Cryptococcus Diffluens Research Articles

An Unusual High Prevalence of Cryptococcus (Naganishia) diffluens Colonization in Neonates Hospitalized in a Referral Neonatal Intensive Care Unit.

Although the Candida species continue to be the most frequent colonizer of neonatal skin, a clear increase of colonization due to rare yeast-like fungi has been reported. In this study, we report an unusual high prevalence of Cryptococcus diffluens colonization in neonates admitted to the neonatal intensive care unit (NICU) over a 1-month period. From January 2020 to June 2021, the study included all neonates who were admitted to the NICU of Bu Ali Sina Hospital at least 28 days old. Skin swabs from different anatomical areas were collected. Sampling was done 3 times/week. Each sample was inoculated into Sabouraud Dextrose Agar containing chloramphenicol and CHROMagar Candida, separately. The plates were incubated at 30 °C and 35 °C, respectively. Identification of the isolates was molecularly confirmed. In vitro antifungal susceptibility testing of the isolates was performed against different antifungal agents using the Clinical Laboratory Standards Institute protocol. Among 1026 samples collected from 78 neonates, 213 yeast isolates were recovered, of which the Candida species were the most common (77.5%), followed by C. diffluens (16.9%). During the study, 55 isolated yeasts were collected from December 26, 2020, to January 26, 2021, of which 65.5% were C. diffluens, while Candida spp. constituted 100% and 98.3% of the isolates before and after this period, respectively. The most frequent sources of C. diffluens were genital regions (27.8%). Of 36 C. diffluens isolates, 13.9%, 22.2%, 52.8%, and 83.3% were non-wild type to fluconazole, amphotericin B, itraconazole and 5-flucytosine, respectively. We reported for the first time an unusual high prevalence of C. diffluens colonization in neonates hospitalized in NICU. Our findings also showed the high minimum inhibitory concentration of amphotericin B and 5-flucytosine against C. diffluens.

Cryptococcus diffluens D44 tarafından üretilen lipaz(lar)ın saflaştırılması ve karakterizasyonuna ait ön çalışma

In the present work, preliminary purification, and characterization of lipases from Cryptococcus diffluens D44, which was isolated from petroleum sludge, were performed. In the purification steps, subsequential to acetone precipitation, lipases from C. diffluens D44 were purified by DEAE Sepharose resulting in two different peaks, named Lip1 and Lip4. Sephadex G-100 size-exclusion chromatography was also performed for further purification of Lip1 and Lip4 and resulted in three different lipases as Lip1-1 (1.0 purification fold with 2.4% recovery), Lip1-2 (0.8 purification fold with 7.2% recovery), and Lip4-1 (1.2 purification fold with 4.5% recovery). As a result of characterization studies of these three lipases resulting from different peaks, optimum temperatures were found as 60 °C, 65 °C, and 65 °C for Lip1-1, Lip1-2, and Lip4-1, respectively. Furthermore, thermal stability studies were conducted at 50 °C, 60 °C, and 70 °C, and lipases of C. diffluens D44 maintained over 70% of their initial activity at 50 °C. The optimum pH for Lip1-1 and Lip1-2 was pH 9.0 although pH 5.0 was for Lip4-1. Considering the organic solvent effect on lipase activity, 10% methanol enhanced the relative activity of Lip1-1 and Lip4-1 while 10% ethanol caused a decrease in the relative activity of lipases except for Lip1-2. According to the indicated features based on the results, these different lipases from C. diffluens D44 could be promising candidates for industrial and biotechnological applications. To the best of our knowledge, this is the first study on the purification of lipases from C. diffluens D44.

A Case of Superficial Fungal Infection caused by Naganishia diffluens

Most superficial fungal infections of the skin are caused due to dermatophytosis or yeasts. However, it is rare for Cryptococcus species to cause infections. Among the fungal infections by Cryptotoccus species, Cryptococcus (C.) neoformans and C. gattii are the most common pathogenic species. However, other rare infections have been reported. Subcutaneous cryptococcosis due to Naganishia (N.) diffluens (formerly Cryptococcus diffluens) was first reported in Turkey. We present the case of a 53-year-old man who had mild pruritic annular, erythematous, scaly patches with inner small, crusted papules and nodules on both axilla and trunk for 3 months. A potassium hydroxide test on his abdomen scales was positive. Fungal culture, light microscopic findings, and the sequencing of an internal transcribed spacer of rRNA gene confirmed the presence of N. diffluens. As a result we diagnosed the patient with a superficial fungal infection caused by N. diffluens and treated it successfully with oral itraconazole and topical isoconazole.

