Illustration of Mycobacterium tuberculosis

1882 Mycobacterium
tuberculosis

The book of science

Tom Sharp

Benjamin Marten, Robert Koch bacteriology Illustration of Mycobacterium tuberculosis

Mycobacterium tuberculosis

Antonie van Leeuwenhock saw bacteria in 1676 but Leeuwenhock didn’t suspect they could cause disease. * Benjamin Marten studied phthisis or consumption of the lungs in 1719 and decided that it was caused by “some certain species Animalcula or wonderfully minute living Creatures, that, by the peculiar Shape, or disagreeable Parts, are inimicable to our Nature; but however capable of subsisting in our Juices and Vessels . . .” and that could be transferred a sound person by close and prolonged contact, such as by sleeping in the same bed and breathing the exhaled air of the infected person. * Robert Koch became convinced that tuberculosis was caused by a bacterium and by 1882 proved, using guinea pigs, that the cause was mycobacterium tuberculosis.

Koch’s postulates

To prove that a microbe causes a disease, Koch postulated: 1 You can find the microbe in abundance in sick but not in healthy organisms (even though some may carry the microbe without symptoms of the disease). 2 You can isolate the microbe and grow it in pure culture (bearing in mind that some microbes won’t grow in your cultures). 3 You can cause the disease by introducing the cultured microbe to a healthy organism (even though some may be immune to the disease). 4 You can find the same microbe in abundance in the organism that you made sick. In the case of TB, Koch’s postulates were sufficient but not necessary. He showed that mycobacterium tuberculosis could be found in guinea pigs suffering from tuberculosis, and he could grow it, introduce it to guinea pigs to cause the disease, and then find the same species of bacteria in the sick ones.

Susceptible

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I credit Benjamin Marten here because he was the first to realize that “animalcules” were the probable cause of tuberculosis, not because the rest of the scientific community paid him any attention. He predated Louis Pasteur’s germ theory (1878) by a hundred and fifty-nine years.

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