SPOJRZENIE NA POSTULATY KOCHA
PO STU LATACH OD ŚMIERCI ICH TWÓRCY
Wykład przedstawiony na Konferencji naukowej
„Mikrobiologia 100 lat po Robercie Kochu"
Polskiego Towarzystwa Mikrobiologów
w Warszawie w dniach 30—31 sierpnia 2010 r.
Marian Binek
Zakład Bakteriologii i Biologii Molekularnej, Katedry Nauk Przedklinicznych Wydziału Medycyny Weterynaryjnej, SGGW, w Warszawie
ul. Ciszewskiego 8, 02-786 Warszawa;
e-mail: marian_binek@sggw.pl
1. Wstęp. 2. Wirusy a postulaty Kocha. 3. Kwasy nukleinowe jako źródło informacji genetycznej a postulaty Kocha. 4. Chorobotwórczość versus choroba. 5. Podsumowanie
A glance at Koch's postulates 100 years after his death
Abstract: Koch's postulates were derived from Robert Koch's work on infectious diseases, such as anthrax and tuberculosis. The postulates served the emerging science of microbiology well during its early years, and gave experimental consistency to the investigation of causal relationships. However, significant limitations to the postulates were soon recognized and restricted their wider scientific application. Rapidly, it became apparent that although there are many microbes, most infections were caused by only a few. Some microbes were classified as pathogens although they did not cause disease in every host, and some microbes were considered as non-pathogens although they did cause disease in certain hosts. The description of the carrier state further muddled the existing definitions of pathogens. It was apparent that pathogenicity was neither an invariant nor a stable characteristic of most microbes and that the acquisition of pathogenic microbes was not necessarily synonymous with disease. Now over a century later, a more rigorous method to test causality still has to be developed. Technological advances led to the discovery of viruses, prions and new classes of microbes that cannot be propagated in pure culture and therefore cannot fulfill Koch's postulates. The discovery of nucleic acids as a source of genetic information enforced the revision of guidelines for defining a causal relationship between a microbe and disease and as a result. Koch postulates have modified. Rivers proposed several approaches to establish causal relationship between a virus and a disease, while Falkov recognized the need for more rigorous genetic criteria for the determinants of disease, and modeled his proposals for molecular biology of pathogenesis on Koch postulates. In the integrated theory of microbial pathogenesis the contribution of both host and pathogen are taken into consideration. The outcome of infection is the result of an interplay between host and microbial factors for a particular microbe in a particular host. This interplay permits some microbes to be commensals in some hosts but to cause disease in others. It seems that the host damage is the relevant outcome of that host-microbe interaction. The colonization, persistence and disease represent the continued presence of microbe(s) in the host with a variable degree of host damage. Progressive damage, which results from colonization and persistency, may lead to disease and death. Disease is a clinical manifestation of the damage. The possibility that the occurrence, course and outcome of infection might be influenced at all levels of biological organization was named biocomplexity. This concept blurred the distinction between pathogens and nonpathogens and challenged our thinking about microbial pathogenesis which was based on Koch's postulates. Still at the time when they were formulated the postulates were essential for the progress of knowledge about infectious diseases.
1. Introduction. 2. Viruses versus Koch's postulates. 3. Nucleic acids sequence technology and the difficulties in proving causation. 4. Pathogenicity versus disease. 5. Concluding remarks
Słowa kluczowe: postulaty Kocha, związek przyczynowy, chorobotwórczość versus choroba
Key words: Koch's postulates, causal relationship, pathogenicity versus disease
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