The 3 examples:

Question 1

Staphylococcus aureus - Features

Answer 1

• Monoderm (gram+ve)
• Opportunistic pathogen
• Divides in 3 planes, its daughter cells remaining stuck together -> this forms clumps and aggregates (important in the formation in biofilm)
• Has carotenoid pigment called staphyloxanthin -> causes the biofilm to have a ‘golden’ colour
• Stable niche

Question 2

Streptococcus pneumonia - Features

Answer 2

• Gram (+)
• Elliptical shape so will fall on its side - where key VFs are located
• Shape is important in pathogenesis and diagnosis
• Opportunistic

Question 3

Clostridioides difficile - Features

Answer 3

• Gram (+)
• Obligate anaerobe
• Spore forming
• Opportunistic

Question 4

What are the infection-associated dynamics of Staphylococcus aureus?

Answer 4

• Infection recognises association with host, via interaction with specific targets
• Proliferation (evading host defence + nutrient acquisition)
• Local damage of tissue (localised symptoms e.g. boils, furuncles)
• Dissemination of pathogen or products into circulatory system (systemic diseases -> e.g. septicaemia, TSS, Endociditis)

Question 5

Which bactericidal mechanisms does S. aureus attempt to modulate and evade?

Answer 5

Priming, activation, chemotaxis, release of reactive oxidants

Question 6

How does the shape of streptococcus pneumoniae aid its pathogenesis?

Answer 6

The shape ensures that if they contact a surface with their pointed end, they’ll roll onto their longer side -> ensures side on contact -> important because its surface proteins are found mid-cell.

Question 7

How many diseases are caused by Streptococcus pneumoniae:

Answer 7

Pneumonia, meningitis, Sepsis, otitis media

Question 8

What is the reservoir of Streptococcus pneumoniae:

Answer 8

• Exclusively human, it is passed human to human

Question 9

What kind of transmission is S. pneumoniae spread by?

Answer 9

Direct contact of respiratory secretion droplets (not strictly airborne)