Host Microbe Interactions

Infection

A condition in which pathogenic microbes penetrate host defenses enter tissues and multiply

Pathogen

Microbe acting as an infectious agent

Infectious disease

An infection that causes damage or disruption to tissues and organs

Resident microbiota (microflora resident microbiome)

Microbes we come into contact with that become normal resident friends

Transients

Microbes that occupy the body for only short periods

Residents

Microbes that become established

Transmission

Mechanism by which microbes transfer from one host to another

Communicable disease

When an infected host can transmit the infectious agent to another host and establish infection

Highly communicable disease

A disease that is contagious

Non-communicable infectious disease

Does not arise through transmission from host to host occurs when a compromised person is invaded by their own microflora or from a non-living reservoir

Direct contact

Physical contact or fine aerosol droplets

Indirect contact

Passes from infected host to intermediate conveyor and then to another host

Vehicle

Inanimate material such as food water biological products or fomites

Airborne transmission

Transmission via droplet nuclei or aerosols

Infectious Dose (ID)

Minimum number of microbes required for infection to proceed

Adhesion/Attachment

Microbe sticks to host using surface structures that bind to host structures

Portal of entry

Site where a pathogen enters a host and gains access to tissues to multiply or act

Invasion

Microbe enters sterile tissues using enzymes toxins and damaging molecules

Toxin

Specific chemical product of microbes plants or animals that has poisonous effects

Toxinoses

Adverse effects of toxins

Toxemias

When toxin spreads through the blood from the infection site

Intoxications

Caused by ingestion of toxins

Endotoxin

Toxin not secreted but released after host cell damage part of gram-negative outer membrane

Exotoxin

Toxin secreted by living bacterial cells into infected tissue

Virulence factor

Characteristic that contributes to a microbes ability to cause disease

Incubation period

Time from initial contact to first symptoms

Prodromal stage

Vague nonspecific symptoms and discomfort

Period of illness

Stage where microbes multiply at high levels and symptoms are specific

Period of decline

Immune system reduces pathogen numbers