Basidiomycotic Yeast Cryptococcus diffluens Converts l-Galactonic Acid to the Compound on the Similar Metabolic Pathway in Ascomycetes

(1) Background: It has been shown that d-galacturonic acid is converted to l-galactonic acid by the basidiomycotic yeast, Cryptococcus diffluens. However, two pathways are hypothesized for the l-galactonic acid conversion process in C. diffluens. One is similar to the conversion process of the filamentous fungi in d-galacturonic acid metabolism and another is the conversion process to l-ascorbic acid, reported in the related yeast, C. laurentii. It is necessary to determine which, if either, process occurs in C. diffluens in order to produce novel value-added products from d-galacturonic acid using yeast strains. (2) Methods: The diethylaminoethy (DEAE)-fractionated enzyme was prepared from the cell-free extract of C. diffluens by the DEAE column chromatography. The l-galactonic acid conversion activity was assayed using DEAE-fractionated enzyme and the converted product was detected and fractionated by high-performance anion-exchange chromatography. Then, the molecular structure was identified by nuclear magnetic resonance analysis. (3) Results: The product showed similar chemical properties to 2-keto-3-deoxy-l-galactonic acid (l-threo-3-deoxy-hexulosonic acid). (4) Conclusions: It is suggested that l-galactonic acid is converted to 2-keto-3-deoxy-l-galactonic acid by dehydratase in C. diffluens. The l-galactonic acid conversion process of C. diffluens is a prioritized pathway, similar to the pathway of ascomycetes.

Multi-objective optimization of a novel crude lipase-catalyzed fatty acid methyl ester (FAME) production using low-order polynomial and Kriging models

ABSTRACTIn this paper, conventional response surface methodology (RSM) based on low-order polynomials and an alternative Kriging-based method are used for the model-based single and multi-objective optimization of fatty-acid methyl ester (FAME) production catalyzed by a novel crude lipase from the yeast Cryptococcus diffluens (D44). The coefficient of determination for the two modeling approaches was calculated as 0.97 for the Kriging method, and 0.86 for RSM; showing a more reliable representation of experimental data by Kriging. Both models were used to perform single (maximizing FAME titer and temporal productivity separately) and multi-objective (maximizing FAME titer and temporal productivity simultaneously) optimizations of four important operating conditions (reaction time and temperature; amount of crude enzyme; and volume of methanol used). In all cases, the highest temperature considered (60°C) gave the best results. A reduction of reaction time in half was seen to be necessary to achieve optimum productivity compared to titer, when the two objectives were considered separately. The observed trade-off between the two objectives was quantified via multi-objective optimization using Pareto-front analysis.

Pathogenicity of Zygosaccharomyces bailii and Other Yeast Species to Mexican Fruit Fly (Diptera: Tephritidae) and Mass Rearing Implications.

