Micropara reviewer

• Disease


  Result of an undesirable relationship between host and pathogen, interruption on the normal functioning of body part/s
• Infection


  Invasion of the body by pathogenic microorganisms, prolonged and close interaction between organisms of different species
• Commensalism

  A form of symbiosis where one organism benefits from another organism without causing harm to it
• Parasitism

  A form of symbiosis where one organism benefits from another organism and at the same time causes harm to it
• Mutualism

  A form of symbiosis where both organisms benefit from the relationship
• Bacteremia

  Presence of bacteria in the blood
• Septicemia

  Presence of actively multiplying bacteria in the blood, usually from a source of infection. The condition is called sepsis.
• Pathogenicity

  Ability of an organism to produce disease, "pathogenic"
• Pollution

  Presence of contaminants that can cause adverse biological effects to humans and communities
• Virulence

  Describes the degree of pathogenicity of an organism or the degree to which an organism can produce disease
• Contamination

  Presence of unwanted materials where they should not be or at concentrations above the normal
• Viremia

  Presence of virus in the blood
• Toxemia

  Presence of toxins in the blood
• Pyemia

  Presence of pus-producing bacteria in the bloodstream
• Koch's Postulates


  • The suspected organism must be absent in healthy individuals but present in those with the disease
  • The suspected organism must be isolated from the infected host and grown in pure culture
  • The organisms grown from pure culture must produce the same disease as that of the infected source when inoculated to a susceptible animal
  • The same organism must be isolated from the experimentally-infected host
• The validity of Koch's postulates lies in the ability of the pathogen to grown in the laboratory using artificial culture media
• There are certain organisms that cannot be grown in artificial culture media, such as viruses which are obligate intracellular parasites that need to be grown in living cells
• Not all people who acquire an infection develop overt disease
• The cultured organism must be inoculated into a susceptible animal, however there are certain organisms that are species-specific and cannot be tested using laboratory animals
• There are certain pathogens that become altered when grown in artificial media
• The development of an infectious disease is a consequence of the interaction among three components:

  • Etiologic agent, the host, and the environment
• Transmission of infection


  1. Pathogenic organisms leave its host or a reservoir through a portal of exit

  2. A susceptible organism acquires the infection through a given mode of transmission, entering the body of the susceptible host through a portal of entry
• Reservoirs


  • Animal reservoirs (zoonotic infections)
  • Human reservoirs (from one individual to another)
  • Environmental reservoirs (water, soil, and plants)
• Carriers


  Developed the disease, got well but still harbor the organism thereby transmitting them to others
• Forms of Carriers


  • Asymptomatic or healthy carriers
  • Incubatory carriers
  • Chronic carriers
  • Convalescent carriers
• Portal of Exit


  Route by which an infectious agent exits its hosts and the site where infectious agent is commonly located or localized
• Mode of Transmission


  • Direct Contact (person-to-person, skin-to-skin, kissing, sexual transmission, droplet spread)
  • Indirect Contact (airborne transmission, vehicle transmission, vector transmission)
• Portal of Entry


  How infectious agents enters a susceptible host, provides access to tissue where the infectious agent can multiply
• Host


  Final link, susceptibility affected by constitutional/genetic factors and immune status
• How Organisms Produce Disease


  1. Mechanical: Invasiveness, Toxin Production

  2. Chemical: Toxin Production

  3. Immunologic
• Mechanical: Invasiveness


  • Directly damaging tissues or body surfaces, invasion of epithelial surface and penetration into deeper tissues
  • Colonization: Ability to enter susceptible host and establish itself in portal of entry
  • Evade host immune defenses
  • Production of extracellular substances that can promote invasion
• Mechanical: Invasiveness


  • Gram-negative bacteria possessing pili
  • Staphylococcus aureus in biofilms
• Chemical: Toxin Production


  • Toxins are poisonous substances that contribute to disease production
  • Exotoxins: Secreted by bacteria as part of their growth and metabolism, mainly proteins and enzymes
  • Endotoxins: Component of outer membrane of Gram-negative bacteria, lipopolysaccharide (LPS) with toxic lipid A and antigenic polysaccharide
• Cytotoxins


  Toxins that kill host cells
• Mycobacterium tuberculosis


  phagosome-lysosome fusion
• Phagosome-lysosome fusion


  Production of extracellular substances that can promote invasion
• Neisseria gonorrheae


  Multiplies within the host cell and is extruded to infect other host cells
• Neisseria gonorrheae


  Causes direct destruction of the host cells
• Clostridium perfringens


  Produces collagenase
• Clostridium perfringens


  Causes development of disease called gas gangrene