Characterization of Trichosporon species isolated from clinical specimens in Kuwait

Trichosporon asahii: emerging challenges in pathogenesis and drug resistance

Trichosporon asahii (T. asahii) is an opportunistic pathogenic fungus that often causes severe infections in immunosuppressed patients. Among Trichosporon species, T. asahii is the most pathogenic and lethal species. Current research faces challenges related to unknown pathogenic mechanisms, complex resistance mechanisms, insufficiently rapid and accurate diagnostic methods, and insufficient research on susceptibility to infection. These issues need to be explored in depth. This review summarizes research progress on the origin and classification of T. asahii, its virulence factors and pathogenic mechanisms, epidemiological characteristics, infection modes, diagnostic methods, drug treatment options, and drug resistance mechanisms. Traditional culture combined with molecular biology techniques, such as polymerase chain reaction and gene sequencing, has improved the accuracy and speed of detection. Treatment relies mainly on azole antifungal drugs and amphotericin B; however, patients are facing the problem of drug resistance. New techniques, such as gene knockout and gene sequencing, have identified resistance mechanisms, thus supporting the development of novel antifungal drugs. In summary, an in-depth study of T. asahii will aid in developing more effective diagnostic and therapeutic methods and improve patient prognosis.

Identification of Trichosporon yeast isolates from superficial infections in male patients from Central Brazil: an approach to the diversity of infections caused by this basidiomycete fungus

The genus Trichosporon are currently recognized as opportunistic pathogens capable of causing superficial "white piedra" infections and potentially fatal invasive diseases (Trichosporonosis). In this work, determine the agent Trichosporon spp. isolated from the skin and appendages of a male population group in the Central-West region of Brazil. The isolates were analyzed by phenotypic, biochemical and molecular methods. Twenty-five strains of Trichosporon were isolated: T. asahii (18; 72%), followed by T. inkin (4; 16%) and T. faecale (3; 12%). Skin infections were the most affected (16; 64%) and the genitocrural region (13; 52%) was the most affected. The highest rate of isolation occurred between the ages of 21 and 30 years (9; 36%), with black men (African descent) (13; 52%) being the most affected by this type of superficial infection. After the advent of molecular techniques, more than 50 subspecies and about 16 different strains have been reported to cause human disease. In this series, three species of the genus Trichosporon of medical importance were highlighted, colonizing the genital and perigenital region of the studied population. For the identifications, classical phenotypic methods associated with genotypic identification were carried out, using molecular techniques based on the study of DNA; using sequence analysis of the DNA intergenic spacer region 1 (IGS1).

Spectrum and management of rare Candida/yeast infections in Kuwait in the Middle East

Invasive fungal infections (IFIs) are associated with high mortality rates and mostly affect patients with compromised immunity. The incidence of IFIs is increasing worldwide with the expanding population of susceptible patients. Candida and other yeast infections represent a major component of IFIs. Rare Candida/yeast infections have also increased in recent years and pose considerable diagnostic and management challenges as they are not easily recognized by routine phenotypic characteristic-based diagnostic methods and/or by the automated yeast identification systems. Rare Candida/yeasts also exhibit reduced susceptibility to antifungal drugs making proper management of invasive infections challenging. Here, we review the diagnosis and management of 60 cases of rare Candida/yeast IFIs described so far in Kuwait, an Arabian Gulf country in the Middle East. Interestingly, majority (34 of 60, 56.7%) of these rare Candida/yeast invasive infections occurred among neonates or premature, very-low-birth-weight neonates, usually following prior bacteremia episodes. The clinical details, treatment given, and outcome were available for 28 of 34 neonates. The crude mortality rate among these neonates was 32.2% as 19 of 28 (67.8%) survived the infection and were discharged in healthy condition, likely due to accurate diagnosis and frequent use of combination therapy. Physicians treating patients with extended stay under intensive care, on mechanical ventilation, receiving broad spectrum antibiotics and with gastrointestinal surgery/complications should proactively investigate IFIs. Timely diagnosis and early antifungal treatment are essential to decrease mortality. Understanding the epidemiology and spectrum of rare Candida/yeast invasive infections in different geographical regions, their susceptibility profiles and management will help to devise novel diagnostic and treatment approaches and formulate guidelines for improved patient outcome.

Identification of Clinical Trichosporon asteroides Strains by MALDI-TOF Mass Spectrometry: Evaluation of the Bruker Daltonics Commercial System and an In-House Developed Library

Trichosporon asteroides is an emerging yeast-like pathogen commonly misidentified by commercial biochemical identification systems. We evaluated the performance of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the identification of 21 clinical T. asteroides strains using the Bruker Daltonics database (BDAL) and an in-house developed library. Mass spectra were obtained by the FlexControl system v.3.4, and characterizations were performed in the Biotyper BDAL database v.4.1 and the developed in-house library. Species identification for T. asteroides failed as all 21 strains were misidentified as T. japonicum (log-scores 1.89-2.19). Extending the existing database was crucial to achieving 100% correct species-level identification and accurate distinction between species. Our results indicate that the commercial BDAL database has no discriminatory power to distinguish between T. japonicum and T. asteroides. Whereas improvement of the current BDAL database is pending, we strongly advise system users not to exclude the possibility of the failure to report T. asteroides.

