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112 Cards in this Set

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What is the worst e coli to get and why?
EHEC because of HUS in children and infants
what is the only bacteria recognized as type I carcinogen by WHO?
H. pylori
what type of bacteria is H. pylori?
gram -
how does H. pylori respire?
microaerophillic (can only have 10% o2)
how do you grow H. pylori?
37C skirrow medium (need a special incubator)
how do H. pylori bore into the stomach?
flagella covered by a sheath
where is urease in H. pylori and what will it do?
cell wall
will increase pH locally thus preventing the normal pH from killing it
how will bleeding manifest in H. pylori?
coffee ground emesis or black, tarry stool (melena)
what is the key to the clincal presentation of H. pylori?
periodicity
what is the key to the transformation from ulcer to cancer?
periodicity
what is the VacA toxin?
from H. pylori
directly influences inflammation
what is the CagA toxin?
from H. pylori
indirectly injures the stomach by sitmulating IL-8 (chemokine) and neutrophil-activating protein
how does H. pylori cause damage?
accumulation of inflammatory cells that release toxic molecules and kill the gastric mucosa
the damaged gastric mucosa can no longer withstand the low pH and forms an ulcer
what is the most toxic radical released by the inflammatory cells in H. pylori?
paroxynitirte
what is the most important method to diagnose a perforated, hollow viscus (i.e. ulcer)?
plain x-ray of abdomen because free air will be trapped in the diaphragm
what is the easiest way to diagnose H. pylori?
urea breath test
what is the definitive way to diagnose H. pylori?
biopsy and culture
what are 4 antibiotics used for H. pylori?
metronidazole
tetracyclin
clarithromycin
amoxycillin
what 2 antibiotics do you never want to combine?
metronidazole and clarithromycin
what are 2 bacteria that release toxins increasing secretion of water and electrolytes?
v. cholerae and e. coli
what are 2 bacteria that release toxins causing cell death and halting protein synthesis?
shigella
shigella-like toxin from EHEC
what is the #2 cause of infantile diarrhea?
EPEC
where will v. cholerae be seen in the US and why?
coastal texas and louisiana because it needs alkaline water
what type of bacteria is v. cholerae?
gram - rod
is v. cholerae motile?
yes highly
single flagella
what will never form spores?
any gram -
how does v. cholerae respire?
aerobic and anaerobic
what will v. cholerae grow on?
TCBS medium
what are 2 strains of v. cholerae?
O1
O139
how is v. cholerae transmitted?
contaminated water, vegetables, and shell-fish
what are 2 bacteria that release toxins causing cell death and halting protein synthesis?
shigella
shigella-like toxin from EHEC
what is the #2 cause of infantile diarrhea?
EPEC
where will v. cholerae be seen in the US and why?
coastal texas and louisiana because it needs alkaline water
what type of bacteria is v. cholerae?
gram - rod
is v. cholerae motile?
yes highly
single flagella
what will never form spores?
any gram -
how does v. cholerae respire?
aerobic and anaerobic
what will v. cholerae grow on?
TCBS medium
what are 2 strains of v. cholerae?
O1
O139
how is v. cholerae transmitted?
contaminated water, vegetables, and shell-fish
what is the toxin in v. cholerae?
AB toxin
how does v. cholerae cause damage?
A factor locks the Gs protein in an activated state leading to sustaines stimulation of adenylate cyclase leading to a large quantity of cyclic AMP production
what does v. cholerae do to the GI epithelial cells?
transforms them from an absorptive cell to a secretory cell leading to loss of Na, Cl, K, and HCO3
what is the classic presentation of v. cholerae?
voluminous diarrhea
acidosis
muscle cramps
what must the fluid replacement for v. cholerae be and why?
isotonic for Na and Cl
hypertonic for bicarb and K because more of that is lost
what damage is done to the epithelial cell in v. cholerae?
none, it's simply transformed it's jobs
what stimulates ToxR to be released?
v. cholerae senses change in temp, pH, and osmolarity which upregulates ToxR
what is ToxR?
a toxin for v. cholerae
what is the direct action of toxR?
activates the cholera genes
what is the indirect action of ToxR?
activates a second protein, ToxT
what is ToxT and what does it do?
a toxin for v. cholerae
activates transcription of virulence genes in both pathogenicity islands, including TCP, CT,and accessory toxins
what 2 tests can be used to confirm v. cholerae diagnosis?
