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1.
Mycoses due to yeasts belonging to other genera than Candida have become common in the last years especially in immuno-compromised patients. Species of the anamorphic basidiomycetous
yeast genus Trichosporon are such opportunistic human pathogenic yeasts which cause several diseases. In this study, Trichosporon faecale is reported in Germany for the first time. The isolate was taken from a human foot, where it was associated with a tinea
pedis. The fungal isolate was identified by investigating the morphology, physiology by a commercial API 32 C-set and molecular
data of SSU and LSU rDNA as well as the ITS region. 相似文献
2.
Microorganisms that live in fluctuating environments must constantly adapt their behavior to survive. The host constitutes an important microenvironment in opportunistic and primary fungal pathogens like Cryptococcus neoformans (C. neoformans) and Cryptococcus gattii (C. gattii). In clonal populations, adaptation may be achieved through the generation of diversity. For fungi phenotype switching constitutes a mechanism that allows them to change rapidly. Both C. neoformans and C. gattii undergo phenotypic switching, which allows them to be successful pathogens and cause persistent disease. Similar to other encapsulated microbes that exhibit phenotypic variation, phenotypic switching in Cryptococcus changes the polysaccharide capsule. Most importantly, in animal models phenotypic switching affects virulence and can change the outcome of infection. Virulence changes because C. neoformans and C. gattii switch variants elicit different inflammatory responses in the host. This altered host response can also affect the response to antifungal therapy and in some cases may even promote the selection of switch variants. This review highlights the similarity and differences between phenotypic switching in C. neoformans and C. gattii, the two dominant species that cause cryptococcosis in humans. 相似文献
3.
Lidiane de Oliveira Dayane Cristina Silva Santos Marilena dos Anjos Martins Maria Walderez Szeszs Marcia Souza Carvalho Melhem 《Current fungal infection reports》2017,11(4):158-162
Purpose of Review
We reviewed data on amphotericin B (AmB) tolerance among Cryptococcus neoformans/C. gattii species complex clinical isolates and present our results of large recent study on this issue.Recent Findings
The standard method to detect antifungal susceptibility is based on MIC (minimal inhibitory concentration) determination; however, there is no interpretative clinical breakpoints defined for antifungal agents against Cryptococcus species, and to date, there is no correlation of MIC and clinical response. The time-kill curves (TKC) methodology seems to provide some correlation with outcome and it could identify distinct profiles of AmB-fungicidal activity.Summary
Our group analyzed 83 human isolates from cryptococcosis cases. The isolates were tested by TKC and showed up 8.3% of tolerance to AmB. Importantly, the AmB-MIC was low for all isolates, including tolerant ones. Our findings are similar to other authors, due the ability of TKC to identify distinct AmB-fungicidal activity and detecting low susceptible isolates.4.
L. M. Feliciano S. D. P. Ramos M. W. Szeszs M. A. Martins L. X. Bonfietti R. A. Oliveira D. C. S. Santos L. H. Fadul D. F. Silva C. R. Paula L. Trilles L. E. A. Silva K. Ferreira-Paim D. J. Mora A. A. Andrade P. R. Silva M. L. Silva-Vergara T. N. Roberto M. S. C. Melhem 《Current fungal infection reports》2017,11(4):190-196
Purpose of Study
To review the literature on heteroresistance to fluconazole (FLC) and investigate the level of heteroresistance to FLC (LHF), we analyzed 100 clinical and environmental Brazilian Cryptococcus strains.Recent Findings
Heteroresistance is a phenomenon described as the emergence of resistant subpopulation cells within a single susceptible strain that can tolerate higher concentrations of fluconazole above the minimal inhibitory concentration (MIC) level.Summary
We found lower FLC-MICs (0.12–64 mg/L) than LHF (8–128 mg/L). Highly heteroresistant adapted subpopulations (256 mg/L) was found in minority (9%) strains, but importantly, 33% showed low FLC-MIC (8 mg/L). We concluded for similar LHF in both species, but higher LHF in clinical strains in comparison to environmental ones. Our findings stressed that the LHF is not correlated to species and pretty is strain-dependent and alert about high heteroresistant subpopulations that hardly reverts to the original LHF even upon the removal of drug pressure.5.
