Diphtheria (corynebacterium Diphtheriae) :: essays research papers

Diphtheria (Corynebacterium diphtheriae)Corynebacteria are Gram-positive, aerobic, nonmotile, bacilliform bacteriarelated to the Actinomycetes. They do not form spores or divide as do theactinomycetes, but they take over the characteristic of forming irregular shaped,club-shaped or V-shaped arrangements in normal growth. They undergo snappingmovements just after cell course of instruction which brings them into characteristicarrangements resembling Chinese letters.The genus Corynebacterium consists of a diverse group of bacteria including physical and plant pathogens, as headspring as saprophytes. Some corynebacteria are deviateof the normal flora of humans, finding a suitable niche in virtually everyanatomic site. The best known and most astray studied 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, pathogen ic mechanism and molecular basis ofexotoxin structure, function, and action have been clearly established.Consequently, highly effective methods of treatment and prevention of diphtheriahave been developed.The take up of Corynebacterium diphtheriae traces closely the development ofmedical 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 first clinical description of diphtheria in the 4thcentury B.C. There are in like manner references to the disease in ancient Syria and Egypt.In the 17th century, murderous epidemics of diphtheria move 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, consentaneous families died of the disease in a f ewweeks.The bacterium that caused diphtheria was first describe by Klebs in 1883, andwas cultivated by Loeffler in 1884, who applied Kochs postulates and decentlyidentified Corynebacterium diphtheriae as the agent of the disease.In 1884, Loeffler concluded that C. diphtheriae produced a disintegrable toxin, andthereby provided the first description of a bacterial exotoxin.In 1888, Roux and Yersin exhibit the presence of the toxin in the cell-freeculture fluid of C. diphtheriae which, when injected into suitable science 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 subjectanimals against the disease. This modified toxin was suitable for immunizinganimals to obtain antitoxin but was found to cause disgustful local reactions inhumans and could not be used as a vaccine.In 1909, Theobald Smith, in the U.S., demonstrated that diphtheria toxin