Microbial Relationships and Infection Factors

Microbial Relationships with Humans

• Humans and microorganisms have a symbiotic relationship.
• The normal microbiome is made up of resident microorganisms found in different parts of the body.
• These microorganisms produce enzymes, antibacterial factors, and metabolites that help in digestion and provide essential vitamins like K and B.

Factors Influencing Infection

• Communicability: The ability of a pathogen to spread from one person to another.
• Infectivity: The pathogen’s ability to invade and multiply in a host.
• Virulence: The pathogen's ability to cause severe disease.
• Pathogenicity: The ability of an agent to produce disease.
• Portal of entry: The route by which a pathogenic microorganism enters a host.
• Toxigenicity: The ability to produce toxins that influence the pathogen's virulence.

Process of Infection

• Pandemic: An epidemic that spreads over a large area, such as a continent or worldwide.

Pathogenic Defense Mechanisms

• Pathogens cause disease by various mechanisms, including:
  • Competing with normal flora.
  • Producing toxins.
  • Producing enzymes to avoid phagocytosis, opsonization, and destruction of connective tissues.
  • Avoiding lysis by degrading complement cascade components.
  • Paralyzing ciliary activity.
  • Producing biofilms to protect from immune cells and antibiotics.

Bacterial Infection

• Bacteria are prokaryotic, meaning they lack a discreet nucleus.
• In the United States:
  • Over 1 million people are living with HIV.
  • New infections are declining or stable in most racial and ethnic groups.
  • New infections have increased by over 30% in American Indian and Alaska Native populations.

HIV: Mechanism of Injury

• HIV is a retrovirus that carries its genetic information in the form of RNA rather than DNA.
• It contains reverse transcriptase, an enzyme that converts RNA into DNA.
• Integrase inserts the new DNA into the infected cell's genetic material, which can lead to:
  • Dormant infection, where no problems develop.
  • Activation of the virus, leading to the development of various problems.
  • Acceleration of cell apoptosis and shedding of infectious HIV.

HIV Structure

• The gp120 protein on the surface of HIV binds to the CD4 molecule found primarily on helper T cells.
• A helper T cell count below 200 cells/mm³ is diagnostic for AIDS.

Diagnosis of AIDS

• Diagnosis of AIDS is made in association with various clinical conditions and laboratory tests, including:
  • Atypical or opportunistic infections and cancers.
  • Presence of antibodies against HIV.
  • CD4+ T-cell numbers at or below 200 cells/mL.

Phases of HIV Disease

• HIV disease progresses through various phases.

Prevention of HIV

• Effective vaccines for HIV have not been developed yet, but significant progress is being made.
• Reducing risk behaviors is crucial in preventing HIV transmission.

Research on HIV

• Research on HIV focuses on developing treatments and cures:
  • Fusion inhibitors interfere with the fusion of HIV and CD4+ cells.
  • Integrase inhibitors have shown promise in slowing disease progression in monkeys and are currently undergoing clinical trials.
  • Entry inhibitors block co-receptor binding.
    • They use monoclonal antibodies to inhibit binding to co-receptors.

Explore the intricate relationships between humans and microorganisms, including the vital role of the microbiome in health. This quiz also covers key factors influencing infections and defense mechanisms of pathogens. Test your knowledge on how infections spread and the body’s response to pathogenic threats.