5: Plaque Microbiology


Plaque microbiology

Table 5.1 Different methods of examining plaque microbial composition.

Method Advantages Disadvantages
Microscopy Recognition of morphological types
Determine spatial arrangements of organisms
Recent novel, sophisticated applications, e.g. atomic force microscopy gives very high image resolution
Slow and labour intensive
Precise speciation using immunological or hybridisation methods only possible for a few species in sample
Culture – predominant Can detect unrecognised species
Provides cultures for further analysis
Very labour intensive
Some uncultivable species
Difficult to culture spirochaetes
Culture – selective media Can detect specific species As above
Need to know which species to investigate
Few suitable media
Limited species identification
Immunofluorescence, ELISA Quite specific
Cheaper than culture
Can distinguish species
Can provide counts or proportions of specific species
Limited numbers of monoclonal or polyclonal antisera available
Takes time to develop
Relatively small numbers can be run
PCR Reasonable sensitivity
Quite specific
With appropriate primers can detect very small numbers of species present
Dichotomous (i.e. detects presence/absence not quantities)
Depends on amplification
Not suitable for large numbers of species in large numbers of samples
Real-time PCR Quantitative
Relatively slow
As above, limited numbers can be processed
DNA–DNA hybridisation Quantitative
Low likelihood of cross-reactions with other species
Only detects species for which probes are available
Modest numbers of species for modest number of samples
Checkerboard DNA–DNA hybridisation Quantitative
Can use whole sample without dilution or amplification by PCR
Large numbers of species and samples

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Jan 14, 2015 | Posted by in Periodontics | Comments Off on 5: Plaque Microbiology
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