Pathogenicity unit 8

Pathogenicity

The ability of an organism to cause disease.

Virulence

The extent or degree to which an organism can cause disease.

Virulence factors

Structures or characteristics that enhance a microbe's ability to cause disease.

Infectivity

The ability of a pathogen to establish an infection and adhere to host tissues.

Invasiveness

The ability of a pathogen to spread within the host and evade the immune system.

ID50

Infectious Dose 50; the number of pathogens required to cause infection in 50% of a test population.

LD50

Lethal Dose 50; the number of pathogens required to kill 50% of a test population.

Exotoxins

Toxins secreted by bacteria that can cause specific damage to host cells.

Endotoxins

Part of the Gram-negative bacterial cell wall that can trigger inflammation and fever.

Superantigens

Antigens that provoke a strong immune response, potentially causing a cytokine storm.

Mucous membranes

Common portal of entry for pathogens, particularly in the respiratory tract.

Biofilms

Complex communities of microorganisms that adhere to surfaces and are covered by a protective matrix.

Antigenic variation

The alteration of surface antigens by pathogens to evade host immune responses.

Exoenzymes

Enzymes secreted by pathogens that facilitate invasion and spread within the host.

Localized infections

Infections that remain confined to a specific area of the body.

Systemic infections

Infections that spread throughout the body and affect multiple systems.

Acute diseases

Diseases characterized by a rapid onset and relatively quick recovery.

Chronic diseases

Diseases with a gradual onset and long-lasting effects.

Primary infection

The initial disease that occurs; can lead to secondary infections.

Signs

Objective evidence of disease that can be measured.

Symptoms

Subjective evidence of disease experienced by the patient.

Pathogenesis

The series of steps or mechanisms involved in the development of a disease.

Capsules

Protective structures that can prevent phagocytosis and help pathogens evade the immune system.

Hyaluronidase

An exoenzyme that breaks down hyaluronic acid, allowing pathogens to invade tissues.

Cytotoxins

Toxins that damage or kill host cells.

Toxemia

The presence of toxins in the blood.

Viremia

The presence of viral particles in the blood.

Necrotizing enzymes

Enzymes that cause rapid destruction of soft tissues, often associated with severe infections.

Cholera toxin

An enterotoxin that causes severe diarrhea by impacting intestinal cells.

Inflammatory response

The body's reaction to infection or injury that involves immune cells and chemicals.

Cytokine storm

An excessive immune response characterized by the release of too many cytokines.

Adhesins

Molecular structures that allow pathogens to adhere to host cells.

Example of attachment

Pili, fimbrae, spikes, capsids

Focal infection

Pathogens spread to secondary infections

Systemic infections spread

Through the entire body

Subacute disease

More sudden than chronic disease, less sudden that acute disease

Example of acute disease

MM and the flu

Example of latent disease

Shingles

Stages of disease

Incubation, prodromal, period of illness, period of decline, convalescent period

Chemical virulence factor example

Exoenzymes, endotoxin, exotoxin

Structural virulence factors example

Adhesions, pili, fimbrae

Capsules prevent?

Phagocytosis

Endotoxin

Gram positive, lipid A, has a inflammation and fever effect on host

Endotoxin

Gram positive & gram negative, protein, causes specific damage to host