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The basidiomycetous yeast Trichosporon may cause severe lung exacerbation in cystic fibrosis patients – clinical analysis of Trichosporonpositive patients in a Munich cohort
© Kröner et al.; licensee BioMed Central Ltd. 2013
Received: 8 February 2013
Accepted: 28 October 2013
Published: 1 November 2013
The relevance of Trichosporon species for cystic fibrosis (CF) patients has not yet been extensively investigated.
The clinical course of CF patients with Trichosporon spp. in their respiratory secretions was analysed between 2003 and 2010 in the Munich CF center. All respiratory samples of 360 CF patients (0 – 52.4 years; mean FEV1 2010 81.4% pred) were investigated.
In 8 patients (2.2%, 3 male, mean age 21.8 years) Trichosporon was detected at least once. One patient carried T. asahii. One patient carried T. mycotoxinivorans and one patient T. inkin as determined by DNA sequencing. As potential risk factors for Trichosporon colonization steroid treatment, allergic bronchopulmonary aspergillosis (ABPA) and CF associated diabetes were identified in 6, 5, and 2 patients respectively. For one patient, the observation period was not long enough to determine the clinical course. One patient had only a single positive specimen and exhibited a stable clinical course determined by change in forced expiratory volume in one second (FEV1), body-mass-index (BMI), C-reactive protein (CRP) and immunoglobulin G (IgG). Of 6 patients with repeatedly positive specimen (mean detection period 4.5 years), 4 patients had a greater decline in FEV1 than expected, 2 of these a decline in BMI and 1 an increase in IgG above the reference range. 2 patients received antimycotic treatment: one patient with a tormenting dry cough subjectively improved under Amphotericin B inhalation; one patient with a severe exacerbation due to T. inkin was treated with i.v. Amphotericin B, oral Voriconazole and Posaconazole which stabilized the clinical condition.
This study demonstrates the potential association of Trichosporon spp. with severe exacerbations in CF patients.
KeywordsCystic fibrosis Trichosporon species Respiratory pathogens Exacerbations
Trichosporon species (T. spp.) belong to the genus of basidiomycetous yeast and are widely distributed in nature. They are found in soil and water and are known to colonize skin and gastrointestinal tract of humans [1, 2]. Numerous Trichosporon spp. have been characterized , while only a few cause human disease including T. asahii, T. inkin, T. asteroides, T. cutaneum, T. mucoides, T. ovoides (formerly subsumed as a single species: T. beigelii[4, 5]) and two more recently described species: T. louberi and japonicum. The most relevant disease entities caused by Trichosporon spp. are white piedra, a mycosis of the hair (T. inkin, T. ovoides) , summer-type hypersensitivity pneumonitis in Japan (T. asahii, T. mucoides and T. dermatis)  and invasive trichosporonosis (local and disseminated; most often caused by T. asahii) . Risk factors for invasive trichosporonosis are immunosuppression, including prolonged corticosteroid treatment, impaired granulocyte function, neutropenia, malignancies, especially leukemia , renal disease, extensive burns and HIV [7, 8]. Invasive Trichosporon infections are the second most common yeast fungaemia in humans [4, 9], especially in patients with haematological malignancies . Symptoms of invasive trichosporonosis range from pulmonary infiltrates, skin lesions and renal failure to local organ infections, such as hepatitis .
The significance of Trichosporon spp. for CF patients has so far not been widely recognized. Only three case reports are available in literature: One 11-year old CF patient suffered from a non-aspergillus allergic bronchopulmonary mycosis due to T. beigelii and recovered within 2 months under intensive steroid and antifungal therapy . One 20-year old, male CF patient died within a few days from admission due to a fulminant pneumonia with T. mycotoxinivorans and one 35-year old CF patient died due to a disseminated fatal infection with T. mycotoxinivorans 29 days after lung transplantation . Aim of this study was to investigate the detection rate of Trichosporon spp. in a German CF cohort and to describe the clinical course of patients positive for Trichosporon.
