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50 Cards in this Set
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ID: Gram (-) curved rod that grows well at 42C
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Campylobacter jejuni
Other properties? |
Motile, microaerophilic, will NOT grow in 3% NaCl or @ 25C
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A patient ate undercooked chicken 7 days ago. Yesterday he had fever, HA and malaise. Now he has diarrhea and cramping with severe abdominal pain in LRQ. Diagnosis?
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Campylobacter jejuni, probably from the undercooked chicken.
What are prodrome symptoms in this patient? |
fever, HA, malaise, myalgia
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What bacterial GI infections mimics appendicitis?
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Camplyobacter jejuni and Yersinia enterolitica
How does C. jejuni mimic appendicitis? |
Due to invasion of mesenteric lymph nodes with inflammation
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Loose stools to frank dysentery, fever and abdominal pain are halmarks of enteritis with diarrhea. What pathogen does this point you towards?
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Campylobacter jejuni
What is incubation period? What is duration of convalescent carriage and excretion? |
Incubation 1-7 days
Convalescence with excretion: 2-3 weeks after disease. |
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Virulence factors of C.jejuni
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1. Invasion factor
2. Cytolethal distending toxin (CDT) 3. Heat labile (LT) enterotoxin What are they? |
Invasion factor= CHO on cell surface-->pathogen directed phagocytosis
CDT=directly damages host DNA-->locks it into G2 phase. Inhibits immune system reaction to infection enterotoxin= similar to ETEC LT (cholera-like toxin) |
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C. jejuni
Invasive or not? Intracellular pathogen or not? |
Invasive
Intracellular |
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Reservoir of Campylobacter jejuni?
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Intestinal tract of birds
Transmission? |
primarily by food source:
undercooked chicken contaminated water unpasteurized milk/dairy rare for person-to-person |
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Seasonality for Campylobacter jejuni?
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Yes, summer.
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Inoculating dose for Campylobacter?
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Low dose: 800 cfu
What demographic usually infected? |
Young adults, around age 20.
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What is more common for Campylobacter: sporadic cases or large-scale outbreaks?
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sporadic cases
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2 complications of Campylobacter jejuni infection
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1. Reiters (reactive arthritis)
2. Guillain-Barre syndrome What other bacteria also had Reiters as a complication? |
Shigella sp.
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2 months following a symptomatic infection, a person risk of this complication is 100X greater than the risk in the normal population. In fact, C.jejuni is the chief precipitant for this disease.
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Guillain-Barre
Why does C.jejuni infection increase the risk of Guillain-Barre? |
B/C the LPS of C.jejuni resembles human ganglioside Gm1 and antibodies will be formed against Gm1 (a myelin component)
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Highly motile curved rods with darting motility and sea gull shapes are seen upon microscopic examination of a patients feces.
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Campylobacter jejuni
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How would a micro lab cultivate Campylobacter jejuni?
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Stool culture at 45C under micoaerophilic conditions with enriched CO2 on special selective medium such as Campy-BAP
Catalase (+), Oxidase (+) What conditions would cause lack of growth? |
No cultivation on 3% Nacl
No @ 25C |
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What rapid tests are available for campylobacter jejuni?
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Latex agglutination (Campyslide) for culture ID
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Treatment for Campylobacter jejuni?
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Usually self-limiting
Erythromycin for severe cases Prevention? |
Thorough cooking and careful handling of poultry are KEY
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Describe cell morphology and lab characteristics of Yersinia enterolytica
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Gram (-) coccobacillus, motile, lactose nonfermenter, 22-29C, facultative intracellular pathogen.
Compare to Campylobacter jejuni |
C.jejuni: gram(-) curved rod, motile, microaerophilic, 42C, Oxidase (+), Catalase (+)
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Where does Yersinia enterocolitica establish infection?
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terminal ileum
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What is the clinical manifestation of Yersinia enterocolitica infection?
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Fever, abdominal pain, vomiting, diarrhea
May also present like acute appendicitis, especially in children under 5y.o. |
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This microbe has been found present in donated blood of asymptomatic individuals.
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Yersinia enterolitica
What is a transfusion reaction? |
The result of blood being transfused to a patient that has been contaminated with Yersinia. It can grow and produce endotoxin while refrigerated
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What is the optimal temperature range for Yersinia enterolitica?
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22-29C
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How does Yersinia enterolitica invade the host?
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Via the M cells of Peyer's patches
Virulence factors? |
Invasin
Enterotoxin YOP |
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This virulence factor binds beta1 integrin and induces endocytosis
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Invasin
(Yersinia enterolitica) When is it synthesized? |
below 37C
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ST-like toxin activates guanylate cyclase and increases cGMP levels.
