7-10 days 2, 1, 3
  • May be slightly more effective than penicillin 2
• Alternative: Benzathine penicillin:
  • Children <6 years: 600,000 units IM as a single dose
  • Persons ≥6 years: 1,200,000 units IM as a single dose 2, 1
  • May be preferred for guaranteed compliance 2

3. Supportive Care

• Monitor for complications:
  • Airway compromise (may require intubation)
  • Myocarditis
  • Neurological complications
  • Renal failure

4. Follow-up

• Repeat cultures after completion of antimicrobial therapy
• If cultures remain positive, administer an additional 10-day course of oral erythromycin 2, 1

Management of Contacts

• Identify all close contacts, including household members and those directly exposed to oral secretions

• For all close contacts regardless of vaccination status:

  • Obtain throat cultures
  • Provide antimicrobial prophylaxis with same regimens used for treatment
  • Monitor daily for 7 days for signs of disease 2, 1

• Update vaccination status:

  • Contacts with <3 doses or unknown status: immediate dose plus completion of primary series
  • Contacts with ≥3 doses but no booster in past 5 years: administer booster dose 2, 1

Important Considerations and Pitfalls

1. Delay in antitoxin administration significantly increases mortality risk. Studies have shown fatal outcomes when treatment is delayed, even with appropriate antibiotics 4.

2. Serum sickness may occur in approximately 5% of patients receiving DAT, typically 7-9 days after administration 5. Monitor patients for delayed hypersensitivity reactions.

3. Both respiratory and cutaneous forms require treatment, but management of contacts differs:

   • For toxigenic strains in cutaneous cases, manage contacts as with respiratory diphtheria
   • For non-toxigenic cutaneous strains, routine investigation or prophylaxis of contacts is not necessary 2

4. Diphtheria can be caused by different Corynebacterium species:

   • C. diphtheriae (most common)
   • C. ulcerans (can cause identical clinical presentation)
   • C. pseudotuberculosis (rare) 6

   Treatment approach is the same regardless of species 2.

5. Vaccination remains the cornerstone of prevention, with case fatality rates of 5-10% even with appropriate treatment, and higher rates in children under 5 and adults over 40 7.