Microbe-Human Interactions Book

Flashcards on Microbe-Human Interactions

Symbiotic

Close and impactful relationship between two organisms, each being a symbiont.

Holobiont

A human plus all of its resident microbiota (its microbiome).

Human microbiome

Microbes that colonize us for the long term and generally do not cause disease.

Infection

A condition in which microbes get past the host defenses, enter the tissues, and multiply.

Disease

Any deviation from health.

Infectious disease

A pathologic state caused directly by microorganisms or their products.

First phase of the Human Microbiome Project (HMP)

Characterized the microbiome in various body sites of healthy hosts.

Second phase of the Human Microbiome Project or Integrative Human Microbiome Project

Examined the role of the microbiome in three deviations from health: pregnancy and pre-term birth, inflammatory bowel disease, and Type 2 diabetes.

Microbial antagonism

Defensive effect "good" microbes have against intruder microorganisms

Endogenous infections

Those caused by biota already present in the body.

Pathogen

A microbe whose relationship with its host is parasitic and results in infection and disease.

Immunocompromised

People with some deficit in their immunity.

Opportunistic

Exploiting a new opportunity in the host.

Virulence

The accurate term for describing the degree of pathogenicity.

To establish themselves in a host

Microbes must enter the host, negotiate the microbiome, attach firmly to host tissues, and survive the host defenses.

To cause damage

Microbes produce toxins or induce a host response that is actually injurious to the host.

Virulence Factor

Any characteristic or structure of the microbe that contributes to the preceding activities.

Infectious dose (ID)

Agent will proceed only if a minimum number is present.

Portal of entry

A characteristic route, the portal of entry, usually through the skin or a mucous membrane, to enter the tissues of the body.

Exogenous

Originating from a source outside the body (the environment or another person or animal).

Endogenous

Already existing on or in the body (normal biota or a previously silent infection).

TORCH

Acronym for common infections of fetus and neonate.

Adhesion

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

Quorum sensing

Chemicals, if blocked, the bacteria are not able to sense the presence of enough cells to mount an effective attack against the host

Phagocytes

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

Epigenetic changes

Changes to the DNA that affect the way it is transcribed, but they are not actual mutations in the sequence.

Localized infection

The microbe enters the body and remains confined to a specific tissue.

Systemic infection

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 into other tissues.

Toxemia

The infection itself remains localized at the portal of entry, but the toxins produced by the pathogens are carried by the blood to the actual target tissue.

Secondary infection

An initial, or primary, infection is complicated by another infection caused by a different microbe, the second infection.

Acute infections

Come on rapidly, with severe but short-lived effects.

Chronic infections

Progress and persist over a long period of time.

Sign

Any objective evidence of disease as noted by an observer.

Symptom

The subjective evidence of disease as sensed by the patient.

Syndrome

When a disease can be identified or defined by a certain complex of signs and symptoms.

Portal of exit

Pathogens depart by a specific avenue.

Sequelae

Long-term or permanent damage to tissues or organs.

Incubation period

The time from initial contact with the infectious agent (at the portal of entry) to the appearance of the first symptoms.

Prodromal stage

The earliest notable symptoms of infection usually appear as a vague feeling of discomfort, such as head and muscle aches, fatigue, upset stomach, and general malaise.

Acute phase

The infectious agent enters the height of the infection, during which it multiplies at high levels, exhibits its greatest virulence, and becomes well established in its target tissue

Convalescent period

The patient’s strength and health gradually return.

Continuation phase

Either the organism lingers for months, years, or indefinitely after the patient is completely well, or the organism is gone, but symptoms continue.

Reservoir

The primary habitat in the natural world from which a pathogen originates.

Infection source

Is the individual or object from which an infection is actually acquired.

Carrier

An individual who inconspicuously shelters a pathogen and can spread it to others without knowing.

Vector

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

Biological vector

Actively participates in a pathogen’s life cycle, serving as a site in which it can multiply or complete its life cycle.

Mechanical vectors

Not necessary to the life cycle of an infectious agent and merely transport it without being infected.

Zoonosis

An infection indigenous to animals but also transmissible to humans.

Communicable

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

Noncommunicable infectious disease

Does not arise through transmission of the infectious agent from host to host.

Horizontal

The disease is spread through a population from one infected individual to another.

Vertical

Transmission from parent to offspring via the ovum, sperm, placenta, or milk.

Direct transmission

In order for microbes to be directly transferred, some type of contact must occur between the skin or mucous membranes of the infected person and those of the new infectee.

Indirect transmission

The infectious agent must pass from an infected host to an intermediate conveyor (a vehicle) and from there to another host.

Vehicle

Specifies any inanimate material commonly contacted by humans that can transmit infectious agents.

Fomite

An inanimate object that harbors and transmits pathogens.

Parenteral transmission

Refers to a puncture, in which material from the environment is deposited directly in deeper tissues.

Droplet Nuclei

Microscopic residues created when microscopic pellets of mucus and saliva are ejected from the mouth and nose.

Aerosols

Suspensions of fine dust or moisture particles in the air that contain live pathogens.

Oral-fecal Route

A fecal carrier with inadequate personal hygiene contaminates food during handling and an unsuspecting person ingests it.

Koch's Postulates

A series of proofs that established classic criteria for etiologic studies.

Exotoxin

A toxin molecule secreted by a living bacterial cell into the infected tissues

Endotoxin

A toxin that is not actively secreted but is shed from the outer membrane