1,2 – Introduction+Fundamentals

Question 1

Prokaryote:

Answer 1

• Unicellular microorganism lacking nucleus and membrane bound organelles
• Asexual reproduction
• Lateral transfer of genetic material
• Circular chromosome
• Ex. bacteria and archaea

Question 2

Eukaryote:

Answer 2

• Uni or multi-cellular organisms containing nuclei and membrane bound organelles

Question 3

Gram positive vs. Gram negative cell wall

Answer 3

• Peptidoglycan: large in gram positive (40-80% of dry weight)
• Membranes: outer and inner membrane in gram negative
  o Outer membrane: barrier to many antimicrobials
• Porins: in gram negative
  o Allows things to get through membrane
• Periplasmic space: between the outer and inner membrane of gram negative

Question 4

Colony forming unit (CFU)

Answer 4

• Clonal population which descended from a SINGLE viable organism (‘ancestor organism)

Question 5

Streak out plates for isolation

Answer 5

• Semi-quantitative
  o Scant = <10 colonies on 1st
  o 1+ = >10 colonies on 1st
  o 2+ = >10 colonies on 2nd
  o 3+ = >10 colonies on 3rd
  o 4+ = >10 colonies on 4th

Question 6

Isolate

Answer 6

• A PURE culture
• Derived from a single colony
• Genetically HOMOGENOUS

Question 7

Selective media

Answer 7

• used to preferentially isolate a particular taxa
  o contains chemicals to inhibit growth on non-target organisms

Question 8

Differential media

Answer 8

• exploits physiological properties of organisms of interest
  o often colourimetric

Question 9

Plasmid

Answer 9

• extrachromosomal
• independently replicating DNA molecule

Question 10

Identification of organisms

Answer 10

-Biochemical tests
-MALDI-TOF
-NAAT

Question 11

• Biochemical tests

Answer 11

o Phenotypic assays
 Colour change, agglutination or change in consistency of media

Question 12

• MALDI-TOF: ‘answer box’

Answer 12

o Fast and inexpensive

Question 13

NAATs (nucleic acid amplification tests)

Answer 13

o PCR
 Polymerase chain reaction
 Used for amplification of target DNA sequences
o RT-PCR
 Real time PCR
 Simultaneous amplification AND detection of target DNA sequences
 May or may not be quantitively

Question 14

Biocontainment level (Canada): level 1

Answer 14

o Unlikely to cause disease if healthy
o Ex. environmental organisms, reference isolates

Question 15

Biocontainment level (Canada): level 2

Answer 15

o Majority of common pathogens

Question 16

Biocontainment level (Canada): level 3

Answer 16

o Important zoonoses and fungi causing systemic mycoses

Question 17

Biocontainment level (Canada): level 4

Answer 17

o Scariest pathogens
o Ex. virus (Ebola, herpes B)

Question 18

Biological risk group

Answer 18

• Consideration of
  o Availability of preventive measures (ex. vaccines)
  o Availability of effective treatments (ex. antibiotics)
  o Pathogenicity
  o Infectious dose
  o Mode of transmission
  o Host range

Question 19

RG1

Answer 19

low individual, low community

Question 20

RG2

Answer 20

moderate individual, low community

Question 21

RG3

Answer 21

high individual, low community

Question 22

RG4

Answer 22

high individual, high community