What happened to Koch's postulates in diarrhoea?

Area of Science:

• Microbiology
• Infectious Diseases
• Gut Microbiome Research

Background:

• Robert Koch's postulates, established in 1890, define criteria for identifying infectious disease agents.
• Understanding of infectious disease pathogenesis has evolved, necessitating revisions to Koch's postulates.
• The role of host commensal microbiota in disease development is a recent area of focus.

Purpose of the Study:

• To review the historical development of Koch's postulates.
• To analyze diarrhea etiology in Bangladesh concerning Koch's postulates.
• To investigate the influence of gut microbiota on infectious disease causation.

Main Methods:

• Historical overview of Koch's postulates.
• Analysis of etiological data for diarrhea in Bangladesh.
• Examination of the relationship between pathogens, microbiota, and disease.

Main Results:

• In areas with poor hygiene, bacterial enteropathogens are necessary but not sufficient for diarrhea.
• Loss of gut microbiota equilibrium (dysbiosis) emerges as a significant co-factor in pathogen-induced diarrhea.
• The traditional '1 pathogen + 1 host = 1 disease' model is insufficient.

Conclusions:

• Koch's postulates require updating to incorporate the role of the gut microbiome.
• Infectious disease etiology is multifactorial, involving pathogens, local environment, and host susceptibility.
• A revised model, 'X (pathogen/s) + Y (local milieu) + Z (host susceptibility) = disease', better reflects complex pathogenesis.