Yeasts from all immature life stages of Mexican fruit fly Anastrepha ludens (Loew) (Diptera: Tephritidae) from diet, insectary air, and rearing materials were isolated, identified and evaluated for pathogenicity. Fifteen species of yeasts with one to genus level were identified from 72 yeast cultures obtained. Zygosaccharomyces bailii was the only yeast found to be highly pathogenic to Mexican fruit fly. Seventy-two hours post inoculation, the diet in bioassay cups with Z. bailii consistently showed signs of fermentation with gas bubbling causing the migration of larvae to the walls and lids of bioassay cups. The spent diet from Z. balii-infested cups was crusty, cracked and had a pasty layer. Many larvae were small, moribund, and discolored, appearing caramel or blackish. Insect yield loss with Z. bailii in comparison to that of control ranged from 10 to 44% for larvae and 14 to 47% for pupae. Additionally, Z. bailii caused a reduction in mean pupal weight. The weakly pathogenic yeasts produced significantly less yield of larvae and pupae than the nonpathogenic ones included Trichosporon montevideense, Clavispora lucitaniae, Candida sp., C. rugosa, and Rhodotorula mucilaginosa. Yield loss of larvae caused by this group ranged from 12 (C. lusitaniae) to 18% (R. mucilaginosa). Yield losses for pupa were similar to that of larvae. The mean pupa weight for these species was above the minimum acceptable (16.50 mg) for the SIT program. The nonpathogenic yeast produced yields of larvae and pupae similar to the control included Cryptococcus diffluens, Pichia kudriavzevii, Meyerozyma guilliermondii, Wickerhamomyces anomalus, Trichosporon asahii, Debaryomyces hansenii, Candida tropicalis, Cryptococcus sp., Candida parapsilosis, and Hanseniaspora opuntiae. In conclusion, the identification and management of insect pathogenic yeasts, such as Z. balii in mass rearing systems of Mexican fruit fly must be considered to avoid their potential negative effects.

Potencial antagónico de bacterias y levaduras marinas para el control de hongos fitopatógenos

La aplicación de fungicidas sintéticos es una práctica común en el control de hongos fitopatógenos. Sin embargo, su uso de manera indiscriminada ha traído problemas para la salud humana, animal, medio ambiente y ha generado resistencia en los fitopatógenos. En la búsqueda de alternativas, el control biológico usando microorganismos puede ser una opción eficiente al uso de fungicidas sintéticos. Aunque bacterias y levaduras aisladas de suelo y plantas han sido evaluadas como agentes de control biológico, la búsqueda de nuevos antagonistas continúa. La microflora oceánica puede ser una opción para la selección de nuevos agentes antagonistas. El objetivo de este estudio fue evaluar el potencial antagónico de diferentes bacterias (Stenotrophomonas rhizophila, Bacillus amyloliquefaciens y B. subtilis) y levaduras (Debaryomyces hansenii, Cryptococcus diffluens y Rhodotorula minuta) aisladas previamente de una laguna hiperhialina contra 13 hongos fitopatógenos de importancia agronómica. Los resultados muestran que diferentes cepas de la bacteria S. rhizophila fueron las que ejercieron mayor inhibición sobre la germinación de esporas y crecimiento micelial de todos los hongos fitopatógenos, superando a los tratamientos con fungicidas sintéticos. Dentro de las levaduras destacaron las cepas de D. hansenii. De acuerdo con su capacidad antagónica, los microorganismos marinos pueden ser una opción para el manejo de enfermedades ocasionadas por hongos fitopatógenos.

Marine yeasts and bacteria as biological control agents against anthracnose on mango

AbstractThe potential of four yeasts (Debaryomyces hansenii, Rhodotorula minuta, Cryptococcus laurentii and Cryptococcus diffluens) and three bacteria (Bacillus amyloliquefaciens, Bacillus subtilis and Stenotrophomonas rhizophila) with antagonistic capacity against anthracnose caused by Colletotrichum gloeosporioides in mango cv. Ataulfo fruit was investigated. Germination of C. gloeosporioides spores was significantly inhibited by all marine yeasts and bacteria strains of an in vitro test. When yeasts and bacteria were tested on mango fruit, the marine yeast D. hansenii 1R11CB strain and marine bacteria S. rhizophilaKM02 strain were the best antagonists to anthracnose (C. gloeosporioides), which significantly decreased disease incidence by 56% and 89%, respectively, and reduced lesion diameter by 91% and 92%, respectively. All the isolated strains of the phytopathogen, yeasts and bacteria were molecularly identified. Our results from in vitro and in vivo experiments suggest that marine yeasts and bacteria strains can be used as some effective biological control agents for anthracnose in mango.

