Microbiology

Question 1

Host-microbe interactions

Answer 1

• symbiosis (commensalist, mutualist, parasite)
• infection
• disease
• host-pathogen interaction does not always result in
  disease

Question 2

Essential microbiota

Answer 2

- symbiotic and mutualistic relationship
   \+ priming of innate immune defences
   \+ colonisation resistance
   \+ vitamin acquisition 
   \+ food degradation
   \+ regulation of energy extraction from food
   \+ terminal differentiation of mucosa
   \+ promotion of epithelial "homeostasis" in the gut

Question 3

Where do infectious agents come from?

Answer 3

• normal endogenous microbiota
• opportunistic pathogens
• classical pathogens
• zoonotic diseases

Question 4

Human pathogens

Answer 4

- prokaryotes
   \+ bacteria
- eukaryotes 
   \+ fungi
   \+ protozoa
   \+ helminths
   \+ ectoparasites 
- non-living
   \+ viruses
   \+ prions

Question 5

Susceptible hosts

Answer 5

• age
• nutrition
• socioeconomic
• co-morbidity
• treatment
• stress
• gender
• genetic predisposition

Question 6

Portals of entry and exit

Answer 6

• endogenous
  + opportunistic pathogens derived from normal regional
  flora
• exogenous
  + pathogens derived from the external environment

Question 7

Reservoirs

Answer 7

- microbe persists
   \+ human
   \+ animal
   \+ non-living
      ~ water
      ~ soil
      ~ biofilms

Question 8

Pathogenesis

Answer 8

• the ability of a microorganism to cause disease
• secretion of proteins that destroy, cripple or subvert
  host target cells (virulence factors e.g. toxins)
• chance encounter

Question 9

Diagnosis of infection

Answer 9

• patient presentation
• specimen collection
• pathogen isolation
• pathogen identification
• treatment
• resolution

Question 10

Specimen collection

Answer 10

- specimen collection is critical
   \+ specimen selection
   \+ timing of specimen collection
   \+ proper collection of specimen
   \+ specimen transport

Question 11

Pathogen isolation

Answer 11

• viable
• isolation in pure culture
• meet metabolic and reproductive requirements
  + nutritional requirements
  + pH
  + atmospheric conditions
  + appropriate media
  + enrichment

Question 12

Phenotypic identification of bacteria

Answer 12

• metabolic activity
• dependent on cell viability
• dependent on cell number

Question 13

Genotypic identification of bacteria

Answer 13

• DNA
• cells may be viable or non-viable
• independent of cell number