Lec 2

Virulence factors

Virulence factors

Bacterial products or strategies that contribute to virulence or pathogenicity, including adhesins, toxins, and enzymes that enhance the microorganism's ability to cause disease and evade the host's defenses. Examples include exoenzymes that break down host tissues, and toxins that disrupt cellular functions.

Virulence

The degree of pathogenicity of a microorganism, often quantified by the infectious dose (ID50) needed to cause disease in 50% of exposed individuals.

ID50

Infectious Dose 50 - the number of microorganisms required to cause disease in 50% of those exposed.

LD50

Lethal Dose 50 - the number of microorganisms required to kill 50% of those exposed.

Virulence factors

Bacterial products or strategies that contribute to virulence or pathogenicity.

Colonization

The process by which bacteria establish themselves within specific organs, tissues, and cells of a host.

Invasiveness

The ability of bacteria to enter host cells and spread from the initial site of infection.

Polysaccharide capsules

Protective outer layers composed of polysaccharides found in many bacteria that help them evade the immune response.

Antigenic switching

The process by which pathogens alter surface proteins or polysaccharides to evade the host immune system.

Exotoxins

Toxic proteins secreted by bacteria that can block protein synthesis and cause paralysis.

Endotoxins

Integral components of Gram-negative bacterial cell walls that induce fever and shock upon release.

Toxicity

The capacity of a substance to cause harm or damage to tissues, often via bacterial toxins.

Bacterial adherence

A key virulence factor that prevents bacteria from being removed by mucus or fluids, allowing for colonization.

Immune evasion

Strategies employed by bacteria to avoid detection and destruction by the host's immune system.

Adhesins

Molecules on the surface of bacteria that enable them to attach to host cells.

Toxins

Substances produced by bacteria that can damage host tissues or disrupt normal cellular functions.

Opportunistic pathogens

Microorganisms that typically do not cause disease in healthy individuals but can cause infections in immunocompromised hosts.

Biofilms

Complex communities of bacteria that adhere to surfaces, encased in a protective matrix.

Transmission

The process of spreading a pathogen from one host to another, which can occur through direct or indirect contact.

Pathogenicity islands

Distinct genetic elements found in bacterial genomes that enhance virulence.

Pathogenesis

The biological mechanism that leads to the development of a disease.

Hemolysins

Exotoxins that lyse red blood cells, allowing bacteria to obtain iron from hemoglobin.

Iron acquisition

Strategies employed by bacteria to obtain iron from the host, which is essential for bacterial growth.

Virulent strains

Specific strains of bacteria that are particularly effective at causing disease.

Serotypes

Distinct variations within a species of bacteria, defined by specific surface antigens.

Vaccines

Biological preparations that provide immunity against specific pathogens.

Antibodies

Proteins produced by the immune system that recognize and neutralize pathogens.

Infectious diseases

Illnesses caused by pathogenic microorganisms such as bacteria, viruses, or fungi.

Bacteremia

The presence of bacteria in the bloodstream, which can lead to serious complications.

Sepsis

A life-threatening condition resulting from the body's extreme response to infection.

Pathogen

A microorganism that can cause disease in a host organism.

Antimicrobial resistance

The ability of bacteria to withstand the effects of medications that once killed them or inhibited their growth.

Disinfection

The process of eliminating or reducing harmful microorganisms from inanimate objects and surfaces.

Sanitation

The process of maintaining hygienic conditions to prevent disease transmission.

Quorum sensing

The ability of bacteria to sense and respond to cell population density through the release of signaling molecules.

Vaccination

The administration of a vaccine to stimulate an individual's immune system to develop adaptive immunity to a pathogen.

Antigen

A substance that induces an immune response, typically by interacting with specific antibodies.

Clinical outcomes

The resulting effects of a medical condition or treatment on a patient's health status.

Infection control

Measures taken to prevent the spread of infections in healthcare settings.