ch 11 Flashcards
colonization
presence of microbes in host
infection
multiplication of organism in host
disease
when infection starts affecting host and causing damage
commensalism
microbe benefits and host is unaffected
mutualism
both benefit, host and microbe
parasitism
pathogens cause damage to host
sites where normal biota are found
skin, upper respiratory tract, vagina, external genitalia, external eyelids, GI tract, outer portion of urethra
sites where normal biota are not found
brain and blood stream
factors that weaken host defenses
–>old age, newborn
–>genetic defenses in immunity
–>surgery/transplants
–>diseases
–>chemotherapy
–>pregnancy
5 sources where newborn acquire microbiota
- in utero
- birth
- milk
- caregivers
- enviornment
pathogenicity vs virulence
pathogenicity: potential to cause disease
virulence: characteristics that contributes to ability cause damage
steps of a microbe must to take to cause disease
- portal of entry
- attach/negotiate with microbiome
- survive host defenses
- cause damage
- exit host
significance of polymicrobial infections
portals of entry
respiratory, gastrointestinal, genitourinary, skin, parenteral
portals of exit
respiratory secretions, feces, urine, blood, genital, secretions, wound exudates
infectious dose
minimum number of microbes necessary to cause an infection
three ways microbes cause tissue damge
- enzymes or toxins (endotoxins and exotoxins)
- inducing hosts defenses to respond excessively
- changes in gene function made to host cells
exoenzymes
enzymes secreted by microbes that break down and damage tissues
4 examples of exoenzymes
mucinase, hyaluroidase, coagulase, kinase
endotoxins vs exotoxins
endotoxins: gram negative, released upon lysis, less potent, lipopolysaccharide
exotoxins: protein with specificity for target, secreted, highly potent
sign vs symptom
sign: evidence of disease as noted by observer
symptom: subjective evidence sensed by patient
signs of blood infection
leukocytosis: increased white blood cell levels
leukopenia: decreased white blood cell levels
septicemia: microorganisms are multiplied in the blood and are present in large numbers
bacteremia/viremia: bacteria/virus present in blood (not multiplying
asymptomatic
no noticeable symptoms produced
pathogen
microorganism that causes disease
sequealae
long term damage to organs caused by infections
virulence factors
characteristic that contributes to ability to establish/cause damage
4 types of reservoirs
human (carriers that are ill), human (recovered, but can spread), animals (pathogens are directly transmitted; eating), arthopods (host of pathogen is mode of transmission; mosquito)
modes of transmission
direct/indirect contanct, droplet, airborne, fecal-oral
horizontal vs vertical transmission
horizontal: disease spread through population from one infected individual to another
vertical: transmitted from parent to offspring (milk)
healthcare associated infection
infectious diseases developed during hospital stay (pneumonia, GI infections)
reservoir
source of infectious agent
transmitter
organism that spreads the infectious agent
zoonosis
an infection indigenous to animals but naturally transmissible to humans
communicable
disease transmissible from one person to another
contagious
easily transmissible
non communicable
not transmissible
goals of epidemiology
study of frequency and distribution of disease
vs tranditional medical practice
diagnosis/ treatment of patient for disease
notifiable/ reportable disease
notifiable: must be reported to health authorities (HIV/AIDS and tuberculosis)
incidence
rate of new cases of disease
prevalence
total number of cases (NOT NEW)
