Bacterial virulence factors Flashcards
What are commensal bacteria and what is their benefit?
They are bacterial living in the human body.
They aid immune development
Colonisation resistance
Metabolic organ - starches are broken down in the gut by bacteria
What are obligate human pathogens?
Spread widely through causing disease in humans - poor survival outside the host
What are opportunistic bacteria?
They take advantage if you are immunocomprimised
If the normal balance of bacteria is disrupted, disease is caused. True or false?
True
What are the two main categories of virulence factors?
Those that promote colonisation and invasion (invasiveness)
Those that damage the host (toxicity)
Which three virulence factors promote colonisation and invasion?
Flagella
Pili
Capsule
Why are flagella good virulence factors?
They allow movement via rotation
Why are pili good virulence factors?
They allow movement via twitching, the mediate attachment and produce biofilm
Why is biofilm useful for bacteria?
It increases the difficulty to treat the bacteria with antibiotics
Which virulence factors cause host tissue damage?
Exotoxins
Endotoxins
Are endotoxins produced by gram positive or negative bacteria?
Negative
What causes the release of endotoxins?
Lysis
Endotoxins can be killed through boiling of bacteria. True or false?
False - they are very heat stable
Exotoxins are actively excreted. True or false?
True
Exotoxins are part of the gram negative wall. True or false?
False - they are actively produced. Endotoxins are part of the LPS of gram negative wall
Capsules create molecular mimicry. True or false?
True
What virulence factors does Strep.pyogenes produce?
Exotoxin
M protein
Hyaluronic acid capsule
Do all strains of S.pyogenes produce the same virulence factors?
No
Strep.pyogenes belongs to which group of streptococcus?
Group A
Which bacteria causes Necrotising Fasciitis?
S.pyogenes
What is necrotising fasciitis?
Infection of the fascia
How can necrotising fasciitis be treated?
IV antibiotics
Debridement
Staph.aureus produce exfoliative toxins. What are these do?
Damage tissues
What is the effect of a superantigen produced by Staph.aureus?
It damages the host through the host’s immune response - leads to drop in bp, fever etc.
What causes scaled skin syndrome and toxic shock syndrome?
Staph.aureus
