Openstax-Microbiology Chapter 15 Microbial Mechanisms of Pathogenicity

infection

Contamination or invasion of body tissue by pathogenic organisms

disease

An abnormal state in which the body is not functioning normally

signs

changes in a body that can be measured or observed as a result of disease

symptoms

the conditions that together tell a doctor what is wrong

noninfectious

diseases that do NOT have a pathogen and you can't catch

infectious

Caused by or capable of being transmitted by infection.

communicable

A disease that may be transmitted directly or indirectly from one individual to another

contagious

Able to be passed easily from one person to another.

noncommunicable

an infectious disease that does not arise through transmission of the infectious agent from host to host

zoonoses

Diseases transmitted from animals to humans

nosocomial diseases

a disease acquired in a health care facility

iatrogenic disease

a condition that is caused by a medical treatment

acute disease

A disease that rapidly impairs the functioning of an organism.

chronic disease

a disease that develops gradually and continues over a long period of time

latent disease

disease with a period of no symptoms when the causative agent is inactive

incubation period

interval between initial infection and first signs and symptoms

prodromal period

short period after incubation; early, mild symptoms

period of illness

disease is most severe

period of decline

signs and symptoms subside

period of convalescence

body returns to its prediseased state

Koch's Postulates

a sequence of experimental steps for directly relating a specific microbe to a specific disease

Molecular Koch's Postulates

Stanley Falkow

focus on virulence genes

shows that gene found in a pathogenic microorganism encodes product that contributes to disease caused by pathogen

compared to Koch's postulates:

1. pathogenic strains- gene present

nonpathogenic strains- gene absent

2. inactivation of gene- loss of pathogenicity/virulence

3. reversion of mutated gene-restoration of pathogenicity

4. gene expressed during infection

5. immunity protective

Virulence

degree of pathogenicity

ID50 (infectious dose)

The number of microbes that must enter the body to establish infection in 50% of test animals is expressed as the ID50

LD50

the amount of a chemical that kills 50% of the animals in a test population

Primary pathogens

cause disease in healthy hosts

opportunistic pathogens

normal microbiota that cause disease under certain circumstances

resident microbiota

Are a part of the normal microbiota throughout life

Are mostly commensal

secondary infection

opportunistic infection after a primary (predisposing) infection

primary infection

acute infection that causes the initial illness

portals of entry

mucous membranes, skin, parenteral route

portals of exit

respiratory tract, gastrointestinal tract, genitourinary tract, skin, blood

virulence factors

traits of a microbe that promote pathogenicity

endotoxin

A toxic component of the outer membrane of certain gram-negative bacteria that is released only when the bacteria die.

exotoxin

A poisonous protein secreted by certain bacteria.

capsules

prevent phagocytosis

antigenic variation

changes in surface antigens that occur in a microbial population

antigenic drift

Minor change in influenza virus antigens due to gene mutation

antigenic shift

major change in influenza virus antigen due to gene reassortment

asymptomatic

showing no symptoms of disease

International classification of diseases

What does ICD stand for?

infectious disease

A disease that is caused by a pathogen and that can be spread from one individual to another.

communicable disease

A disease that can be spread from one person or species to another.

Latogenic disease

Disease that are contracted as the result of a medical procedure.

nosocomial infection

an infection acquired during hospitalization

zoonotic disease

a disease communicable from animals to humans under natural conditions; also know as zoonosis

noncommunicable infectious diseases

are not spread from one host to another

noninfectious disease

A disease that cannot spread from one individual to another

inherited disease

genetic disease that results from defective alleles passed from parents to offspring

degenerative disease

any disease in which deterioration of the structure or function of tissue occurs

nutritional deficiency diseases

these diseases lower resistance to infectious diseases and contribute to the severity of infections

endocrine diseases

Results of dysfunction of or increase/decrease of secretion of hormone

neoplastic disease

Diseases that result in new, abnormal tissue growth or related to tumor

idiopathic disease

a disease that develops without a known or apparent cause

pathogencity

ability of an organism to cause disease

Virulence

degree of pathogenicity

primary pathogen

a microbe able to cause disease in an otherwise healthy individual

opportunistic pathogens

cause disease in compromised individuals

Portal of entry (Define)

Part of the body where organisms enter

portal of exit

any body opening on an infected person that allows pathogens to leave

Biofilm

A microbial community that usually forms as a slimy layer on a surface.

local infections

Infections that are only in one part of the body

focal infections

pathogen spreads from a local infection to other tissues

systemic infection

an infection throughout the body

secondary infection

opportunistic infection after a primary (predisposing) infection

Bacteremia

presence of bacteria in the blood

Viremia

viruses in the blood

Toxemia

presence of toxins in the blood

septicemia

infection in the blood

-blood poisoning

septic

infection

septic shock

a serious condition that occurs when an overwhelming bacterial infection affects the body

Toxins

Various poisonous substances produced by some microorganisms (bacteria and viruses).

Toxigenicity

ability of a microorganism to produce a toxin

Endotoxins

A toxic component of the outer membrane of certain gram-negative bacteria that is released only when the bacteria die.

Exotoxins

toxic substances that bacteria secrete into their environment

Superantigens

cause an intense immune response due to release of cytokines from host cells