Candida auris
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Ascomycota
Class:	Saccharomycetes
Order:	Saccharomycetales
Family:	Saccharomycetaceae
Genus:	Candida
Species:	C. auris
Binomial name
Candida auris Satoh & Makimura, 2009[1]
Type strain
DSM 21092[2]

Candida auris is aspecies offungus that grows asyeast.^[1] It is one of the few species of the genusCandida which causecandidiasis in humans. Often, candidiasis isacquired in hospitals by patients withweakened immune systems.C. auris can cause invasive candidiasis (fungemia) in which thebloodstream, thecentral nervous system, and internalorgans are infected. It has attracted widespread attention because of itsmultiple drug resistance. Treatment is also complicated because it is easily misidentified as otherCandida species.

Candida auris was first described in 2009 after it was isolated from the ear canal of a 70-year-old Japanese woman at the Tokyo Metropolitan Geriatric Hospital in Japan. In 2011, South Korea saw its first cases of disease-causingC. auris. Reportedly, this spread across Asia and Europe, and first appeared in the U.S. in 2013.^[3]

DNA analysis of four distinct but drug-resistant strains ofCandida auris indicate anevolutionary divergence taking place at least 4,000 years ago, with a common leap among the four varieties into drug-resistance possibly linked to widespreadazole-type antifungal use in agriculture.^[3] However, explanations for its emergence remain speculative.

Identification and morphology

First identified in 2009,Candida auris is aspecies ofascomycetous fungus of the genusCandida that grows as ayeast.^[1] Its name comes from the Latin word for ear,aus (genitiveauris).^[4] It forms smooth, shiny, whitish-gray, viscous colonies on growth media. Microscopically, cells are ellipsoid in shape.^[1]

Genome

Several draftgenomes fromwhole genome sequencing have been published.^[5][6]C. auris has a genome size of 12.3–12.5Mb with aGC-content of 44.5–44.8%.^[5][6] TheC. auris genome was found to encode several genes for theABC transporter family, amajor facilitator superfamily, which helps to explain itsmultiple drug resistance.^[5] Its genome also encodes virulence-related gene families such aslipases,oligopeptide transporters,mannosyl transferases andtranscription factors which facilitate colonization, invasion, and iron acquisition.^[5] Another factor contributing toantifungal resistance is the presence of a set of genes known to be involved inbiofilm formation.^[5]

More studies are needed to determine whether the phylogenetic divergence ofC. auris clones exhibits region-specific patterns of invasiveness, virulence, and/or drug resistance.^[7]

Clinical significance

Candida auris has attracted increased clinical attention because of itsmultiple drug resistance.^[5][9][3]

In vitro, more than 90% ofC. auris isolates are resistant tofluconazole^[10][11] and a range of 3–73% ofC. auris isolates are resistant tovoriconazole,^[11][12] while other triazoles (posaconazole,itraconazole, andisavuconazole) display better activity.^[10][11][12] Of isolates, 13% to 35% were reported resistant to amphotericin B;^[10][12] however, most isolates are susceptible toechinocandins.^[10][11][12]

Treatment is complicated becauseC. auris is easily misidentified as various otherCandida species.^{[5][9][13][14]} A brief outline of its clinical relevance as of 2016^[update], understandable by general audiences, was published by theCenter for Infectious Disease Research and Policy at theUniversity of Minnesota.^[15]

According to papers published from 2011 to 2016, mortality of people withC. auris bloodstream infections (BSI) ranged from 30 to 60%.^[16] Many of these people had other serious illnesses and conditions (comorbidities) that increased their risk of death.^[16]

In October 2023, the Faculty of Medicine of theUniversity of Porto published a study which proved thathydrogen peroxide is extremely effective at killing C.auris in hospital surfaces, preventing it from spreading.^[17]

Vaccine development

As of October 2024^[update] there is no human vaccine againstCandida auris.^[18] Experiments involving the NDV-3A vaccine have successfully immunizedmice against the fungus.^[19] The vaccine also improved the protective efficacy of the antifungal drug micafungin againstC. auris infection in the mouse bloodstream.^[20]

Epidemiology

Geographical differentiation

Thephylogenetics ofC. auris suggest distinctgenotypes exist in different geographical regions with substantial genomic diversity.^[7] A variety of sequence-based analytical methods have been used to support this finding.^{[citation needed]}

Whole genome sequencing and analyses of isolates from Pakistan, India, South Africa, Venezuela, Japan, and previously sequencedC. auris genomes deposited in theNational Center for Biotechnology Information's Sequence Read Archive^[22] identified a distinct geographic distribution of genotypes.^[10] Four distinctclades separated by tens of thousands ofsingle-nucleotide polymorphisms were identified.^[10] The distribution of these clades segregated geographically to South Asia (India and Pakistan), South Africa, Venezuela, and Japan with minimal observed intraregion genetic diversity.^[10]

Amplified fragment length polymorphism analysis ofC. auris isolates from the United Kingdom, India, Japan, South Africa, South Korea, and Venezuela suggested that the London isolates formed a distinct cluster compared to the others.^[23]

Comparison ofribosomal DNA sequences ofC. auris isolates from Israel, Asia, South Africa, and Kuwait found that the strains from Israel were phylogenetically distinct from those from the other regions.^[24]Chatterjee et al. wrote in 2015, "Its actual global distribution remains obscure as the current commercial methods of clinical diagnosis misidentify it asC. haemulonii."^[5]

