Lec10 Colonization, Infection, and Disease

Colonization

The action of an organism establishing itself in an area.

Infection

A condition in which pathogenic microorganisms penetrate host defenses, enter the tissues and multiply.

Pathologic State

Cumulative effects of infection damage, including disruption of tissues and organs.

Disease

Any deviation from health.

Factors that cause disease

Infections, Diet, Genetics, Aging.

Infectious Disease

Disruption of tissues or organs caused by microbes or their products.

Resident Biota

Large and diverse collection of microbes living on and in the body.

Normal Biota

Also known as resident, commensal, or indigenous biota; includes an array of bacteria, fungi, protozoa, viruses.

Microbial antagonism

The general antagonistic effect 'good' microbes have against intruder microorganisms.

Initial colonization of the newborn

Fetuses are likely inoculated with normal microbiota in utero.

Endogenous infections

Infections caused by biota already on or in the body.

Pathogen

An organism that has a parasitic relationship with its host.

True pathogen

Capable of causing disease in healthy persons with normal immune function.

Opportunistic pathogen

Causes disease when host defenses are compromised or when introduced into a body compartment they don’t normally occupy.

Virulence

Relative severity of the disease potential of a particular microorganism.

Portal of entry

A characteristic route taken by a microbe to initiate infection.

Exogenous

Originating from outside the body.

Endogenous

Already existing in the body.

Infectious Dose (ID)

A minimum number of microbes required for an infection to proceed.

Adhesion

A process by which microbes gain a more stable foothold on host tissues.

Phagocytes

White blood cells that engulf and destroy pathogens by means of enzymes and antimicrobial chemicals.

Antiphagocytic factors

Factors like capsules and proteins that help pathogens evade destruction by phagocytes.

Localized Infection

An infection where microbe enters the body and remains confined to a specific tissue.

Systemic Infection

When an infection spreads to several sites and tissue fluids, usually in the bloodstream.

Focal Infection

Exists when the infectious agent breaks loose from a local infection and is carried to other tissues.

Mixed Infection

When several agents establish themselves simultaneously at the infection site.

Inducing Host Response

Many cases of microbial diseases are the result of indirect damage from the host’s excessive or inappropriate response.

Portal of Exit

Avenue of departure for pathogens to exit the host.

Respiratory and Salivary Portals

Escape media for pathogens that infect the upper and lower respiratory tract.

Fecal Exit

Pathogens causing irritation in the intestinal mucosa that increases bowel motility.

Vector

A live animal that transmits an infectious agent from one host to another.

Incubation Period

The time from initial contact with the infectious agent to the appearance of first symptoms.

Prodromal Period

When the earliest notable symptoms of infection appear.

Period of Invasion

When the infectious agent multiplies at high levels and exhibits greatest virulence.

Convalescent Stage

When the patient responds to the infection and symptoms decline.

Epidemiology

The study of disease transmission, including how a disease spreads and locating its source.