Koch's postulates

Examples of Koch's postulates in the following topics:

• Koch's Postulates

  • Koch's postulates are four criteria designed in the 1880's to establish a causal relationship between a causative microbe and a disease.
  • Koch's postulates are four criteria designed to establish a causal relationship between a causative microbe and a disease.
  • Currently, a number of infectious agents are accepted as the cause of disease despite their not fulfilling all of Koch's postulates.
  • Koch's postulates have also influenced scientists who examine microbial pathogenesis from a molecular point of view.
  • Koch's postulates are four criteria designed in the 1880's to establish a causal relationship between a causative microbe and a disease.

• Exceptions to Koch's Postulates

  • Even in Koch's time, it was recognized that infectious agents could be responsible for disease without fulfilling all of the postulates.
  • Koch's postulates were developed in the 19th century as general guidelines to identify pathogens that could be isolated with the techniques of the day.
  • Even in Koch's time, it was recognized that some infectious agents were clearly responsible for disease, even though they did not fulfill all of the postulates.
  • Currently, a number of infectious agents are accepted as the cause of diseases despite their not fulfilling all of Koch's postulates.
  • In summary, a body of evidence that satisfies Koch's postulates is sufficient but not necessary to establish causation.

• Identification of Microbes Based on Molecular Genetics

  • The use of these new methods has led to revised versions of 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's postulates are often referred to as virulence factors (i.e., what makes the pathogen virulent).
  • The following set of Koch's postulates for the 21st century have been suggested:

• Koch and Pure Culture

  • Robert Koch identified anthrax as a disease agent and formulated postulates that are still used to research diseases today.
  • Probably as important as his work on tuberculosis, for which he was awarded a Nobel Prize in 1905, are Koch's postulates.
  • These postulates stated that to establish that an organism is the cause of a disease, it must be found in all cases of the disease examined.
  • By using his methods, Koch's pupils found the organisms responsible for diphtheria, typhoid, pneumonia, gonorrhoea, cerebrospinal meningitis, leprosy, bubonic plague, tetanus, and syphilis.
  • Koch's research and methods helped link the causal nature of microbes to certain diseases, including anthrax.

• Intracellular Pathogens

  • Although prions fail to meet the requirements laid out by Koch's postulates, the hypothesis of prions as a new class of pathogen led Stanley B.

• Leprosy

  • Due to extensive loss of genes necessary for independent growth, M. leprae and M. lepromatosis are obligate pathogens, and are unculturable in the laboratory, a factor that leads to difficulty in definitively identifying the organism under a strict interpretation of Koch's postulates.

• Modern Microbiology

  • Louis Pasteur and Robert Koch were contemporaries of Cohn's and are often considered to be the father of microbiology and medical microbiology, respectively.
  • Koch is best known for his contributions to the germ theory of disease, proving that specific diseases were caused by specific pathogenic microorganisms.
  • He developed a series of criteria that have become known as the Koch's postulates.
  • Koch was one of the first scientists to focus on the isolation of bacteria in pure culture resulting in his description of several novel bacteria including Mycobacterium tuberculosis, the causative agent of tuberculosis.
  • While Pasteur and Koch are often considered the founders of microbiology, their work did not accurately reflect the true diversity of the microbial world because of their exclusive focus on microorganisms having direct medical relevance.

• History of Microbiology: Hooke, van Leeuwenhoek, and Cohn

  • The existence of unseen microbiological life was postulated by Jainism, which is based on Mahavira's teachings as early as 6th century BCE.
  • In 1876, Robert Koch (1843–1910) established that microbes can cause disease.
  • Based on these experiments, he devised criteria for establishing a causal link between a microbe and a disease and these are now known as Koch's postulates.
  • Although these postulates cannot be applied in all cases, they do retain historical importance to the development of scientific thought and are still being used today.
  • Explain how Van Leeuwenhoek, Spallanzani, Pasteur, Cohn and Koch contributed to the field of microbiology

• Intro and major themes

  • Developed Koch’s postulates to definitively link cause and effect in infectious disease.

• Origins of Antimicrobial Drugs

  • The history of antimicrobials begins with the observations of Pasteur and Koch, who discovered that one type of bacteria could prevent the growth of another.
  • In 1928 Alexander Fleming observed antibiosis against bacteria by a fungus of the genus Penicillium and postulated the effect was mediated by an antibacterial compound, penicillin, and that its antibacterial properties could be exploited for chemotherapy.