Fungi

Image from: National Park Service. "Swelter Shelter Petroglyphs." Page Last Updated August 8, 2021. Accessed June 30, 2023. https://www.nps.gov/places/sweltershelterpetroglyphs.htm

In 2004, Archaeologists working in the Swelter Shelter site in Dinosaur National Monument in Utah experienced an outbreak of coccidioidomycosis, which was not previously thought to be endemic to this region.

Petersen LR, Marshall SL, Barton-Dickson C, Hajjeh RA, Lindsley MD, Warnock DW, Panackal AA, Shaffer JB, Haddad MB, Fisher FS, Dennis DT, Morgan J. Coccidioidomycosis among workers at an archeological site, northeastern Utah. Emerg Infect Dis. 2004 Apr;10(4):637-42.

1. Choose the mechanism of action for Amphotericin B.

A. Nucleoside analogue that is converted to an antimetabolite in fungal cytoplasm and disrupts RNA synthesis
B. Binds to ergosterol in the cell membrane of most fungi which forms ion channels and leads to leakage of essential cations

C. Targets lanosterol 14-alpha-demethylase and interrupts ergosterol synthesis, ultimately disrupting cell membrane function
D. Inhibits the synthesis of 1->3 beta-D-glucan, disrupting cell wall construction

Answer below.
-

B. Binds to ergosterol in the cell membrane of most fungi which forms ion channels and leads to leakage of essential cations

Groll AH, Walsh TJ. "Antifungal Agents," in: Cherry JD, ed. Feigin and Cherry's Textbook of Pediatric Infectious Diseases. 8th edition. Elsevier; 2019: 2437-2466.

2. Choose the mechanism of action for echinocandins, like micafungin or caspofungin.

Answer below.
-

D. Inhibits the synthesis of 1->3 beta-D-glucan, disrupting cell wall construction

Groll AH, Walsh TJ. "Antifungal Agents," in: Cherry JD, ed. Feigin and Cherry's Textbook of Pediatric Infectious Diseases. 8th edition. Elsevier; 2019: 2437-2466.

3. Choose the mechanism of action for azoles, like fluconazole.

Answer below.
-

C. Targets lanosterol 14-alpha-demethylase and interrupts ergosterol synthesis, ultimately disrupting cell membrane function

Groll AH, Walsh TJ. "Antifungal Agents," in: Cherry JD, ed. Feigin and Cherry's Textbook of Pediatric Infectious Diseases. 8th edition. Elsevier; 2019: 2437-2466.

4. Choose the mechanism of action for flucytosine.

Answer below.
-

A. Nucleoside analogue that is converted to an antimetabolite in fungal cytoplasm and disrupts RNA synthesis

Groll AH, Walsh TJ. "Antifungal Agents," in: Cherry JD, ed. Feigin and Cherry's Textbook of Pediatric Infectious Diseases. 8th edition. Elsevier; 2019: 2437-2466.

5. What percentage of individuals with coccidioidomycosis develop asymptomatic pulmonary residua on radiographs (e.g. cysts, nodules, cavitary lesions, coin lesions)?

A. 5%
B. 50%

C. 25%
D. 90%

Answer below.
-

A. 5%

American Academy of Pediatrics. Coccidioidomycosis In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 277-80

6. What percentage of Blastomyces infections in humans are asymptomatic?

A. 5%
B. 50%
C. 25%
D. 90%

Answer below.

B. 50%

American Academy of Pediatrics. Blastomycosis. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 232-3

7. What percentage of symptomatic Blastomyces infections in humans are disseminated?

A. 5%
B. 50%
C. 25%
D. 90%

Answer below.

C. 25%

American Academy of Pediatrics. Blastomycosis. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 232-3

8. Describe the treatment of severe pulmonary disease in blastomycosis.

Free response.

1-2 weeks of IV amphotericin B deoxycholate or lipid formulation followed by 6-12 months of itraconazole therapy.

American Academy of Pediatrics. Blastomycosis. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 232-3

9. Outline the treatment for cryptococcal meningitis.

Free response.

Induction with Amphotericin B deoxycholate or lipid formulation or liposomal formulation PLUS oral flucytosine for at least 2 weeks and until repeat CSF culture is negative, followed by consolidation therapy with fluconazole for a minimum of 8 weeks.

Perfect JR, Dismukes WE, Dromer F, Goldman DL, Graybill JR, Hamill RJ, Harrison TS, Larsen RA, Lortholary O, Nguyen MH, Pappas PG, Powderly WG, Singh N, Sobel JD, Sorrell TC. Clinical practice guidelines for the management of cryptococcal disease: 2010 update by the infectious diseases society of america. Clin Infect Dis. 2010 Feb 1;50(3):291-322.

