Microbiology - Microbial Mechanisms of Pathogenicity Lecture 15

Pathogenicity

The ability of a microorganism to cause disease.

Virulence

The extent or degree of ability of an organism to cause disease.

Portal of Entry

The route through which a pathogen enters the body.

Epithelial Membrane

A tissue that covers body surfaces and lines cavities, serving as a barrier to pathogens.

Mucous Membrane

Membranes lining respiratory, gastrointestinal, and genitourinary tracts that can serve as portals of entry.

Cytopathic Effect

Damage caused to host cells by pathogens.

Adherence

The process by which pathogens attach to host cells.

Infective Dose 50 (ID50)

The number of pathogens required to infect 50% of a test population.

Lethal Dose 50 (LD50)

The amount of a toxin that kills 50% of a test population.

Biofilms

Aggregates of microorganisms that adhere to surfaces and are protected by a slimy matrix.

Capsule

A protective outer layer of some bacteria that inhibits phagocytosis.

Siderophores

Molecules produced by bacteria to sequester iron from the host.

Antigenic Variation

The ability of a microorganism to change its surface proteins to evade the immune response.

Exotoxins

Toxins secreted by microorganisms, often proteins with enzymatic activity.

Endotoxins

Components of the outer membrane of gram-negative bacteria, released when the bacteria die.

Superantigens

A class of exotoxins that activate a large number of T-cells non-specifically.

Hemolysins

Exotoxins that lyse red blood cells and damage host cell membranes.

Plasmid

A small molecule of DNA that replicates independently and may carry genes for exotoxins.

Lipopolysaccharide (LPS)

The toxic component of gram-negative bacterial cell walls responsible for causing fever.

Septic Shock

A serious condition caused by severe bacterial infection leading to tissue injury and low blood pressure.

Portals of Exit

Routes through which pathogens leave the host to infect other individuals.

Parenteral Route

A method of administering substances by piercing the skin or mucosal membranes.