chapter 15

Pathogen

A microbe that causes disease

Host

The organism that a pathogen lives in or on

Mutualism

Both host and microbe benefit

Commensalism

Microbe benefits and host is unaffected

Parasitism

Microbe benefits and host is harmed

Contamination

Presence of microbes without growth or infection

Infection

Microbes multiplying in or on the body

Infestation

Large parasites living on/in the body

Disease

The body isn't functioning normally due to infection or infestation

Pathogenicity

A microbe’s ability to cause disease

Virulence

How serious or harmful a disease is

Increase in virulence

By passing through hosts (animal passage)

Decrease in virulence

By attenuation or lab cultivation

Resident microflora

Microbes that are always present in certain body areas

Transient microflora

Microbes temporarily present under certain conditions

Opportunistic bacteria

Normally harmless microbes that cause disease under special conditions

Inherited disease

Caused by genetic factors

Congenital disease

Present at birth

Degenerative disease

Results from aging or tissue breakdown

Nutritional deficiency disease

Caused by lack of essential nutrients

Endocrine disease

Caused by hormone imbalance

Mental disease

Affects emotional or psychological health

Immunological disease

From immune system problems

Neoplastic disease

Abnormal cell growth (tumors or cancer)

Iatrogenic disease

Caused by medical treatment

Idiopathic disease

Cause is unknown

Communicable disease

Can spread from person to person

Noncommunicable disease

Does not spread between people

Virulence factor

A trait that helps a microbe cause disease

How bacteria enter host

Through skin

Fomite

A non-living object that can carry pathogens

Adhesion

Attachment of bacteria using pili

Colonization

Bacteria grow on body surfaces

Invasiveness

Bacteria enter and spread through tissues

Hyaluronidase

Breaks down tissue cement to help spread

Coagulase

Forms clots to protect bacteria

Streptokinase

Breaks down clots to allow spreading

Exotoxins

Proteins secreted by bacteria that damage cells

Endotoxins

Released from Gram-negative bacteria upon death

Neurotoxins

Toxins that affect the nervous system

Enterotoxins

Toxins that affect the intestines

endotoxins are released upon death and cause general symptoms

Hemolysis

Breakdown of red blood cells

Alpha hemolysis

Partial breakdown (green zone)

Beta hemolysis

Complete breakdown (clear zone)

Gamma hemolysis

No breakdown

Staph diseases

Skin infections

Strep diseases

Strep throat

S. agalactiae

Disease in newborns

tested in pregnant women

S. pyogenes

Strep throat

S. pneumoniae

Pneumonia and meningitis

S. aureus

Skin infections

Cytopathic effect

Virus damages or kills cells (lysis

Productive infection

Virus enters and multiplies

Abortive infection

Virus enters but doesn’t reproduce

Latent infection

Virus stays dormant and reactivates later

Persistent infection

Virus is slowly produced over time

Eukaryotic pathogens

Fungi

Sign

Observable or measurable effect of disease (fever

Symptom

Felt by the patient (pain

Syndrome

A group of signs and symptoms that occur together

Acute disease

Sudden and short-lived

Subacute disease

Between acute and chronic

Chronic disease

Long-lasting or lifelong

Latent disease

Inactive but may reactivate

Local infection

Confined to one body area

Focal infection

Starts local

Systemic infection

Spreads throughout the body

Primary infection

Initial infection

Secondary infection

Comes after primary infection

Superinfection

New infection during treatment of another

Mixed infection

Infection with multiple microbes

Subclinical infection

No noticeable symptoms but infection is present

Incubation stage

Time between infection and symptoms

Prodromal stage

Mild symptoms begin

Invasive stage

Full symptoms appear (acme = worst point)

Decline stage

Symptoms start to fade

Convalescence stage

Recovery and healing