Microbe-Host Interactions Study Guide

Contamination

Pathogens are introduced to the body but are not replicating.

Infection

Pathogens are replicating inside or on the body.

Disease

The body deviates from its normal state due to infection.

Normal microbiota

Microbes that normally inhabit the body and aid in preventing harmful organisms.

Transient microbiota

Microbes that are temporarily present on body surfaces due to daily activities.

Opportunistic pathogens

Harmless organisms that can cause disease when the opportunity arises.

Pathogenicity

The ability of an organism to cause disease.

Virulence

The degree to which an organism can cause disease.

Virulence factor

Molecules that help microbes invade and multiply within a host.

Portals of entry

Routes through which pathogens enter a host, including the skin, GI tract, urogenital tract, and respiratory tract.

Modes of transmission

Ways pathogens are spread, including direct, indirect, vector, and parenteral transmission.

Exotoxins

Protein enzyme released by bacteria that results in unique signs and symptoms.

Endotoxins

Toxins that are part of the bacterial structure and can cause systemic effects when released.

Localized infection

An infection confined to one location in the body.

Systemic infection

An infection that spreads throughout the body, often through the bloodstream.

Sign

Objective evidence of disease observed by another person.

Symptom

Subjective evidence of disease experienced by the patient.

Phases of infection

Stages of an infection including incubation, prodromal, invasive, acme, decline, and convalescent phases.

Coagulase

An enzyme that induces coagulation, helping bacteria to protect themselves from phagocytes.

Protease

An enzyme that destroys proteins.

Hemolysins

Proteins (exotoxins) that destroy red blood cells (RBC).

Leukocidins

A protein toxin produced by bacteria that target and damage white blood cells.

Hyaluronidase

An enzyme that breaks down hyaluronic acid, which is the 'glue' that holds cells together.

streptokinase

An Exoenzyme that can break down clots after bacteria have hidden within the clot. Transports phosphate groups to things.

Antigenic Variation

A process where bacteria change their surface molecules to evade recognition by the host's immune system.

Flagella

Tail-like structures that enable some bacteria to move and can help them evade immune responses by outrunning phagocytes.

Mixed Infection

Several agents establish themselves simultaneously at the infection site.

Primary & Secondary Infections

Primary infection is the initial infection. Secondary infection occurs when a primary infection is complicated by another infection caused by a different microbe.

Acute Infection

An infection that comes on rapidly and goes away quickly.

Chronic Infection

An infection that progresses and persists over a long period of time.

Latent Infection

An infection characterized by a period of inactivity.

Modes of Transmission

Indirect (via fomite or vehicle), Direct (coughing, kissing, vertical), Vector (biological or mechanical), Parenteral (penetrates skin via needle).

Exoenzymes

Hyluronidase, Protease, Streptokinase, and Coagulase,