(1/27/15) Gram-negative Pathogens of Mucosal Surfaces [1] (Bailey) Flashcards
surface that interacts with air that has associated glands for secreting mucus
mucosal surfaces
what are the 4 main mucosal surfaces for gram-negative pathogens
- oral cavity
- respiratory tract
- reproductive/urinary tract
- GI tract
what are the three types of defenses of mucosal surfaces that the body has against pathogens
- innate immunity
- adaptive immunity
- nonspecific barrier defenses
what is the annual cost on GI tract diseases?
10 billion dollars
what are the “seven F’s” that describe the possible modes of transmission for gram negative mucosal pathogens?
- feces
- food
- fluids
- fingers
- flies
- fomites
- fornication
the inoculum size of shigella is as little as ______ organisms
50-100
size of the colony of bacteria that is required to cause disease
inoculum
what are the three types of natural barrier defenses that are used by our bodies?
- secretory substances
- anatomical and physiological barriers (acidity, motility, tight junctions, etc)
- indigenous bacteria
what are the 4 types of anatomical and physiological properties that assist with creating a physical barrier?
- acidity (ranges from 1-9)(both acid and base)
- motility (fluid rushes bacteria away)
- mucus layer & underlying glycocalyx
- tight junctions
type of anatomical barrier that ranges from 1-9 making it so that bacteria must be able to survive in acidic and alkaline environments
acidity
type of anatomical barrier that is a movement of fluid that can wash away unwanted bacteria
motility
type of anatomical barrier that is used to trap the bacteria and kill it
mucus layer & underlying glycocalyx
type of anatomical barrier that makes it hard for bacteria to diffuse into the body
tight junctions
why are there more functional anaerobes in the colon than in the stomach?
bc there is much less oxygen in the colon
what do our body’s normal bacteria do in order to make is so we are not constantly infected with pathogens?
creates a blanket on the GI walls that outocmpetes the incoming pathogens
enzyme used by immune system to cleave the beta 1,4-glycosidic linkages between N-acetylnuramic acid and N-acetylglucosamine
lysozyme
because of its function, what is the only type of bacteria that lysozyme can effectively degrade?
gram +
used by the body to sequester iron so that it cannot be used by the bacteria
lactoferrin
used by the body to disrupt bacterial membranes of Gm- and Gm+ (as well as fungi)
cathelicidin
used by the body to create pores in microbes. composed of alpha and beta subunits
defensins
where are the alpha defensins derived from?
neutrophils and paneth cell (in intestine)
where are the beta defensins derived from?
epithelial cells
microbes with low infectious doses tend to be ____ ____
acid resistant
shigella and enteroinvasive E. Coli
used by the pathogens to adhere to tissue to resist being shed
fimbriae/pili
for both Gm- and Gm+, the cell _____ have sensitivities to bactericidal compounds
membranes
bacteria often initiate _____ ____ _____ into their cell membrane to reduce effects of cationic antimicrobial peptides (interaction of charges)
cationic amino acids
bacteria use _____ to sequester iron in low iron environments (or to get it away from the lactoferins used by the body)
sideophores
macrophages recognize microbes via ____ _____ receptors leading to the activation of the macrophages and the ability to kill many microbes
pattern recognition receptors
in macrophages, the activation of the pattern response receptors also initiates the ______ response
inflammatory
which TLR receptor is the most important for this class and recognizing lipopolysaccharides?
TLR 4
what is the negative aspect of initiating the inflammatory response at mucosal surfaces?
inflammatory cytokines, such as TNF-alpha can disrupt the tight junctions between the epithelial cells
what do bacteria develop to resist phagocytosis
capsule
they also develop a mechanism that can neutralize the phagocytic compartment of macrophages
most of our immune response is at mucosal surfaces bc the _____ _____ are also at most of the mucosal surfaces
lymph nodes
type of pathogens that are usually found in the large intestine, have SMALL volume of stool, bloody stool, leukocytes in the stool, and have tissue ulcerations?
invasive bacterial pathogens
what are the two examples of invasive bacterial pathogens?
- salmonella spp.
- shigella spp.
type of pathogens that are usually found in the small intestine, have copious amounts of watery stool, NO blood in stool, NO leukocytes in stool, and cause NO tissue damage
toxin-producing bacterial pathogens
type of pathogens that are found in lower small intestine and upper large intestine. their colonization causes attaching and effacing lesions, and they cause blood to be in the stool
“hybrid” misfit pathogens
what distinguishes the four different types of shigella species?
the O antigen
for shigella, the inoculum size is _____
small
for shigella, the acid resistance is controlled by a global regulatory system of genes under the control of RpoS made in the _____ _____
stationary phase
shigella will usually multiply and colonize the _____
colon
simply put, how do shigella cells invade?
they enter M cells lining the mucosal surface and spread throughout the adjacent epithelial cells, staying away from the immune system, via IcsA and ATPase
during shigella, what develops when invaded cells die and slough off?
ulcer
all species of shigella will induce an inflammatory diarrhea with ____ in the stool
leukocytes
only shigella type that produces shiga toxin and disrupts the Na absorption
shigella dyseteriae type 1
what are the two types of salmonella that we need to know about in this class
- gastroenteritis
- typhoid fever
the inoculum for salmonella is ______
large (10-100 million)
salmonella is more _____ _____ than shigella
acid sensitive
in salmonella, the low pH of the stomach induces the expression of at least 40 proteins found on _____ ______ on large virulence plasmids (triggered by the acid)
pathogenicity islands
simply put, how does salmonella spa invade?
inc. cellua Ca+ levels that inc the uptake of the salmonella, remain in the cells for many hours (unlike shigella), induces NaCl loss from host cell
simply put, how does salmonella typhi invade?
-enters LYMPHATIC SYSTEM then replicates within microphages throughout the body
_______ is a localized infection, whereas _____ occurs all over the body
- shigella
- salmonella
salmonella _______ is strictly a human pathogen (no animal reservoir)
typhi
salmonella typhi is known to have _______ ______ that show no symptoms of the disease but have it colonized in their gall bladders and the organisms can be cultured from their feces
asymptomatic carriers (typhoid mary)
for asymtomatic carriers of salmonella typhi, where are the organisms colonized?
gall bladder (spread through the feces)
what are the two similarities between the two invasive enteric pathogens? (salmonella and shigella)
- both invasive so more in large intestine than small intestine (induce diharrea)
- both are able to respond to environmental changes
what are the 3 differences between the two invasive enteric pathogens? (salmonella and shigella)
- inoculum size (shigella=small || salmonella=large)
- bacteremia (shigella contained in intestines || salmonella is widespread)
- species that cause severe disease are very dissimilar
what is a possible treatment of all enteric diseases?
oral rehydration
what is a possible treatment of shigella?
antibiotics
what is a possible treatment of salmonella?
2nd generation fluoroquinolones
what is a possible treatment of typhoid fever?
- fluoroquinolones or surgical removal of gall bladder
- vaccine to the capsule of S. Typhi
