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

Iturrieta-González IA, Padovan AC, Bizerra FC, Hahn RC, Colombo AL - PLoS ONE (2014)

Bottom Line: Voriconazole exhibited the best in vitro activity against all species 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.

View Article: PubMed Central - PubMed

Affiliation: Laboratório Especial de Micologia, Disciplina de Infectologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil.

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.

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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.
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pone-0109553-g004: 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.

Mentions: The MIC readings of susceptibility tests for both planktonic and biofilm forming cells were performed after 48 h of incubation. Table 2 summarizes the planktonic MIC50, MIC90, and MIC ranges (μg/ml) and the geometric means (GM) obtained for the 54 clinical isolates of Trichosporon spp. against 4 antifungal agents. Of note, T. asahii, T. asteroides and T. faecale isolates exhibited MIC50 values for AMB ≥2 µg/ml. Trichosporon asahii isolates exhibited higher MIC values for all antifungals tested except for VRZ (Table 2 and Figure 4). Figure 4 depicts the comparison between MIC values obtained for T. asahii and non-T. asahii isolates. In general, significant differences were found between the two groups considering FLC, ITC and AMB, whereas VOR was the azole that exhibited the best in vitro activity against all Trichosporon species.


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

Iturrieta-González IA, Padovan AC, Bizerra FC, Hahn RC, Colombo AL - PLoS ONE (2014)

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.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4215839&req=5

pone-0109553-g004: 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.
Mentions: The MIC readings of susceptibility tests for both planktonic and biofilm forming cells were performed after 48 h of incubation. Table 2 summarizes the planktonic MIC50, MIC90, and MIC ranges (μg/ml) and the geometric means (GM) obtained for the 54 clinical isolates of Trichosporon spp. against 4 antifungal agents. Of note, T. asahii, T. asteroides and T. faecale isolates exhibited MIC50 values for AMB ≥2 µg/ml. Trichosporon asahii isolates exhibited higher MIC values for all antifungals tested except for VRZ (Table 2 and Figure 4). Figure 4 depicts the comparison between MIC values obtained for T. asahii and non-T. asahii isolates. In general, significant differences were found between the two groups considering FLC, ITC and AMB, whereas VOR was the azole that exhibited the best in vitro activity against all Trichosporon species.

Bottom Line: Voriconazole exhibited the best in vitro activity against all species 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.

View Article: PubMed Central - PubMed

Affiliation: Laboratório Especial de Micologia, Disciplina de Infectologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil.

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.

Show MeSH
Related in: MedlinePlus