04-16 L1 E. Coli Flashcards
What are the 6 variulence factors of E. Coli
- Cell wall
- Outer membrane
- Colanic acid
- Flagella
- pili
- Toxins
Role of cell wall in E. Coli
- G-
- cell wall is composed of thin layer of peptidoglycan
- Peptidoglycans
- responsible for osmotic stability and shape of E. Coli
- inflammasomes
- the cell wall is important in promoting teh inflammasome (via intracelluarl receptors, and driving IL-1beta, T-cells Th17 change)
What ist he role of the outer membrane in E. coli
- lipid layer
- asymmetricl lipid bilaye
- LPS
- lipopolysaccharide is polar
- potent virulence factor of G-
- O antigen
- is the basis for serogroup classifications
- subtype O157:H7
What is the role of Colanic acid in E. Coli?
- blunts phagocytosis
- its a surface polysaccharide
- Resembles a capsule
What is the role of flagella in E. Coli
- Flagella is motile and uses the flagellum to propel itself
- flagellin is recognized by the innate immune system.
What is the role of pili in E. coli?
Pili
- thinner than flagella
- Serve to adhere to host cells, aggregation and genetic exchange through conjugation.
Define the two types of secretion systems
and provide examples
- Secretion systems
- type 2: in which enzymes and toxins are exported to the periplasmic space and then to the external environment
-
Type 3: exports proteins through inner and outer bacterial membranes, injects them into host cells
- seen in EPEC
- Toxins
- hemolysins
- Heat-stable enterotoxin
- Heat-liable enterotoxin
- Seen in ETEC
Where is E. Coli located
Where can it be pathogenic and how does it get into the host?
- GI
- normal constituent of the gut microbiome
- Pathogen
- Uropathogenic E. Coli are more likely than fecal strains to produce P fimbraie
- P fimbraie: bind glycoplipid receptors
- type 1 fimbraie: promote binding to bladder epithelium.
What is the role of type 1 pilius
type 1 pilus mediates bacterial attachment to teh bladder epithelium.
What are risk factors for UTI
What are the symptoms and diagnosis of cystitis
- UTI
- Obstruction
- Presence of a catheter
- Renal transplant
- Cystitis
- symptoms: dysuria, increased freq, urgency, suprapubic pain, hematuria
-
Diagnosis:
- pyuria: greater 5 WBC/hpf
- Nitrite + (many G- Do, some G+)
- Urinte culture
Name the antibiotics that are used for treatment of UTI
- Treatment
- Nitrofurantoin (5-7 day regimen)
- Trimethoprim/Sulfamethoxazole (3 day regimen)
- Fosfomycin: single dose
- Second line therapy: quinolones-ciprofloxacin for 3 days
- Beta lactam: amoxicillin/clavulanate or oral cephalosporin for 3-5 days
What do you use to treat pyelonephritis
ceftraxone
or ampicilin
What is the first and second most common cause of neonatal meningitis
- Group B stretococcus
- E. coli
- freq has K1 capsule which is considered to be facilitate high level septicemia
What is the role of K1 capsule in E. Coli
-
K1 capsule
- is considered to facilitate high level septicemia
- promotes transport across the BBB
- strains of E. Coli cause neonatal meningitis (also express a # of toxins like hemolysin, cytotoxin necrotizing factor)
- impairs host cell cytoskeleton and cytolethal distending toxin which has DNAas activity.
ETEC
common cause
how is it acquired
symptoms
pathogenesis
ETEC
- common cause: most common cause of travelers diarrhea in the world
- how is it acquired: ingestino of containmenated water.
- symptoms: diarrhea, nausea, vomiting, severe cramps, fever not typical
- pathogenesis: pili attaching to the gut epithelium and produce heat stable and heat labile enterotoxins that cause release of fluids.
