ABSTRACT

Koch rather quickly disregarded his first postulate because he realized the existence of latent subclinical infections,1 which in laboratory animal bacteriology today is also the most common condition for bacterial

1.1 Foundation of the discipline of bacteriology ........................................ 1 1.2 The need for securing the absence of zoonoses ................................... 2 1.3 Eradication of bacterial pathogens ......................................................... 2

1.3.1 The early age of laboratory animal pathology.......................... 2 1.3.2 Specific pathogen-free animal breeding and health

monitoring ..................................................................................... 3 1.3.3 New agents with a research-interfering potential ................... 4 1.3.4 The development of health monitoring ..................................... 4

1.4 The impact of the symbiotic microbiota ................................................ 5 1.4.1 The development of gnotobiotechnology .................................. 5 1.4.2 Schaedler’s flora ............................................................................ 6 1.4.3 Microbiome studies ...................................................................... 7

1.5 The future of laboratory animal bacteriology ...................................... 8 References .......................................................................................................... 10

infections. The second and the fourth postulate can be questioned as well because many infections (caused by, e.g., Spirillum minus, which for years has been known as a potential cause of rat bite fever) cannot be cultivated. What is left today is the third postulate, which still seems to have some validity when discussing primary pathogens, such as Salmonella, but also is under heavy pressure because many bacteria act in conjunction with other agents. Additionally modern techniques have been used to show that diseases such as diabetes and colitis not primarily seen as infections are also under strong bacterial impact (e.g., from bacteria such as Akkermansia muciniphila, which may act protectively against some diseases2 and induce other diseases3). In general, the postulate works poorly for complex pathogeneses, such as those of cancer viruses.4 On the other hand, Koch’s third postulate should not be fully disregarded; that is, an agent must be proved to make some sort of difference in the host organism if it is to be regarded as causative of a pathophysiological condition.