Giuseppe Ferrara María Mercedes Panizo Víctor Alarcón Nataly García Maribel Dolande 《Current fungal infection reports》2017,11(4):163-170
Purpose of Review
The purpose of this review is to provide a current view of the importance of the determination and use of epidemiological cutoff values (ECVs) for Cryptococcus neoformans, since there are no clinical breakpoints (CBPs).Recent Findings
ECVs have been proposed for some antifungal agents and C. neoformans, using standardized methodologies by the Clinical and Laboratory Standards Institute (CLSI) and by the European Committee for Antimicrobial Susceptibility Testing (EUCAST), based on the distribution of minimum inhibitory concentrations (MICs). There is no sufficient evidence for the determination of ECVs for C. neoformans using commercial methods; however, as these methods are routinely used in the microbiology laboratory, it is recommended for the establishment of local ECVs using these methods and following the criteria for their determination.Summary
Due to the geographic and genetic variations inherent to C. neoformans, it is important to calculate ECVs, since they are useful in clinical practice to guide therapy in the absence of CBPs.6.
7.
Cryptococcus neoformans var. grubii and C. gattii were repeatedly isolated from decaying wood of trunk hollows in living trees growing in Jabalpur City in Central India. The
isolation of C.␣gattii has been reported from decayed wood inside trunk hollow of Tamarindus indica (15.6%), Mangifera indica (2.2%), Pithecolobium dulce (12.5%), Syzygium cumini (14%), and one from bark of S.␣cumini. C. n. var. grubii was isolated from decaying wood debris of T. indica (4.4%), M. indica (13.3%), Terminalia arjuna (25%), S. cumini (2%), Cassia fistula (4.5%), and two from bark of S. cumini. The two varieties never co-occurred in the same hollow. C. gattii and C. n. var. grubii isolates belonged to serotype B and serotype A respectively. The data strongly supported the colonization of the pathogen
in␣decaying wood hollow of all six-tree species. Evidence of this was found by repeated isolation up to 820 days. P. dulce is being reported for the first time as natural habitat of C. gattii and T.␣arjuna and C. fistula as natural habitat for C. n. var. grubii. M. indica is being reported for the second time as the natural habitat of both varieties (C. n. var. grubii and C. gattii). The population density of these pathogens from decaying wood debris of various tree species ranged between 0.5 × 103 cells/g and 6 × 105 cells/g. The seasonal variation has been seen in isolation of this yeast. Our result further reinforce the recently emerging
evidence that the natural habitat of C. n. var. grubii and C. gattii is more generalized. 相似文献
8.
Cryptococcus neoformans, the predominant etiological agent of cryptococcosis, can cause life-threatening infections of the central nervous system in immunocompromised and immunocompetent individuals. Cryptococcal meningoencephalitis is the most common disseminated fungal infection in AIDS patients, and remains the third most common invasive fungal infection among organ transplant recipients. The administration of highly active antiretroviral therapy (HAART) has resulted in a decrease in the number of cases of AIDS-related cryptococcosis in developed countries, but in developing countries where HAART is not readily available, Cryptococcus is still a major concern. Therefore, there is an urgent need for the development of novel therapies and/or vaccines to combat cryptococcosis. Understanding the protective immune responses against Cryptococcus is critical for development of vaccines and immunotherapies to combat cryptococcosis. Consequently, this review focuses on our current knowledge of protective immune responses to C. neoformans, with an emphasis on innate immune responses. 相似文献
9.
Histoplasmosis and cryptococcosis are the most prevalent systemic mycoses in HIV-infected patients. The authors report a 20-year-old
Brazilian HIV-positive woman with concomitant disseminated histoplasmosis and cryptococcosis. In addition, we review the reported
cases described in the medical literature. 相似文献
10.
