Diagnostic and typing methods Flashcards
What are the bacteria associated with periodontal disease
p. gingivitis
a. actinomycetemcomitans
p. intermedia
b. forsythus
What are the 3 bacterial detection methods
microbiological culture
molecular biological
What is the microbial culture
culture on suitable agar medium
isolate bacteria
identify by characterization of enzyme activities and sugar fermentation test
What is the molecular biology
DNA probes
polymerase chain reactions (PCR)
What are the advantages of culture methods
yields bacterial isolates for future testing and study e.g antibiotic sensitivities
What are disadvantage of culture methods
requires viable cells insensitive only small numbers of samples can be analyzed at once inconclusive results labour intensive
What is the advantages of PCR
highly specific
sensitive
can be sued to directly detect bacteria in clinical specimens
What do PCR primers target
16S rRNA gene
What are the advantages of DNA probes and PCR
less time consuming than culture methods
v sensitive
can directly detect bacterial DNA within clinical samples
do not require viable cells, samples do not have to be analyzed immediately
can detect uncultivable species
What are the disadvantages of DNA probes and PCR
may detect dead cells
detect only pre-selected species
Why is it important to subtype bacteria
it tracks routes of transmission during disease outbreaks
study pathogenicity of specific strains
What are the traditional methods for sub typing bacteria
testing for 1 or more phenotype markers
serotyping
biotyping
What are the problems for traditional methods for sub typing bacteria
limited discriminatory capacity
organism specific methods
specialized reagents required
What are the molecular typing methods
restriction enzyme analysis gene probe typing ribotyping IGS DNA sequencing
What is a DNA probe
segments of DNA that have been labelled with chemiluminescent, fluoroscent or radioactive agents
