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AUGUST 2007

M072-5 Blood culture: Trichosporon inkin

-GRADING-Maximum grade = 4

HISTORY A simulated blood culture sample, with the history of collection from a 35-year old bone marrow transplant recipient with fever, was sent to category A laboratories for set up and reporting as per your laboratory protocol. Participants were informed that the sample was considered clinically significant. It was anticipated that all laboratories would report the presence of yeast and identify it as Trichosporon inkin.

IDENTIFICATION: 79% (57/72) of category A laboratories received either a grade of 4/4 or 3/4.

NOTES 1. Most Trichosporon species are urease positive, which may lead to confusion with other urease positive yeast, i.e., Cryptococcus and Rhodotorula spp. and some strains of C. krusei and C. (Yarrowia) lipolytica 1. 2. With the increase in invasive procedures and immunosuppresCMPT QA The sample contained pure growth of sion accompanying modern medical practice, clinicians and Trichosporon inkin viable for 14 days. microbiologists need to be alert to the possibility of unusual fungal infections such as T. inkin. GRADING (maximum grade = 4) This sample was accept-

Microscopic morphology 2,3 Microscopic examination of growth from cornmeal-Tween 80 agar following 72 hours incubation at 25°C, will reveal true hyphae and pseudohyphae with blastoconidia singly or in short chains. Rectangular or cylindrical arthroconidia form on older cultures and measure approxiA grade of 4 was assigned to identification for a maximum mately 2-4 x 3-9 (or larger) µm; septations within the arthrocograde of 4. Overall, 52% (37/72) of category A laboratories renidia are formed. The presence of blastoconidia along the hyported the correct genus; 29% (21/72) reported the correct spephae differentiates Trichosporon from Geotrichum species, cies. Species identification within the genus can be difficult and another yeast-like organism that also forms arthroconidia. Inlaboratories were given full credit for genus identification. oculation of malt extract broth at room temperature will enConsistent with CMPT policy, 2 laboratories that reported eicourage blastoconidium production in Trichosporon species ther T. inkin or Trichosporon species were downgraded for when required, usually within 48-72 hours 1. As well, reporting other organisms in the sample, (which were probably Geotrichum species are urease negative and do not grow on due to a contamination event within the performing laboratory.) SDA at 37°C. Blastoschizomyces capitatus is another yeast that Laboratories that recognized this isolate was a yeast/fungus, can form annelloconidia resembling arthroconidia, but this latbut not a Candida species and noted it would be referred for ter yeast can also be distinguised by growth and biochemical further investigation received a grade of 3. Results received and properties (growth on cylcoheximide containing media, growth grades assigned are listed in Table 1 (on page 2). Most laboratoat 45°C, and failure to hydrolyze urea) 1. ries reported using classical tests with and without a commerColony morphology T. inkin does not grow on media concial identification method. taining cycloheximide. Yeast like colonies will grow on blood IDENTIFICATION Trichosporon are considered yeast-like agar and Sabouraud dextrose agar (SDA) at 37°C, and has varifungi, classified within the Basidiomycetes, and are closely able growth at 42°C 4. On SDA at 25°C, colonies are initially 1 related to Cryptococcus . Older classification schemes identiyeast-like, cream coloured, smooth, moist and soft. Older colofied most isolates from clinical sources as T. beigelii or T. cutanies become finely cerebriform (wrinkled), powdery or crumbneum, although the criteria for identification were based on like, with the centre becoming heaped, and the colony adhering variable characteristics. The recognition of several morphologito and cracking the agar. Colony size is 9-12 mm after 7 days cal and biochemical patterns among clinical and environmental incubation and the colour may darken to yellowish grey 2,3. isolates of Trichosporon beigelii led to reclassification of the 2,3 genus in 1992 13. In this new schema, 19 taxa were recognized, Tests for Identification Commercial identification systems of which the following six are thought to be the most common may be used to identify Trichosporon species but laboratorians human pathogens: T. inkin, T. asahii, T. cutaneum, T. should be aware of the organisms tested in the system database 4 mucoides, T. asteroides, and T. ovoides. The new taxonomic . Trichosporon spp. do not ferment carbohydrates. In assimilaclassification identifies species which exhibit epidemiological tion tests T. inkin is inositol positive, but negative with arabiand pathogenic differences, supporting the validity of this new nose, sorbitol, rhamnose, melibiose, raffinose, ribitol, xylitol, 1,2 approach. However, the difficulty distinguishing species has and galactitol . Species differentiation can sometimes be led some mycologists to continue to use the designation T. done by determination of growth at 37°C and results of assimibeigelii for Trichosporonoses 1. T. asahii and T. mucoides are lation of inositol, arabinose, and sorbitol. These tests are not the most common species associated with systemic infection, always definitive however and reference laboratory testing is while the other species cause superficial mycotic infections of sometimes required. the skin and hair. In addition, there have been case reports of Urease Most Trichosporon species are urease positive, which invasive infection due to other rare species. may lead to confusion with other urease positive yeast, i.e.,

(Continued on page 3)

able for grading as 93% of the reference laboratories reported an acceptable identification. Identifications received included: Trichosporon inkin (10), Trichosporon species (3) and Trichosporon beigelii (1). One reference laboratory reported 2 morphotypes of gram positive bacilli , resembling coryneform bacilli.

