Host Microbe Relationships and Disease Processes Flashcards
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
noncommunicable disease
disease that cannot be spread from one host to another
Exotoxins
soluble substances secreted into host tissues
Endotoxins
part of the cell wall of and are released into host tissues when the bacteria die or divide.
Hemolysins (2 types)
exotoxin
lyse red blood cells. 2 types:
- Alpha-hemolysins hemolyze blood cells and partially break down hemoglobin (creates a green ring)
- Beta-hemolysins also hemolyze blood cells but completely break down hemoglobin (creates a clear ring)
Leukocidins (exotoxin)
damage or destroy certain kinds of white blood cells called neutrophils and macrophages
toxoid
an altered toxin that has lost its ability to cause harm but that retains antigenicity. Basically what you are receiving when you get a tetanus booster shot
Bacillus Antracis
Anthrax (cytotoxin)
Bacillus cereus
Enterotoxin
Clostridium botulinum
botulism (neurotoxins, most dangerous toxin known)
Clostridium perfringens
gas gangrene (alpha toxin, hemolysin) Food poisoning (enterotoxin)
Clostridium tetani
tetanus (neurotoxin)
Corunebacterium diphtheria
Diphtheria (cytotoxin)
E Coli
traveler’s diarrhea (enterotoxin)
Pseudomonas aeruginosa
various infections (exotoxin A)
Shigella sysenteriae
Bacillary Dysentary (enterotoxin)
Staphylococcus aureus
food poisoning (enterotoxin) scalded skin syndrome (exfoliatin)
Streptococcus pyrogenes
scarlet fever ( erythrogenic toxin)
Vibrio Chlerae
Cholera (enterotxin)
Acute Disease
symptoms develop rapidly, runs course quickly
Chronic disease
symptoms develop slowly, slow to disappear
subacute disease
symptoms intermediate between acute and chronic
latent disease
symptoms may appear and/or reappear long after infection
local infection
confined to a small region of the body
focal infection
confined region from which pathogens travel to other regions of the body
systemic infection
infection in which the pathogen is spread throughout the body
septicemia
presence and multiplication of pathogen in blood
bacteremia
Presence but no multiplication of bacteria in blood
viremia
Presence but no multiplication of viruses in blood
toxemia
Presence of toxins in blood
sapremia
Presence of metabolic products of saprophytes in blood
primary infection
infection in a previously healthy person
secondary infection
infection that immediately follows a primary infection
superinfection
Secondary infection that is usually caused by an agent resistant to the treatment for the primary infection
mixed infection
infection caused by two or more pathogens
inapparent infection
Infection that fails to produce full set of signs and symptoms
Infectious Disease: Stage 1
Incubation period: time between infection and the appearance of signs and symptoms
Infectious Disease: Stage 2
Prodromal Phase: a short period during which nonspecific, often mild, symptoms sometimes appear
Infectious Disease: Stage 3
Invasive Phase: period during which the individual experiences the typical signs and symptoms of the diesease
Infectious Disease: Stage 4
Decline Phase: period of illness during which host defenses and the effects of treatments finally overcome the pathogen
Infectious Disease: Stage 5
Convalescence Period: tissues are repaired, healing takes place, and the body regains strength and recovers