Diphtheria (corynebacterium Diphtheriae) :: essays research papers

Diphtheria (Corynebacterium diphtheriae)Corynebacteria are Gram-positive, aerobic, nonmotile, rod-shaped bacteriarelated to the Actinomycetes. They do not variate spores or branch as do theactinomycetes, but they have the characteristic of forming irregular shaped,club-shaped or V-shaped arrangements in normal growth. They undergo snappingmovements just after jail cell division which brings them into characteristicarrangements resembling Chinese letters.The genus Corynebacterium consists of a diverse group of bacteria includinganimal and plant pathogens, as well as saprophytes. Some corynebacteria are fall inof the normal flora of humans, finding a worthy niche in virtually everyanatomic site. The best known and most widely analyse species is Corynebacteriumdiphtheriae, the causal agent of the disease diphtheria.History and BackgroundNo bacterial disease of humans has been as successfully studied as diphtheria.The etiology, mode of transmission, pathogenic mechanism and molecu lar basis ofexotoxin structure, function, and action have been clearly established.Consequently, highly effective methods of treatment and prevention of diphtheriahave been developed.The study of Corynebacterium diphtheriae traces closely the development of checkup microbiology, immunology and molecular biology. Many contributions tothese fields, as well as to our understanding of host-bacterial interactions,have been made studying diphtheria and the diphtheria toxin.Hippocrates provided the archetypical clinical description of diphtheria in the 4th one C 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 reachedepidemic proportions in 1735. Often, whole families died of the disease in a fewweeks.The bacterium that caused diph theria was first described by Klebs in 1883, andwas cultivated by Loeffler in 1884, who applied Kochs postulates and properlyidentified Corynebacterium diphtheriae as the agent of the disease.In 1884, Loeffler concluded that C. diphtheriae produced a soluble toxin, andthereby provided the first description of a bacterial exotoxin.In 1888, Roux and Yersin demonstrated the presence of the toxin in the cell-freeculture fluid of C. diphtheriae which, when injected into suitable lab animals,caused the systemic manifestation of diphtheria.Two years later, von Behring and Kitasato succeeded in immunizing guinea pigswith a heat-attenuated form of the toxin and demonstrated that the sera ofimmunized animals contained an antitoxin capable of protecting other susceptibleanimals against the disease. This modified toxin was suitable for immunizinganimals to obtain antitoxin but was found to cause severe local reactions inhumans and could not be used as a vaccine.In 1909, Theobald Smith, in the U .S., demonstrated that diphtheria toxin