Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2014 Oct 31;9(10):e109553.
doi: 10.1371/journal.pone.0109553. eCollection 2014.

Multiple species of Trichosporon produce biofilms highly resistant to triazoles and amphotericin B

Isabel Antonieta Iturrieta-González  1 , Ana Carolina Barbosa Padovan  2 , Fernando César Bizerra  1 , Rosane Christine Hahn  3 , Arnaldo Lopes Colombo  1
Affiliations

Multiple species of Trichosporon produce biofilms highly resistant to triazoles and amphotericin B

Isabel Antonieta Iturrieta-González et al. PLoS One. .

Abstract

Invasive infections caused by Trichosporon spp. have increased considerably in recent years, especially in neutropenic and critically ill patients using catheters and antibiotics. The genus presents limited sensitivity to different antifungal agents, but triazoles are the first choice for treatment. Here, we investigated the biofilm production and antifungal susceptibility to triazoles and amphotericin B of 54 Trichosporon spp. isolates obtained from blood samples (19), urine (20) and superficial mycosis (15). All isolates and 7 reference strains were identified by sequence analysis and phylogenetic inferences of the IGS1 region of the rDNA. Biofilms were grown on 96-well plates and quantitation was performed using crystal violet staining, complemented with Scanning Electron Microscopy (SEM). Susceptibility tests for fluconazole, itraconazole, voriconazole and amphotericin B were processed using the microdilution broth method (CLSI) for planktonic cells and XTT reduction assay for biofilm-forming cells. Our results showed that T. asahii was the most frequent species identified (66.7%), followed by T. faecale (11.1%), T. asteroides (9.3%), T. inkin (7.4%), T. dermatis (3.7%) and one T. coremiiforme (1.8%). We identified 4 genotypes within T. asahii isolates (G1, G3, G4 and G5) and 2 genotypes within T. faecale (G1 and G3). All species exhibited high adhesion and biofilm formation capabilities, mainly T. inkin, T. asteroides and T. faecale. Microscopy images of high biofilm-producing isolates showed that T. asahii presented mainly hyphae and arthroconidia, whereas T. asteroides exhibited mainly short arthroconidia and few filaments. Voriconazole exhibited the best in vitro activity against all species tested. Biofilm-forming cells of isolates and reference strains were highly resistant to all antifungals tested. We concluded that levels of biofilm formation by Trichosporon spp. were similar or even greater than those described for the Candida genus. Biofilm-forming cells were at least 1,000 times more resistant to antifungals than planktonic cells, especially to voriconazole.

PubMed Disclaimer

Conflict of interest statement

Competing Interests: Dr. Colombo has received research and educational grants from Astellas, MSD, Pfizer and United Medical in the last two years. All the other authors report no conflicts of interest relevant to this article. The authors alone are responsible for the content and the writing of the paper.

Figures

Figure 1
Figure 1. Median-joining genotypes network of T. asahii, T. faecale and T. coremiiforme based on IGS1 rDNA sequences related to biofilm quantitation.
Dashed square groups the 12 different genotypes (G1 to G12) of T. asahii. Dashed circle groups the 3 different genotypes of T. faecale. Circumference sizes are proportional to the genotype frequencies. Black dots (mv = median vectors) are hypothetical missing intermediates.
Figure 2
Figure 2. Inter and intra species variation in the biofilm production of 54 Trichosporon spp. clinical isolates and 7 reference strains.
A- 19 isolates from blood identified as T. asahii, T. asteroides, T. coremiiforme and T. dermatis. B- 20 isolates from urine identified as T. asahii. C- 15 isolates from superficial mycosis/skin colonization identified as T. asahii, T. dermatis, T. faecale and T. inkin. D- 7 reference strains from CBS obtained from different sources.
Figure 3
Figure 3. Scanning electron microscopy of 4 Trichosporon spp. strains grown on catheter surfaces.
A and B: Low biofilm producer T. asahii 05-001 (CV-A570  =  0.287); C and D: Medium biofilm producer T. asahii 18-001 (CV-A570  =  1.557); E and F: High biofilm producer T. asahii 07-001A (CV-A570  =  3.337); and G and H: High biofilm producer T. asteroides 13-001 (CV-A570  =  2.755).
Figure 4
Figure 4. Comparative analysis of MIC values obtained against planktonic cells of T. asahii (36 isolates) versus non-T. asahii (18) isolates for all antifungals tested.
A- Fluconazole; B- Itraconazole; C- Voriconazole and D- Amphotericin B.
See this image and copyright information in PMC

References

    1. Colombo AL, Padovan AC, Chaves GM (2011) Current knowledge of Trichosporon spp. and Trichosporonosis. Clin Microbiol Rev 24: 682–700. - PMC - PubMed
    1. Magalhaes AR, Mondino SS, Silva M, Nishikawa MM (2008) Morphological and biochemical characterization of the aetiological agents of white piedra . Mem Inst Oswaldo Cruz 103: 786–790. - PubMed
    1. Pfaller MA, Diekema DJ, Rinaldi MG, Barnes R, Hu B, et al. (2005) Results from the ARTEMIS DISK Global Antifungal Surveillance Study: a 6.5-year analysis of susceptibilities of Candida and other yeast species to fluconazole and voriconazole by standardized disk diffusion testing. J Clin Microbiol 43: 5848–5859. - PMC - PubMed
    1. Pfaller MA, Diekema DJ, Gibbs DL, Newell VA, Meis JF, et al. (2007) Results from the ARTEMIS DISK Global Antifungal Surveillance study, 1997 to 2005: an 8.5-year analysis of susceptibilities of Candida species and other yeast species to fluconazole and voriconazole determined by CLSI standardized disk diffusion testing. J Clin Microbiol 45: 1735–1745. - PMC - PubMed
    1. Pfaller MA, Diekema DJ, Gibbs DL, Newell VA, Bijie H, et al. (2009) Results from the ARTEMIS DISK Global Antifungal Surveillance Study, 1997 to 2007: 10.5-year analysis of susceptibilities of noncandidal yeast species to fluconazole and voriconazole determined by CLSI standardized disk diffusion testing. Journal of Clinical Microbiology 47: 117–123. - PMC - PubMed

Publication types

LinkOut - more resources