History

Candida auris was first described in 2009 after it was isolated from theear canal of a 70-year-old Japanese woman at the Tokyo Metropolitan Geriatric Hospital in Japan.^[1] It was isolated based on its ability to grow in the presence of the fungicidemicafungin, anechinocandin class fungicide.^[1] Phenotypic, chemotaxonomic and phylogenetic analyses establishedC. auris as a new strain of the genusCandida.^[1][25]

The first three cases of disease-causingC. auris were reported from South Korea in 2011.^[26] Two isolates had been obtained during a 2009 study and a third was discovered in a stored sample from 1996.^[26] All three cases had persistent fungemia, i.e. bloodstream infection, and two of the patients subsequently died due to complications.^[26] Notably, the isolates initially were misidentified asCandida haemulonii andRhodotorula glutinis using standard methods, until sequence analysis correctly identified them asC. auris.^[26] These first cases emphasize the importance of accurate species identification and timely application of the correct antifungal for the effective treatment of candidiasis withC. auris.^[26]

During 2009–2011, 12C. auris isolates were obtained from patients at two hospitals in Delhi, India.^[27] The same genotype was found in distinct settings: intensive care, surgical, medical, oncologic, neonatal, and pediatric wards, which were mutually exclusive with respect to health care personnel.^[27] Most had persistent candidemia and a high mortality rate was observed.^[27] All isolates were of the same clonal strain, however, and were only identified positively by DNA sequence analysis.^[27] As previously, the strain was misidentified with established diagnostic laboratory tests.^[27] The Indian researchers wrote in 2013 thatC. auris was much more prevalent than published reports indicate since most diagnostic laboratories do not use sequence-based methods for strain identification.^[27]

The fungus spread to other continents and eventually, a multi-drug-resistant strain was discovered in Southeast Asian countries in early 2016.^[28]

The first report of aC. auris outbreak in Europe was an October 2016 inRoyal Brompton Hospital, a London cardio-thoracic hospital.^[23] In April 2017,CDC directorAnne Schuchat named it a "catastrophic threat".^[29] As of May 2017^[update] the CDC had reported 77 cases in the United States. Of these, 69 were from samples collected in New York and New Jersey.^[30]

As of 31 August 2019^[update] the number of cases of people having contractedC. auris in the United States had risen to 806, with 388 reported in New York, 137 in New Jersey and 227 in Illinois, according to the CDC.^[3][31]

Since it was first observed in the United Kingdom, it has spread to more than 20NHS Trust hospitals and infected 200 people.^[32]

As of April 2019^[update], the CDC has documented cases ofC. auris from the following countries: Australia, Austria, Belgium, Canada, China, Colombia, France, Germany, India, Iran, Israel, Japan, Kenya, Kuwait, Malaysia, Mexico, the Netherlands, Norway, Oman, Pakistan, Panama, Russia, Saudi Arabia, Singapore, South Africa, South Korea, Spain, Switzerland, Taiwan, Thailand, the United Arab Emirates, the United Kingdom, the United States, and Venezuela.^[31]

Candida auris fungus (C. auris) is a multi-drug–resistant fungal infection that spreads in hospitals and is extremely deadly—killing as many as one in three who get it.

—Abby Haglage ofYahoo! Lifestyle,^[33] citing theCenters for Disease Control and Prevention^[34]

Arturo Casadevall, MD, PhD, and Molecular Microbiology and Immunology chair at Johns Hopkins Bloomberg School of Public Health stated:

What this study suggests is this is the beginning of fungi adapting to higher temperatures, and we are going to have more and more problems as the century goes on. Global warming will lead to selection of fungal lineages that are more thermally tolerant.^[33]

TheCOVID-19 pandemic has taken resources away from combating and tracking the fungus, which has led to outbreaks.^[35] Shortages ofpersonal protective equipment forced medical personnel to reuse of gowns and masks during the pandemic, which has contributed to the fungi's spread.^[35] In 2021, the CDC identified strains ofCandida auris that were immune to all existing medications used to treat fungal infections.^[36] Research published inAnnals of Internal Medicine tracking the spread ofCandida auris from 2019 through 2021 revealed the fungus was present in over half of American states.^[37][38][39]

Context

Antimicrobial resistance in general is an increasingly common phenomenon. In 2010, two million people were reported to have contracted resistant infections in the United States – 23,000 fatally.^{[upper-alpha 1]} "[M]ore recent estimates from researchers atWashington University School of Medicine put the death toll at 162,000. Worldwide fatalities from resistant infections are estimated at 700,000 per year.^[3][40]C. auris is one of the many microbial contributors to this global AMR estimation.^[40]

See also

• Candida blankii

References

Notes

Citations

External links

• Candida Genome DatabaseArchived 18 November 2016 at theWayback Machine

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• Articles with unsourced statements from August 2022
• Articles containing potentially dated statements from May 2017
• Articles containing potentially dated statements from August 2019
• Articles containing potentially dated statements from April 2019
• 21st-century epidemics
• Antimicrobial resistance
• Candida (fungus)
• Fungi described in 2009
• Pathogenic microbes
• Fungal pathogens of humans
• Yeasts
• Fungus species