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55 Cards in this Set
- Front
- Back
Which diarrheal diseases are primarliy toxin mediated?
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Cholera
ETEC (EHEC) Yersinia enterocolitis |
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Enterotoxigenic E. Coli: Symptoms
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watery diarrhea, nausea, abdominal cramps, low grade fever
travelers diarrhea and infantile diarrhea |
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Describe the virulence of ETEC?
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Enterotoxin (Cholera like)
LT: heat labile; similar to cholera toxin but milder ST: heat stabile; causes increase in cGMP has fimbriae and CFAs for colonization in the Small Intestine |
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ETEC: What common disease does it cause?
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Traveller's diarrhea
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Enteroinvasive E. Coli(EIEC): Describe its mode of infection and symptoms.
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INVASION of Large intestine epithelium similar to Shigella
causes dysentery w/ fever, abd. cramping, blood and pus in stool |
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Enteropathogenic E. Coli: What common disease state does it cause?
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Infant diarrhea
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EPEC: Describe its mode of pathogenecity?
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ADHERENCE to enterocytes (Small intestine)
effacement of microvilli expresses intimin- mediates entry in to cell bundle forming pilli for attachment |
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EPEC: Describe pathogenesis
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ADHERENCE to sm. intestine enterocytes
EFFACEMENT of microvilli *inflammatory response may cause ulceration |
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What strain of EHEC causes disease?
Where is it typically found? |
the O157:H7 serotype
it is found in cattle, beef products, and fruit and veggies that have been fertilized with tainted manure |
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What characteristic differentiates EHEC from other strains of E. coli?
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Its inability to ferment sorbitol.
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Describe the symptoms caused by EHEC.
What is its primary pathogenic mehcanism? |
hemorrhagic colitis, bloody diarrhea, abd. cramping
HUS - possibly because of specific LPS |
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What is the pathogenic mechanism of EHEC?
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Shiga like TOXIN
Attachment and Effacing of microvilli leading to their death Large Intestine |
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Yersinia enterocolitica: clinical presentations?
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enterocolitis involving fever, diarrhea, and abdominal pain
nonenteric lymphadenitis may lead to septicemia |
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Yersinia enterocolitica: pathogenesis?
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INVASION of M cells in small intestine
secretion of a toxin similar to E. Coli Heat stable toxin * resevior is farm animals |
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T/F: S. typhii has no animal reservoir while S. enteritidis does.
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True.
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How is E. Coli Diagnosed and treated?
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detection is difficult, some labs may serotype
treated with fluid replacement, antibiotics EHEC strains grow on Sorbitol agar |
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What are the steps involved in the pathogenesis of S. typhii?
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*binds M cells of GI epithelia *endocytosed and transferred to Peyer's patch *replicates intracellularly *passes through basal lamina *taken up by macrophage and spread thru RES
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A chronic carrier state is possible with S. typhii. What organ is notorious for sequestering the bacteria?
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Gall bladder
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EAEC: what is its primary pathogenic mechanism?
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ADHERENCE to enterocytes
Heat stabile toxin called EAST that eleveates cGMP attaching and effacing lesions |
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What are general characteristics of Enterobacteriaceae?
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Gram(-) bacteria that are part of the normal intestinal flora
non spore formers ferment glucose Facultive anearobes |
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What are the 4 genus' of enterics?
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enterobacteriaceae, vibrionaceae, pseudomonadaceae, bacteroidaceae
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What are general characteristics of Enterobacteriaceae?
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Gram(-) bacteria that are part of the normal intestinal flora
non spore formers ferment glucose Facultive anearobes |
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Vibrio Cholera: clinical manifestations?
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Classic "rice water" stool diarrhea w/ high fluid output
infxn may be asymptomatic, cause mild diarrhea, or result in a carrier state |
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Vibrio Cholera: pathogenesis?
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polar flagellum (H-ag) - motility
pili- adherance cholera toxin *mucinase to digest mucous layers *NON INVASIVE! |
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Describe the Cholera toxin?
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two A subunits bridged by disulfide bonds and 5 identical B subunits
A1 is active subunits-enters cell upregulates adenyl cyclase --> increased cAMP leading to cause massive efflux of Na= and H20 *regulon family of genes |
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Vibrio Cholera: Diagnosis?
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darkfeild microscope
isolation on thiosulfate-citrate-bile-sucrose(TCBS) agar agglutination in specific antisera |
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Vibrio Cholera: Rx?
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Rehydration orally
IV Tetracycline |
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Vibrio Cholera: Immunity?
