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