Fermentative production of l-galactonate by using recombinant Saccharomyces cerevisiae containing the endogenous galacturonate reductase gene from Cryptococcus diffluens

The GAR1 gene, encoding d-galacturonate reductase in Cryptococcus diffluens, was isolated, and the GAR1-expression plasmid was constructed by insertion of GAR1 downstream of the yeast constitutive promoter in the yeast-integrating vector. Recombinant Saccharomyces cerevisiae expressing C.diffluensd-galacturonate reductase from a genome integrated copy of the gene was cultured for use the conversion of d-galacturonic acid to l-galactonic acid. The optimum conditions for l-galactonic acid production were determined in terms of the initial concentration of d-galacturonic acid, fermentation pH, and mixed sugars. The following conditions yielded high efficiency in the conversion of d-galacturonic acid to l-galactonic acid in large-scale cultures: 0.1% initial d-galacturonic acid concentration, pH 3.5, and glucose as additional sugar. The aerobic condition was necessary for the conversion of d-galacturonic acid. Subculture of that recombinant was not showing to decrease of the d-galacturonic acid conversion rate even though it was repeated in ten generations. Culturing in scale-up, the conversion rate of d-galacturonic acid to l-galactonic acid was increased.

Organic solvent stable lipase from Cryptococcus diffluens D44 isolated from petroleum sludge

Microbial lipases, especially yeast lipases, are extensively used for biodiesel production. In order to reduce biodiesel production cost, development of stable enzymes under extreme conditions is one of the important prominences. To this end, the properties of a lipase of Cryptococcus diffluens D44, isolated from petroleum sludge, has been investigated. Crude extracellular D44 lipase showed maximal activity at pH 9.0 and 45°C. Half-life of the enzyme at 30, 40, 50 and 60°C was 79.67, 45.90, 39.16 and 2min, respectively. Activation energy of p-nitrophenyl palmitate (pNPP) hydrolysis was 30.13kJmol⿿1. D44 lipase was active within a broad range of pH from 6.0 to 10.0 with the optimum pH at 9.0. SDS-PAGE and MALDI-TOF fingerprint analyses revealed the molecular weight of the enzyme to be 45.7kDa. Its inhibition with ethylenediaminetetraacetic acid (EDTA) indicated that D44 lipase requires metal ions as cofactors. Km and Vm values were 1.92ÿ10⿿4mM (0.000073mg/ml) pNPP and 96.15U/min, respectively. Lipase activity was enhanced in the presence of Ca2+, Mg2+, K+ and Mn+, while Na+ and Ni+ has not altered enzyme activity. Methanol, tert⿿butyl alcohol, acetonitrile and ethanol resulted in an increase in percentage residual activity after 1 and 12h of incubation. Highest residual activity, 276.43%, was obtained in 10% methanol following 12h of incubation. The extensive stability of D44 lipase in aqueous methanol makes C. diffluens D44 lipase suitable for biodiesel production, since moderate reaction conditions and less organic solvent concentrations are required for oil based fuel production. This is the first report of the biochemical characterization of a lipase from C. diffluens.

Screening and molecular characterization of polycyclic aromatic hydrocarbons degrading yeasts

Objective: Disasters such as leakages and accidental falls are the main causes of environmental pollution by the petroleum industry product. Since no commercial yeast strain with biodegradation capacity is available, we aimed to isolate and characterize hydrocarbon degrading yeasts. Methods: Yeast isolates used in the study were isolated from samples of wastewater, active sludge and crude oil, which was obtained from a petroleum refinery as well as from soil samples, which were contaminated with crude oil. Yeast isolates used in the study were isolated from wastewater, active sludge and petroleum samples obtained from petroleum refinery and soil samples contaminated with petroleum. Degradation of naphthalene, phenanthrene, pyrene and crude petroleum by yeasts were determined using a microtiter plate-based method. Molecular characterization was achieved by performing a sequence analysis of the ITS1-5.8S rRNA-ITS2 and 26S rRNA regions. Results: In total, 100 yeast isolates were obtained from four different samples. Following the incubation in media containing different polycyclic aromatic hydrocarbon compounds (naphthalene, phenanthrene, pyrene) and crude petroleum, 12 yeast isolates were detected to degrade more than one polyaromatic hydrocarbon. Sequence analyses of rRNA regions revealed that the identified yeasts represented 10 species belonging to 6 genera. The isolates were identified as Candida parasilopsis, Candida sinolaborantium, Cryptococcus albidus, Cryptococcus diffluens, Cryptococcus uzbekistanensis, Pichia kudriavzevii, Rhodosporidium diobovatum, Rhodotorula glutinis, Rhodotorula muciloginosa and Saccharomyces cerevisiae. Conclusion: Yeast strains that are capable of degrading more than one polycyclic aromatic hydrocarbon compound have the potential of being utilized in future research.

