Diphtheria Treatment Guidelines

Primary Treatment Approach

The Centers for Disease Control and Prevention recommends a 14-day course of oral erythromycin (children: 40 mg/kg/day; adults: 1g/day) for active diphtheria infection to eliminate the organism and prevent toxin production 1, 2
Alternative treatment is benzathine penicillin administered as an intramuscular injection (600,000 units for persons less than 6 years old and 1,200,000 units for those greater than or equal to 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 3

Diphtheria antitoxin (equine) must be administered promptly in conjunction with antibiotics for patients with clinical diphtheria 1, 4
Antitoxin neutralizes circulating toxin but cannot reverse damage already done by the toxin 4
Sensitivity testing should be performed before administering equine antitoxin due to risk of allergic reactions 2, 4

Early administration of antimicrobial therapy is critical - treatment initiated during the catarrhal stage or early paroxysmal stage has better outcomes 5
If cultures remain positive after treatment, an additional 10-day course of erythromycin should be administered 2, 3

All close contacts of diphtheria patients should receive antimicrobial prophylaxis regardless of vaccination status 2, 3
Prophylaxis options include erythromycin orally for 7-10 days (children: 40 mg/kg/day; adults: 1g/day) 3
Unvaccinated or incompletely vaccinated contacts should receive diphtheria toxoid-containing vaccine 1, 3

For toxigenic strains causing cutaneous diphtheria, the same antimicrobial regimen is recommended as for respiratory diphtheria 3
Equine antitoxin carries risk of allergic reactions (7% immediate hypersensitivity, 5% serum sickness) and requires sensitivity testing 2