Diagnosis

Doctors may suspect diphtheria in a sick child who has a sore throat with a gray membrane covering the tonsils and throat. Growth of C. diphtheriae in a lab culture of material from the throat membrane pins down the diagnosis. Doctors can also take a tissue sample from an infected wound and have it tested in a lab to check for the type of diphtheria that affects the skin (cutaneous diphtheria).

If a doctor suspects diphtheria, treatment begins immediately, even before the results of bacterial tests are available.