American Academy of Pediatrics. Cryptococcus neoformans and Cryptococcus gattii Infections. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 285-8

10. Describe the typical CSF profile in Coccidioides meningitis.

Free response.

A mixed or lymphocytic pleocytosis (sometimes with eosinophils), elevated protein (sometimes markedly so), and hypoglycoracchia.

Bays DJ, Thompson GR 3rd. Coccidioidomycosis. Infect Dis Clin North Am. 2021 Jun;35(2):453-469.

11. Describe the morphology of Sporothrix schenckii under light microscopy.

Free response.

Sporothrix schenckii is a dimorphic fungus. When cultured at 25 degrees Celsius, it assumes a filamentous form with septate hyphae 1-2 um wide and with tear-shaped or clavate conidia. In human or animal tissue, it grows as yeastlike cells, round to oval in shape, 2-6 um in diameter, and potentially with characteristic cigar-shaped buds on a narrow base that may be 2 x 3 x 10 um in size.

Barros MB, de Almeida Paes R, Schubach AO. Sporothrix schenckii and Sporotrichosis. Clin Microbiol Rev. 2011 Oct;24(4):633-54.

12. What pathologic features would you expect to see in widespread lymphocutaneous or multifocal sporotrichosis on biopsy?

Free response.

Mixed pyogranulomatous inflammation, potentially with characteristic cigar-shaped yeast forms and stellate, periodic acid Schiff-positive eosinophilic material (Asteroid bodies).

Barros MB, de Almeida Paes R, Schubach AO. Sporothrix schenckii and Sporotrichosis. Clin Microbiol Rev. 2011 Oct;24(4):633-54.

13. Which azole remains the first-line drug for cutaneous and extracutaneous sporotrichosis in immunocompetent individuals?

A. Fluconazole

B. Voriconazole

C. Itraconazole

D. Posaconazole

Answer below.

C. Itraconazole

Barros MB, de Almeida Paes R, Schubach AO. Sporothrix schenckii and Sporotrichosis. Clin Microbiol Rev. 2011 Oct;24(4):633-54.

14. When should neutropenic patients with candidemia undergo fundoscopic examination?

A. Immediately after identification of candidemia

B. Upon count recovery

C. One week following clearance of candidemia from the bloodstream

D. Fundoscopic examination is recommended primarily for neonates with candidemia

Answer below.

B. Upon count recovery.

It should be noted that the principle likewise extends to the radiographic identification of lesions in the brain, kidney, liver, heart, or spleen via ultrasonography, computed tomography, or magnetic resonance imaging. Neutropenic patients lack the ability to recruit granulocytes to sites of invasion/proliferation of the offending pathogen, and therefore an inflammatory lesion may not be apparent by these imaging modalities until sufficient neutrophil count recovery is established.

Pappas PG, Kauffman CA, Andes DR, Clancy CJ, Marr KA, Ostrosky-Zeichner L, Reboli AC, Schuster MG, Vazquez JA, Walsh TJ, Zaoutis TE, Sobel JD. Clinical Practice Guideline for the Management of Candidiasis: 2016 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2016 Feb 15;62(4):e1-50.

American Academy of Pediatrics. Candidiasis. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 246-52

15. Which patient populations with candidemia are indicated to undergo fundoscopic examination to screen for candidal endophthalmitis?

A. Neutropenic patients and neonates

B. Neonates and patients who complain of vision changes

C. Neonates alone

D. All patients with candidemia

Answer below.

D. All patients with candidemia.

"All patients with candidemia should have a dilated retinal examination, preferably performed by an ophthalmologist, within the first week of therapy in nonneutropenic patients to establish if endophthalmitis is present... For neutropenic patients, it is recommended to delay the examination until neutrophil recovery."

Pappas PG, Kauffman CA, Andes DR, Clancy CJ, Marr KA, Ostrosky-Zeichner L, Reboli AC, Schuster MG, Vazquez JA, Walsh TJ, Zaoutis TE, Sobel JD. Clinical Practice Guideline for the Management of Candidiasis: 2016 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2016 Feb 15;62(4):e1-50.

16. Which antifungals should be used for initial, empiric therapy in Candida auris infections?

A. Echinocandins

B. Fluconazole

C. Amphotericin B formulations

D. Second-generation azoles

Answer below.