All respiratory samples of 360 CF patients (mean age 2010 18.11 years, range 0 – 52.4; mean FEV1 81.4% pred; range 16 – 136% pred; 12.5% with associated diabetes mellitus) who attended the CF Center at the Children’s University Hospital in Munich were studied between January 1st, 2003 and December 31st, 2010 for the presence of bacterial and/or fungal pathogens. Other detected fungi included Aspergillus species (approximately 16% of the cohort, >90% Aspergillus fumigatus) and Candida species (approximately 40% of the cohort, >90% Candida albicans). 15% of the patients exhibited intermittent Pseudomonas aeruginosa colonization, 48% chronic colonization. Patient visits took place on average every three months, if indicated more often. At each visit, sputum samples or throat smears were taken and the patients were investigated clinically; routine laboratory examinations including inflammatory parameters and lung-function tests were performed. On average 4 respiratory samples/patient/year were analysed, approximately 70% of the samples were throat swabs, 30% expectorated sputum. The clinical course of Trichosporon positive patients was analysed retrospectively based on forced expiratory volume in one second (FEV1,%pred), body mass index (BMI) and the inflammatory markers CRP (mg/l) and immunoglobulin G (IgG, g/l), the latter known to be associated with chronic inflammation and inversely correlated with lung function and long-term prognosis [14, 15]. The erythrocyte sedimentation rate 1 h (ESR, mm) was also recorded; however, insufficient data was available for analysis. Decline in FEV1 was defined as a drop of the yearly mean FEV1 of >1%pred/year from first detection to the end of the observation period of the individual patient, based on the average yearly drop of FEV1 values of 1% in large CF registries . Any change in BMI was recorded, increase in CRP was defined as an increase by >5 mg/l and an increase in IgG was defined as an increase by >3 g/l from first detection to the end of the observation period. Informed consent was obtained from all participants and the study was approved by the institutional review board of the University of Munich.
Microbiological examinations were routinely performed at the department of microbiology at the Dr. von Hauner Children’s hospital in Munich. Specimen with newly identified microorganisms were also analysed at the Max von Pettenkofer-Institute in Munich (National Consiliary Laboratory for CF Bacteriology, South Germany). Clinical specimens were diluted 1:2 with Dithiothreitol (DTT; Sigma, Deisenhofen, Germany) solution (1 mg/ml) for liquefaction. For quantitative bacteriology sputum samples were diluted 10-1, 10-4 and 10-5 with 0,9% NaCl and plated on Trypticase soy agar (TSA) and McConkey Agar. DTT-pretreated samples were further streaked on Columbia Agar with 5% sheep blood, Chocolate agar, Sabouraud-Glucose-Agar for fungi as well as on selective media containing either 8 μg/ml Meropenem or 16 μg/ml Polymyxin B to recover Carbapenem-resistent gram-negative bacteria and Burkholderia cepacia complex isolates, respectively. Columbia Agar and Chocolate agar were incubated at 32°C under anaerobic conditions to prevent overgrowth of clinically important bacteria such as H. influenza by P. aeruginosa, while all other media were incubated aerobically at 32°C. All bacteriological cultures were incubated for 3–5 days and Sabouraud-Glucose-Agar for at least 10 days. Species identification was performed by routine microbiological procedures. Yeasts were isolated on chromogenic Agar plates for differentiation. Filamentous fungi were primarily differentiated by micromorphological examinations.
Trichosporon spp. in pts 1,2,4,6,7,8 were identified by alternative biochemical test (API 20 C AUX and ID 32 C galleries bioMérieux, Mercy l’Etoile, France). T. asahii (patient 2) was identified by microscopic identification, biochemical testing and Matrix Assisted Laser Desorption Ionisation – Time of flight Mass Spectrometry (MALDI-TOF MS Biotyper system Bruker Daltonics). Three strains (two strains of patient 3, one strain of patient 5) were further analysed - prompted by the clinical deterioration of these patients after Trichosporon detection. In a first step these strains were identified by the MALDI-TOF MS BioTyper system; in a second step DNA sequencing was performed to confirm the MALDI-TOF results. MALDI-TOF MS is a reliable method to rapidly identify fungal species, and can be used as an alternative to PCR-based techniques [17, 18], which have been extensively used for the identification of Trichosporon spp.. DNA sequencing of conserved (D1/D2 region of the 28S rDNA) and variable regions (ITS and IGS1 regions) are common methods to determine Trichosporon spp.[20, 21].
