LETTER
The recently published update of fungal nomenclature (1) generated heated debate on social media with predictions of patient harm and disruption of mycological literature, one example being the following Tweets from the Twitter exchange at https://twitter.com/ABsteward/status/1313985253405536264 (accessed 23 October 2020).
LeonardH (@OSheaLaos): Why the change? Do they no longer belong to the Candida family? (8 October 2020, 10:20 a.m.)
S. Kidd (@thefunguskidd): “Candida” is an artificial construct for white yeasts - It has no taxonomic value. The ‘new’ names represent the phylogenetic basis for these genera/species. (8 October 2020, 8:50 p.m.)
B. Spellberg (@BradSpellberg): I’m sure the families of patients who are harmed due to wrong treatment being given caused by name change will take comfort in the knowledge that their loved one’s sacrifice helped advance taxonomic science. (9 October 2020, 9:37 p.m.)
Nomenclature changes are not new and have been increasing in mycology, for reasons well explained by the authors. For example, reassignment of various species out of the “genus” Candida is apt because “Candida” is an artificial grouping of white budding yeasts with little reflection of the evolution of species which were placed within this genus.
Arguments that taxonomic changes have clinical repercussions, however valid, can be mitigated. As the authors state, laboratories can support the transition by including in the report the more familiar species name, e.g., “Pichia kudriavzevii (formerly referred to as Candida krusei).” If repeated consistently, over time the new genus/species names will become associated with the clinical knowledge attributed to the previous names. Not many clinicians today will recall that Cryptococcus neoformans was previously Torula histolytica, among other names, with similar resistance encountered to the change. There are also potential clinical benefits which should not be overlooked; renaming Candida krusei (Pichia kudriavzeveii), and Candida glabrata (Nakaseomyces glabrata), for example, emphasizes fluconazole nonsusceptibility in keeping with traits of genera Pichia and Nakaseomyces, but in contrast to other Candida species.
Current nomenclature changes include those of common pathogenic fungi and to achieve change safely, communication between the clinical microbiology laboratory and clinicians is key, but such practice is already a requirement. Additionally, commercial fungal identification databases are slow in update implementation, and education of laboratory staff on detecting and reporting identifications with obsolete nomenclature is essential. We note however, that the recently updated Clinical and Laboratory Standards Institute documents M27-Edition 4, M59-Edition 3, and M60-Edition 2 continue to refer to Candida species by their previous names (2–4); this requires urgent discussion.
Concerns about disruptions to mycology literature are likely overstated. NCBI databases for journal articles and molecular data are underpinned by a standardized taxonomy database, which ensures that searches for a particular organism retrieve all relevant material, regardless of the species name they were originally submitted under (5).
The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) Mycology external quality assurance (EQA) module has taken a progressive approach to fungal nomenclature changes with the goal of promoting consistent reporting among Australasian laboratories. A list of clinically important fungal species is updated and distributed annually, indicating nomenclature changes with explanation where appropriate. Commentary is provided in survey reports, and superseded taxonomy is removed from the dropdown list of species for EQA result submission. To further reinforce nomenclature changes within clinical laboratories, since 2018, EQA participants reporting species names that have been communicated as obsolete for >1 year are scored with a minor discordance. Initially, 43% of participants were penalized for reporting an obsolete species, but this decreased to <1% over only 2 years.
In conclusion, we acknowledge that fungal nomenclature change will take time to embed but support the advice of Borman and Johnson (1), that with clear guidance to support clinicians and laboratories, we can move forward with taxonomic progress while minimizing risk to patients.
Footnotes
For the author reply, see https://doi.org/10.1128/JCM.02896-20.
REFERENCES
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