Identification and characterisation of xylanolytic yeasts isolated from decaying wood and sugarcane bagasse in Brazil.

In this study, yeasts associated with lignocellulosic materials in Brazil, including decaying wood and sugarcane bagasse, were isolated, and their ability to produce xylanolytic enzymes was investigated. A total of 358 yeast isolates were obtained, with 198 strains isolated from decaying wood and 160 strains isolated from decaying sugarcane bagasse samples. Seventy-five isolates possessed xylanase activity in solid medium and were identified as belonging to nine species: Candida intermedia, C. tropicalis, Meyerozyma guilliermondii, Scheffersomyces shehatae, Sugiyamaella smithiae, Cryptococcus diffluens, Cr. heveanensis, Cr. laurentii and Trichosporon mycotoxinivorans. Twenty-one isolates were further screened for total xylanase activity in liquid medium with xylan, and five xylanolytic yeasts were selected for further characterization, which included quantitative analysis of growth in xylan and xylose and xylanase and β-D-xylosidase activities. The yeasts showing the highest growth rate and cell density in xylan, Cr. laurentii UFMG-HB-48, Su. smithiae UFMG-HM-80.1 and Sc. shehatae UFMG-HM-9.1a, were, simultaneously, those exhibiting higher xylanase activity. Xylan induced the highest level of (extracellular) xylanase activity in Cr. laurentii UFMG-HB-48 and the highest level of (intracellular, extracellular and membrane-associated) β-D-xylosidase activity in Su. smithiae UFMG-HM-80.1. Also, significant β-D-xylosidase levels were detected in xylan-induced cultures of Cr. laurentii UFMG-HB-48 and Sc. shehatae UFMG-HM-9.1a, mainly in extracellular and intracellular spaces, respectively. Under xylose induction, Cr. laurentii UFMG-HB-48 showed the highest intracellular β-D-xylosidase activity among all the yeast tested. C. tropicalis UFMG-HB 93a showed its higher (intracellular) β-D-xylosidase activity under xylose induction and higher at 30°C than at 50°C. This study revealed different xylanolytic abilities and strategies in yeasts to metabolise xylan and/or its hydrolysis products (xylo-oligosaccharides and xylose). Xylanolytic yeasts are able to secrete xylanolytic enzymes mainly when induced by xylan and present different strategies (intra- and/or extracellular hydrolysis) for the metabolism of xylo-oligosaccharides. Some of the unique xylanolytic traits identified here should be further explored for their applicability in specific biotechnological processes.

Molecular characterization and lipase profiling of the yeasts isolated from environments contaminated with petroleum

In the present study, 120 yeast isolates from different sources (active sludge, soil, and wastewater samples obtained from petroleum refinery and soil contaminated by petroleum) were obtained. The yeast isolates were screened for lipase production and twelve of the isolates (D3, D17, D24, D27, D30, D38, D40, D42, D44, D46, D56, and D57) exhibited lipase activity. Molecular characterization of the yeasts showing the lipase production was performed with RFLP of ITS1-5.8S-ITS2 and 18S rRNA and sequence analysis of D1/D2 domain of 26S rRNA. The 26S rRNA sequencing revealed that four new strains, D38, D40, D44 and D57 identified as Rhodotorula slooffiae, Candida davisiana, Cryptococcus diffluens, and Cryptococcus uzbekistanensis, respectively, are lipase producing yeast species. This study is the first report showed lipase production by these species. The other lipase producing strains identified as Candida parapsilosis (D3), Rhodotorula muciloginosa (D17 and D42), Cryptococcus albidus (D24, D27, D30, and D56), and Wickerhamomyces anomalus (D46).

