Robert Koch, Medical Doctor, Microbiologist
Infectious Disease Principles, Koch's Postulates Pure Culture Method
Mar 15, 2009
In the 1800's medical doctors were frustrated and helpless. Time and again they would see their patients die. Deaths were often quick and very characteristic. Diseases such as anthrax and cholera felled the unfortunate victims all too soon. Anthrax blackened the tissues with necrotic hemorrhages on the skin and internal organs of its European white victims. Cholera was distinctive with massive, watery diarrhea with white flecks of intestinal cells (rice water stools) and death ensued in a few days or so. On the other hand, tuberculosis was slow and insidious, but always marked by distinct and characteristic signs- coughing, bloody sputum, wasting and thinning of the body and eventual death.
For Koch A Connection and A New Idea Emerges
These were typical scenes to Robert Koch who, upon receiving a wonderful microscope as a birthday gift from his wife Emmy, thought of the possible causes and effects of these diseases: anthrax, cholera and tuberculosis. Koch pondered - If wines can be made sick by strange types of cells, as Pasteur has shown, perhaps people can be made sick by other kinds of cells.
A Microbiological Kitchen Becomes An Important Part of the Laoratory
Specialized media and conditions were developed to permit different kinds of microbes to be grown on surfaces where they could be seen as individual colonies. In liquid cultures, as were commonly used at that time, microbes were mixed and often could not be told apart. They were small. Some were motile, others were passive. At first, sliced potatoes were used to capture single cells streaked by a thin wire or loop over the surface of the potato. As a single cell doubled repeatedly, a mass of millions of bacteria appeared as a visible colony!
Later, gelatin and agar (from seaweed) were used to make clear solid media. These media usually contained added food or nutrients to permit microbial growth. Mycobacterium was the hardest to cultivate because it was slow to grow and colonies were not seen for three to four weeks.The microbial kitchen continued to make appetizing menus to feed the different appetites of their tiny, deadly guests.
Hard Work Turns Into Rewarding Results
Step by step, hour after hour, and month after month and year upon year, Koch's laboratory slowly, yet efficiently, hammered out the logic and wonders of modern microbiology and critical scientific thinking. Koch's lab developed:
- Solid agar media to replace nutrient liquid
- Postulates for infectious disease to prove definite causation by that microbe which can be
- always associated and isolated from the patient with the disease
- grown in pure culture and can be characterized as to its distinct shape and features- bacillus, coccus, spiral, and its characteristic colony growth and chemistry
- injected or inoculated into an animal and cause disease
- re-isolated in pure culture
These thoughtful and tireless efforts led Koch and his colleagues to discover and prove that Bacillus anthracis, Vibrio cholerae and Mycobacterium tuberculosis were, in fact, the very causes of distinct human diseases.
All can be thankful for the intelligent, energetic pursuit of scientific and medical truth by persons like Pasteur and Koch.
Science opportunities abound and new adventures and discoveries in science await those who engage in thoughtful pursuit. Careers in chemistry, biology, physics and medicine and allied fields (e.g. nursing, medical and respiratory technology and physical therapy) are promising now and will continue well into the future.
Sources and Resources
De Kruif, P. 1964. 30th printing. The Microbe Hunters. Pocket Cardinal. Pocket Books Inc. New York, N.Y. 342 pp
Read more: Microbiology Seeing Understanding the Unseen: Leeuwenhoek and Pasteur Microbiology Begins
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