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Diphtheria (Corynebacterium Diphtheriae)

Diphtheria (Corynebacterium diphtheriae)


Corynebacteria are Gram-positive, aerobic, nonmotile, rod-shaped bacteria
related to the Actinomycetes. They do not form spores or branch as do the
actinomycetes, but they have the characteristic of forming irregular shaped,
club-shaped or V-shaped arrangements in normal growth. They undergo snapping
movements just after cell division which brings them into characteristic
arrangements resembling Chinese letters.

The genus Corynebacterium consists of a diverse group of bacteria including
animal and plant pathogens, as well as saprophytes. Some corynebacteria are part
of the normal flora of humans, finding a suitable niche in virtually every
anatomic site. The best known and most widely studied species is Corynebacterium
diphtheriae, the causal agent of the disease diphtheria.

History and Background

No bacterial disease of humans has been as successfully studied as diphtheria.
The etiology, mode of transmission, pathogenic mechanism and molecular basis of
exotoxin structure, function, and action have been clearly established.
Consequently, highly effective methods of treatment and prevention of diphtheria
have been developed.

The study of Corynebacterium diphtheriae traces closely the development of
medical microbiology, immunology and molecular biology. Many contributions to
these fields, as well as to our understanding of host-bacterial interactions,
have been made studying diphtheria and the diphtheria toxin.

Hippocrates provided the first clinical description of diphtheria in the 4th
century B.C. There are also references to the disease in ancient Syria and Egypt.


In the 17th century, murderous epidemics of diphtheria swept Europe; in Spain
"El garatillo" (the strangler"), in Italy and Sicily, "the gullet disease".

In the 18th century, the disease reached the American colonies and reached
epidemic proportions in 1735. Often, whole families died of the disease in a few
weeks.

The bacterium that caused diphtheria...