Microbiology and Immunology Definitions

Contamination

Presence of microbes in or on the body.

Infection

The successful invasion of a host by an pathogenic organism.

4 Portals of Entry

Skin, mucous membranes, placenta, and parenteral route.

Adhesion

Process by which microorganisms attatch themselves to cells.

Adhesion Factors

Specialized attachment molecules and surface structures that pathogens use to stick to host cells.

Pathogens

Microorganisms that are harmful to the human body.

Virus

Infectious agent that consists of nucleic acids (genetic material), wrapped in a capsid (protein shell).

4 Types of Symbiosis

Mutualism, commensalism, amensalism, and parasitism.

Mutualism

Symbiotic relationship where both organisms benefit from another, sometimes to the point that they cannot live without one another.

Commensalism

Symbiotic relationship where one organism benefits, but the other is neither harmed nor benefited.

Amensalism

Symbiotic relationship where one organism is harmed, but the other is neither harmed nor benefitted.

Parasitism

Symbiotic relationship where one organism benefits, while the other is harmed.

2 Types of Microbiome of Humans (Normal Microbiota)

Resident microbiota, and transient microbiota.

Resident Microbiota

Normal microbiota throughout the entire lifespan of a human.

Transient Microbiota

Remains in a host for a short period of time.

Axenic

Free of microorganisms.

Opportunistic Pathogens

Normal microbiota that cause disease under certain circumstances.

Reservoirs of Infection

Sites where pathogens are maintained as a source of infection.

3 Types of Reservoirs

Animal reservoir, human reservoir, and non

Zoonoses

Animal reservoir that naturally spreak from animal host to humans.

Types of Zoonoses

Helminthic, protozoan, fungal, bacterial, and viral.

Human Carriers

Asymptomatic infected individuals.

Adhesins

Specialized surface proteins that allow them to stick to host cells.

Disease

Results if the invading pathogen alters normal body functions. Also referred to as morbidity.

Symptoms

Subjective characteristics of disease, felt only by the patient.

Signs

The observed and measured aspects of disease.

Syndrome

A collection of symptoms and signs that characterize a disease or an abnormal condition.

Asymptomatic/Subclinical Infections

Lacking symptoms,but may still have signs of infection.

Etiology

Study of the cause of disease.

2 Virulence Factors of Infectious Agents

Pathogenicity and Virulence.

Pathogenicity

Ability of a microorganism to cause disease.

Virulence

Degree of pathogenicity.

5 Virulence Factors that Contribute to Virulence

Adhesion factors, biofilms, extracellular enzymes, toxins, antipagocytic factors.

Lethal Dose

LD50 is the number of cells of a pathogen that kills 50% of the animals in a test group.

Extracellular Enzymes

Secreted by a pathogen, dissolves structural chemicals in the body, helps pathogen maintain infection, invade, and avoid body defenses.

Toxins

Chemicals that harm tissues or trigger host immune responses that cause damage.

Toxemia

Refers to the presence of toxins in the bloodstream.

2 Types of Toxins

Exotoxins and endotoxins.

Endotoxins

Toxic lipopolysaccharide substances (Lipid A) that are part of the outer membrane of the cell wall of gram-negative bacteria.

Exotoxins

Proteins produced inside pathogenic bacteria, most commonly-gram-positive bacteria.

Pyrexia

Fever

Gram-positive

A bacterium that has a thick cell wall that holds a purple dye during a laboratory test.

Gram-negative

A bacterium that does not hold a purple dye during a laboratory test.