Diagnostics Flashcards
What testing can be done for bacteria?
Microbiological culture with agar
DNA probe
Polymerise chain reaction
What is PCR?
DNA is denatured and unwound
Primers are added to induce bonding of single free nucleotides to duplicate DNA
DNA can then be cultured and tested further
How does selective agar work?
Specific medium used to inhibit growth of unwanted bacteria
Allows target bacteria to grow and form visibility colonies
After growth, the bacteria present can be viewed and identified and treated, or tested further
Main periodontal bacteria?
Porphyromonas gingivalis
Prevotella intermedia
Treponema denticola
Tannerella forsythia
Dental caries bacteria?
Strep mutans
Main bacteria in RC infection?
Porphyromonas endodontalis
Fusobacterium nucleatum
Bacterial detection methods?
Microbiological culture
- agar
- isolate bacteria
PCR
- amplify and replicate bacteria
16s rRNA ribosome sequencing
What is a ‘DNA probe’ and its function?
Segments of DNA that have been labelled with chemoluminescent, fluorescent or radioactive agents
Used to search for its complementary sequence in sample organisms
What is 16S rRNA gene?
Found in all bacteria and is essential for their survival
- it has been sequenced for all known bacteria
- can use DNA probes to identify bacteria, or primers
The gene is then sequenced to and analysed to identify the bacteria
Advantages of DNA probes and PCR?
Less time consuming than culture
Very sensitive
Directly detect bacterial DNA within samples
Do not require viable cells and samples do not have to be analysed immediately
Can detect uncultivable species
Disadvantages of DNA probes and PCR?
May detect dead cells
Can -only detect pre-selected species (primer for species)