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post infection Abs
gastric acidity vaccines are KILLED WHOLE CELLS |
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Vibrio parahemolyticus
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marine org, infects shellfish
major cause of FP in Japan and in US from eating raw shellfish explosive diarrhea (w/o blood or mucous), cramps, nausea, vomiting *produces a toxin |
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Vibrio vulnificus
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found in salt h2o, infects sun bathers and those ingesting raw shellfish
can cause a fatal bacteremia immunocompromised, liver diseased and thalassemia increase risk |
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Campylobacter jejuni: transmission?
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transmitted by contaminated milk, H20, poultry
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Camplylobacter jejuni: clinical manifestations?
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bloody, pus-filled diarrhea, severe ab pain, fever
high pediatric incidence no1 cause of gastroenteritis in developed world *assoc. w/Guillan-Barre syndrome |
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Camplylobacter jejuni: bacterial characteristics?
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G- curved rod
microaerophilic motile INVASIVE |
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Helicobacter pylori: clinical manisfestations?
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cause of gastritis, PEPTIC and DUODENAL ULCERS
makes a urease theat produces NH3 from urea cured with Antibiotics |
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Shigella species: clinical manifestations?
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shigellosis- fever, chills, abdominal cramps, tenesmus
blood/ pus/ mucous in stool can cause convulsions and meningitis in infants S. dysenteriae cause most severe infections; S.sonnei and S.flexneri most common in US |
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Shigella species: transmission?
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man is primary host
P to P: fecal-oral transmission or by vectors(food, fingers, feces, flies) associated w/ overcrowding and poor sanitation |
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Shigella species: Pathogenesis?
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invades/ damages mucosa of large intestine, ulceration, and appearance of PMNS --> scarring
invasion genes are on plasmid, involves actin polymerization non motile Shiga toxin, INVASION |
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Shigella species: Describe the Shiga toxin?
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A+B toxin (similar to Cholera)
inhibits protein synthesis by inactivating the 60s ribosome also behaves as neurotoxin *not essential for virulence *associated w/HUS |
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Shigella species: diagnosis?
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rectal swab
stool culture *Shigella IS NOT Normal Flora |
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Shigella species: Rx and immunity?
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rehydration
antibiotic resistance emerging previous infection only gives short lived immunity, no vaccine |
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Salmonella gastroenteritis: clinical manifestations?
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diarrhea, fever, cramping, nausea, vomiting, headache
onset 24-48 hrs after ingestion diarrhea has rotten egg smell blood stream invasion may occur, but disease is usually self limiting |
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Salmonella gastroenteritis: organisms
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S.typhi --> typhoid fever
S.typhimurium - most common causitive org in US S. enterica |
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What are the 3 clinical sydromes that can result from infection with Salmonella species?
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1. enteric fever
2. septicemic syndrome 3. gastroenteritis |
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Salmonella gastroenteritis: transmission?
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fecal-oral route
pet turtles chicken, raw eggs, mayonaise unpasteurized OJ, apple cider |
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Salmonella gastroenteritis: pathogenesis?
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attachment and invasion of mucosal (M cells) of SMALL INTESTINE, damages tissue
may produce a toxin but not major virulence factor *INVASIONS |
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Salmonella gastroenteritis: diagnosis?
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fecal culture on selctive/differential agar (Salm are lac-)
slide agglutination for serogroups |
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Salmonella gastroenteritis: Rx and immunity?
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flouroquinolones (ciprofloxacin)
antimotility drugs no vaccine |
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Enteric Fevers: causitive agents?
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S. typhi - typhoid fever, Vi antigen (capsular polysacchride)
S. paratyphi and S.schotmulleri cause milder fevers |
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Enteric Fevers: clinical manifestations?
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intially malaise, headache, anorexia
wk1: gradual stepwise rise in fever, constipation or diarrhea wk2: rose spots, hi fever, septecemia wk3: fever remits, may have ulceration and gut perforation --> bloody diarrhea |
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Enteric Fevers: pathogenesis?
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ingested and multiply in small intestine
penetrate mucosa at distal end ileum through M cells at Peyers Patches, move through blood stream --> bacteremia infection of gall bladder can lead to chronic carrier state or reinfection |
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Enteric Fevers: Transmission?
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S.typhi only infects humans by direct contact or ingesting food contaminated by orgs shed by carrier (Typhoid Mary)
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Enteric Fevers: Diagnosis?
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isolation of org on agar or serotyping
blood is positive in wk1 of infection stool is positive after wk1 Widal test |
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Enteric Fevers: Rx and immunity?
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Short course, fluoroquinolones
Abs protects, infection stimulates cellular immunity Vaccines: killed whole cells, live attenuated, IV injected capsular polysacchride |
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Septicemic Syndrome: organism and clinical manifestations?
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S. cholraesuis
causing spiking fevers w/ frequent seeding to various organs --> abscesses, meningitis, pneumonia, osteomyelitis, endocarditis |
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General characteristics of Enteric Bacteria
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Gram - bacilli
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