Systematic Bacteriology I

Question 1

What 4 categories can microscopy help identify?

Answer 1

Pure culture or polymorph
Shape, size, grouping
Structure
Staining

Question 2

What are the 3 most common shapes of bacteria?

Answer 2

Cocci (spheres)
Bacilli (rods)
Spiral-shapes

Question 3

How does coccus create cocci?

Answer 3

Division in one plane of coccus to produce two cocci, division in one plane produces chains of 4-20 cocci or division in 3 planes produces clumps

Question 4

What type of bacilli can be produced from bacillus?

Answer 4

Bacillus (rod-shaped bacteria) divides into chains of bacilli

Question 5

Is bacilli chaining more prominent in gram +ve or -ve?

Answer 5

+ve

Question 6

What type of gram is more common in vibrio (curved rod)?

Answer 6

Gram -ve

Question 7

How many recognised species of vibrio are there?

Answer 7

34

Question 8

What 2 types of spiral-shaped bacterium are there?

Answer 8

Rigid - spirillum

Flexible - Spirochaete

Question 9

How is it easier for spiral shaped bacteria to be motile?

Answer 9

Corkscrew movement through viscous liquid

Question 10

What are three common structures of bacteria?

Answer 10

Flagella, pili and capsules

Question 11

How are spores created?

Answer 11

Germination, binary fission, sporulation = prespore, endospore, cell lysis = spore

Question 12

What is a gram stain?

Answer 12

A simple method that distinguishes two major classes of bacteria according to cell wall structure (gram -ve and gram +ve)

Question 13

Why would an organism not strain well with Gram stain?

Answer 13

Lipid rich/waxy cell wall that doesn’t take up the stain, or no cell wall at all

Question 14

BMJ best practice
Dynamed
CDC atlanta
European centre for disease prevention and control

Answer 14

Microbiology resources

Question 15

What does respiration of obligate anaerobes use instead of oxygen?

Answer 15

Another electron receptor with a smaller reduction potential than oxygen - less proton motive force across membrane (in ATP synthase ) and less energy released per molecule oxidised

Question 16

What is selective media?

Answer 16

A media that selects for the growth of specific prokaryotes eg Mannitol Salt agar, or salmonella shigella

Question 17

What does selective media allow?

Answer 17

Presence of a specific substrate permits the growth of one organism over another

Question 18

What does differential medial allow?

Answer 18

Incorporation of chemicals produces visible changes in colonies that facilitate identification

Question 19

Eg of differential media?

Answer 19

MacConkay agar and eosi and methylene blue (EMB)

Question 20

How is Streptococcus identified?

Answer 20

Haemolysis - alpha (greening of the colonies), beta (Lancefield Grouping due to colony size) and gamma (no haemolysis)

Question 21

What characteristics are looked at in metabolic profiling?

Answer 21

Utilisation of carbon sources, utilisation of amino acids and eco-enzyme production

Question 22

What characteristics are looked at in metabolic profiling?

Answer 22

Utilisation of carbon sources, utilisation of amino acids and exo-enzyme production

Question 23

What is a serological test?

Answer 23

Host immune response to antigen by the raising of antibodies. Antibodies specific to microbe/virus (polyclonal) or single component (monoclonal) detect presence of specific IgM Ab

Question 24

In DNA technology why is a specific primer necessary?

Answer 24

To amplify a specific piece of DNA

Question 25

What does successful amplification of DNA indicate?

Answer 25

The presence of an organism or even a specific virulence factor

Question 26

What is MLST?

Answer 26

Multi locus sequence typing

Question 27

What is MALDI-TOF?

Answer 27

Matrix assisted laser desorption ionisation time-of-flight

Question 28

How does MALDI-TOF work?

Answer 28

An ion source ionises and transfers analyte ions into gas phase. A mass analyser separates ions by mass to charge ratio (m/z) into a detection device which detects the spectrum of proteins released from a sample resulting in a characteristic signature

Question 29

What are the advantages to MALDI-TOF?

Answer 29

Powerful, rapid, precise and cost-effective

Question 30

What is Linnaean classification?

Answer 30

Kingdom, phylum, class, order, family, genus, species (sub species - strain, resistance, toxin information etc