Koch's postulates

[6][9] Since the 1950s, Koch's postulates have been treated as obsolete for epidemiology research, but they are still taught to emphasize historical approaches to determining the microbial causative agents of disease.

[14] Similarly, evidence that some oncovirus infections can contribute to cancers has been unfairly criticized for failing to fulfill criteria developed before viruses were fully understood as host-dependent.

[15] The bacterial pathogen Staphylococcus aureus showcases lethal synergy with the opportunistic fungi Candida albicans by using the latter's extracellular matrix to protect itself from host immune cells and antibiotic compounds.

[16] Biofilm-producing species aim to clump individual cells on solid or liquid surfaces, growing poorly in a pure culture and leaving those that survive potentially too weak to cause disease if transferred to a healthy organism, violating the second and third postulates.

[20] Modern DNA sequencing allows researchers to identify whether the genes of specific pathogens are only present in infected hosts, offering a modified approach for determining correlation between viruses and certain diseases.

Additionally, this method has supported correlations between prions (pathogenic misfolded proteins) and conditions like Creutzfeldt–Jakob disease because Koch's postulates are focused on foreign microorganisms, rather than the results of host mutations.

Robert Hermann Koch (11 December 1843 – 27 May 1910) was a German physician who developed Koch's postulates. [ 1 ]
Koch's postulates of disease.