Fundamentals of Disease – Key Terms and Pathogenesis (Crossword-Based Notes)

Virulence

factor of a microbes pathogenicity that relates to the extent or severity of disease it can cause.

Virulence factors

characteristics of a microbe that let it cause disease

Symptoms

The subjective results of a disease that are felt or experienced by the patient

Signs

Objective evidence of disease that can be measurable

obligate pathogens

“strict” can cause disease in healthy individuals

Opportunistic pathogens

Pathogens that cause disease only when predisposing factors are present (only in immunocompromised patients)

disseminated infection

An infection that occurs when a pathogen spreads to secondary target organs

Parasitism

all microbial pathogens ; one organisms benefits while other is harmed

Adhesion

The attachment of a microbe to host cells or tissues, a key early step in establishing infection.

Blood

A normally sterile body site that is frequently collected when testing for infection (e.g., blood cultures); presence of microbes indicates bacteremia/septicemia.

Exogenous infections

Infections whose pathogens originate from outside the human host ; all obligate pathogens ; many opportunistic (environment)

Intracellular growth

Growth that occurs after a pathogen penetrates into host cells, often shielding the microbe from certain immune defenses.

Pathogenesis

The process of development of a disease; the mechanism by which a disease arises and progresses.

Mutualism

A type of host-microbe relationship in which both host and microbe benefit.

Normal flora / microbiota

Microbes that regularly colonize the host and exist in a mutualistic or commensal relationship, potentially protecting against pathogens.

Exposure/Entry ; mechanism of pathogenesis step 1

Microbe comes into contact with host barriers (skin, mucosa, or other portals of entry).

Adhesion ; mechanism of pathogenesis step 2

tissue adhesion/attachment and infection

Invasion/Immune avoidance ; mechanism of pathogenesis step 3

Microbe penetrates epithelial layers or tissue barriers to access deeper tissues.

Colonization and Growth / Damage ; mechanism of pathogenesis step 4

Microbes establish a niche at the site, multiply, and establish a foothold.

Exit/Shedding of pathogen (only for communicable disease)

Avoiding or dampening immune responses (e.g., capsules, antigenic variation, hiding within cells, toxin-mediated damage).

Pathogen

A microbe that causes disease

commmensalism

colonizes host and gets food and stable environment ; one organisms benefits while other is unaffected

mutualism

colonizes host and gets food and stable environment while host gets vitamins, protextion from pathogenic microbes and necessary immune stimulation ; both organisms benefit

What happens after adherence to host cells?

extracellular growth (grows outside host cells)

what happens after adherence and penetration into host cells?

intracellular growth (grows inside)

expression (production) of virulence factors

is required to complete all steps of mechanisms of pathogenesis

microbio

microbes that cause disease

immunology

how the host responds to the microbes

clinical medicine

diagnosis and treatment of disease

public health

methods for prevention of microbial infections

thucydides

father of science ; 430 BCE ; first person to state disease can spread from infected person to others

germ theory of disease

1546 girolamo fracastro ; studied syphilis and notes “seed-like” entities that transmit infection (microbes haven’t been discovered)

1670 anton van

first observed microbes ; father of microbiology and created microscope

microbiome

genomes of microbes

colonize

growing on our skin without causing disease

sterility

absence of microbes (blood, bones, joints, internal body sites)

if normal microbiota enters sterile site

they can cause damage

culture tests positive for microbes in sterile site

bad

passive defense

barriers that prevent entry of pathogens (skin)

active defense

eliminates pathogens

disease

abnormal state of host ; normal structure/function is damaged or impaired

syndrome

collection of signs and symptoms

host range

spectrum of hosts that a microbe can replicate in

bacteria and fungi

many and mostly opportunistic ; some and few obligate

viruses and parasites

mostly obligate!!

endogenous infection

infection established by microbes that normally colonize host ; some opportunistic