Histopathological alterations induced by marine environmental pollutants on the bivalve Cerastoderma glaucum (Bruguière 1789) from Temsah Lake, Suez Canal, Egypt

Bivalves are considered a main consumed matrix for coastal communities worldwide and classified as hyperaccumulators of pollutants. The present study aims to determine some micro-organisms, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and okadaic acid (OA) levels in Cerastoderma glaucum collected from Temsah Lake, Egypt, and their induction through histopathological damage and caspase-3 protein expression. During the autumn, it was found different types of biological and chemical pollutants, especially benzo[a]pyrene (BaP) that accumulated in C. glaucum soft tissues and exceeded the safety limit for shellfish consumption. Dioxin-like PCB3 was predominant in C. glaucum soft tissues during autumn, but the total levels of PCBs in these tissues have not exceeded the permissible limit. Chlorophyll-a (Chl. a), nutrient concentrations, and Prorocentrum lima dinoflagellates in the water significantly increased during autumn. High P. lima abundance was confirmed by high OA in the soft tissues during this season compared to the other seasons. The measured contaminants may render C. glaucum more susceptible to bacterial and fungal infections. The autumn season showed a significant increase in the colony-forming units (CFU). C. glaucum showed calcification abnormalities and adhering of abnormal brown organic material to the inner surface of the shell valves, which was related to poor water conditions and Vibrio infection. Damages or injuries on gills and digestive gland tissues indicated an impact of the pollutants on C. glaucum. Also, high expressions of caspase-3 were recorded in these tissues during all the seasons. So, C. glaucum cockles, collected from Temsah Lake, may induce serious diseases to consumers, especially when eaten raw or insufficient cooking.

Trichosporon inkin fungemia case report: clinical and laboratory management

Trichosporon species are emerging as opportunistic pathogens that mainly affect immunocompromised patients. Patients with onco-hematological diseases usually present with fungemia by Trichosporon species, especially by T. asahii. Reports of this infection by other species of the genus are uncommon. Thus, in this paper, we present a case of T. inkin fungemia in a 39-year-old female patient with intestinal obstruction and absence of malignant hematological diseases. The late mycological diagnosis, the ineffective control of her pre-existing conditions and consequent failure to start antifungal therapy were the contributing factors for the patient's death.

Comparing the phenotypic, genotypic, and proteomic identification of Trichosporon species: A globally emerging yeast of medical importance

Trichosporon spp. are widely distributed in the nature, comprising species that inhabit different ecological niches and can be found in the water, soil, and body surface of animals and humans. Such microorganisms have been classically associated with superficial infections; however, in the last decades, they have also been related to disseminated infections in immunocompromised patients, behaving as opportunistic agents, which demands rapid and accurate species identification for efficient therapy. Concordance level between the traditional phenotypic method and the molecular technique (gold standard) in the identification of all 59 Trichosporon samples was 59.3%. Identification concordance between MALDI-TOF spectrometry and the molecular technique was 71.2%. No isolate of environmental origin was identifiable by MALDI-TOF mass spectrometry (MS), and 100% of such environmental isolates were discordant for IGS region sequencing and phenotypic characterization. Both comparisons evidenced greatest concordance in the identification of T. asahii. The species T. debeurmannianum, T. dermatis, T. venhuisii and T. insectorum were not properly identified by both MALDI-TOF MS and the phenotypic technique. MALDI-TOF MS, in particular, seems to be appropriate to investigate yeasts of the genus Trichosporon; however, database updates are still necessary, especially for species that are not common in the clinical routine. With the aim of helping understand the aspects involved in early and accurate diagnosis of infections caused by this opportunistic agent, the present study compared the phenotypic, molecular (IGS region) and mass-spectrometry (MALDI-TOF) identification of 59 yeasts of the genus Trichosporon which had clinical and environmental origin and were kept in a mycology collection.

Strain Typing of Trichosporon asahii Clinical Isolates by Random Amplification of Polymorphic DNA (RAPD) Analysis

Objective The aim of this study was to identify and isolate Trichosporon asahii ( T. asahii ) from clinical samples and to assess the genetic relatedness of the most frequently isolated strains of T. asahii using random amplification of polymorphic DNA (RAPD) primers GAC-1 and M13.

Methods All the clinical samples that grew Trichosporon species, identified and confirmed by polymerase chain reaction (PCR) using Trichosporon genus-specific primers, were considered for the study. Confirmation of the species T. asahii was carried out by T. asahii- specific PCR. Fingerprinting of the most frequently isolated T. asahii isolates was carried out by RAPD using random primers GAC-1 and M13.

Results Among the 72 clinical isolates of Trichosporon sp. confirmed by Trichosporon -specific PCR, 65 were found to be T. asahii as identified by T. asahii- specific PCR. Fingerprinting of the 65 isolates confirmed as T. asahii using GAC-1 RAPD primer yielded 11 different patterns, whereas that of M13 primer produced only 5 patterns. The pattern I was found to be the most predominant type (29.2%) followed by pattern III (16.9%) by GAC-1 primer.

