Enterobacteriacae Flashcards
What is MacConkey agar?
- contains bile salts to suppress the growth of most gram (+) organisms
- suppresses growth of Neisseria & Haemophilus
- also contains lactose & a pH indicator
What type of agar plates do we use to test lactose fermentation in Gm (-) organisms?
MacConkey agar
Which surface antigen on Gm (-) organisms confers motility?
Flagella
(H Antigen)
What do fibriae do for Gm (-) bacteria?
- allows attachment to host cell
- exhibit phase variation
(used for UTI)
What does it mean if bacteria can form a biofilm?
-they have a capsule
Why can’t organisms that have lipooligosaccharide grow in the gut?
-sensitive to bile salts
What infection is caused by bacteria with P-fimbriae?
Pyelonephritis
What does LPS do to the host?
Activates the sepsis cascade
What are siderophores?
- allow Gm (-) bacteria to scavenge Fe from environment
- Gm (-) bacteria need iron to live
What is the K antigen a part of?
-the gram (-) capsule
What diseases are caused by Klebsiella?
- UTI
- Pneumonia
- multiple nosocomia infections (biliary infection, peritonitis, wound infxn)
When are Morganella and Providencia infections seen?
-individuals with long-term catheters
*very close cousins of Proteus
What diseases are caused by Proteus mirabilis?
- UTI
- Staghorn calculus
What diseases are caused by Citrobacter?
- Catheter associated UTI
- Brain abscess in neonates
What mediates adhesion of E. Coli to intestinal mucosa?
Fimbriae (Pili)
In what organism do we see Hemolytic uremia syndrome (HUS)?
- Enterohemorrhagic E. Coli (EHEC)
- Shigella
What are the three components of Hemolytic uremic syndrome?
- Renal failure
- Hemolytic anemia
- Thrombocytopenia
Pt has renal failure, hemolytic anemia, and thrombocytopenia. What organism are we thinking?
- Enterohemorrhagic E. Coli (EHEC)
- Shigella
* these are the components of Hemolytic uremic syndrome, seen in EHEC infection
What diseases are caused by Enteropathogenic E. Coli (EPEC)?
-acute diarrhea in infants
What diseases does Enteroaggregative E. Coli (EAEC) cause?
- chronic diarrhea & malnutrition in developing countries
- # 2 travelers diarrhea
How do we identify Enteroaggregative E. Coli (EAEC)?
stacked brick adherence to tissue culture cells in Hep-2 cell assay