A. Echinocandins. Approximately 90% of C. auris isolates can be resistant to fluconazole. Echinocandins (caspofungin, micafungin, anidulafungin) are active in vitro against most Candida species and remain the recommended first-line drugs for Candida infections in severely ill or immunocompromised patients.

17. What percentage of neonates with Candida meningitis have a positive blood culture?

A. 100%

B. 90%

C. 75%

D. 50%

Answer below.

D. 50%. Neonatal candidiasis may present with only subtle signs and symptoms of infections. While candidemia is strongly associated with central nervous system disease and meningitis, only half of infants with meningitis may have a positive blood culture.

18. Which neonates with Candidal infections should undergo dilated fundoscopic examination and lumbar puncture with CSF analysis and culture?

A. Neonates with any positive culture from any body site

B. Neonates with positive cultures from the urine or blood

C. Neonates with positive culture from the blood only

D. Neonates with any cutanous or oropharyngeal evidence of infection

Answer below.

B. Neonates with positive cultures from the urine or blood

"A lumbar puncture and a dilated retinal examination are recommended in neonates with cultures positive for Candida species from blood and/or urine (strong recommendation; low-quality evidence)."

Pappas PG, Kauffman CA, Andes DR, Clancy CJ, Marr KA, Ostrosky-Zeichner L, Reboli AC, Schuster MG, Vazquez JA, Walsh TJ, Zaoutis TE, Sobel JD. Clinical Practice Guideline for the Management of Candidiasis: 2016 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2016 Feb 15;62(4):e1-50.

19. What is the recommended treatment duration for candidemia in all patients without metastatic complications?

A. 14 days

B. 7-10 days

C. 4 weeks

D. 5-7 days

Answer below.

A. 14 days.

"The recommended minimum duration of therapy for candidemia without metastatic complications is 2 weeks after documented clearance of Candida from the bloodstream, provided neutropenia and symptoms attributable to candidemia have resolved (strong recommendation; low-quality evidence)."

Note that while this recommendation applies generally to neonates and neutropenic/nonneutropenic patients alike, it is important that a thorough evaluation searching for metastic complications was completed, that signs/symptoms associated with candidemia are resolved, that the blood cultures remain sterile, and that if the patient was neutropenic, the neutropenia must be resolved before antifungal therapy is completed.

Pappas PG, Kauffman CA, Andes DR, Clancy CJ, Marr KA, Ostrosky-Zeichner L, Reboli AC, Schuster MG, Vazquez JA, Walsh TJ, Zaoutis TE, Sobel JD. Clinical Practice Guideline for the Management of Candidiasis: 2016 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2016 Feb 15;62(4):e1-50.

20. Which Aspergillus species is known for its extremely aggressive, invasive infections in patients with chronic granulomatous disease?

A. A. terreus

B. A. niger

C. A. nidulans

D. A. calidoustus

Answer below.

C. A. nidulans

"A. nidulans is the second most encountered mold in patients with chronic granulomatous disease, causing almost exclusively invasive infections in this specific host characterized by its aggressive behavior including lung infection that invades the chest wall with contiguous osteomyelitis and chest wall abscesses."

21. Which Aspergillus species is often resistant to most triazoles, amphotericin B, and echinocandins?

A. A. terreus

B. A. niger

C. A. nidulans

D. A. calidoustus

Answer below.

D. A. calidoustus

American Academy of Pediatrics. Aspergillosis. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 211-5

Varga J, Houbraken J, Van Der Lee HA, Verweij PE, Samson RA. Aspergillus calidoustus sp. nov., causative agent of human infections previously assigned to Aspergillus ustus. Eukaryot Cell. 2008 Apr;7(4):630-8.

22. Which Aspergillus species is intrinsically resistant to Amphotericin B?

A. A. terreus

B. A. niger

C. A. nidulans

D. A. calidoustus

Answer below.

A. A. terreus

American Academy of Pediatrics. Aspergillosis. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 211-5

Lass-Flörl C. Treatment of Infections Due to Aspergillus terreus Species Complex. J Fungi (Basel). 2018 Jul 9;4(3):83.

23. Which endemic mycoses are associated with erythema nodosum?

Free response.

Coccidioides and Histoplasma. This phenomenon is much rarer with Blastomyces.

American Academy of Pediatrics. Blastomycosis. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 232-3

24. Describe the recommended treatment for immunocompetent patients with an asymptomatic coccidioidal pulmonary cavity.

Free response.

No treatment is necessary.