Conclusions This study being the first of its kind in India on strain typing of T. asahii isolates by adopting RAPD analysis throws light on genetic diversity among the T. asahii isolates from clinical samples. Fingerprinting by RAPD primer GAC-1 identified more heterogeneity among the T. asahii isolates than M13.

Molecular Identification, Genotyping, Phenotyping, and Antifungal Susceptibilities of Medically Important Trichosporon, Apiotrichum, and Cutaneotrichosporon Species

Recently, Trichosporon taxonomy has been reevaluated and new genera of the Trichosporonaceae family have been described. Here, 26 clinical isolates were submitted for identification via sequencing of the intergenic space 1 (IGS1) region, genotyping, and investigation of virulence factors. Antifungal susceptibility was determined using the CLSI broth microdilution method for fluconazole (FLC), itraconazole (ITC), and amphotericin B (AMB). Of these, 24 isolates were identified, including 12 T. asahii, 4 T. inkin, 3 T. faecale, 1 T. coremiiforme, 1 T. japonicum, 2 Cutaneotrichosporon dermatis (formerly T. dermatis), and 1 Apiotrichum mycotoxinivorans (formerly T. mycotoxinivorans). Species-level identification of 2 isolates was not successful; they were described as Trichosporon sp. We observed optimal colonial development at 35-40 °C. Lipase was the major extracellular enzyme produced (100%); caseinase was not produced (0%). Biofilms were produced by all isolates (classified as low). High AMB minimum inhibitory concentration (MIC) was observed, with all strains resistant. Fluconazole was the most active drug among the antifungals tested. However, high MICs for FLC were observed in C. dermatis and A. mycotoxinivorans species, which also showed resistance to ITC and AMB. This study, conducted in the Northern region of Brazil, identified 5 Trichosporon species along with C. dermatis and A. mycotoxinivorans and demonstrated their pathogenic potential through their ability to produce important virulence factors. This may contribute to our understanding of the epidemiology and factors related to the pathogeneses of species in the Trichosporonaceae family.

Yeast identification by sequencing, biochemical kits, MALDI-TOF MS and rep-PCR DNA fingerprinting

No study has comprehensively evaluated the performance of 28S nrDNA and ITS sequencing, commercial biochemical test kits, MALDI-TOF MS platforms, and the emerging rep-PCR DNA fingerprinting technology using a cohort of yeast strains collected from a clinical microbiology laboratory. In this study, using 71 clinically important yeast isolates (excluding Candida albicans) collected from a single centre, we determined the concordance of 28S nrDNA and ITS sequencing and evaluated the performance of two commercial test kits, two MALDI-TOF MS platforms, and rep-PCR DNA fingerprinting. 28S nrDNA and ITS sequencing showed complete agreement on the identities of the 71 isolates. Using sequencing results as the standard, 78.9% and 71.8% isolates were correctly identified using the API 20C AUX and Vitek 2 YST ID Card systems, respectively; and 90.1% and 80.3% isolates were correctly identified using the Bruker and Vitek MALDI-TOF MS platforms, respectively. Of the 18 strains belonging to the Candida parapsilosis species complex tested by DiversiLab automated rep-PCR DNA fingerprinting, all were identified only as Candida parapsilosis with similarities ≥93.2%, indicating the misidentification of Candida metapsilosis and Candida orthopsilosis. However, hierarchical cluster analysis of the rep-PCR DNA fingerprints of these three species within this species complex formed three different discrete clusters, indicating that this technology can potentially differentiate the three species. To achieve higher accuracies of identification, the databases of commercial biochemical test kits, MALDI-TOF MS platforms, and DiversiLab automated rep-PCR DNA fingerprinting needs further enrichment, particularly for uncommonly encountered yeast species.

Spatial and compositional variation in the fungal communities of organic and conventionally grown apple fruit at the consumer point-of-purchase

The fungal diversity in harvested apples from organic or conventional management practices was analyzed in different fruit locations (stem end, calyx end, peel, and wounded flesh) shortly after fruit purchase (T1) and after 2 weeks of storage (T5). A total of 5,760,162 high-quality fungal sequences were recovered and assigned to 8,504 Operational Taxonomic Units. Members of the phylum Ascomycota were dominant in all samples and accounted for 91.6% of the total number of detected sequences. This was followed by Basidiomycota (8%), Chytridiomycota (0.1%), and unidentified fungi (0.3%). Alpha and beta diversity analyses revealed the presence of significantly different fungal populations in the investigated fruit parts. Among detected fungi, the genus Penicillium prevailed in the peel and in the wounded flesh while Alternaria spp. prevailed in the calyx and stem end samples that included apple core tissues. Several taxonomic units that appear to be closely related to pathogenic fungi associated with secondary human infections were present in peel and wounds. Moreover, significantly different populations were revealed in organic and conventional apples and this result was consistent in all investigated fruit parts (calyx end, peel, stem end, and wounded flesh). Several unique taxa were exclusively detected in organic apples suggesting that management practices may have been a contributing factor in determining the taxa present. In contrast, little differences were revealed in the two assessment times (T1 and T5). Results of the present study represent an advancement of the current knowledge on the fungal microbiota in collected fruit tissues of apple.