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Enterotoxin
(Yersinia enterolitica) When is the toxin synthesized? |
Synthesized only below 37C
(like Invasin) |
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This is a plasmid encoded virulence factor that inhibits phagocytosis and the macrophage respiratory burst.
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Yops
(Yersinia enterolitica) Also causes contact dependent cytotoxic activity that depolymerizes actin filaments of cell. When is the toxin synthesized? |
At 37C and when Ca2+ levels are low
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What is the treatment for Yersinia enterolitica infection?
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Supportive, maintain fluid and electrolyte balance
Aminoglycosides, quinolone |
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How does a lab culture Yersinia enterolitica?
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Cold temp enrichment(room temp).
But, grows too slow to hep clinically Morphology of MacConkey agar? |
Small white colonies (non lactose fermentation)
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Seasonality of Yersinia enterolitica
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Infection more common in winter.
Reservoir? |
Ubiquitous in the environment. Infects a wide variety of wild and domestic animals with epizootic outbreaks recognizable
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Recent outbreaks have been more common in children, day care centers especially.
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Yersinia enterolitica
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Once thought to be solely a high dose organism, fecal-oral transmission is now recognized
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Yersinia enterolitica
How are cargivers transmitting to infants? |
Transmission to infants from caregivers who prepared food harboring this bacterium have been documented
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What food sources are known to harbor Yersinia enterolitica?
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milk, meat products, especially pork
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Along with campylobacter jejuni, this bacterium is also shed for weeks after recovery
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Yersinia enterolitica
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Chronic active gastritis and peptic ulceration are consequences of infection with what bacterium?
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Helicobacter pylori
Where do they colonize? |
only colonize the mucous-secreting epithelial cells of the pylorus
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Describe the morphology of Helicobacter pylori
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gram (-) curved rod
highly motile Giemsa stain What do they produce copious amounts of? |
Urease
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Severe gastritis with cramps, halitosis, nausea, vomiting. gram (-) curved rods, stained with Giemsa.
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Helicobacter pylori infection
What acts as a natural antibiotic in the host? |
gastic mucin
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T or F: eradication of the bacterium does not result in relief of symptoms.
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True: eradication is not correlated with relief of symptoms.
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There are many strains in circulation of H. pylori, but not all are equally virulent. What do about 1/2 of the strains carry that make them more virulent?
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The virulence plasmid "cag" which carries numerous virulence factors.
What does it disturb? |
Host cell signaling.
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Type IV secretion system
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Virulence factor of H. pylori
injects antagonistic factors directly into the host cell |
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Urease and HspB
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Helicobacter pylori virulence factors
Urease: Produces CO2 and NH4-->protective of organism against acidic environment HspB function? |
enhances urease expression
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H. pylori virulence factors
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Type IV secretion system, urease, heat shock protein B, acid inhibitory protein, flagella/adhesion proteins, peptidoglycan
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A virulence factor for H. pylori that dampens the acid production by host
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Acid inhibitory protein
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How is the H. pylori flagella a virulence factor?
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It gives the organism motility to aid invasion and also allows the microbe to evade the inflammatory response.
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Source is obscure, but about half of the world population is thought to be colonized.
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H. pylori
Where in the world is it most common? |
developing world. Carriage rates are declining in the developed nations.
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How is H. pylori spread?
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oral carraige may be common. Microbe may spread by fingers.
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Smoking is a risk factor of (one answer)
a. E.coli infection b. C. jejuni c. Y. enterolitica d. H. pylori |
H. pylori
what stomach pathology is the organism associated with? |
stomach adenocarcinoma
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CLO test reveals ________activity visible by pH indicator in a specimen of 2 hours.
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urease activity
(h. pylori diagnosis) |
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How does the lab culture H. pylori?
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Special conditions required:
microaerophilic w/ high humidity 7 days @ 37C on blood-containing medium Oxidase positive, catalase positive, urease producer What other organism(s) are catalase and oxidase positive? |
Campylobacter jejuni (also microaerophilic)
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Does H. pylori has a seasonality?
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Nope
How about an age trend? |
Yes, increase likelihood of infection with age.
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Diagnosis techniques for H. pylori
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Histologic from fresh biopsy and culture is considered optimal.
Breath test or urine ammonia assay Screen for antigens in stool Serology- detect antibodies (will persist for years) |
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Treatment for H. pylori infection
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Combination of antibiotics plus bismuth-containing drugs as needed
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