Lecture 6 - Gastrointestinal Disease 2 Flashcards Preview

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Flashcards in Lecture 6 - Gastrointestinal Disease 2 Deck (26):
1

What can light microscopy show us when investigating GIT disease?

Cysts
'Pus' cells --> inflammation
Parasites

2

What can electron microscopy show us when investigating GIT disease?

Viruses

3

Describe the process of Latex agglutination / EIA / ELISA?

1. Known Ab place on bottom
2. Unbound sites blocked
3. Antigen added from sample
4. Known Ab with conjugated enzyme added
5. Substrate for enzyme added
6. Colour is read

4

What are routine media?

DCA
MAC

5

What are specialised media?

CAMP
BCSA
BP
CIN

6

What are enrichment media?

Selenite broth

7

How would we first identify significant isolates?

Biochemical tests

8

How would we confirm the pathogen?

Serological tests

9

How do we compare strains?

Phage typing
PFGE

10

How do we look for specific virulence determinants?

PCR
Gel electrophoresis

11

What are the features of Enterobacteriaceae?

GNR
Ox. Negative
Fermenters

12

What are the features of Vibrio (Vibrionaceae)?

GN (curved) R
Ox. positive
Fermenters
Motile

13

What are the features of Campylobacter (Vibrionaceae)?

GN (curved) R
Oc. positive
LNF

14

What does MAC allow to grow?

E. coli

Salmonella, Shigella

15

How do we differentiate between E. coli, Shigella and Salmonella on MAC?

Lactose fermenters --> pink (E. coli)

LNF --> Yellow / colourless (Salmonella, Shigella)

16

What does DCA allow to grow?

Similar to MAC

Salmonella: black dot

17

What do we do after culture on routine media?

Look for suspicious colonies:
LNF: Shigella, Salmonella, Yersinia

These are not normal flora of the gut

18

What does Selenite broth allow to grow?

Salmonella spp. --> brick red

19

What does BP select for?

Staphylococcus aureus --> black with zone of clearing

20

What does BCSA select for?

Bacillus cereus --> blue + white precipitate

21

What does CAMP select for?

Campylobacter

22

Describe how an agglutination reaction works

Bacteria + antibody --> visibly agglutinates

23

What is phage typing used for?

To determine the source: same phage types --> same source?

24

Describe the process of phage typing

1. Lawn culture of bacteria applied to plate
2. Panel of phages dotted onto a grid
3. Incubation of plate
4. Pattern of areas of lysis read
5. Phage type assigned

25

What bacteria is phage typing used for?

Salmonella
S. aureus

26

What is PCR used for?

Determining the presence of specific virulence determinants

eg. LT, ST and bfp