Epidemiology and Outcome of Trichosporon Fungemia: A Review of 185 Reported Cases From 1975 to 2014

We first reviewed the English-language literature for reported cases of Trichosporon fungemia over the past four decades, and did comprehensive analysis in order to guide our understanding of epidemiology and outcome-related aspects, especially the antifungal treatment and CVC management.

Background. Trichosporon species have emerged as an important non-Candida spp yeast pathogen in immunocompromised patients in recent decades; however, the systemic analysis of Trichosporon epidemiology has seldom been reported.

Methods. We reviewed 185 reported cases of Trichosporon fungemia from 1975 to 2014 in the English-language literature, and the epidemiology and prognostic factors of the included cases are described.

Results. The number of cases reported has increased with time, especially over the past decade. During the 3 decades from 1975 to 2004, the most commonly used antifungal compounds were amphotericin B/liposomal amphotericin B; however, in recent decades (2005–2014), triazoles (especially voriconazole) have become the most widely used agents, significantly improving outcome in the reported cases. Correlation analysis revealed that negative outcome is associated with several prognostic factors, including a history of antimicrobial use, bacterial bloodstream coinfection, prophylactic/empirical antifungal therapy, Trichosporon beigelii infection, and receiving the antifungal regimen of amphotericin B/liposomal amphotericin B. In addition, a significantly greater proportion of patients with a positive outcome had fungemia without invasive tissue infection and received a voriconazole regimen or an AmB-triazole combined regimen. Significant positive outcome was also associated with patients who had recovered from neutropenia or after central venous catheter removal.

Conclusions. Voriconazole can be recommended as a first-line antifungal compound to treat Trichosporon fungemia; the immune status of the host plays a crucial role in the outcome of this infection, and the removal of vascular catheters should be considered if feasible.

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

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.

Identification of medically relevant species of arthroconidial yeasts by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was used for an extensive identification study of arthroconidial yeasts, using 85 reference strains from the CBS-KNAW yeast collection and 134 clinical isolates collected from medical centers in Qatar, Greece, and Romania. The test set included 72 strains of ascomycetous yeasts (Galactomyces, Geotrichum, Saprochaete, and Magnusiomyces spp.) and 147 strains of basidiomycetous yeasts (Trichosporon and Guehomyces spp.). With minimal preparation time, MALDI-TOF MS proved to be an excellent diagnostic tool that provided reliable identification of most (98%) of the tested strains to the species level, with good discriminatory power. The majority of strains were correctly identified at the species level with good scores (>2.0) and seven of the tested strains with log score values between 1.7 and 2.0. The MALDI-TOF MS results obtained were consistent with validated internal transcribed spacer (ITS) and/or large subunit (LSU) ribosomal DNA sequencing results. Expanding the mass spectrum database by increasing the number of reference strains for closely related species, including those of nonclinical origin, should enhance the usefulness of MALDI-TOF MS-based diagnostic analysis of these arthroconidial fungi in medical and other laboratories.

Current knowledge of Trichosporon spp. and Trichosporonosis

Trichosporon spp. are basidiomycetous yeast-like fungi found widely in nature. Clinical isolates are generally related to superficial infections. However, this fungus has been recognized as an opportunistic agent of invasive infections, mostly in cancer patients and those exposed to invasive medical procedures. It is possible that the ability of Trichosporon strains to form biofilms on implanted devices, the presence of glucuronoxylomannan in their cell walls, and the ability to produce proteases and lipases are all factors likely related to the virulence of this genus and therefore may account for the progress of invasive trichosporonosis. Disseminated trichosporonosis has been increasingly reported worldwide and represents a challenge for both diagnosis and species identification. Phenotypic identification methods are useful for Trichosporon sp. screening, but only molecular methods, such as IGS region sequencing, allow the complete identification of Trichosporon isolates at the species level. Methods for the diagnosis of invasive trichosporonosis include PCR-based methods, Luminex xMAP technology, and, more recently, proteomics. Treating patients with trichosporonosis remains a challenge because of limited data on the in vitro and in vivo activities of antifungal drugs against clinically relevant species of the genus. Despite the mentioned limitations, the use of antifungal regimens containing triazoles appears to be the best therapeutic approach.