Galgiani JN, Ampel NM, Blair JE, Catanzaro A, Geertsma F, Hoover SE, Johnson RH, Kusne S, Lisse J, MacDonald JD, Meyerson SL, Raksin PB, Siever J, Stevens DA, Sunenshine R, Theodore N. 2016 Infectious Diseases Society of America (IDSA) Clinical Practice Guideline for the Treatment of Coccidioidomycosis. Clin Infect Dis. 2016 Sep 15;63(6):e112-46.

25. For patients with coccidioidal meningitis who become asymptomatic on initial therapy, when can treatment be stopped?

Free response.

Azole treatment is recommended for life; treatment should never be stopped.

Galgiani JN, Ampel NM, Blair JE, Catanzaro A, Geertsma F, Hoover SE, Johnson RH, Kusne S, Lisse J, MacDonald JD, Meyerson SL, Raksin PB, Siever J, Stevens DA, Sunenshine R, Theodore N. 2016 Infectious Diseases Society of America (IDSA) Clinical Practice Guideline for the Treatment of Coccidioidomycosis. Clin Infect Dis. 2016 Sep 15;63(6):e112-46.

26. What are the 3 patterns associated with cutaneous sporotrichosis?

Free response.

Lymphocutaneous spread (classic sporotrichoid pattern, wherein inoculation occurs at the site of minor trauma, with subsequent growth of a papule or ulcerative lesion, followed by secondary lesions developing along the lymphatic distribution proximal to the initial lesion); localized cutaneous or fixed cutaneous form (solitary crusted papule or papuloulcerative or nodular lesion); disseminated cutaneous form.

American Academy of Pediatrics. Sporotrichosis. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 676-7

27. What risk factor are Malassezia central line-associated bloodstream infections associated with?

Free response.

Total parenteral nutrition with fat emulsion.

American Academy of Pediatrics. Other Fungal Diseases. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 328-332

28. What percentage of people experience symptoms from Histoplasma infection?

A. 5%
B. 50%
C. 25%
D. 90%

Answer below.

A. 5%

American Academy of Pediatrics. Histoplasmosis. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 417-421

29. Describe the treatment for severe acute or progressive disseminated histoplasmosis.

Free response.

Initial induction with lipid formulation of amphotericin B. Addition of methylprednisolone may be considered if severe respiratory complications develop. After clinic improvement over the next 1-2 weeks, this should be followed by itraconazole therapy for an additional 12 weeks.

American Academy of Pediatrics. Histoplasmosis. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 417-421

30. What could lead to a false-positive Histoplasma antigen test result?

Free response.

Cross-reactivity with other dimorphic fungal diseases, like blastomycosis, coccidioidomycosis, paracoccidioidomycosis, sporotrichosis, etc.

31. What is the component of IV voriconazole formulations that leads to its relative contraindication in individuals with creatinine clearance < 50 mL/min?

Free response.

Cyclodextrin. Otherwise known as sulfobutylether-β-cyclodextrin, this component may accumulate in patients with poor creatinine clearance and cause further renal injury.

Yasu T, Konuma T, Kuroda S, Takahashi S, Tojo A. Effect of Cumulative Intravenous Voriconazole Dose on Renal Function in Hematological Patients. Antimicrob Agents Chemother. 2018 Aug 27;62(9):e00507-18.

32. Which country has experienced cat-associated outbreaks of sporotrichosis?

Free response.

Brazil. "S brasiliensis is responsible for hyperendemic cutaneous sporotrichosis involving mostly women and children in Rio de Janeiro."

33. List some predisposing conditions or risk factors in mucormycosis infections.

Free response.

Trauma and burns (in immunocompetent patients); hematologic malignancies; stem cell transplantion; solid organ malignancies; solid organ transplantation; diabetes mellitus and ketoacidosis; corticosteroid use and rheumatologic disease; iron overload and chelation therapy with DFO; prolonged voriconazole use (controversial).

Petrikkos G, Skiada A, Lortholary O, Roilides E, Walsh TJ, Kontoyiannis DP. Epidemiology and clinical manifestations of mucormycosis. Clin Infect Dis. 2012 Feb;54 Suppl 1:S23-34.

34. Name the 3 genera of Mucorales most commonly recovered from clinical specimens.

Free response.

Rhizopus, Lichtheimia, and Mucor.

Petrikkos G, Skiada A, Lortholary O, Roilides E, Walsh TJ, Kontoyiannis DP. Epidemiology and clinical manifestations of mucormycosis. Clin Infect Dis. 2012 Feb;54 Suppl 1:S23-34.

35. Which enzyme produced by Cryptococcus spp. is virtually absent in almost all other fungal species?

Free response.

Urease is absent in almost all other fungi except Trichosporon and some Candida species.