A total of 36 Cryptococcus neoformans strains originating from South Africa were screened for wood degrading enzymes. All strains tested positive for cellulase
activity while none where capable of xylan degradation. Three C. neoformans var. grubii strains, originating from clinical and environmental samples, representing the same genotype (VNI/AFLP1—C. neoformans var. grubii) and MATα, were evaluated for growth on debris of two common tree species in South Africa: Acacia mearnsii and Eucalyptus camaldulensis. The mating capability of all the C. neoformans strains was evaluated on similar debris. Strains grown on A. mearnsii yielded substantially greater yeast populations. A total of 26%, 6%, 46%, and 80% of the 36 C. neoformans strains tested were either able to mate or develop filaments when crossed on A. mearnsii and E. camaldulensis debris, V8 juice, and yeast carbon base (YCB) agar, respectively. Filamentation and monokaryotic fruiting was observed in
3% of strains when C. neoformans was cultured on either A. mearnsii, E. camaldulensis debris, or YCB. The results indicate that this fungus is capable of completing its life cycle and can produce basidiospores
on woody debris. In the future, these findings should be considered when studying the epidemiology, microbial ecology, and
proposed infection process of this global pathogen. 相似文献
11.
12.
Experimental modulation of capsule size is an important technique for the study of the virulence of the encapsulated pathogen
Cryptococcus neoformans. In this paper, we summarize the techniques available for experimental modulation of capsule size in this yeast and describe
improved methods to induce capsule size changes. The response of the yeast to the various stimuli is highly dependent on the
cryptococcal strain. A high CO2 atmosphere and a low iron concentration have been used classically to increase capsule size. Unfortunately, these stimuli
are not reliable for inducing capsular enlargement in all strains. Recently we have identified new and simpler conditions
for inducing capsule enlargement that consistently elicited this effect. Specifically, we noted that mammalian serum or diluted
Sabouraud broth in MOPS buffer pH 7.3 efficiently induced capsule growth. Media that slowed the growth rate of the yeast correlated
with an increase in capsule size. Finally, we summarize the most commonly used media that induce capsule growth in C. neoformans.
Published: March 3, 2004 相似文献
13.
Background
Inositol is a key cellular metabolite for many organisms. Cryptococcus neoformans is an opportunistic pathogen which primarily infects the central nervous system, a region of high inositol concentration, of immunocompromised individuals. Through the use of myo-inositol oxygenase C. neoformans can catabolize inositol as a sole carbon source to support growth and viability. 相似文献14.
Zhe Xu Yafei Zhi Jianzhang Dong Benfeng Lin Di Ye Xiaoguang Liu 《Journal of microbiology (Seoul, Korea)》2016,54(7):487-491
Cryptococcus neoformans is a major cause of fungal meningitis in individuals with impaired immunity. Our previous studies have shown that the VPS41 gene plays a critical role in the survival of Cryptococcus neoformans under nitrogen starvation; however, the molecular mechanisms underlying VPS41-mediated starvation response remain to be elucidated. In the present study, we show that, under nitrogen starvation, VPS41 strongly enhanced ICL1 expression in C. neoformans and that overexpression of ICL1 in the vps41 mutant dramatically suppressed its defects in starvation response due to the loss of VPS41 function. Moreover, targeted deletion of ICL1 resulted in a dramatic decline in viability of C. neoformans cells under nitrogen deprivation. Taken together, our data suggest a model in which VPS41 up-regulates ICL1 expression, directly or indirectly, to promote survival of C. neoformans under nitrogen starvation. 相似文献
15.
