1876 – Germany
‘Koch’s postulates – four conditions that need to be satisfied to be sure that a particular type of bacteria causes disease’
Koch developed methods of staining bacteria that enabled him not only to see them under a microscope, but also to differentiate between the various strains of microorganisms that he found.
Koch proved that specific organisms cause specific diseases and in addition, that pollution could spread disease.
He developed methods for obtaining pure cultures of bacteria and laid down Koch’s Postulates.
His colleague RICHARD JULIUS PETRI (1852-1921) designed a shallow flat dish that allowed him to grow microorganisms on a solid flat surface, and thus easily separate colonies of bacteria. Until then scientists had grown bacteria in flasks, or injected them into animals.
Koch’s rules for identifying harmful bacteria
- – the micro-organism must be identified and seen in all animals that suffer the same disease
- – it must be cultured through several generations
- – these later generations of bacteria must be capable of causing the disease
- – the same agent must be found in a newly infected animal as was found in the original victim
Using this set of criteria he identified the organisms responsible for more than twenty diseases, including tuberculosis, salmonella, cholera, pneumonia and meningitis.