Host Microbe Relationships and Disease Processes Flashcards
(64 cards)
Parasitism
one organism, the parasite, benefits from the relationship whereas the other organism, the host, is harmed by it.
Mutualism
both members of the association living together benefit from the relationship
Commensalism
two species live together in a relationship such that one benefits and the other one neither benefits nor is harmed
Virulence
the degree of intensity of the disease produced by a pathogen; varies among different microbial species; also varies among members of the same species of pathogen
pathogenicity
the capacity to produce disease; an organism’s pathogenicity depends on its ability to invade a host, multiply in the host , and avoid being damaged by the host’s defenses
Infection
The multiplication of a parasite organism, usually microscopic, within or upon the host’s body
contamination
the presence of microorganisms on epithelial surfaces such as skin or mucous membranes
colonization
Growth of microorganisms on epithelial surfaces such as skin or mucous membranes
attenuation
the weakening of the disease producing ability of an organism.
disease
A disturbance in the state of health wherein the body cannot carry out all its normal functions
Opportunistic Organisms
Among the resident and transient microflora are some species of organisms that do not usually cause disease but can do so under certain conditions. These organisms are called opportunists because they take advantage of particular opportunities to cause disease
Conditions that allow opportunists to work
- failure of the host’s normal defenses
- introduction of said organisms into unusual body sites
- disturbances in the normal microflora.
Iatrogenic Disease
caused by medical procedures and/or treatments
Idiopathic Diseases
diseases whose cause is unknown
Virulence factor
a structural or physiological characteristic that helps a pathogen cause infection and disease.
Adhesin
proteins or glycoproteins that are found on attachment pilli and capsules. Permit the pathogen to adhere only to receptors on membranes of certain cells or tissues.
Hyaluronidase
a spreading factor, digests hyaluronic acid, which is a substance that helps hold the cells of certain tissues together
Coagulase
accelerates the clotting of blood
streptokinase
dissolves blood clots
Properties of exotoxins
- produced by almost all gram positive organisms and some gram negative
- located in the extracellular matrix
- made of mostly polypetides
- very unstable
- among the most powerful toxins known
- highly specific effect on tissues
- little or no fever production
- stimulates antibody production and immunity
- converted to a toxoid through heat or chemical treatment
examples of exotoxins
botulism, gas gangrene, tetanus, diphtheria, staphylococcal food poisoning, cholera, enterotoxins, plague
Properties of Endotoxins
- produced by almost all gram negative organisms
- bound within the bacterial cell wall
- composed of lipopolysaccharide complex
- weak toxicity but can be lethal in large doses
- non specific effect on tissues
- high fever production
- recovery from disease often does not produce immunity
- cannot be converted to toxoid
Examples of endotoxins
salmonellosis, tularemia, endotoxic shock
Communicable disease
disease that can be spread from one host to another