M072-5 Blood culture: Trichosporon inkin (continued from page 1)

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Table 1. M072-5 Results received from category A laboratories and grades assigned. Identification Reported Trichosporon inkin, +/- refer

A

Method

API 20 aux, classical* (6) & Auxacolor 2 (1); API 20 aux (3); Vitek2 (3); API 20 AUX, Vitek2 (3); Vitek2, classical (2); API 20C, classical (1); Auxacolor2, classical (1) Uni-Yeast Vitek2, classical API 20 aux, classical (2), classical (2), Vitek2 (2), API 20 aux, Vitek2 (1), API 20 aux, Vitek2, classical (1), Auxacolor2, classical (1), refer (1), Uni-Yeast, classical (1), Vitek (1), Vitek2, Auxacolor2, classical (1) RapID Yeast plus, classical classical (8), refer (2) Classical classical (4), refer (1) classical Vitek2, classical Vitek2, classical classical classical Classical, Vitek API 20E, classical (1), classical (1) Classical refer API Coryne API ID32, Vitek2, classical refer /

Grade 4

20

Trichosporon beigelii, refer Trichosporon asahii, refer Trichosporon species +/- refer

1 1 13

4 4 4

Yeast species, not C. albicans or Cryptococcus neoformans, refer Yeast species, refer +/- not C. .albicans or Cryptococcus sp. Yeast species, not C.albicans, possibly Cryptococcus sp., snnp, refer Yeast, refer Fungus, refer Trichosporon inkin, +/- refer Arthrobacter species Trichosporon species, refer and Kocuria species

Candida albicans, presumptive, refer Candida krusei, refer (1); Candida species, refer +/- possible C.krusei (2) C. albicans, presumptive, refer and Acinetobacter species Bacillus cereus +/- group Bacillus species, refer +/- (not anthracis or cereus) gram positive bacilli, not Clostridium species, refer gram positive bacilli, 2 types, resembling coryneform bacilli, refer Micrococcus luteus/lylae Unknown, refer Blood culture samples not routinely processed, refer

1 10 1 5 5 1 1 1 3 1 2 2 1 1 1 1 5 77

3 3 3 3 3 1 1 1 1 0 0 0 0 0 0 0 ungraded

Total

/

* Classical tests included one or more of the following: germ tube, India ink, wet prep, cornmeal agar, Sabouraud agar, Potato Dextrose agar, lactophenol cotton blue, Candiselect plate, phytone agar, pigment production, urea, nitrate, spore stain, TSI, starch, oxidase, catalase, motility, esculin, lecithinase, citrate maltose, arginine, mannitol, sucrose, trehalose, dextrose, maltose, VP, gelatin.

M072-5 Blood culture: Trichosporon inkin (continued from page 2)

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Cryptococcus and Rhodotorula spp. Differentiation from these yeasts can be made when a pink pigment is present (Rhodotorula), and by the typical round morphology and capsule demonstrated by most Cryptococcus species. Urease positivity may also be demonstrated by some strains of C. krusei and C. (Yarrowia) lipolytica 1. Cross reactivity with Cryptococcal latex agglutination tests. Trichosporon and Cryptococcus species are related and share antigens. Patients with systemic Trichosporon infections have been demonstrated to have positive results when testing serum with cryptococcal latex agglutination tests 12 . CLINICAL SIGNIFICANCE T. inkin is most commonly associated with the superficial condition known as white piedra, a superficial infection with 0.5 mm nodules attached to the hair shafts on the head, axilla or genital area. T. inkin is particularly associated with infections of the pubic hair while T. ovoides is primarily implicated in white piedra of the scalp 1, 5. It has been reported mainly in temperate and semitropical climates and is more frequent in women than in men. Trichosporon species do not appear to be associated with the hospital environment. They are found in soil and water and are occasionally found in the human flora, normally associated with skin and nails 6. The first documented case of systemic infection caused by T. inkin, formerly Sarcinosporon inkin, was reported in 1990 as progressive pneumonia in a young male with chronic granulomatous disease 7. In recent years, T. inkin invasive infections have been documented in patients with factors predisposing them to infections. The most common risk factors include neutropenia with hematological malignancy, immunosuppression due to other reasons such as AIDS or steroids, extensive burns, intravenous catherters or other implanted prosthetic devices. The spectrum of infections is broad and ranges from progressive pneumonia, lung abscess, peritonitis associated with continuous ambulatory peritoneal dialysis, central venous catheter infections, vascular access infection, invasive infection following cardiac surgery, and endocarditis 4-11. The new taxonomy has made most of the early literature on this genus unusable due to the inability to determine which species was involved. Since the reclassification of the genus, all cases of endocarditis caused by Trichosporon species have been identified as T. inkin infections. It is impossible to say whether the cases of endocarditis classified as due to T. beigelii (or T. cutaneum) before reclassification were actually due to T. inkin or to one of the other members of the Trichosporon group 6. The prognosis of patients with Trichosporon infections after surgical valve implantation is very poor, with a mortality rate of 82%. This number is significantly higher than the mortality rates reported for prosthetic valve endocarditis caused by other organisms (25 to 60%) 4. Patients are probably infected during their operations, as has been described for other prosthetic infections. With the increase in invasive procedures and immunosuppression accompanying modern medical practice, clinicians and microbiologists need to be alert to the possibility of unusual fungal infections such as T. inkin.