Bipolaris hawaiiensis as etiologic agent of allergic bronchopulmonary mycosis: first case in a paediatric patient

Allergic bronchopulmonary mycosis (ABPM) is a worldwide hypersensitivity lung disease of multiple etiologies with Aspergillus fumigatus as the most common etiologic agent. We report the first instance of Bipolaris hawaiiensis causing ABPM in a paediatric patient. A six-year-old girl presented in June 2009 with productive cough, exertional dyspnoea, occasional wheezing, restricted air entry in left infra-scapular and infra-axillary areas, 7% eosinophils (absolute count 540/mm(3)) and total IgE 1051.3 IU/m in the sera. Bronchoscopy revealed narrowing of left main bronchus and mucoid impaction of the left lower lobe segmental bronchi. Cytological examination of BAL revealed few eosinophils, Charcot-Leyden crystals and mucus embedded hyphae. Examination of KOH wet mounts of repeated sputum and BAL specimens revealed septate, brownish hyphae and culture of the specimens resulted in the isolation of multiple colonies of a fungus later identified as B. hawaiiensis based on phenotypic characters and sequencing of internal transcribed spacer and D1/D2 regions of rDNA. In addition, (1-3)-β-D-glucan was demonstrated in serum (316 pg/ml) by Fungitell kit, supportive of fungal infection/colonization. Histopathologic studies of a bronchial biopsy revealed necrotic debris, macrophage aggregates, lymphocytes, polymorphs and PAS positive hypae. The patient was administered oral itraconazole for 12 weeks, intravenous liposomal amphotericin B for one month, weekly bronchoscopic suctioning and voriconazole instillation, resulting in reduced mucopurulent secretions and considerable clinical improvement. A serum sample collected on 5 November demonstrated precipitins against antigens of the B. hawaiiensis isolate. In March 2010, intradermal skin testing revealed a strong, type I hypersensitivity (induration diam-12 mm) against B. hawaiiensis. The patient relapsed with wheezing and difficulty in respiration in April 2010. Considering the positive type I cutaneous hypersensitivity, the aforementioned laboratory and clinical observations, the patient was finally diagnosed as having ABPM and was successfully treated with oral prednisone. A high index of clinical suspicion with requisite investigations is crucial for early diagnosis and appropriate therapy of ABPM in order to prevent the late sequelae of irreversible broncho-pulmonary damage.

Rhinoentomophthoromycosis due to Conidiobolus coronatus. A case report and an overview of the disease in India

Rhinoentomophthoromycosis due to Conidiobolus coronatus is a rare, chronic, granulomatous disease, occurring mainly in tropical Africa, South and Central America and south-east Asia, including India. We report a case of rhinoentomophthoromycosis in a 30-year-old male farmer, a resident of Gorakhpur city in Uttar Pradesh, which was diagnosed by histopathology and isolation C. coronatus in culture. The patient presented with a swollen nose with obstruction that had progressed slowly over one year. His nasal swelling was bilateral, diffuse, mildly tender, erythematous, non-pitting, with mucosal crusting and hypertrophy of inferior turbinates but no regional lympha-denopathy. A contrast-enhanced computed tomography (CECT) scan revealed bilateral pan-sinusitis with nasoethmoid polyposis. Culture of tissue from the nasal biopsy on Sabouraud glucose agar yielded multiple colonies of a mold with satellite smaller colonies at periphery. The isolate demonstrated the macroscopic and microscopic morphologic characteristics of C. coronatus. Its identity was further confirmed by direct DNA sequencing of internal transcribed spacer (ITS) and D1/D2 regions of rDNA. Haemotoxylin and eosin stained tissue sections of the skin biopsy revealed irregular epidermal acanthosis, marked inflammatory and granulomatous reaction with sparse, non-septate hyphae. The patient was treated successfully with a combination therapy of oral saturated potassium iodide solution, itraconazole, and intravenous infusion of amphotericin B. An overview of rhinoentomophthoromycosis cases reported to-date in India is presented.

Isolation of Cryptococcus magnus and Cryptococcus chernovii from nasal cavities of pediatric patients with acute lymphoblastic leukemia

We report the isolation of Cryptococcus magnus and Cryptococcus chernovii in cultures inoculated with nasal specimens of pediatric cancer patients with acute lymphoblastic leukemia. The phenotypic characteristics of the isolates are described and their identity confirmed by sequencing of rDNA. Both species were resistant to caspofungin, anidulafungin, 5-flucytosine and itraconazole, but susceptible to amphotericin B, posaconazole and voriconazole. To the best of our knowledge, the isolation of these two species from nasal cavities has not been reported previously.

Levels of (1→3)-β-D-glucan, Candida mannan and Candida DNA in serum samples of pediatric cancer patients colonized with Candida species

BACKGROUND

Surveillance cultures may be helpful in identifying patients at increased risk of developing invasive candidiasis. However, only scant information exists on the effect of Candida colonization on serum levels of diagnostic biomarkers. This prospective surveillance study determined the extent of Candida colonization among pediatric cancer patients and its possible impact on serum levels of (1-3)-β-D-glucan (BDG), Candida mannan and Candida DNA.

METHODS

A total of 1075 swabs originating from oropharynx (n = 294), nostrils (n = 600), rectum (n = 28), groin (n = 50), ear (n = 54), and axilla (n = 49) of 63 pediatric cancer patients were cultured for the isolation of Candida spp. Patients yielding Candida spp. from any sites were considered as colonized. Serum samples were collected from patients at the time of first surveillance culture for detection of BDG by Fungitell kit and Candida mannan by Platelia Candida Ag. Candida DNA was detected by using panfungal primers and identification was carried out by using species-specific primers and DNA sequencing.

