Introduction to Infectious Diseases Microbes and Microbial Morphology Flashcards
pathogen
any disease-causing microorganism
primary pathogen
cause disease in any host
opprotunistic pathogens
can only cause disease in hosts with impaired or damaged defense mechansisms
infection
microorganism penetrates body surfaces, enters host tissue, multiplies, damages tissues, causes host to react with immune response
virulence
ability of organism to cause disease
avirulent
organism which cannot cause disease
virulence factors/determinants
properties or gene products of microorganisms that enhance their disease-producing capabilities
examples of virulence factors/determinants
colonization
invasion
tissue damage
asymptomatic carriage
state where infection exists with no clinical symptoms
famous example of asymptomatic carriage
typhoid mary
colonization
establishment of microbial growth on body surface
humans are exposed to potentially disease-causing agents from 3 general sources:
exogenous microbes: human to human
exogenous microbes: animal to human
endogenous agents: normal flora
What are 4 types of transmissions for human to human
respiratory
salivia
fecal-oral
venereal
Zoonotic infections
animal to human transmission
vector ( biting athropod) ex.
ticks spread Rocky Mountain Spotted Fever
vertebrate reservoirs ex.
dogs and bats spread rabies
vector-vertebrate reservoir ex.
bubonic plaque spread from rats to fleas to man
fomites
inanimate objects which harbor microorganisms
nosocomial infections
impaired defense system, poor sanitation in hospitalized patients
3 cases where disease results from microbe’s ability to alter normal immune response
autoimmunity
superantigens
septic shock
autoimmune activation
pathogen produces protein similar to host protein ( cross-reactive material), causes host to attack itself
superantigens
elaboration of superantigens which result in the activation of many T cells
when does normal flora become a source of infection
microorganism move from normal habitat and invade areas which are sterile or devoid of organism in question
sterile tissues
microorganisms typically laden absent
example of sterile tissue
blood
alveoli
muscle
where are normal flora generally laden with microbes
external surfaces,
skin, GI, upper respiratory