M2

Question 1

what is the procedure of sampling as part of a clinical practice/ research?

Answer 1

• handling of specimen
• laboratory processing and reporting
• interpretation and use of information

Question 2

Describe isolating and identifying organism.

Answer 2

• Sample- (for culture,microbial product detection, Ab detection)
• Timing- (secondary infection)
• Handling- ( rapid/match transport medium)
• Request form- (relevant clinical information,thorough and concise)

Question 3

How do you sample purulent infection?

Answer 3

• aspirate of pus
• prevents contamination
• maintains anaerobes

Question 4

How do you sample mucosal infections?

Answer 4

• yeast,swab or oral wash

- herpes,lesion swab

Question 5

how long after are results received for sample cultures?

Answer 5

within 2-5 days

Question 6

Describe the process of samples for culture.

Answer 6

-Streaked on Blood Agar, aerobic & anaerobic
– Smear of pus fixed and analysed by Gram stain
– Initial plate seeded for Antibiotic sensitivity
– Visible colonies analysed at 24-48 hours
– Biochemical profiling
– Antibiotic sensitivity determined (24-48 hours)
– Prolonged incubation for slow growing species optional

Question 7

what are the reasons for culturing?

Answer 7

• determines viability (aerobic versus anaerobic)
• component species (mixture of species
• provides pure materials (amplifies the bacteria/fungus responsible, choose single colony for further characterisation)

Question 8

what is the primary inoculum?

Answer 8

clean loop to spread bacteria

Question 9

what is general media?

Answer 9

transport media :

-excess of nutrients

Question 10

what is enrichment media?

Answer 10

addition of blood/serum/extracts will support growth of fastidious organisms

Question 11

what is selective media?

Answer 11

• a media that selects for the growth of specific prokaryotes
• presence of specific substances permits the growth of one organism over another

Question 12

what is differential media?

Answer 12

Incorporation of chemicals produces visible changes in colonies that facilitate identification

Question 13

How are colonies identified?

Answer 13

Microscopy (single colony or pus sample):
– Pure culture or polymorph
– Shape, size, grouping
– Structures (capsules, flagella, spores)
– Staining (Gram)

Question 14

what is the shape of cocci?

Answer 14

spheres

Question 15

what are the arrangements of cocci?

Answer 15

• single coccus
• pair of cocci (diplococci)
• cluster of cocci (staphylococci)
• chains of cocci (streptococci)

Question 16

what is the difference between staphylococci and streptococci?

Answer 16

staphylococci changes direction and forms cluster whereas streptococci growths in one direction to form poles

Question 17

Describe the process spores and involved in.

Answer 17

• binary fission
• sporulation
• prespore
• endospore
• cell lysis
• spore
• germination

Question 18

Describe biochemical characterisation.

Answer 18

Metabolic profiling:

• utilisation of carbon sources
• utilisation of amino acids

Question 19

Describe serological tests.

Answer 19

Host immune response to Ag by the raising of
Abs.
• Ab specific to microbe/virus (polyclonal), or
single component (monoclonal)
• Detect presence of specific IgM Ab to virus/ microbe
• Demonstrate in vitro by agglutination (aggregation) reaction
• Rapid detection of viruses (24 hours), even possible to identify the stage of infection using two different tests.
• Can identify specific Serotypes of bacteria

Question 20

Name 3 immunological techniques.

Answer 20

• agglutination reactions (clumping)
• direct fluorescence antibody test (DFA)
• ELISA

Question 21

what does agglutination do?

Answer 21

slide agglutination use Ag/Ab specificity

Question 22

what is 16sRNA?

Answer 22

RNA component of Holoenzyme used as molecular signature

molecular signature of bacteria that allows us to assign them to a general species

Question 23

what does MALDI-TOF do?

Answer 23

-Generates a series of ions from a sample dependent on its constituents
• Separates the ions according to mass & charge
• Detects the spectrum of proteins released from a sample
• Results in characteristic signature

Question 24

what is effective about MALDI-TOF?

Answer 24

• powerful-99% correct
• rapid- colony tested in 6 mins
• precise
• cost-effective