Microbial pathogenesis is a field of

microbiology Microbiology () is the scientific study of microorganisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). Microbiology encompasses numerous sub-disciplines including virology, bacteriology, prot ...

started at least as early as 1988, with the identification of the triune Falkow's criteria aka

molecular Koch's postulates Molecular Koch's postulates are a set of experimental criteria that must be satisfied to show that a gene found in a pathogenic microorganism encodes a product that contributes to the disease caused by the pathogen. Genes that satisfy molecular Koch ...

. In 1996 Fredricks and Relman proposed a seven-point list of "Molecular Guidelines for Establishing Microbial Disease Causation", because of "the discovery of

nucleic acids Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main clas ...

" by

Watson and Crick "Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid" was the first article published to describe the discovery of the double helix structure of DNA, using X-ray diffraction and the mathematics of a helix transform. ...

"as the source of

genetic information A nucleic acid sequence is a succession of bases signified by a series of a set of five different letters that indicate the order of nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. By convention, sequences are usua ...

and as the basis for precise characterization of an

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

." The subsequent development of the "ability to detect and manipulate these nucleic acid molecules in microorganisms has created a powerful means for identifying previously unknown microbial pathogens and for studying the host-parasite relationship." __TOC__

Postulates for the detection of microbial pathogens

In 1996, Fredricks and Relman suggested the following postulates for the novel field of microbial pathogenesis.The seven points enumerated here are "paraphrases" of the original material, whose seven points are itemized in roman numerals for ease of reference, see p.30 in original # (i) A nucleic acid sequence belonging to a putative pathogen should be present in most cases of an infectious disease. Microbial nucleic acids should be found preferentially in those organs or gross anatomic sites known to be diseased, and not in those organs that lack pathology. # (ii) Fewer, or no, copies of pathogen-associated nucleic acid sequences should occur in hosts or tissues without disease. # (iii) With resolution of disease, the copy number of pathogen-associated nucleic acid sequences should decrease or become undetectable. With clinical relapse, the opposite should occur. # (iv) When sequence detection predates disease, or sequence copy number correlates with severity of disease or pathology, the sequence-disease association is more likely to be a causal relationship. # (v) The nature of the microorganism inferred from the available sequence should be consistent with the known biological characteristics of that group of organisms. # (vi) Tissue-sequence correlates should be sought at the cellular level: efforts should be made to demonstrate specific in situ hybridization of microbial sequence to areas of tissue pathology and to visible microorganisms or to areas where microorganisms are presumed to be located. # (vii) These sequence-based forms of evidence for microbial causation should be reproducible.

References

Microbiology Diseases and disorders Epidemiology Causality {{Microbiology-stub