Implications for the laboratory

Ref ID: 19458

Author:

R. Barnes

Author address:

Cardiff Universty School of Medicine, United Kingdom

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

Traditional morphological identification schemes are being replaced
by phylogenetic classifications determined by molecular genomic,
proteomic and metabolomic criteria.
DNA markers based in ITS regions and conserved genes can be
used to identify fungi to the species level by PCR and this technology
is routinely available in most laboratories. Increasingly, mass spectro-
scopic techniques such as MALDITOF can identify fungal isolates
extremely rapidly. This is becoming the preferred method for yeast
identification in some larger centres although further evaluation is
required for mould identification and the capital outlay for equipment
is substantial.
Pyrosequencing and even whole genome sequencing are becoming
more available and costs and time are decreasing with new genera-
tion high throughput sequencers. Electronic noses capable of detect-
ing patterns of volatile gases in exhaled breath condensate are
showing promise in the identification of Aspergillus and other moulds and open up the possibility of near patient testing but further work is
needed,
Most of these identification techniques are applied in the labora-
tory after a fungal species has been isolated from a clinical specimen
usually by routine culture. Consequently the time savings and clini-
cal impacts for the patient may be minimal. PCR/electron spray Ioni-
zation-Time-of-Flight-Mass Spectrometry has the potential to detect
organism directly in clinical specimens but is not routinely available
yet.
Some interpretation of the clinical significance of isolates needs to
be made prior to identification to avoid over-interpration of potential
contaminating organisms and optimise clinical utility of these new
techniques.
Rapid identification to the species level facilitates the laboratory by
enabling more rational choice and interpretation of antifungal sus-
ceptibility testing and can improve initial patient management.
The laboratory may also be confounded by the taxonomic name
changes and species variants brought about by the genomic era. In
addition to complete reclassification amongst the mucoraceous
mould, Aspergillus ustus, Candida orthoparapsilosis etc are now com-
mon findings Sexual teleomorphs identified through mating type loci
analysis turn Aspergillus into Neosartorya. Little is known of theimpli-
cations that these ’names’ have for virulence and disease potential.
Until clinical utility and impact can be demonstrated it is difficult to
justify routine molecular identification of all fungi to species level
outside of reference laboratories. Algorithms will help identify the
most clinically useful.

Abstract Number: w10.3

Conference Year: 2013

Link to conference website: NULL

New link: NULL

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