Characterization of the skin fungal microbiota in patients with atopic dermatitis and in healthy subjects

Patients with atopic dermatitis (AD) are highly susceptible to viral, bacterial, and fungal skin infections because their skin is dry and this compromises the barrier function of the skin. Therefore, the skin microbiota of patients with AD is believed to be different from that of healthy individuals. In the present study, the skin fungal microbiota of nine patients with mild, moderate, or severe AD and ten healthy subjects were compared using an rRNA clone library. Fungal D1/D2 large subunit analysis of 3647 clones identified 58 species and seven unknown phylotypes in face scale samples from patients with AD and healthy subjects. Malassezia species were predominant, accounting for 63%-86% of the clones identified from each subject. Overall, the non-Malassezia yeast microbiota of the patients was more diverse than that of the healthy individuals. In the AD samples 13.0 ± 3.0 species per case were detected, as compared to 8.0 ± 1.9 species per case in the samples taken from healthy individuals. Notably, Candida albicans, Cryptococcus diffluens, and Cryptococcus liquefaciens were detected in the samples from the patients with AD. Of the filamentous fungal microbiota, Cladosporium spp. and Toxicocladosporium irritans were the predominant species in these patients. Many pathogenic fungi, including Meyerozyma guilliermondii (anamorphic name, Candida guilliermondii), and Trichosporon asahii, and allergenic microorganisms such as Alternaria alternata and Aureobasidium pullulans were found on the skin of the healthy subjects. When the fungal microbiota of the samples from patients with mild/moderate to severe AD and healthy individuals were clustered together by principal coordinates analysis they were found to be clustered according to health status.

Characterization of d-galacturonate reductase purified from the psychrophilic yeast species Cryptococcus diffluens

D-Galacturonic acid reductase was purified from a psychrophilic yeast strain of Cryptococcus diffluens, which was isolated from Satho, a traditional alcohol drink in Thailand. This enzyme, named Cd-GalUAR, assimilates D-galacturonic acid and requires NADPH as a cofactor. Cd-GalUAR is about 45 kDa and stable from pH 6.5 to 7.5 and up to 35°C. Its optimum pH and temperature are pH 7.0 and 40°C, respectively. However, 80% of its maximum activity remained at 4°C. The reaction of Cd-GalUAR from D-galacturonic acid produces L-galactonic acid, which was identified by (13)C NMR and LC-MS. Three amino acid sequences were determined from trypsin-digested peptides of Cd-GalUAR. Similar sequences are found in many NAD or NADP oxidoreductases, including some D-galacturonate reductases. Our results suggest that Cd-GalUAR is the first D-galacturonate reductase identified in yeast.

Chiral derivatives of Butenafine and Terbinafine: synthesis and antifungal activity

Two series of allylamines/benzylamines have been synthesised and evaluated for their antifungal activity towards Cryptococcus neoformans. All compounds are chiral derivatives of Butenafine and Terbinafine, having additional substituents at the carbon connected to the central nitrogen atom. In both series, the antifungal activity was strongly dependent on both the steric bulk and the electronic nature of the substituents. Compared to the parent compounds (Butenafine and Terbinafine), the activity was maintained when the hydrogen was replaced with a methyl group. Lower activity was observed for ethyl, whereas introduction of –CH 2F, –CHF 2, –CF 3 or –CN substituents removed all antifungal activity. Testing of ( R)- and ( S)- N-(4- tert-butylbenzyl)- N-methyl-1-(naphthalen-1-yl)ethanamine against C. neoformans, Cryptococcus diffluens and Trichosporon cutaneum revealed that most of the activity resides in the ( R)-enantiomer. The ( R)-enantiomer performed as well as, or better (lower MIC values) than Butenafine against each test strain, suggesting that antimycotics based on this compound might be an improvement of existing Butenafine-based formulations.