Characterization and follow-up of CF patients positive for Trichosporon
Age at first detection (y)
Age at last detection (y)
Follow up (y) *
Other isolated organisms from sputum (at first detection)
Ps ae (chron), Ps ae muc
E col, Prot mirab
Norcard farc, Inqu lin, Burc cep, Asp fum, Penicill sp
Ps ae (chron), Cand alb
Acinet baum, fungi (not spec), Ps ae (chron)
Ps ae (chron), Ps ae muc, Cand alb
Ps ae muc (chron), Cand alb
Other isolated organisms from sputum (throughout observation period)
Pseudoall boyd (rep), Cand glab (rep), Cand alb (rep), Cand paraps (rep), Enteroc spp. (rep), Asp fum (rep)
Prot mirab (rep), Asp fum (rep)
Asp fum (rep), Sten mal (rep), Cand alb (rep), Sa (rep)
Inqu lin (rep), Burc cep (rep), Penicill sp (rep), Acinet fum (rep), Ps put (once)
E coli (rep), Sten malt (rep), Asp flav (rep)
Acinet baum (rep), Pet sord (rep)
Asp fum (rep), Prot mirab (rep), Sa (rep), Enteroc spp (rep), Cand alb (rep)
Cand paraps (rep)
Antibiotic regimen prior to first detection (agent; regimen)
Cefur (cont), Cip (2 w on/off)
Cep (cont), Cip (2 w on/off)
Ceph (cont), Cip (2 w on/off)
Ceph (cont), cip (2 w on/off)
Tob/col (2 w on/off)
Col (2 w on/off)
Tob/col (2 w on/off)
Gern (2 w on/off)
Gern (2 w on/off)
Gern/col (2 w on/off)
Diabetes mellitus (at first detection)
ABPA (years prior to first detection)
1 y after first detection
At first detection
Nebulized/inhaled steroids prior to first detection (duration)
Yes (5y, rep)
Yes (from first detection on)
Intermittent systemic steroids prior to first detection
Yes (from first detection on)
Lung function FEV 1 (% pred) **
At first detection
At end of observation
BMI (kg/m 2 ) ***
At first detection
At end of observation
IgG (g/l) ****
At first detection
At end of observation
At first detection
At end of observation
Clinical course of patients positive for Trichosporon
Patients 3 and 5 received antimycotic treatment due to an unexplained but marked deterioration of the clinical status. Patient 5 with a prolonged detection period of T. mycotoxinivorans exhibited a recurrent and tormenting dry cough; she reported a substantial subjective improvement of the dry cough after inhalation with nebulized Amphotericin B (not liposomal, 15 mg 1:1 diluted with distilled water, 1x/day for 4–8 weeks, 3x/year). T. mycotoxinvorans however persisted in the sputum. Patient 3 is described in detail below.
Clinical course of patient 3
The relevance of fungal colonization in CF patients has only recently been recognized . Colonization with C. albicans and A. fumigatus –also in non-ABPA patients- has for example been associated with a decline in lung function and a negative effect on the clinical outcome [23, 24]. A. fumigatus in particular was demonstrated to have a pro-inflammatory effect on the CF epithelium . However, the available studies are limited by important confounders, such as the lack of standardized detection methods or co-infection with other microorganisms. The contribution of fungi to CF lung disease thus remains controversial as does the indication to a non-risk free antifungal therapy.
The prevalence and the relevance of Trichosporon spp. in CF has to date not been investigated. In the present study Trichosporon spp. was found in respiratory samples of 2.2% of the cohort over an eight year period. Colonization rates of Trichosporon spp. in non-CF patients range between 0.8% in throat cultures and 3.1% in stool cultures of patients in a large Veterans hospital  and 3.7% in stool, skin or urine of 317 immunosuppressed hosts .
Risk factors for colonization and/or infection with Trichosporon in CF are also unknown. Invasive trichosporonosis in non-CF patients has been associated with mucosal disruption and general immune dysfunction due to HIV or malignancies , however, the exact pathophysiology of Trichosporon infections is unknown. It is possible that mucosal disruption in CF also predisposes for Trichosporon colonization. Our data suggest that age, prior systemic or inhaled steroid treatment, ABPA and possibly CF associated diabetes might predispose for Trichosporon colonization. 3 of 8 patients carried a stop mutation in addition to dF508, which is higher than the general frequency of stop mutations in German CF population (1.8% for R553X; <1% for S466X) . Our data further indicate that longer Trichosporon detection periods may be associated with a decline in lung function and BMI, and increased inflammation. Chronic airway colonization with Trichosporon may harbour the risk of clinically relevant infection leading to unstable lung disease. Further studies will have to corroborate these findings.
Limitations of the current study include the relatively small amount of patients, the retrospective design, the presence of other microorganisms as a confounder and the lack of specification of all Trichosporon spp. Standardized diagnostic procedures were subsequently introduced.
Up to now three case reports of CF patients have demonstrated the potential of exacerbation and in two cases of a fatal, disseminated infection due to Trichosporon spp.[11–13]. Here we add another patient (3) whose course was significantly affected by infection with T. inkin. This conclusion is based on the unexplained failure of intensive antibacterial and supportive therapy and the clear improvement and stabilization of the clinical status after the initiation of antifugal therapy. Repeated detection of Trichosporon spp. may indicate CF patients at risk for deterioration; preemptive treatment may be considered.
To conclude, emerging pathogens relevant for CF lung disease may include the basidiomycetous yeast Trichosporon. Its detection in respiratory secretions in patients not responding to standard antimicrobial therapy may warrant targeted antifungal therapy.
We thank Ms Traudl Wesselak for her support in the acquisition of data. The authors were not funded for this study.
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