Trichosporon inkin: An Uncommon Agent of Scalp White Piedra. Report of Four Cases in Brazilian Children

First report of white piedra caused by Cutaneotrichosporon debeurmannianum

Piedras are small nodules found on the hair shafts. White piedra was initially described as caused by Trichosporon beigelii, which was later reclassified in several species. We describe the first case of white piedra caused by Cutaneotrichosporon debeurmannianum. Affected hairs were examined in natura with scanning electron microscopy, after gold metallization. The typical whitish cerebriform creamy colony was obtained in Sabouraud medium. Fungal genomic DNA extracted from cultures and locus was amplified with the NL1/NL4 primer pair from the D1/D2 region of the large ribosomal subunit (LSU) of 28S rRNA. With scanning electron microscopy, nodules are easily identified surrounding the hair shaft; with high magnifications, rounded structures adhered to each other were identified. Comparison of the nucleotide sequences of IMT-1703 Cutaneotrichosporon debeurmannianum revealed 99.6% similarity with the 28S large ribosomal unit rDNA sequence. This case of white piedra was caused by Cutaneotrichosporon debeurmannianum.

Multidrug-resistant Trichosporon species: underestimated fungal pathogens posing imminent threats in clinical settings

Species of Trichosporon and related genera are widely used in biotechnology and, hence, many species have their genome sequenced. Importantly, yeasts of the genus Trichosporon have been increasingly identified as a cause of life-threatening invasive trichosporonosis (IT) in humans and are associated with an exceptionally high mortality rate. Trichosporon spp. are intrinsically resistant to frontline antifungal agents, which accounts for numerous reports of therapeutic failure when echinocandins are used to treat IT. Moreover, these fungi have low sensitivity to polyenes and azoles and, therefore, are potentially regarded as multidrug-resistant pathogens. However, despite the clinical importance of Trichosporon spp., our understanding of their antifungal resistance mechanisms is quite limited. Furthermore, antifungal susceptibility testing is not standardized, and there is a lack of interpretive epidemiological cut-off values for minimal inhibitory concentrations to distinguish non-wild type Trichosporon isolates. The route of infection remains obscure and detailed clinical and environmental studies are required to determine whether the Trichosporon infections are endogenous or exogenous in nature. Although our knowledge on effective IT treatments is rather limited and future randomized clinical trials are required to identify the best antifungal agent, the current paradigm advocates the use of voriconazole, removal of central venous catheters and recovery from neutropenia.

Species distribution and antifungal susceptibility of 358 Trichosporon clinical isolates collected in 24 medical centres

OBJECTIVES

To provide species distribution and antifungal susceptibility profiles of 358 Trichosporon clinical isolates collected from 24 tertiary-care hospitals.

METHODS

Species identification was performed by sequencing the IGS1 region of rDNA. Antifungal susceptibility testing for amphotericin B, fluconazole, voriconazole and posaconazole followed the Clinical and Laboratory Standards Institute reference method. Tentative epidemiologic cutoff values (97.5% ECVs) of antifungals for Trichosporon asahii were also calculated.

RESULTS

Isolates were cultured mostly from urine (155/358, 43.3%) and blood (82/358, 23%) samples. Trichosporon asahii was the most common species (273/358, 76.3%), followed by T. inkin (35/358, 9.7%). Isolation of non-T. asahii species increased substantially over the last 11 years [11/77 (14.2%) from 1997 to 2007 vs. 74/281, (26.3%) from 2008 to 2018, p0.03]. Antifungal susceptibility testing showed high amphotericin B minimum inhibitory concentrations against Trichosporon isolates, with higher values for T. faecale. The ECV for amphotericin B and T. asahii was set at 4 μg/mL. Among the triazole derivatives, fluconazole was the least active drug. The ECVs for fluconazole and posaconazole against T. asahii were set at 8 and 0.5 μg/mL, respectively. Voriconazole showed the strongest in vitro activity against the Trichosporon isolates; its ECV for T. asahii was set at 0.25 μg/mL after 48 hours' incubation.

CONCLUSIONS

Trichosporon species diversity has increased over the years in human samples, and antifungal susceptibility profiles were species specific. Trichosporon asahii antifungal ECVs were proposed, which may be helpful to guide antifungal therapy.

White Piedra: Clinical, Mycological, and Therapeutic Experience of Fourteen Cases

Background

White piedra (WP) is an asymptomatic superficial mycosis that affects the hair stems, forming whitish nodules caused by various species of the genus Trichosporon.

Objective

To present a case series of WP of the head, its epidemiological data, as well as clinical, mycological, and therapeutic experience.

Methods

We conducted a 12-year retrospective and observational study of WP cases tested by dermoscopy, mycological study, and the identification of species through morphology, biochemistry, and proteomics (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry). The treatment was based on ketoco-nazole shampoo as well as keratolytics.

Results

We included 14 cases of WP, all located in the head and 1 case with both head and scrotum affected. Nine cases (64.3%) presented in children aged < 15 years. The majority of the cases (13/14, 92.8%) were women. Two cases were associated with hyperkeratosis and intertrigo. Most patients had long hair and excessive moisture. In all cases hair nodules were observed and Trichosporon inkin (11/14, 78.6%) was usually isolated. Eleven cases (78.6%) were cured by administering 2% ketoconazole shampoo.

Conclusion

WP was observed in school-age girls. The diagnosis was based on the observation of hair nodules and its main etiologic agent was T. inkin, with good response to treatment in most cases.