Discussion:

Correct answer: 4. Both options 2 and 3 are correct and should be considered when evaluating patients with C haemulonii candidemia. Starting appropriate antifungal therapy and verifying Candida spp. identification should both be undertaken.

Answer 1 is incorrect. The current guidelines of the Infectious Diseases Society of America (IDSA) recommend starting intravenous echinocandin for the initial treatment of candidemia for most cases, with fluconazole reserved as an alternative for patients who are not critically ill and who are considered unlikely to have a fluconazole-resistant Candida spp.¹ That is not the situation found in this case, given this gentleman’s presentation and the culture results, as explained below.

While answer 2 is correct, it is not complete. Starting an echinocandin for the treatment of candidemia is recommended,¹ but it’s also important to confirm the species identification.

Answer 3 is a correct answer, but it is also not complete. Learning about the instrument used in identifying Candida species in your lab is a crucial step in combating C auris. Certain instruments used for phenotypic analysis have been reported to misidentify C auris as a different Candida spp. These instruments include the VITEK 2 YST, API 20C, BD Phoenix yeast identification system, and MicroScan. C auris can be misidentified as organisms including Candida haemulonii. Systems that can identify C auris are DNA sequencing, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) systems with an updated library, and the GenMark ePlex Blood Culture Identification Fungal Pathogen (BCID-FP) Panel and BioFire FilmArray BCID2, which have been FDA-approved as molecular tests for C auris identification in positive blood cultures.²

Additional Points:

Learning about C auris epidemiology and different identification methods is crucial to its management. C auris was first identified in Asia in 2009, and since then, it has spread across the globe. There are five different strains (or clades) from different regions (South American or clade IV, African or clade III, South Asian or clade I, East Asian or clade II, and Iranian or clade V),³ In the United States, all but clade V have been isolated.⁴

Since 2015, cases of C auris have tripled, which has posed significant difficulties to infection control and prevention and to clinicians treating them. Besides the difficulties in containing the spread of C auris, the lack of rapid diagnostics, and the costs related to identification methods and running antifungal susceptibilities continue to be problematic, especially in small hospitals. As shown in this case, the identification of C auris can be delayed, which complicates the efforts to prevent this organism from spreading within healthcare settings. Moreover, the nature of multi-drug resistance harbored by C auris has indeed placed an obstacle to providing an affordable and accessible antifungal regimen.⁵

Discussion:

Correct answer: 4, as it recommends both important steps: removing the central line and starting echinocandin therapy.

Answer 1 is correct but not complete. However, recognizing central lines as a possible source of candidemia is a crucial step in the clinical management of this case.¹ The answer should have included starting treatment. C auris colonizes the skin and can be transferred through direct contact, and central lines can introduce this pathogen into the bloodstream and result in sepsis. Moreover, Candida spp. can create a biofilm in the intravenous catheter, which subsequently makes it resistant to eradication by antifungal therapy alone and can result in treatment failure. Therefore, one of the crucial steps in controlling C auris candidemia is source control and removal of the central venous line.

Answer 2 is correct but not complete. Echinocandins are the recommended first-line therapy for candidemia according to the IDSA guidelines, and this drug class is also the recommended therapy for C auris infection according to the Centers for Disease Control and Prevention (CDC) C auris guidelines.^6,7 However, removing central lines (source control) should also be included in the first steps of treating C auris candidemia.¹

Answer 3 is incorrect. Liposomal amphotericin B has activity against C auris; however, about 30% of isolates tend to be resistant to liposomal amphotericin B, compared to echinocandins (<5%); therefore, CDC guidelines recommend the latter to be used as first-line therapy.⁸

The management of C auris is challenging, and while the current IDSA guidelines do not address C auris specifically, it is recommended to follow the general guidelines for the management of candidemia and invasive candidiasis, including removal of intravenous catheter and also obtaining dilated ophthalmoscopy to evaluate for endophthalmitis.