RESULTS

Seventy-five (7.6%) swab cultures from 35 (55.5%) patients yielded Candida spp. These isolates included C. albicans (n = 62), C. dubliniensis (n = 8), C. glabrata and C. tropicalis (n = 2 each) and C. krusei (n = 1). Eleven patients were colonized at three or more sites. Eight of 36 serum samples from 6 colonized patients yielded BDG values higher than the currently recommended cut-off value of ≥80 pg/ml. However, none of the serum samples yielded Candida mannan levels ≥0.5 ng/ml and PCR test for Candida DNA was also negative in all the serum samples of colonized patients. During the study period, only two colonized patients subsequently developed candidemia due to C. tropicalis. Besides positive blood cultures, C. tropicalis DNA, BDG and Candida mannan were also detected in serum samples of both the patients.

CONCLUSIONS

The present study demonstrates that while mucosal colonization with Candida species in pediatric cancer patients is common, it does not give rise to diagnostically significant levels of Candida mannan or Candida DNA in serum specimens. However, BDG values may be higher than the cut-off value in some pediatric patients without clinical evidence of invasive Candida infection. The study suggests the utility of Candida mannan or Candida DNA in the diagnosis of invasive candidiasis, however, the BDG levels in pediatric cancer subjects should be interpreted with caution.

Trichosporon peritonitis following duodenal perforation

Fungal peritonitis, which was once a rare entity, is becoming increasingly common due to various immunocompromised conditions. Candida species are considered the common cause of fungal peritonitis in most cases. However, at present, other yeasts and filamentous fungi are replacing the dominance of Candida albicans as well as other Candida species. Trichosporon species are widely distributed in nature and are normal flora in the gastrointestinal tract of humans. Ever since the report of disseminated trichosporonosis in 1970, several cases of infections by various Trichosporon species in different clinical patients have been published. Here, we present a patient with Trichosporon peritonitis after duodenal perforation. To the best of our knowledge, this is the first case report of its kind from India.

Cryptococcus randhawai sp. nov., a novel anamorphic basidiomycetous yeast isolated from tree trunk hollow of Ficus religiosa (peepal tree) from New Delhi, India

A novel anamorphic Cryptococcus species is described, which was isolated in New Delhi (India) from decaying wood of a tree trunk hollow of Ficus religiosa. On the basis of sequence analysis of the D1/D2 domains of the 26S rRNA gene and the internally transcribed spacer (ITS)-1 and ITS-2 region sequences, the isolate belonged to the Cryptococcus albidus cluster (Filobasidiales, Tremellomycetes) and was closely related to Cryptococcus saitoi, Cryptococcus cerealis and Cryptococcus friedmannii with 98% sequence identity. Phenotypically, the species differed from C. saitoi with respect to growth temperature (up to 37degrees C), presence of a thin capsule, ability to grow in the absence of vitamins, and inability to assimilate citrate and ethylamine. With respect to C. friedmannii, it differed in growth temperature, ability to assimilate lactose, raffinose, L: -rhamnose, myo-inositol, and inability to utilize citrate. Furthermore, our isolate also differed from C. cerealis in growth temperature, presence of capsule and inability to assimilate L: -sorbose. In view of the above phenotypic differences and unique rDNA sequences, we consider that our isolate represents a new species of Cryptococcus, and therefore, a new species, Cryptococcus randhawai is proposed for this taxon. The type strain J11/2002 has been deposited in the culture collection of the Centraalbureau voor Schimmelcultures (CBS10160) and CABI Biosciences (IMI 393306).

Rapid molecular differentiation and genotypic heterogeneity among Candida parapsilosis and Candida orthopsilosis strains isolated from clinical specimens in Kuwait

Recent molecular studies have led to the recognition of three distinct species within the Candida parapsilosis complex, namely Candida parapsilosis, Candida orthopsilosis and Candida metapsilosis. As currently available yeast identification systems fail to differentiate these species, there is a paucity of information on their occurrence in different geographical regions. This study describes a simple PCR-based protocol for rapid discrimination among C. parapsilosis, C. orthopsilosis and C. metapsilosis strains by using primers derived from unique sequences within the internally transcribed spacer 1 (ITS1)-5.8 rRNA-ITS2 region. Retrospective analysis of 114 C. parapsilosis-complex isolates recovered from clinical specimens in Kuwait identified 109 as C. parapsilosis, five as C. orthopsilosis and none as C. metapsilosis. The results were further validated by PCR-RFLP patterns of the secondary alcohol dehydrogenase gene fragment. DNA sequencing of the ITS region and the D1/D2 regions of the 28S rRNA gene confirmed the species-specific identification of all five C. orthopsilosis strains. The amplicon length of the intergenic spacer between the 28S and 5S rRNA genes (IGS1) was also species-specific, and PCR-RFLP analyses of the IGS1 region identified two distinct genotypes among the five C. orthopsilosis strains, which corresponded with the ITS region sequence data. The three bloodstream C. orthopsilosis strains were confined to a single genotype. Among 81 randomly selected C. parapsilosis strains, two genotypes were detected by IGS1 region analyses, indicating limited genotypic heterogeneity among C. parapsilosis sensu stricto strains. As far as is known, this is the first report on the identification of C. orthopsilosis from a bloodstream infection in the Arabian Gulf region.

