medmicro

• Medical Microbiology


  The study of microorganisms that cause infectious diseases

  
• Disciplines of Medical Microbiology

  • Medical Bacteriology
  • Medical Virology
  • Prion studies
  • Medical Mycology
  • Medical Parasitology
  • Immunology

  
• Medical microbiology Deals with


  • Transmission
  • Acquisition
  • Progression
  • Treatment
  • Prevention
• History of Microbiology


  • Spontaneous Generation
  • Another term for Spontaneous Generation
  • Louis Pasteur's Experiment on Spontaneous Generation
  • Germ Theory of Disease
  • Koch's Postulates
• Spontaneous Generation Theory


  The belief that living organisms can arise from non-living matter
• Abiogenesis


  The generation of life from non-living matter
• Biogenesis


  The generation of life from pre-existing life
• Case 2: Observation

  • Since there were no refrigerators, the mandatory, daily trip to the butcher shop, especially in summer, meant battling the flies around the carcasses. Typically, carcasses were "hung by their heels," and customers selected which chunk the butcher would carve off for them.
• Conclusion of Case 2

  The rotting meat that had been hanging in the sun all day was the source of the flies.
• The Scientific Method


  1. Had 3 containers, with positive and negative controls

  2. Same kind of meat (source, size, type)

  3. The only variable is the setup

  4. The gauze allowed the air to enter through the jar

  5. Conclusion: Flies deliver the maggots with the smell of rotting meat
• Needham's results


  • Boiling was done to kill the pre-existing microorganisms
  • The second flask is a sterile medium
  • Microorganisms still developed, supporting spontaneous generation

  
• Spallanzani's results


  • Supported Biogenesis
  • Prevented microbial contaminants from the air (second flask)
  • Disproves spontaneous generation and abiogenesis
  • Main Criticism: there were not sufficient factors that allow life (Oxygen)
• Pasteurization


  • Supports Biogenesis
  • Pasteurization allowed for the introduction of Oxygen through the swan neck feature of the glass
  • Contaminating organisms will theoretically settle in the opening only (like with the cotton plugs)

  
• Possible Answers


  • It is possible because of thermophilic microorganisms that were not killed by the heat
  • Boiling is not a sufficient form of sterilization
• Miasma Theory


  Disease originated from the decomposition of organic matter causing a noxious vapor harboring disease-causing agents, i.e., bad air or polluted air
• Implications on transmission, identification of causes of diseases, control, prevention, and treatment of diseases?

  
• Koch's Postulates


  • Shows the cause and effect of diseases
  • Identifies the etiologic agent or the source of disease

  
• Koch's Postulates


  • Must be present in all variations of the disease, and absent in healthy samples
  • Must be grown in pure culture
  • Must cause the same symptoms in the healthy animal
  • Re-isolation of the suspected pathogen

  
• Helicobacter pylori


  • Thought that peptic ulcer (stomach, gastric cavity) was due to hyperacidity
  • Countered by proton pump inhibitors
  • Peptic ulcer may also be caused by H. pylori
  • Proven via Koch Postulates (3rd postulate)
• HIV → Acquired Immunodeficiency Syndrome


  • Followed Koch's postulates
• Koch could not produce the same disease in the healthy animal, because you do not have available laboratory animals that can carry the same symptoms of the disease

  
• Molecular Koch's Postulates


  • Phenotypes (Virulence or Pathogenicity) should be associated with the pathogenic strains of a species. Must prove that the virulent genes are present in a specific strain
  • Removal of genes inactivates the virulence trait of the organism.
  • Virulence factor can be reproduced upon reversion/replacement of the inactivated gene by the wild-type gene

  
• Zoonotic Diseases


  Animal diseases acquired by man
• Fomites


  Inanimate objects (door knobs, handkerchief)
• Endogenous flora


  Our normal flora can become an infectious agent and become opportunistic
• Rickettsia


  Bacteria, gram-negative

  
• Healthcare-Associated/Hospital Acquired Infections (HAIs)


  Even if its from your own flora, its still called an HAI just as long as its obtained within the hospital
• Balance of microflora is upset because of a lot of antibiotics over a long period of time
• Epidemiology


  The study of the occurrence, distribution, and determinants of health and disease in populations
• Disease Surveillance


  The observation, recognition, and reporting of diseases as they occur—and then analyze the data provided by local and national health authorities to reveal trends and signals of disease outbreaks.

  
• Incidence of a particular disease

  The number of new cases in a population in a given time period
• Prevalence of a particular disease


  The total number of new and existing disease cases in a population in a given time period
• Endemic disease


  Constantly present, typically in low numbers, in a population
• Epidemic disease


  Simultaneously infects an unusually high number of individuals in a population
• Pandemic disease


  Widespread, usually global epidemic
• Mortality


  Incidence of death in a population
• Morbidity


  Incidence of disease in a population
• Basic Reproduction Number (R0)


  Predicts infectivity of a pathogen using mathematical models

  
• Herd Immunity


  The risk of infection among susceptible individuals in a population is reduced by the presence of adequate numbers of immune individuals (due to natural infection or vaccination)
• Threshold of immunity needed for this indirect protective effect depends on: transmissibility of the infectious agent, nature of the vaccine-induced immunity, distribution of the immune individuals