SN6 SHORT NOTE 5M ★ High-yield

Describe Candida auris and the emerging antifungal resistance.

Microbiology · 2nd Professional — Para-Clinical

Candida Auris

First described in 2009 from an ear canal in Japan, and now reported worldwide; India has a particularly high burden and was among the first countries to report large hospital outbreaks
Four distinct clades emerged simultaneously on different continents, which is biologically remarkable and remains unexplained; global warming and agricultural azole use have both been proposed
Why it matters — it is unique among Candida species in combining several dangerous properties:

Property	Consequence
Multidrug resistance	Most isolates are fluconazole resistant; many resist amphotericin B; and some resist echinocandins, leaving essentially no options. Pan-resistant strains have been reported
Persistence in the environment	Unlike other Candida species it survives for weeks on bed rails, mattresses, trolleys, thermometers and blood pressure cuffs, and resists many common disinfectants — so it behaves like a hospital bacterium rather than a yeast
Skin colonisation	It colonises the axilla and groin rather than the gut, so it is spread by contact and by shared equipment between patients
Misidentification	Conventional biochemical systems frequently report it as C. Haemulonii, Rhodotorula or Saccharomyces; correct identification requires MALDI-TOF or sequencing — so an outbreak may be invisible
Thermotolerance and salt tolerance	Grows at 42°C, which most Candida species do not

CLINICAL PEARL

Candida auris behaves like a resistant hospital bacterium, and must be controlled like one. Other Candida infections are endogenous — the patient's own flora invading through a line. C. Auris spreads patient to patient via hands, equipment and the environment, and persists on surfaces for weeks. So the response is not primarily antifungal stewardship but contact precautions, single rooms or cohorting, dedicated equipment, screening of contacts, and terminal cleaning with a sporicidal agent.

Management and Control

Echinocandins are first-line pending susceptibility results, since most isolates retain some susceptibility; combination therapy and newer agents where resistance is present
Always request species identification and susceptibility testing; empirical fluconazole will usually fail
Remove or replace infected lines and devices, as with other candidaemia
Infection control — contact precautions, isolation or cohorting, dedicated or thoroughly disinfected equipment, screening of contacts (axilla and groin swabs), and environmental cleaning with hypochlorite or hydrogen peroxide; quaternary ammonium compounds are inadequate
Notify and investigate a single isolate as a potential outbreak, since by the time several are found, colonisation is usually widespread

Other Emerging and Resistant Fungi

Organism	Concern
Trichophyton indotineae	Emerged in INDIA and spread internationally; causes extensive steroid-modified tinea and carries squalene epoxidase mutations conferring terbinafine resistance
Azole-resistant Aspergillus fumigatus	Resistance selected in the environment by agricultural azole fungicides, so patients acquire an already-resistant organism without any previous antifungal exposure — a direct parallel with antibacterial resistance from agriculture
Candida glabrata and C. Krusei	Rising as fluconazole use increases; C. Krusei is intrinsically fluconazole resistant, and C. Glabrata is increasingly echinocandin-resistant
Fusarium and Scedosporium	Intrinsically resistant to many antifungals; cause keratitis and disseminated disease in the neutropenic
Mucormycosis	Surged in India during the COVID-19 pandemic through the combination of diabetes, corticosteroids and the infection itself

Applied Aspects

Antifungal resistance is following the same trajectory as antibacterial resistance, and for the same reasons — empirical use, prophylaxis, incomplete courses and agricultural application — but with far fewer drug classes available to lose
There are only four antifungal classes in common use (polyenes, azoles, echinocandins and flucytosine), against many antibacterial classes, so each loss is proportionally far more serious
Identify Candida to species level rather than reporting "Candida species"; the species predicts susceptibility and therefore the treatment
Environmental azole use selects resistant Aspergillus, so a patient may present with azole-resistant invasive aspergillosis having never taken an antifungal — which is an argument for treating agriculture as part of stewardship
India is central to several of these emergences — C. Auris, T. Indotineae and COVID-associated mucormycosis — reflecting the combination of a large at-risk population, unregulated drug availability and limited mycology laboratory capacity
Investing in diagnostic mycology is the practical response; resistance cannot be managed without identification and susceptibility testing, and most Indian laboratories currently lack both

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