 Koch’s postulates are a general method to identify causal outcomes from specific bacteria. Microorganisms isolated and grown from diseased hosts are introduced to non-diseased hosts to see if the same disease obtains. Cultures from that new disease site then confirm the presence and activity of the suspect microbe (Ross &amp; Woodward 2016; Gillies 2016). Once it could be established that these causal effects are highly specific and stable, the germ theory of disease could then draw all such findings into one common framework with predictive power (e.g., tuberculosis will always be caused by a particular bacterium, then known as the tubercle bacillus). The systematicity and experimentality underlying germ theory thus began the transformation of medicine from a purely observational and often anecdotal activity to an increasingly experimental and scientifically robust programme of research that had therapeutic and preventive successes (Worboys 2000; Vernon 1990). As a consequence, the investigation of bacteria and other microbes was integrated into a range of established disciplines in universities, hospitals and independent institutions (including industry) from the late nineteenth century onwards (Vernon 1990).