Introduction to Infection

Question 1

What is an infection?

Answer 1

Invasion of a host’s tissues by micro-organisms

Question 2

What can the disease from an infection be caused by?

Answer 2

Microbial multiplication, toxins, host response

Question 3

What are microbiota/commensals?

Answer 3

Microbes carried on skin/mucosal surfaces that are normally harmless (sometimes beneficial) but can be harmful when transferred to other sites

Question 4

What is an example of an infection where a vector is necessary?

Answer 4

Malaria (mosquito)

Question 5

What is an example of an infection passed onto humans from animals?

Answer 5

Rabies (eg bitten by infected dog)

Question 6

What are some modes of horizontal transmission?

Answer 6

Contact (direct, indirect, vectors)
Inhalation (droplets, aerosols)
Ingestion

Question 7

What is a mode of vertical transmission?

Answer 7

Mother to child, before or at birth

eg HIV can be passed on in this way

Question 8

In which two ways can micro-organisms cause disease?

Answer 8

Release of toxins (exo and endo)

Host cellular damage

Question 9

What are some disease determinants in a pathogen?

Answer 9

Virulence factors, inoculum size, antimicrobial resistance

Question 10

What are some disease determinants in a patient?

Answer 10

Site of infection, co-morbidities

Question 11

What are some supportive investigations?

Answer 11

Full blood count, CRP, blood chemistry, LFT, imaging, histopathology