Bacteria Invasion Process

Bacteria Invasion

• Bacteria invasion is the entry and possible multiplication of pathogenic microbes in an individual or population/community through a particular route, resulting in an infection or disease when vital functions or systems are damaged.
• There are four major steps involved in bacteria invasion: Introduction, Establishment, Growth and Spread, and Impact.

Host Defense

• The human body has three primary lines of defense against foreign invaders: physical and chemical barriers, non-specific innate responses, and specific adaptive responses.
• Physical and Chemical Barriers:
  • Destroy pathogens on the outer body surface and inner body linings.
  • Examples include sweat, mucus, tears, and saliva containing enzymes that kill pathogens; urine with acidic properties that kill pathogens; and semen containing zinc that most pathogens cannot tolerate.
• Body Natural Defense Mechanisms:
  • Skin, mucous membranes, tears, earwax, mucus, and stomach acid act as natural barriers.
  • Normal flow of urine washes out microorganisms that enter the urinary tract.

Immune Response

• Non-Specific Immune Responses (Innate Immunity):
  • Defense system with which one is born.
  • Protects against all antigens.
  • Involves barriers that keep harmful materials from entering the body.
• Specific Immune Response:
  • Refers to an immune response against a specific antigen.
  • Activated due to the failure of the innate immune system to fight against pathogens.
  • Major elements include lymphocytes and antibodies.
  • Lymphocytes possess surface receptors and secrete proteins (antibodies) that bind specifically to antigens, which may destroy pathogens.

Bacteria Virulence

• Virulence: the ability of a bacterium to infect the host and cause a disease.
• Virulence factors: molecules that assist the bacterium in colonizing the host at the cellular level.
• Examples of virulence factors:
  • Motility: contacting host cells and disseminating within a host.
  • Adherence: ability to stick to host cells.
  • Resisting physical removal due to appropriate attachment structures.
  • Ability to invade host cells.
  • Ability to compete for iron and other nutrients.

Theory of Contagion

• Contagion: the concept of a disease being spread from person to person.
• Contagious disease: a disease that can be spread through direct contact, indirect contact, or droplets.
• Examples of contagious diseases: leprosy.