Gram Negative Rods Flashcards
Biochemical and growth properties of Pseudomonas aeruginosa
Opportunistic aerobe, makes pigments in humans and agar (green), oxidase positive
What types of diseases does Pseudomonas aeruginosa cause?
Opportunistic infection and nosocomial (hospital acquired infections)
What is Pseudomonas relationship to cystic fibrosis and burns?
CF: Cl- transporter (CTFR) pumps little Cl- = thick mucous due to no water released to thin it out
Burns: can get deeper into body bc no barrier (sepsis)
What are the 3 major bacterial structures used for attachment/colonization in Pseudo?
- Type 4 Pili: adhesions that attach to surface sialic acid
- Flagella: adhesions that attach to surface mucins
- Alginate Slime: thick polysacc that surrounds mucin (binds mucins to host lung cells)
What does Type IV pili do in Pseudo?
Helps with movement (pili shrinks and grows), proteases degrade fibronectin (exposes sugars for pili)
What are the host targets of the bacterial structures used for attachment in Pseudo?
- Type 4 Pili: surface sialic acid
- Flagella: surface mucins
- Alginate Slime: mucins on host lung cells
How does Pseudo obtain iron, phosphate, and other nutrients?
Iron: Siderophores that scavenge Fe to bacteria (pyochelin and pyoverdin)
Phosphate: Phospolipases that destroys phospo bilayer that releases phosphate
Other: Lemolysins that destroy tissues = releases lots of nutrients
What is the function of elastase, phospholipase, and exotoxin A in Pseudo?
Elastase: secreted and destroys ECM (collagen, elastin, fibronectin)
Phospholipase: destroy eukaryotic cells (blood cells)
ExoA: MOST TOXIC stops translation and cell dies
What do ExoS, T, U, and Y proteins do and how do they get into the cell in Pseudo?
Toxins in Type 3 secretions systems that injects directly into target cell (not exposed to immune invasion)
What is the role of inflammation in the damage of Pseudo?
Endotoxin can cause Lipid A to activate TNFa = hypertension, shock, death
How do the bacteria evade host attack in Pseudo?
- Production of biofilm
- Elastase destroying antibodies
- Exoenzymes alter cytoskeleton structure
How is Pseudo diagnosed?
Grow on blood agar OR EMB (look for florescence)
How is Pseudo treated?
Multiple antibiotics bc resistant and avoids easily
How is Pseudo prevented?
Common in hospitals so clean throughly
- Clean contacts, wounds, jacuzzi, etc
What is the role of Type III secretion in the pathogenesis of Pseudo?
Helps avoid immune response (phagocytosis and endocytosis) bc injected directly into target cell
Biochemical and growth properties of Helicobacter pylori
Spiral rod, fastidious, and causes ulcers
What types of diseases does H. pylori cause?
ulcers, gastritis, different forms of stomach cancer (only bacteria found to cause stomach cancer)
How prevalent is H. pylori in the population and how is it thought to be transmitted?
1/3 of world infected (higher in elderly/developing countries) - clinical is 10-15%
Transmission thought to be person to person or fecal-oral (not sure)
How does H. pylori survive the pH of the stomach?
Produces urease that turns urea into ammonia (ammonia inc pH to more basic)
How does H. pylori attach to the mucus above the epithelium?
Via a membrane-bound form of urease (replicates well and can survive for a long time)
Why does H. pylori move through the stomach mucus and how does it do so (how does it know where to go)?
Why: Certain genes only turned on when bound to cell (moves with flagella like corkscrews)
How: Follows concentration gradient of urea and mucins
How does H. pylori attach to the stomach cells directly?
BabA , HopZ, Alp proteins that target sugars on cell surface = triggers binding in both cells
What is a Type IV secretion system and what is it used for?
Type 4 secretion system is used to inject other virulence factors (CagA and VacA)
What is the role of cagA and vacA in H. pylori?
CagA: disrupts cell junctions, turns on cell signaling that alters cell division, cell death
VacA: induces vacuolation and increased membrane permeability that leads to cell death and release of nutrients (more holes in them that kills cells)