TCBS culture
agglutination test
what is the difference between agglutination and precipitation?
when the antigen is soluble, it is precipitation
when the antigen is insoluble (i.e. latex), it is precipitation
what antibiotic should you give for v. cholerae? (3)
tetracycline
OR TSX and erythromycin in children and pregnant women
who is usually more susceptible to v. cholerae?
people with low gastric acids (gastroctomy due to cancer and achlorhydria from malnutrition)
what is unique about vibrio parahemolyticas?
history of travelling on a cruise ship and consuming shellfish
what is unique about vibrio vulvinnicus?
can cause cellulitis with pus formation and has a history of contact with oysters (eg. shucking, salt water) without a chronic infection
what will cause a cellulitis and granulomatous fomation and be associated with fresh-water (tropical fish enthusiast)?
mycobacterium merinum
what type of bacteria is campylobacter jejuni?
gram- rod
is campylobacter jejuni motile?
yes
what is campylobacter jejuni positive for?
oxidase
how does campylobacter jejuni respire?
microaerophilic
what will campylobacter jejuni grow on?
42C skirrow agar
what makes campylobacter jejuni different from H. pylori?
campylobacter jejuni will grow at 42
H pylori will grow at 37
what will campylobacter jejuni look like and why?
seagull appearance due to polar flagella
what is the #1 cause of diarrhea in the US?
campylobacter jejuni
how is campylobacter jejuni transmitted?
animals, especially poultry
may be in milk and goat cheese
when will symptoms manifest with campylobacter jejuni?
1-7 days after ingestion
what is the clincial course with campylobacter jejuni?
watery diarrhea --> bloody
self limiting by may become toxic
later may have frank blood per rectum
what is the toxin in campylobacter jejuni?
cytolethal distending toxin but it doesn't cause diarrhea
how does campylobacter jejuni cause diarrhea?
invasive pathogen causes inflammation in epithelial cell
what has a strong tie to campylobacter jejuni infection?
guillain-barre syndrome
what is the association between gullian-barre syndrome and campylobacter jejuni believed to be due to?
anti-ganglioside antibody used against the LPS core in campylobacter jejuni will cross-react wil similar molecules in the myelin of the host peripheral nerve
what has molecular mimicry similar to rheumatic fever sitmulated by GAS?
Guillian barre syndrom caused by campylobacter jejuni
how do you treat campylobacter jejuni?
quinolone or macrolide if it becomes toxic
what will campylobacter jejuni not respond to?
beta-lactams
how long does immunity last with campylobacter jejuni?
long lasting
what is the #2 cause of bacterial enteritis in the US?
salmonella
what colonies will be black on HE agar?
proteus
salmonella
what colonies will be yellow on HE agar?
citrobacter
enterobacter
e. coli
klebsiella
what colonies will be colorless on HE agar?
shigella
yersinia
what are 2 antibiotics used for typhe?
quinolone and cephalosporin
why is the chloramphenicol used for typhi important?
it can cause bone-marrow suppression
what shigellas are most common in the US? (2)
sonnei
flexneri
who most commonly gets shigella?
children
how much shigella is needed to cause disease?
may only need 1
what type of pathogen is shigella?
invasive
where does shigella replicate?
in the macrophage
how does shigella become motile?
it takes the actin-filament system and uses it as its own flagella
how does shigella infect other cells?
laterally
never re-enters the lumen
what does the shiga-toxin do?
inhibits the 50s subunit of the ribosome
what is a key clinical presentation of shigella dysenteae? (3)
small amounts of stool mixed with blood, pus, and WBC
severe abdominal cramps
tenesmus
how will shigella sonnei and flexneri present?
watery diarrhea
what is shigella clincially impossible to differentiate from?
EIEC
what 2 antibiotics are used for shigella?
quinolone
cephalosporins
what is contraindicated in shigella?
anti-spasmodics
what are 4 lactose fermenters?
citrobacter
enterobacter
e. coli
klebsiella
what will be white on mac agar?
citrobacter
enterobacter
e. coli
klebsiella
what are 4 lactose non-fermenters?
shigella
yersinia
proteus
salmonella
what will be clear on mac agar?
shigella
yersinia
proteus
salmonella
what will be different between food poisoning caused by salmonella enterica and staph aureus?
salmonella will manifest the next day
staph will be within 6 hours (because it has toxins)
what is typically found during an outdoor pot-luck with consumption of potato salad?
salmonella enterica
what is strictly a human disease?
salmonella typhi
how is salmonella typhi transmitted?
fecal-oral (usually carrier contaminates water)
why does salmonella require a large amount to cause infection?
because it is acid sensitive
how does typhi survive in the macrophage?
inhibits phago-lysosome fusion and directly supresses oxygen dependent and independent killing
what allows salmonella typhi to withstand complement-mediated killing?
VI antigen
what are 3 unique clinical presentations of typhi?
high fever in a step wise fashion
rose spot on abdomen or chest where pathogen can be isolated
constipation OR diarrhea
what are 2 complications of typhi?
cholecystitis
intestinal perforation because of recurrent/chronic infection
what is significant about typhi being in the gallbladder?
it will be concentrated there
what type of immunity is important in typhi?
humoral
cell mediated
what is a test that can be used to detect typhi?
widal test to test for flagella antigen and somatic antigen