Salmonella
Does salmonella ferment glucose or lactose?
Glucose fermenter, Non-lactose fermenter, Produces H2S
Does Shigellosis have watery or bloody diarrhea?
Inflammatory diarrhea- watery that progress to bloody diarrhea
What is the full name of cholera species?
Vibrio cholerae
Is Listeria monocytogenes gram (+) or (-)?
Gram (+) bacilli
Is Yersinia enterocolitica gram (+) or (-)?
Gram (-) bacilli
How is Salmonella transmitted?
undercooked poulty, raw eggs, pet reptiles (turtles)
Do you expect black or green colonies on Hektoen agar?
GREEN (lactose-fermenting). black indicated H2S production (salmonella)
What is the shape of cholera?
Gram (-) "comma shaped" bacilli with darting motility
Name a food that Listeria is associated with.
Unpasteurized dairy, Cold deli meats, Raw fruits and veggies, Refrigerated smoked seafood
What GI pathology does a Yersinia infection mimic?
appendicitis
What virulence factor does ONLY Salmonella typhi (NOT Salmonella enteritidis) have?
Vi antigen = capsular polysaccharide that prolongs intracellular macrophage replication
Typhoid toxin = DNA-damaging AB exotoxin, causing neurologic symptoms
Why does Shigella require a lower ID50 for infection than Salmonella?
Shigella is acid-stable. Salmonella is not.
What type of diarrhea does cholera cause (Brooke's LI)?
Secretory diarrhea- severe "rice water" diarrhea
What is the treatment for Listeria?
IV ampicillin
What is a potential source of Yersinia enterocolitica?
Undercooked pork, pet feces, contaminated water or veggies
When do you treat Salmonella with antibiotics?
Typhoid fever
Name a complication of Shigella infection.
HUS, Reiter's syndrome
How is cholera transmitted?
Water contamination- raw shellfish, salt or brackish water, resource-limited areas
What serious complication should you look out for in Listeriosis of neonates and immunocompromised pts?
meningitis, sepsis
What part of GI tract does Yersinia proliferate in?
Terminal ileum, then migrate to mesenteric lymph nodes
Name an agar used to identify Salmonella and what type of colonies you will see.
Hektoen agar- green colonies with black center (H2S producing)
MacConkey agar- white colonies (non-lactose fermenting)
What is the mechanism of Shiga toxin?
A subunit- inhibit 60S ribosomal subunit by cleaving 28S rRNA to inhibit protein synthesis
B subunit- bind to receptor for host cell entry
What is the mechanism of cholera toxin?
A subunit permanently activates alpha subunit of Gs protein in enterocytes. Thus, adenylyl cyclase produces lots of cAMP that opens CFTR channels, allowing Cl- and H2O secretion into GI lumen.
How does Listeria get from cell to cell?
Propels itself using ActA surface protein that triggers actin polymerization
What agar is used to isolate Yersinia?
Cefsulodin-irgasan-novobiocin (CIN) agar-clear uneven colonies with red center