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.
