Editing Koch's postulates (section)

==History==
Robert Koch developed the postulates based on pathogens that could be isolated using 19th century methods.<ref>{{cite journal | vauthors = Walker L, Levine H, Jucker M | title = Koch's postulates and infectious proteins | journal = Acta Neuropathologica | volume = 112 | issue = 1 | pages = 1–4 | date = July 2006 | pmid = 16703338 | pmc = 8544537 | doi = 10.1007/s00401-006-0072-x | s2cid = 22210933 }}</ref> Nonetheless, Koch was already aware that the causative agent of cholera, ''[[Vibrio cholerae]]'', could be found in both sick and healthy people, invalidating his first postulate.<ref name=Koch1893/><ref name=Koch1884/> 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.<ref name="evans78" /><ref name=huebner57>{{cite journal | vauthors = Huebner RJ | title = Criteria for etiologic association of prevalent viruses with prevalent diseases; the virologist's dilemma | journal = Annals of the New York Academy of Sciences | volume = 67 | issue = 8 | pages = 430–438 | date = April 1957 | pmid = 13411978 | doi = 10.1111/j.1749-6632.1957.tb46066.x | s2cid = 84622170 | bibcode = 1957NYASA..67..430H }}</ref>

Koch formulated his postulates too early in the [[history of virology]] to recognize that many viruses do not cause illness in all infected individuals, a requirement of the first postulate. [[HIV/AIDS denialism]] includes claims that the viral spread of HIV/AIDS violates Koch's second postulate, despite that criticism being applicable to all viruses. Nonetheless, HIV/AIDS fulfills all of the other postulates with all AIDS patients being HIV-positive and laboratory workers exposed to HIV eventually developing the same symptoms of AIDS.<ref>{{Cite web | vauthors = Steinberg J |date=June 23, 2009 |title=Five Myths about HIV and AIDS |url=https://www.newscientist.com/article/dn17326-five-myths-about-hiv-and-aids/ |access-date=2023-01-14 |website=[[New Scientist]] |language=en-US}}</ref> Similarly, evidence that some [[oncovirus]] infections can contribute to [[cancer]]s has been unfairly criticized for failing to fulfill criteria developed before viruses were fully understood as host-dependent. <ref name="moore13">{{cite journal | vauthors = Moore PS, Chang Y | title = The conundrum of causality in tumor virology: the cases of KSHV and MCV | journal = Seminars in Cancer Biology | volume = 26 | pages = 4–12 | date = June 2014 | pmid = 24304907 | pmc = 4040341 | doi = 10.1016/j.semcancer.2013.11.001 }}</ref>

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.<ref name="todd19">{{cite journal | vauthors = Todd OA, Peters BM | title = ''Candida albicans'' and ''Staphylococcus aureus'' Pathogenicity and Polymicrobial Interactions: Lessons beyond Koch's Postulates | journal = Journal of Fungi | volume = 5 | issue = 3 | page = 81 | date = September 2019 | pmid = 31487793 | pmc = 6787713 | doi = 10.3390/jof5030081 | doi-access = free }}</ref> [[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.<ref name="hrg19">{{cite journal | vauthors = Hosainzadegan H, Khalilov R, Gholizadeh P | title = The necessity to revise Koch's postulates and its application to infectious and non-infectious diseases: a mini-review | journal = European Journal of Clinical Microbiology & Infectious Diseases | volume = 39 | issue = 2 | pages = 215–218 | date = February 2020 | pmid = 31440916 | doi = 10.1007/s10096-019-03681-1 | s2cid = 201283277 }}</ref>

Physicians [[Barry Marshall]] and [[Robin Warren]] argued that ''[[Helicobacter pylori]]'' contributes to [[peptic ulcer disease]], but throughout the early 1980s, the scientific community initially rejected their findings because not all ''H. pylori'' infections cause peptic ulcers, violating the first postulate.<ref>{{cite journal | vauthors = Marshall BJ, Armstrong JA, McGechie DB, Glancy RJ | title = Attempt to fulfil Koch's postulates for pyloric Campylobacter | journal = The Medical Journal of Australia | volume = 142 | issue = 8 | pages = 436–439 | date = April 1985 | pmid = 3982345 | doi = 10.5694/j.1326-5377.1985.tb113443.x | s2cid = 42243517 }}</ref>

[[Priority effect]]s are another major concern, as the success of pathogenic bacteria is dependent on the other species already colonizing that habitat, as the earliest resident microbes establish the environmental conditions, providing [[colonization resistance]] against certain species.<ref name="byrd16">{{cite journal |vauthors=Byrd AL, Segre JA |date=January 2016 |title=Infectious disease. Adapting Koch's postulates |journal=Science |volume=351 |issue=6270 |pages=224–226 |bibcode=2016Sci...351..224B |doi=10.1126/science.aad6753 |pmid=26816362 |s2cid=29595548}}</ref>