Molecular identification and susceptibility of Trichosporon species isolated from clinical specimens in Qatar: isolation of Trichosporon dohaense Taj-Aldeen, Meis & Boekhout sp. nov

Trichosporon species have been reported as emerging pathogens and usually occur in severely immunocompromised patients. In the present work, 27 clinical isolates of Trichosporon species were recovered from 27 patients. The patients were not immunocompromised, except for one with acute myeloid leukemia. Sequence analysis revealed the isolation of Trichosporon dohaense Taj-Aldeen, Meis & Boekhout sp. nov., with CBS 10761(T) as the holotype strain, belonging to the Ovoides clade. In the D1-D2 large-subunit rRNA gene analysis, T. dohaense is a sister species to T. coremiiforme, and in the internal transcribed spacer analysis, the species is basal to the other species of this clade. Molecular identification of the strains yielded 17 T. asahii, 3 T. inkin, 2 T. japonicum, 2 T. faecale, and 3 T. dohaense isolates. The former four species exhibited low MICs for five antifungal azoles but showed high MICs for amphotericin B. T. dohaense demonstrated the lowest amphotericin B MIC (1 mg/liter). For the majority of T. asahii isolates, amphotericin B MICs were high (MIC at which 90% of isolates were inhibited [MIC(90)], > or = 16 mg/liter), and except for fluconazole (MIC(90), 8 mg/liter), the azole MICs were low: MIC(90)s were 0.5 mg/liter for itraconazole, 0.25 mg/liter for voriconazole, 0.25 mg/liter for posaconazole, and 0.125 mg/liter for isavuconazole. The echinocandins, caspofungin and anidulafungin, demonstrated no activity against Trichosporon species.

Bloodstream infections due to Trichosporon spp.: species distribution, Trichosporon asahii genotypes determined on the basis of ribosomal DNA intergenic spacer 1 sequencing, and antifungal susceptibility testing

The reevaluation of the genus Trichosporon has led to the replacement of the old taxon Trichosporon beigelii by six new species. Sequencing of the ribosomal DNA (rDNA) intergenic spacer 1 (IGS1) is currently mandatory for accurate Trichosporon identification, but it is not usually performed in routine laboratories. Here we describe Trichosporon species distribution and prevalence of Trichosporon asahii genotypes based on rDNA IGS1 sequencing as well as antifungal susceptibility profiles of 22 isolates recovered from blood cultures. The clinical isolates were identified as follows: 15 T. asahii isolates, five Trichosporon asteroides isolates, one Trichosporon coremiiforme isolate, and one Trichosporon dermatis isolate. We found a great diversity of different species causing trichosporonemia, including a high frequency of isolation of T. asteroides from blood cultures that is lower than that of T. asahii only. Regarding T. asahii genotyping, we found that the majority of our isolates belonged to genotype 1 (86.7%). We report the first T. asahii isolate belonging to genotype 4 in South America. Almost 50% of all T. asahii isolates exhibited amphotericin B MICs of >or=2 microg/ml. Caspofungin MICs obtained for all the Trichosporon sp. isolates tested were consistently high (MICs >or= 2 microg/ml). Most isolates (87%) had high MICs for 5-flucytosine, but all of them were susceptible to triazoles, markedly to voriconazole (all MICs <or= 0.06 microg/ml).

Mucor circinelloides as a cause of invasive maxillofacial zygomycosis: an emerging dimorphic pathogen with reduced susceptibility to posaconazole

A case of maxillofacial zygomycosis caused by Mucor circinelloides, identified by phenotypic and molecular methods and treated successfully with liposomal amphotericin B (AmBisome) and surgical debridement, is described. The isolate was resistant to posaconazole. This report underscores the importance of prior susceptibility testing of zygomycetes to guide therapy with the most effective antifungal agent for an improved prognosis.

Biological diversity of yeasts in the gastrointestinal tract of weaned piglets kept under different farm conditions

The study was conducted to determine yeasts present in the gastrointestinal tract (GIT) of piglets kept under experimental farm (EF) and commercial farm (CF) conditions. Ninety five German Landrace full- and half-sibling piglets were sacrificed at 39 days of age. Sixty eight piglets were weaned at 28th day of life, when they were offered one diet ad libitum. Twenty seven piglets remained unweaned by their dams. None of the piglets received any creep feed before weaning. Digesta samples were collected from 1/3 distal small intestine (SI), caecum and proximal colon. One hundred seventy three colonies of isolated yeasts were characterized by sequence analysis of the PCR-amplified D1/D2 domain of the 26S rRNA gene with following alignment of the recovered sequences to GenBank entries. From the 17 phylotypes found, isolates most closely related to Galactomyces geotrichum, Kazachstania slooffiae and Candida catenulata dominated in the GIT of CF piglets. Kazachstania slooffiae and Candida glabrata dominated in GIT of EF piglets. Sørenson and Morisita-Horn similarity indices between farms were low (0.44 and 0.54 respectively) and the Simpson diversity index was higher for EF (7.58) than for CF (4.34). The study brings new data on yeasts composition in the pig GIT and shows differences in yeasts biodiversity between farms operated at different hygiene conditions.