American Academy of Pediatrics. Cryptococcus neoformans and Cryptococcus gattii infections. In: Kimberlin DW, Barnett ED, Brady RT, Jackson MA, Long SS, eds. Red Book: 2018-2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2018: 302

36. Name a Candida species that demonstrates intrinsic/primary resistance to Amphotericin B.

Free response.

Candida lusitaniae. Reports of resistance to amphotericin B from Candida guilliermondii and Candida auris vary by study.

Perea S, Patterson TF. Antifungal resistance in pathogenic fungi. Clin Infect Dis. 2002 Nov 1;35(9):1073-80. doi: 10.1086/344058. PMID: 12384841.

Pfaller MA, Diekema DJ, Mendez M, Kibbler C, Erzsebet P, Chang SC, Gibbs DL, Newell VA. Candida guilliermondii, an opportunistic fungal pathogen with decreased susceptibility to fluconazole: geographic and temporal trends from the ARTEMIS DISK antifungal surveillance program. J Clin Microbiol. 2006 Oct;44(10):3551-6.

Černáková L, Roudbary M, Brás S, Tafaj S, Rodrigues CF. Candida auris: A Quick Review on Identification, Current Treatments, and Challenges. Int J Mol Sci. 2021 Apr 25;22(9):4470.

37. Name some species of Candida known for fluconazole resistance.

Free response.

Candida krusei, Candida glabrata, Candida auris.

38. What percentage of patients with Cryptococcal meningitis have antigen isolated from the CSF or serum?

A. 95%

B. 66%

C. 50%

D. 33%

Answer below.

A. 95%

American Academy of Pediatrics. Cryptococcus neoformans and Cryptococcus gattii infections. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 286

39. Which species of Aspergillus is the most common cause of invasive aspergillosis across all patients?

A. A. flavus

B. A. niger

C. A. fumigatus

D. A. calidoustus

Answer below.

C. A. fumigatus (>75%). Of note, flavus is the next most common.

40. Describe what makes invasive aspergillosis unique in patients with chronic granulomatous disease, as compared to other immunocompromised patient groups.

Free response.

Invasive aspergillosis in patients with chronic granulomatous disease is usually more indolent with a lack of angioinvasion. Serum galactomannan testing is often false-negative. In general, patients with chronic granulomatous disease don't appear as sick as one would expect, even in the face of a disseminated or invasive mold infection. It is easy to be lulled into a false sense of security.

41. When is the risk highest for Aspergillus infection among solid organ transplant recipients?

A. 6 days

B. 6 weeks

C. 6 months

D. 6 years

Answer below.

C. 6 months, or if later if immunosuppression is increased

42. What is the drug of choice for all Aspergillus infections?

Free response.

Voriconazole, except in neonates (who should receive Amphotericin B deoxycholate), and perhaps patients with chronic granulomatous disease, who might have better response with posaconazole.

43. Describe the recommended therapy for Candida osteoarticular infections.

Free response.

Daily fluconazole for 6-12 months, or an echinocandin (caspofungin, micafungin, or anidulafungin) for at least 2 weeks followed by daily fluconazole for 6-12 months. Lipid formulation AmB for 2 weeks followed by 6-12 months of fluconazole is also an option, albeit with more potential side effects.

44. Where is Histoplasma capsulatum var duboisii found?

Free response.

Central and Western Africa.

45. Which antifungal agent is well-known for causing hallucinations, vision discoloration, and photodermatitis as side effects?

Free response.

Voriconazole.

American Academy of Pediatrics. Antifungal Drugs for Systemic Fungal Infections. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH, eds. Red Book: 2021 Report of the Committee on Infectious Diseases. Itasca, IL: American Academy of Pediatrics. 2021: 921

46. Which electrolyte disturbances are most common on amphotericin B deoxycholate therapy?

Free response.

Hypokalemia and hypomagnesemia.

47. Which toxicity is of highest concern on flucytosine therapy?

Free response.

Bone marrow suppression.

48. Which household ingredient can increase culture yield of Malassezia furfur and some other members of this genus on standard fungal agars (i.e. Sabouraud dextrose agar)?

Free response.

Olive oil. "With the exception of M. pachydermatis, 17 of the 18 Malassezia species are lipid dependent. Their isolation in culture requires the use of a lipid-enriched culture medium." Traditionally this is accomplished through the addition of a thin layer of olive oil.

Patterson TF, Canete-Gibas CF, Widerhold NP. "Malassezia Species," in: Long SS, ed. Principles and Practice of Pediatric Infectious Diseases. 6th ed. Elsevier Inc. 2023: 247, 1274-1277.e2