Corynebacterium diphtheriae

Corynebacterium diphtheriae is a pathogenic bacterium that causes diphtheria. Also called the Klebs-Löffler bacillus, because it was discovered in 1884 by German bacteriologists Edwin Klebs (1834–1912) and Friedrich Löffel (1852–1915).

C. diphtheriae is an aerobic Gram positive organism, characterized by non-encapsulated, non-sporulated, immobile, straigtht or curved rods with a lenght of 1–8 µ and width of 0,3–0,8 µ, which form ramified aggregations in culture (looking like "Chinese characters"). It is a strictly human micro-organism. It produces a proteic exotoxin with 62 kiloDaltons, which is responsible for the signs of diphtheria. The inactivation of this toxin with a antitoxic serum (anatoxin) is the basis of the antidiphtheric vaccination.

The bacterium is sensitive to the majority of antibiotics, such as the penicillins, ampicillin, cephalosporin, quinolones, chloramphenicol, tetracyclines, cefuroxime and trimethoprim.