Introduction to Pathogens Flashcards
bacterial strain
population of organisms w/in a species that descends from a single organism
how do strains evolve
mutation or acquiring new genes via horizontal transfer
what are the ways bacteria obtain new genes?
1 conjugation- (mating b/t bacteria)
2 transduction- (DNA moved via bacteriophage from one cell to another)
transformation- bacteria take up free DNA from environment
bacterial serotype
strain that is differentiated by serological means
what is serotyping?
the use of antisera containing antibodies reactive to bacterial surface antigens
what are the common bacterial antigens?
O- polysaccharide component of LPS- repeating sugars that can vary w/in a strain
H- the flagellar antigen
K- polysaccharide capsule component
are infections caused by a single strain or multiple? epidemics?
both single strains
infectious dose
approximate number of microbes that on average are required to cause an infection
virulence factors
secreted enzymes involved in nutrient acquisition that directly cause damage to the host (direct damage, immune modulation, diarreha, cough, etc)
can be referred to as toxins/exotoxins b/c they are excreted from the cell
virulence determinant
virulence factors that are required for disease
endotoxin
lipid A component of LPS
causes fever and shock
how does the host innate immune system respond to low [endotoxin]
1 macrophages activated and secrete TNF
2 increased phagocyte/lymphocyte/platlet activation and migration
3 phagocytosis of bacteria
4 occlusion of local blood vessels
5 plasma cells drain to local lymph
6 infection removed
endotoxic shock
caused by excess endotoxin; highly lethal
causes: 1 fever 2 inflammation 3 hypotension 4 DIC/bleeding 5 organ ischemia and failure
treated w/ oxygen, fluids, medicine to control BP
bacteremia
presence of bacteria in the blood
septicemia
body wide response to bacteria or bacterial products in the blood