TREATMENT Due to the rarity of invasive trichosporonosis, the optimal antimicrobial treatment is currently unclear. Trichosporon species are generally resistant to caspofungin in vitro, as are the other basidiomycetous yeasts, such as Cryptococcus species 4. Consequently, this agent is not recommended for treatment. All six human species of Trichosporon have been shown to have resistance to 5-flucytosine, to have higher fluconazole MICs than most Candida species, and to be variably sensitive to amphotericin B, ketoconazole, and itraconazole. Furthermore, studies suggest that amphotericin B is only inhibitory to Trichosporon species 1. REFERENCES

1. Hazen KC, Howell SA. 2007. Candida, Cryptococcus, and other yeasts of medical importance. p. 1762-1788. In PR Murray et al. (eds.) Manual of Clinical Microbiology. 9th ed. Vol. 2. Ch. 119. ASM Press, Washington, DC. 2. Larone DH. 2002. p. 140-141. Medically important fungi A Guide to Identification. 4th ed. ASM Press, Washington, D.C. 3. http://www.doctorfungus.org/thefungi/Trichosporon_inkin.htm 4. Ramos JM, Cuenca-Estrella M, Gutierrez F, Elia M, RodriguezTudela JL. 2004 . Clinical case of endocarditis due to Trichosporon inkin and antifungal susceptibility profile of the organism. J. Clin. Microbiol. 42:2341-2344. [PubMed]. 5. Taj-Aldeen SJ, Al-Ansari HI, Boekhout T, Theelen B. 2004. Co-isolation of Trichosporon inkin and Candida parapsilosis from a scalp white piedra case. Med Mycol. 42:87-92. 6. Davies F, Logan S. Johnson E, Klein JL. 2006. Sternal wound infection by Trichosporon inkin following cardiac surgery. J Clin Microbiol. 44 (7):2657-2659. 7. Kenney RT, Kwon-Chung KJ, Witebsky FG, Melnick DA, Malech HL, Gallin JI. 1990. Invasive infection with Sarcinosporon inkin in a patient with chronic granulomatous disease. Am J Clin Pathol. 94(3):344-50. 8. Wynne SM, Kyung JK-W, Shea YR, Filie AC, Varma A, Lupo P, Holland SM. 2004 . Invasive infection with Trichosporon inkin in 2 siblings with chronic granulomatous disease. J. Allergy Clin. Immunol. 114:1418-1424. [PubMed]. 9. Madariaga MG, Tenorio A, Proia L. 2003. Trichosporon inkin peritonitis treated with caspofungin. J. Clin. Microbiol. 41:5827-5829. [PubMed]. 10. Chaumentin G, Boibieux A, Piens MA, Buttard P, Berrand JL, Peyramond D. 1996 . Trichosporon inkin endocarditis: shortterm evolution and clinical report. Clin. Infect. Dis. 23:396-397. [PubMed]. 11. Piwoz JA, Stadtmauer GJ, Bottone EJ, Witzman I, Shlasko E, Cunningham-Rundles C. 2000 . Trichosporon inkin lung abscess presenting as a penetrating chest wall mass. Pediatr. Infect. Dis. J. 19:1025-1027. [PubMed]. 12. McManus EJ, Jones JM. 1985. Detection of a Trichosporon beigelii Antigen Cross-Reactive with Cryptococcus neoformans Capsular Polysaccharide in Serum from a Patient with Disseminated Trichosporon Infection. J. Clin. Microbiol. 21:681-685. 13. Gueho E, Smith MT, deHoog GS, Billon-Grand G, Christen R, Batenburg-vanderVegte WH. 1992. Contributions to a revision of the genus Trichosporon. Antonie Leeuwenhoek J. Microbiol. Serol. 61:289-316.

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