What is the treatment and prevention for diphtheria?

Treatment and Prevention of Diphtheria

The treatment of diphtheria requires immediate administration of diphtheria antitoxin followed by a 14-day course of antibiotics, while prevention relies on complete vaccination with diphtheria toxoid-containing vaccines. 1

Clinical Presentation

• Diphtheria typically presents with sore throat, low-grade fever, and an adherent gray-colored pseudomembrane on the tonsils, pharynx, and/or nose 2
• Extension of the pseudomembrane into the respiratory tract can cause life-threatening airway obstruction 2
• Systemic complications include toxin-mediated myocarditis and neuropathy due to toxin absorption 2
• Cutaneous diphtheria can also occur, presenting as skin lesions with a pseudomembranous base 3

Treatment Algorithm

Step 1: Immediate Antitoxin Administration

• Administer diphtheria antitoxin (equine) as soon as diphtheria is suspected, without waiting for laboratory confirmation 1, 3
• Antitoxin neutralizes circulating toxin but cannot reverse existing damage 1
• Perform sensitivity testing before administering equine antitoxin due to risk of allergic reactions (7% immediate hypersensitivity, 5% serum sickness) 3, 1

Step 2: Antimicrobial Therapy

• Administer a 14-day course of oral erythromycin (children: 40 mg/kg/day; adults: 1g/day) 1, 4
• Alternative treatment is benzathine penicillin as an intramuscular injection (600,000 units for persons <6 years old and 1,200,000 units for those ≥6 years old) 1, 3
• Erythromycin may be slightly more effective at eliminating the organism, but penicillin has the advantage of single-dose administration which improves compliance 1, 3

Step 3: Monitoring and Follow-up

• Obtain follow-up cultures after completion of antimicrobial therapy 3
• If cultures remain positive, administer an additional 10-day course of oral erythromycin 3, 1

Management of Contacts

• All close contacts should have throat cultures taken regardless of vaccination status 3
• Provide antimicrobial prophylaxis to all close contacts without waiting for culture results 3
  • Options include erythromycin orally for 7-10 days (children: 40 mg/kg/day; adults: 1g/day) or benzathine penicillin IM 3
• Assess vaccination status of all contacts 3
  • Contacts with <3 doses or unknown vaccination status should receive immediate diphtheria toxoid-containing vaccine 3, 1
  • Contacts with completed primary series but no booster within 5 years should receive a booster dose 3

Prevention Strategies

Primary Prevention

• Complete vaccination with diphtheria toxoid-containing vaccines is the cornerstone of prevention 3
• Recommended childhood immunization schedule includes diphtheria toxoid as part of combination vaccines 3
• Adults should receive a diphtheria-toxoid-containing vaccine booster every 10 years 3

Special Considerations

• For cutaneous diphtheria caused by toxigenic strains, the same treatment approach should be used as for respiratory diphtheria 3
• Non-toxigenic cutaneous infections do not require contact investigation or prophylaxis 3

Common Pitfalls and Caveats

• Delayed administration of antitoxin significantly increases mortality - do not wait for laboratory confirmation before initiating treatment 1
• Equine antitoxin carries significant risk of allergic reactions, requiring sensitivity testing before administration 3, 1
• Underimmunization of adults contributes to disease susceptibility - ensure all adults receive recommended boosters 3, 5
• Antimicrobial resistance may be emerging in some regions, emphasizing the need for follow-up cultures 6
• Diphtheria can be clinically indistinguishable whether caused by C. diphtheriae or C. ulcerans - both require the same urgent treatment approach 3