Bacteriology Flashcards Preview

Y2 LCRS - Diganostics 3-5 > Bacteriology > Flashcards

Flashcards in Bacteriology Deck (20):
1

What are the 4 most common diagnostic techniques?

Culture (sterile or nonsterile sites)
Serology
Molecular techniques e.g. PCR
Antimicrobial susceptibility testing

2

What are the different types of agar plate that can grow bacteria?

Chocolate agar
Macconkey agar
Neomycin agar

3

What is the chocoalte agar plate and what is the most common bacteria that grows on it?

haemolysed blood
Haemophilus Influenzae

4

What is the maccokey agar plate for?

Gram negative bacteria
Should be in done before giving antibiotics except for meningitis and meningococcal septicaemia

5

What is the neomycin agar plate for?

Anaerobic bacteria

6

What is the difference in gram negative and gram positive bacteria?

Gram positive has large peitdoglycan wall. Gram negative has smaller, outer membrane and LPS.

7

What is the gram stain useful for?

Selecting antibiotics. Some antibiotics target the cell wall and so they won't be very good for gram negative bacteria e.g. vancomycin

8

What colour are gram positive bacteria and why?

Purple as they hold the gram stain

9

What colour are the gram negative bacteria and why?

Pink (counterstain) as they have an outer membrane which stops them taking up the stain

10

What is the staphylococci coagulase test for and what are the results?

Differentiate between the different Staphyloccoci bacteria. Coagulase positive = Staphyloccocus aureus. (MRSA)
Coagulase negactive - common skin microbes

11

How are the two groups of streptoccoci identified?

Grow them on blood agar.
Alpha haemolysis - incomplete haemolysis, green colour. Streptococcus pneumoniae.
Beta haemolysis - complete haemolysis, clear the agar. Group A - Streptocuccos pyogenes. Group B - Streptococcus agalaticae.

12

What pathogens can cause diarrhoea?

Bacteria - salmonella, shigella, campylobacter, E.coli, C diff, cholera

Parasites - amoeba, giarda, cyrptosporidium

Viruses

13

What 3 pathogens are routinely checked for in stools in the UK?

Salmonella, camplyobacter and shigella

14

How is C diff identified?

Difficult to grow on plates. So mixture of toxin detection and PCR toxin gene

15

What special agar plate is used for salmonella and what are the results?

Xylose lysine deoxylate

Balck colonies formed - cannot ferment xylos

16

How long does campylobacter take to grow?

48hrs

17

What special agar plate is used for cholera?

TCBS - thiosulphate citrate bile salts sucrose. Green colour

18

What is the minimum inhibitory concentration?

the lowest amount of antibiotics required to inhibit the growth of bacteria?

19

What does it mean when the MIC is above the breakpoint?

it should be reported as resistant

20

What is the traditional way of testing antibiotic sensitivity?

Disc diffusion - place discs of different antibiotic concentration on agar plate of bacteria and incubate for 24hrs. The zone size is interpreted using the breakpoints.