Gram (-) Bacteria Flashcards
Stephanie moved into her dorm and soon after came down with meningitis. What bacterium infected her?
Neisseria meningitidis
If you see a gram (-) diplococci that looks like “kissing kidney beans” under a microscope, what genus does it belong to?
Neisseria
The outer membrane of Neisseria sp. contains what lipid?
LPS - lipopolysaccharide
LPS contains what toxins? What do the toxins cause?
Lipid A- endotoxin - causes sepsis
O antigen - used for serotyping
Describe the main virulence factors of N. meningitidis.
Lipid A (endotoxin) and Polysaccharide capsule (13 serotypes)
What is meningococcemia?
Meningitis and sepsis occurring simultaneously, due to infection with N. meningitidis.
By what route is N. meningitidis spread?
Respiratory route. Breathe it. (That’s why people in close quarters…dorms, bunkers…. get it so easily)
Why is the N. meningitidis vaccine not always helpful?
There are 13 serotypes of the polysaccharide capsule. The vaccine doesn’t cover them all.
If your patient walks in and has “purulent urethritis or cervicitis,” what does she have and why did she get it?
Gonorrhea. STD.
Gonorrhea is second only to ___________ for reported bacterial infections, and the two often occur simultaneously.
Chlamydia
Leading cause of Pelvic Inflammatory Disease?
Gonorrhea
Key virulence factors for N. gonorrheae?
PILI
Attachment, antiphagocytic
ANTIGENIC VARIATION OF THE PILI - more than 100 serotypes!
IgA protease as well.
What member of the normal throat flora (also considered part of the Neisseria family) can cause sinusitis, otitis media, bronchitis, and pneumonia?
Moraxella catarrhalis
What is the morphology of gram (-) glucose fermenters?
RODS!
What is the most famous Gram (-) rod? (Also the top cause of of UTIs)
Escherichia coli
What virulence factor does E. coli possess that makes it the top cause of UTI’s?
P-type pills lets it adhere to upper urinary tract epithelium.
What disease can babies get from mom’s normal flora gone wild? (E.coli) What virulence factor contributes to this disease?
Neonatal meningitis…. K1 capsule.
Remember: all bacteria that cause meningitis are encapsulated
T/F: Normal flora E.coli can cause enteric (diarrheal) diseases.
FALSE: can only get enteric diseases from external sources of E. coli.
Bloody diarrhea is characteristic of which toxin produced by what species of bacteria?
Shiga toxin, produced by E. coli.
What type of toxin is Shiga Toxin and how does it work?
A exotoxin that inhibits protein synthesis.
What type of secretion system does E.coli predominately use?
Type 3: pilus!!
Enterohemmorragic diarrhea is characterized by what symptom, and it caused by what specific species of E. coli?
Bloody diarrhea: from shiga toxin.
EHEC - enterohemorrhagic E. coli.
Bacterial infection of the blood is called_____________. What virulence factors of E. coli contribute to this infection?
Bacteremia: caused by capsule and LPS
The award for top cause of food poisoning goes to………? (name the bacterial species)
Salmonella
You go camping and break your water bottle. You are forced to drink from a river. Later, it feels like the river is coming out your butt. You have traveler’s diarrhea. What bacteria caused it? What toxins contributed?
ETEC (enterotoxigenic E.coli) - 2 exotoxins, one of which is similar to cholera toxin.
Not endogenous to the gut!
Remember: watery diarrhea = cholera toxin, or cholera- like toxin.
What is Hemolytic Uremic Syndrome, and what toxin causes it?
Siga toxin disseminates through the blood to cause anemia and renal failure. Result of E.coli infection of the very young.
What category of pathogens do Salmonella sp. fall under? (Frank, Opportunistic)
Frank.
What are the 2 species of Salmonella that cause Entercolitis (Salmonellosis)? …. AKA food poisoning.
What virulence factor is used?
S. Typhimurium and S. Enteriditis.
Have type 3 secretion systems and the ability to kill macrophages
What bacteria begins in the GI tract, then insidiously disseminates to reside within macrophages and kill you?
Salmonella Typhi. Typoid fever.
How does death by S. Typhi occur?
hemorrhage at ruptured Peyer’s patches.
What are the main virulence factors of S. Typhi?
Ability to reside within macrophages, and
Vi antigen that inhibits neutrophil phagocytosis.
How is S. Typhi able to reside in macrophages?
Prevents phagolysosome fusion.
You’re on the Oregon Trail, but you don’t make it. Not because your conestoga wagon got stuck in the river, but because you died of Dysentery. What is dysentery and what bacteria causes it?
Dysentery is bloody diarrhea caused by Shigella sp.
Since the Oregon trail is in America, the specific shigella species is S. sonnei.
If you got dysentery in another country, what species of bacterium would cause it?
Shigella dysenteriae. More severe symptoms than dysentery caused by S. sonnei, which id more common in the US.