Gram Negative Bacteria Flashcards

1
Q

List the virulence factors that make *Pseudomonas *such a formidable pathogen.

A
  1. Flagellum (for motility)
  2. Capsule/ slime layer (avoid phagocytosis, retain moisture/ prevent dehydration, prevent antimicrobial penetration)
  3. Quorum sensing (cell-to-cell communication, biofilm coordination, cell aggregation)
  4. Endotoxins (release of toxins causing shock)
  5. Cytophores (acquisition of iron from the host, important for bacteria undergoing binary fission)
  6. Polysaccharide coating (hinders attachment of membrane attack complexes)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Epidemiology of Pseudomonas aeruginosa

A
  • “The green pus bacteria”
  • Environmental organism
  • Found in water, soil, on the skin, intestinal tract
  • Opportunistic pathogen/ secondary invader (often affecting wounds, bites scratches, damaged tissues or immunocompromised individuals)
  • Common in noscomial infection (e.g. IV and urinary catheters)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Pathogenesis of Pseudomonas aeruginosa

A
  • Wide array of virrulence factors (capsule, slime layer, flagellum, quorum sensing, adhesions/ pilli, endotoxins, polysacharide coating)
  • Resisitant to many antimicrobials
  • Umbicuitous (non-specific in nature, infecting many species and humans)
  • Found everywhere (soil, skin, intestines, water etc.)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why is pseudomonas an opportunistic and not a primary pathogen?

A
  • Becuase of its route of entry, causing infection
  • Enters via damaged tissue (e.g. bites, scratches, wounds, samaged tissue) or via immunocompromised individuals
  • It has a widespread resistance to antimicrobials which aid its its host defences
  • umbicuitous (can infect many species including humans)
  • Common noscomial infections associated (IV catheter or urinary catheter)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How would you diagnose a Pseudomonas infection?

A
  • Important to remember that pseudomonas is an aerobic pathogen and will only grow in aerobic environments (Mconkey Agar)
  • Depends on the location of wound for sample (opportunisitc infection)
  • Culture on Mconkey Agar

For example:
* Cystic fibrosis: respiratory aspirates
* Burn: pus from site
* Mastitis: milk sample

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Treatment of a Pseudomonas infection

A
  • Debridment of wound
  • Treatment varies depending on cause of bacterial overgrowth
  • Invitro suseptibility testing should be performed on all isolated to determine drug of choice
  • Can us a combination of an aminoglycoside and B lactam in serious cases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly