May 13th – Diphtheria is caused by Corynebacterium diphtheriae. Corynebacterium diphtheriae is a Gram-positive, aerobic, nonmotile, toxin-producing, rod-shaped bacteria belonging to the order Actinomycetales, which are typically found in soil, but also have pathogenic members such as streptomyces and mycobacteria. C. diphtheriae is best known for causing the disease Diphtheria in human beings, which results from production of Diphtheria toxin in conjunction with infection by a bacteriophage which provides it with the toxin-producing gene. Because historically it has been a very deadly disease, especially for children where mortality rates before vaccines and antitoxin amounted to nearly 80%, it has been heavily studied. Oddly enough, mice and other rodents are naturally immune to the Diphtheria toxin so it has been difficult to study Diphtheria in the lab. Diseases resembling Diphtheria were described as early as the 4th Century BCE by Hippocrates. It was named in 1826 by French physician Pierre Bretonneau, who gave it the name Diphtheria from the Greek word which means “leather hide”. It was named “leather hide” because of the leathery layer that grows on the tonsils, throat, and nasal passages. C. diphtheriae was first described in 1884 by Edwin Klebs and Friedrich Loffler, giving it the name Klebs-Loffler bacillus by which it used to be known. #365DaysOfMicroscopy
