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Flashcards in Principles of Pathogenesis 2 Deck (48)
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describe the stages of acute infection

incubation phase: period from exposure till first symptom
prodrome: having symptoms but cannot pinpoint what the problem is -- low level symptom
peak of acute phase symptoms: most severe symptom
convalescence: immune system kicks in and severity of symptom goes down


difference between acute and chronic infection

chronic has longer incubation phase and prodrome and also severity of symptoms stay at a constant low level because for some reason immune system cannot clear it out


terminology for chronic infections

latent - microorganisms is present and not replicating at a high level or not replicating at all
persistent - not being cleared, not being eradicated from the body
carrier - individual's is persistently shedding microorganism and can be harmful to someone else


compare the two infection types chronic and acute for the following: growth rates of pathogen, symptom onset speed, duration of symptoms, risk to others of infection, advantages to pathogen

chronic - slower, slower, longer but less severe, yes, there are advantages and disadvantages

acute - faster, faster, shorter, yes, there are advantages and disadvantages


define pathogenicity and virulence

pathogenicity is the ability to cause damage and virulence is how we measure that ability


fact about virulence

virulence can be different depending on who it is or can even vary where in the body it is


key to pathogen success

it recognizes in its environment, communicates it, then responds to it


how does pathogen respond to environmental signal

it has a receptor (membrane protein) on itself that receives signal from environmental changes then sends signal to response regulator --> genes --> mRNA --> protein and enzyme released which helps with appropriate adaptation to the environment


the ability to cause damage



what is pathogenicity islands (PAIs)

cluster of genes encoding for virulence factors


what is the role of clustering genes together

you can control them with the same switch


what is the difference between exogenous and endogenous in term of exposure and entry

exogenous - externally acquired
endogenous - home grown


what does it mean by you can get a cross over between exogenous and endogenous exposure and entry

your endogenous infection can become transmitted to someone else and become a exogenous infection to the other individual


vibrio cholerae in water has 10^4 - 10^6 infectious dose while vibrio cholerae in food has 10^2 - 10^4 infectious dose. Why is the infectious dose lower for V. cholerae when it is in food compared to in water?

probably because of heat from cooking but the levels in the water can be brought down to the levels in food if sodium bicarbonate is added to the water

Food and Sodium Bicarb help protect the virus from stomach acid.

If the virus was in just water, then many of the virions would be destroyed prior to getting to their site of infection.

But taken with food, a greater percentage of virions reach the site of infection so you need fewer in the infectious dose.


what is so important about the site of entry in which a microorganism gets in

same way they get in, is the same way they shed


what are some specialized adhesion structures and when do microorganisms express them

pili and fimbrae
expressed when it is beneficial for them - depending on the environmental conditions


what helps define tissue specificity

tissue tropism
specific adhesion
biofilm formation


what is streptococcus mutans' bacterial adhesin and attachment site

bacterial adhesin - cell bound protein
attachment site - pellicle of tooth


what is Enterotoxigenic E. coli's bacterial adhesin and attachment site

bacterial adhesin - Type I fimbriae
attachment site - Intestinal epithelium


what is Plasmodium sp.'s bacterial adhesin and attachment site

bacterial adhesin - MSP
attachment site - erythrocytes


what are some options for acquiring iron for microorganisms that need them

forming siderophores to chelate iron (this way the have a higher affinity for iron than the compound in which iron is attached to)

bind iron containing compounds

breakdown of iron containing compounds


some microorganisms need a host to survive: what is the difference between facultatively intracellular and obligately intracellular

facultatively - they need to be intracellular in some of their stages

obligately - they need to be intracellular at all times to survive


examples of organisms that are facultatively intracellular and those that are obligately intracellular

facultatively - salmonella histoplasma

obligately - chlamydia and all viruses


what normally happens to a phagocytosed bacterium that is trying to resist being broken down

a. Prevent fusion of phagosome and lysosome
b. Escape from phagolysosome
c. Resist/inactivate lysosomal enzymes
d. Inactivate harmful oxygen species


what is a way in which a pathogen can try to disguise itself

antigenic variation -- changing its recognizable surface antigen making it more difficult to recognize and eradicate


how effective is the immune system to antigenic variation and how does this affect the body?

it is hard for it to recognize since pathogen can repeatedly change its surface antigen

hence one can have multiple infections from the same pathogen due to its constant change in surface antigen


what is the most common defense system used by bacteria



composition of capsule

low immunogenicity
mimic body's own substances


importance of understanding composition of capsule

helpful for identification and vaccine development


in the spread and disseminate phase: what happens in the presence and absence of streptokinase

presence - barrier is broken down enabling the spread of pathogen

absence - barrier is not broken and the infection is walled off by fibrin barrier