In 1883, Klebs successfully identified the bacterium Corynebacterium diphtheriae as the etiological cause of diphtheria. This bacterium is also known as the Klebs-Löffler bacillus. The bacterial genus Klebsiella is named in honor of his work. Klebs' works preceded some of the most important discoveries in medicine. He described acromegaly in 1884, two years before Pierre Marie. In 1878, he successfully inoculated syphilis in monkeys, antedating Élie Metchnikoff and Émile Roux by 25 years. He isolated colonies of bacteria nine years before Robert Koch. He was the first to produce tuberculosis experimentally in animals by the injection of milk from infected cows. He identified the typhoid bacillus before Karl Joseph Eberth.
Fundamental tests in bacteriology
Klebs identified four "Grundversuche" that provided a basis for his own research strategy, as well as general bacteriological research. According to Klebs, the bacteriological tests consist of the following postulates:
First, all bacteria are pathological.
Second, bacteria never occur spontaneously.
Third, every disease is caused only by bacteria.
Fourth, the bacteria that cause distinguishable disease are distinguishable.
Although some of these hypotheses are literally false, they are in general the foundation of modern experiments in bacteriology.
Scientific blunders
Klebs made some significant errors about infectious diseases. He believed, for example, that malaria was caused by a bacterium. In 1879, Corrado Tommasi-Crudeli and he claimed that they isolated a bacterium from the waters of Pontine Marshes in Roman Campagna. They concluded that the bacterium was the pathogen for malaria as they discovered it from damp soil in the region of malaria epidemics. They gave it the name Bacillus malariae. They further experimented with the bacterial isolate which they injected into rabbits. They observed that infected rabbits developed fever and enlarged spleen, characteristics of malaria. They proposed that the malarial bacterium was transmitted by drinking contaminated water or inhalation from air. Klebs reported that antimalarial drugquinine killed the germ. The discovery was supported by leading malariologists of the time. It was then declared that the malaria problem was solved. When a French Army physician Charles Alphonse Laveran correctly discovered in 1880 that malaria was caused by a protozoan parasite, the discovery was ignored in preference of the bacillus theory of Klebs and Tommasi-Crudeli. An American physician, though, George Miller Sternberg, proved that the bacillus did not cause specific symptoms of malaria in 1881. The bacillus theory was eventually proved wrong by the experimental demonstration of the mosquito-malaria theory in 1898. Klebs also made mistakes in claiming the existence of Microzoon septicum as causative agent of wound infection, and "monadines" as the pathogen for rheumatism.