Actinomucor elegans var. kuwaitiensis isolated from the wound of a diabetic patient

The new variety of Actinomucor elegans var. kuwaitiensis, isolated from an open necrotic wound of a diabetic patient is described. This strain differed from the two previously described varieties of A. elegans, A. elegans var. elegans and A. elegans var. meitauzae by nearly 1% or more sequence divergence within D1/D2 regions of 28S rRNA and the ITS region of rRNA genes. Like the other two varieties, no zygospores were observed; however, there was evidence suggesting intersexual diploidy, a feature not described previously in this species. Additionally, A. elegans var. kuwaitiensis was pathogenic to white mice causing 100% mortality within 5 days.

Diagnostic value of DNA, (1-3)-β-d-glucan, and galactomannan detection in serum and bronchoalveolar lavage of mice experimentally infected with Aspergillus terreus

The aim of this study was to evaluate the diagnostic value of Aspergillus terreus-specific DNA, (1-3)-beta-d-glucan (BDG), and galactomannan (GM) in immunosuppressed mice infected intravenously with A. terreus conidia and sacrificed in groups of 12 each on days 1, 3, 5, 7, and 9. A. terreus-specific DNA, BDG, and GM in serum and bronchoalveolar lavage (BAL) were detected by nested polymerase chain reaction (nPCR), Fungitell kit (Associates of Cape Cod, E. Falmouth, MA), and Aspergillus Platelia kit (Bio-Rad, Marnes-laCoquette, France), respectively. Cultures of lung homogenate of all the animals yielded A. terreus. The BDG positivity, GM positivity, and nPCR positivity in serum specimens were 43%, 78%, and 73%, respectively. Combined detection enhanced the positivity to 95% for A. terreus DNA and GM, 83% for GM and BDG, and 95% for DNA, GM, and BDG. In BAL, the GM positivity and nPCR positivity were 80% and 81%, respectively, whereas combined detection increased the positivity to 98%. Detection of GM and DNA offers a sensitive and specific diagnostic option for invasive aspergillosis.

Supplemental utility of nested PCR for the pathological diagnosis of disseminated trichosporonosis

Disseminated trichosporonosis is known to be a severe opportunistic mycosis and has a high mortality rate. In autopsy cases, it is often difficult to diagnose as trichosporonosis because the causative Trichosporon species are pathologically similar to other fungi, especially the Candida species. Immunohistochemical analysis is essential for the differential diagnosis, but an antibody to Trichosporon is not available commercially. In the present study, we investigated the supplemental utility of nested polymerase chain reaction (PCR) for the pathological diagnosis of trichosporonosis from formalin-fixed and paraffin-embedded tissues. Total DNA was purified from 30 major organs in three autopsy cases, and Trichosporon DNA was specifically amplified by nested PCR using three sets of primers. Of 22 organs in which Grocott's stain was positive for fungal infection, 170- and 259-bp PCR products were detected in 20 (91%) and 12 (55%) organs, respectively. In short-term fixation (about 1 day), these bands were highly detected in ten (100%) and nine (90%) organs, whereas the detection efficiency tended to decrease after long-term fixation and decalcification. No PCR product of 412 bp was detected in any organs. These findings suggest that nested PCR from short-term-fixed tissues is useful for supportive pathological diagnosis of disseminated trichosporonosis.

Cerebral aspergillosis diagnosed by detection of Aspergillus flavus-specific DNA, galactomannan and (1→3)-β-d-glucan in clinical specimens

A case of cerebral aspergillosis was diagnosed by the detection of Aspergillus flavus-specific DNA in brain biopsy and serum specimens. The diagnosis was also supported by detection of elevated levels of galactomannan and (1→3)-β-d-glucan in serum specimens. Despite the presence of dichotomously branched septate hyphae in brain biopsy, the culture remained negative. The inability to isolate the organism in culture suggested that combined therapy of AmBisome and caspofungin was fungicidal for the fungus in the brain abscess.

Catheter-associated fungemia due to Exophiala oligosperma in a leukemic child and review of fungemia cases caused by Exophiala species

A case of catheter-associated fungemia due to Exophiala oligosperma in a 3-year-old leukemic child is presented. The etiologic agent was isolated from blood specimens and the catheter tip. The isolate was identified by its morphological characteristics and DNA sequencing of the internal transcribed spacer region of rDNA. Despite initial amphotericin B and itraconazole therapy, the child's fever subsided only after removal of the catheter. A review of the medical literature revealed 29 cases of infection due to Exophiala species. Twenty-three of these 29 patients had a CVC in place when they developed fever or other manifestations of fungemia. Withdrawal of the CVC together with amphotericin B and/or itraconazole therapy generally resulted in a good prognosis.

Use of DNA sequencing analysis to confirm fungemia due to Trichosporon dermatis in a pediatric patient

This is the first reported case of human disease caused by Tricosporon dermatis, an organism recently transferred to the genus Trichosporon from Cryptococcus and now confirmed to be a human pathogen.