Identification and Characterization of a Psychrophilic Yeast Strain Newly Isolated from the Fermentative Starter (Loog-pang) of a Traditional Drink in Thailand

One psychrophilic yeast strain, that grew well in a cold environment such as in a refrigerator, was isolated from the yeast starter (Loog-pang) of a traditional alcohol drink in Thailand. The isolated strain OPU-FC11 was identified as Cryptococcus diffluens by the assay for 26S ribosomal DNA and the test for carbon source assimilation. OPU-FC11 showed a good amount of growth at 4 degrees 0 at which a commonly found yeast like Saccharomyces cerevisiae did not grow, and produced cold-adapted enzymes that showed a relatively high activity at lower temperatures.

Susceptibility testing ofCryptococcus diffluensagainst amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole

Cryptococcus diffluens is a recently re-established species that shares several phenotypic features with Cryptococcus neoformans. We evaluated the application of the Clinical Laboratory Standards Institute (CLSI, formerly NCCLS) macro- and microbroth dilution methods and the E-test agar diffusion method to determine the in vitro susceptibilities of known strains of C. diffluens against amphotericin B (AMB), flucytosine (5-FC), fluconazole (FLC), itraconazole (ITC) and the novel triazoles, voriconazole (VRC) and posaconazole (PSC). Seven strains were found to be resistant in vitro to AMB (MICs >/=2 microg/ml), five were resistant to 5-FC (MICs of >/=32 microg/ml), four were resistant to FLC (MICs of FLC >/=32 microg/ml) and nine were resistant to ITC (MICs of ITC >1 microg/ml). In contrast, VRC and PSC showed good in vitro activity against C.diffluens strains, even those with elevated MICs to amphotericin B and/or established azoles. Most of the isolates were inhibited by 0.5 microg/ml of both VRC and PSC. A clinical isolate showing phenotypic switching exhibited elevated MICs to both agents, i.e., VRC (>16 microg/ml) and PSC (>8 microg/ml).

Evaluation of the Levels of Specific IgE against Cryptococcus diffluens and Cryptococcus liquefaciens in Patients with Atopic Dermatitis

Cryptococcus diffluens and Cryptococcus liquefaciens, 2 basidiomycetous yeasts, frequently colonize the skin of patients with atopic dermatitis (AD). In this study, we investigated the presence of specific IgE antibodies against C. diffluens and C. liquefaciens in the sera of AD patients by using an enzyme immunoassay . Of the 122 AD serum samples tested, 43 (35.2%) and 50 (41.0%) were positive for specific IgE antibodies against C. diffluens and C. liquefaciens, respectively. The levels of specific IgE against the C. diffluens antigen and that against the C. liquefaciens antigen were strongly correlated (r=0.96). In contrast, no remarkable correlation was observed between the levels of specific IgE against the 2 Cryptococcus species and that of specific IgE against Malassezia restricta. Competitive enzyme-linked immunosorbent assay (ELISA) inhibition tests revealed that C. diffluens and C. liquefaciens shared common antigens. This finding was consistent with the IgE immunoblotting data which demonstrated that several IgE-binding proteins with molecular masses of 77, 54, and 30 kDa were recognized in both C. diffluens and C. liquefaciens antigens . These results suggest that fungal components from C. diffluens and C. liquefaciens may act as allergens and play a role in the pathogenesis of AD.

Groups and Sources of Yeasts in House Dust

House dust contains bacteria, mycelial fungi, microarthropods, and yeasts. The house dust samples collected in 25 apartments in Moscow and the Moscow region were found to contain yeasts belonging to the genera Candida, Cryptococcus, Debaryomyces, Rhodotorula, Sporobolomyces, and Trichosporon. The most frequently encountered microorganisms were typical epiphytic yeasts, such as Cryptococcus diffluens and Rhodotorula mucilaginosa, which are capable of long-term preservation in an inactive state. The direct source of epiphytic yeasts occurring in the house dust might be the indoor plants, which were contaminated with these yeasts, albeit to a lesser degree than outdoor plants. Along with the typical epiphytic yeasts, the house dust contained the opportunistic yeast pathogens Candida catenulata, C. guillermondii, C. haemulonii, C. rugosa, and C. tropicalis, which are known as the causal agents of candidiasis. We failed to reveal any correlation between the abundance of particular yeast species in the house dust, residential characteristics, and the atopic dermatitis of the inhabitants.