BIOL243 - L10

  • Created by: Katherine
  • Created on: 27-04-17 17:41
What is gram staining?
It is used as a basis for traditional bacterial identification schemes - it is cheap, rapid and reliable.
1 of 60
What is gram staining based on?
Cell wall structure
2 of 60
When was gram staining devleoped?
1884
3 of 60
What are the limitations of gram staining?
Low sensitivity for some samples (need high bacterial load to detect), limited information
4 of 60
What is a direct wet film?
The sample is put in saline to keep wet.
5 of 60
What is direct wet film staining used for?
To detect /view parasites/cysts/ova, fungi.
6 of 60
What are the pros of wet film staining?
Cheap, high specificity, versatile, 'wet', can be used with stains to enhance features.
7 of 60
What are the cons of wet film staining?
It is time consuming to review slides - it requires skileld technician, heavy pathogen load is needed
8 of 60
What is an acid fast stain?
Known as auramine phenol or Ziehl-Neelsen - uses fluorescence of stain to highlight microorganisms.
9 of 60
How does the acid fast stain work?
Mycolic fatty acid in the cell wall blocks acid/alcohol
10 of 60
When is the acid fast stain used?
In the lab for TB, it is a very rapid test, it is cheap and targets the pathogen
11 of 60
What are the cons of acid fast stain?
Dependant on high bacterial load and skill of technician
12 of 60
What are the agar culture methods? Types of media
Define or non-defined media.
13 of 60
What are the four groups of agar?
Basal/nutrient, enriched, selective or differential.
14 of 60
Agars can be a mixture of these groups, what makes blood agar?
Enriched and differential
15 of 60
What is the mixture of agar that makes up MacConkey agar?
Selective and differential
16 of 60
What is the mixture of agar that makes up Thayer-Matin agar?
Enriched and selective
17 of 60
What is the mixture of agar that makes up URIselect/chromogenic?
Nutrient and differential
18 of 60
When is liquid culture used?
In automated culture systems, e.g. blood culture or mycobacteria. It is often used for enrichment.
19 of 60
What does liquid culture do?
It enables bacteria to grow in tranditional natural morphology
20 of 60
Most liquid culture invovles...
eventual inoculation onto solid agar
21 of 60
What does an immunoassay do?
Determines the presence or quantity of a molecule (antigen, antibody, toxin or protein) in a solution
22 of 60
What does the immunoassay method involve?
Antibodies developed to a specific target.
23 of 60
What are types of immuno assay?
ELISA,
24 of 60
What is an ELISA:
Antibodies are developed to an antigen or antibody detects it's presence
25 of 60
What are ELISAs used to detect?
Antigens or antibodies.
26 of 60
What is the method?
Antibody developed (monoclonal or polyclonal depending on target desired.
27 of 60
What are the features of an ELISA?
Can be automated to increase reliability, speed and consistency. Can have cross reactions and must ensure procedure followed exactly to remove unbound antibody.
28 of 60
What is an immunochromatographic test?
A type of assay - also called lateral flow or ***** tests
29 of 60
What does an immunochromatographic test look like?
Paper impregenated with speciic anyibodies, using same principles as ELSE
30 of 60
What is the immunochromatographic test used for
Able to use various sample types. Can detect one or multiple pathogens.
31 of 60
What are the pros of immunochromatographic tests?
Minimal sample preparation, rapid, simple to interpret results, limits range or targets, variable sensitivity.
32 of 60
What do immunochromatographic tests do?
Detect one or multiple pathogens
33 of 60
What are the pros of immunochromatographic tests
Able to ue various sample types, can detect one or multiple pathogens, minimal sample preparaion, rapid, simple to interpret results, limited range of targets, variable sensitivity
34 of 60
What is the latex/slide agglutination used for?
To detect antigens (e.g. specific surface antigens or bacterial products)
35 of 60
How does latex/slide agglutination work?
Inert latex particles bound to specific manufactures antibodies.
36 of 60
What is required in latex/slide agglutination?
Direct agglutination or extraction process may be required by heating or acid.
37 of 60
What can the latex/slide agglutination test for?
Single or multiple things in single serum. Polyvalent salmonella sera. Staph aureus latex d
38 of 60
What are the pros of the latex slide agglutination method?
Rapid, cheap, invaluable tool
39 of 60
What are the cons of the late/slide agglutination method?
False positives due to auto-agglutination, can be identified by control latex.
40 of 60
What are the main molecular techniques?
Molecular methods which involve targeting the genetic components of a pathogen.
41 of 60
What are types of NAAT?
PCR
42 of 60
How is PCR done?
A target section of DNA is matched to a primer and replicated several times to a detectable quanitiy, may use multiple targets.
43 of 60
When is PCR used?
For chlamydia and gonorrhoea.
44 of 60
What are the pros of NAAT methods?
Works on damages and low quality DNA, IS RAPID AND ABLE TO ISOLATE dna FROM A MIXTURE.
45 of 60
What are the cons of NAAT methods?
Contamination risks, targeet site can change.
46 of 60
What is proteomics?
Study of protein structure and function
47 of 60
What are methods of proteomics?
MALDI-TOF MS - Matrix assisted aser desorption ionization time of flight mass spectrometry
48 of 60
What does the MALDI TOF MS do?
Soft ionization and vaporisation of biomolecules produces distinctive fingerprints which can be applied to bacteris, virus and fungi identification.
49 of 60
Why is the formation of fingerprints useful?
Library database allows identification of rare and difficult organisms.
50 of 60
What are the pros oc proteomics?
RAPID,
51 of 60
What are the cons of proteomics?
Needs pure culture and it is expensive.
52 of 60
What is campylobacter?
Pathogen causes enteritis in 1972.
53 of 60
How is campylobacter cultured?
Using blood free charcoal agar. Incubated at 42'C in microaerophillic environment
54 of 60
How is campylobacter identified?
Identify cultures from simple gram film and oxidase test
55 of 60
What caused 1977 Pseudomembraneous colitis?
Clostridium difficile
56 of 60
How do you diagnose Clostridium difficile? Previously
Agar culture followed by tissue cytotoxin neutralisation assay. ELISA testing for toxin A and/or B.
57 of 60
How is Clostridium Difficile identified now?
Immunochromatographic tests for: Glutamate dehydrogenase- enzyme produced by some bacteria. Toxin A and B. Only produced by C.difficile. Calprotection - protein biomarker for inflammation.
58 of 60
How long does it take to diagnoise Clostridium difficile?
1 hr. Epidemiology monitored by annual submission of samples to reference lab for typing and sensitivity testing.
59 of 60
What are points to consider?
Bacteria and viruses evolve faster than we can develop. They mutate and swap insert code sections.
60 of 60

Other cards in this set

Card 2

Front

What is gram staining based on?

Back

Cell wall structure

Card 3

Front

When was gram staining devleoped?

Back

Preview of the front of card 3

Card 4

Front

What are the limitations of gram staining?

Back

Preview of the front of card 4

Card 5

Front

What is a direct wet film?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Medical resources »