Encapsulated yeast, Cryptococcus gattii (Cg) is a primary and emerging fungal pathogen in North America. It has a predilection for invading the central nervous system
of both healthy and immunocompromised humans and animals. Recently, we initiated molecular pathogenesis studies in Cg strain NIH444 (ATCC 32609). In this report, we compared the biology and pathogenic potential of NIH444 to those of WM276,
an Australian environmental isolate that is being used for the whole genome-sequencing project. Our data indicated that NIH444
is comparatively more virulent in a mouse model of cryptococcosis than is WM 276. We found robust mating of NIH444, and no
mating of WM276, when tested against Cg MATa strain, NIH198. WM276 but not NIH444 was defective in filamentation and sporulation (haploid fruiting). Interestingly, NIH444
has a VGII/AFLP6 genotype similar to that of the genotype of the recent outbreak strains from Vancouver Island, British Columbia,
Canada. Additionally, comparisons of nucleotide sequences of various genes also showed differences between NIH444 and WM276.
Based on these observations, we conclude that NIH444 should remain the strain of choice for understanding Cg pathogenesis, especially on the North American continent. 相似文献
16.
Abdel-Salam HA 《Folia microbiologica》2003,48(2):261-268
The cryptococcal polysaccharide antigen was detected in 10 cerebrospinal fluid (CSF) and 23 serum samples from cryptococcal meningitis and intestinal cryptococcosis by the cryptococcal antigen latex agglutination system (CALAS). CALAS titers in CSF and serum samples of cryptococcal meningitis ranged over 8-2048 and 32-2048, respectively, while in cases of intestinal cryptococcosis, serum titers ranged over 8-2048. The isolates of yeast Cryptococcus neoformans were determined to be of serotype A or of the A/D pair. The total leukocyte count and biochemical parameters in CSF were significantly increased as indicators of microbial infection. Furthermore, the in vitro change of the teleomorph (sexual state) to the anamorph (asexual state) was also detected and the teleomorph state changed in vivo to the encapsulated anamoph state which is more virulent during infection in vivo than the yeast-like noncapsulated form. Two primers for internal transcribed spacer (ITS) regions of ribosomal DNA were used for molecular detection of C. neoformans. After PCR amplification, a DNA band of 415 bp, visualized on agarose gel, indicated the presence of C. neoformans cells in the tested CSF and serum samples. The primer sensitivity was also characterized using purified yeast chromosomal DNA as template; it was about 20 pg or more chromosomal DNA which represents about 10 cells of C. neoformans. The primers were also specific for ITS regions of C. neoformans and gave negative results with Candida albicans and E. coli chromosomal DNA templates. 相似文献
17.
Cryptococcus gattii is an emerging fungal pathogen in the Pacific Northwest of North America, where it has caused more than 50 human infections
since its emergence in 2004. Among residents of British Columbia, where the disease emerged in 1999 on Vancouver Island, many
infections have occurred in immunocompetent persons. The cause for the emergence is currently unknown. The pathogenic profile
of Cryptococcus gattii in North American patients appears to be different from that seen previously for C. gattii and from the profile of infection among patients with Cryptococcus neoformans. Treatment duration and the need for patient follow-up may be different between patients infected with C. gattii and C. neoformans. For this reason, physicians treating atypical patients with Cryptococcal spp infection, particularly HIV-uninfected patients, should obtain a travel history and obtain a species identity for Cryptococcus isolates. 相似文献
18.
Cryptococcus gattii is an endemic fungus predominantly isolated in the tropical and subtropical regions, causing predominantly pulmonary disease with a predilection for the central nervous system. Herein, we report a case of rapidly progressing C. gattii pneumonia in an immune-deficient but virologically suppressed host with underlying human immunodeficiency viral (HIV) infection, exhibiting various fungal morphologies from bronchoalveolar lavage (BAL) cytological specimens. A 51-year-old Chinese male with known HIV disease was admitted to the Singapore General Hospital for evaluation of functional decline, febrile episodes, and a left hilar mass on chest radiograph. Computed tomography (CT) showed consolidation in the apical segment of the left lower lobe. He underwent bronchoscopy and BAL. Positron emission tomography-computed tomography done 10 days after the initial CT showed approximate doubling of the pulmonary lesion. Cytological examination of the fluid revealed yeasts of varying sizes. Subsequent fungal culture from BAL fluid grew C. gattii 10 days later. 相似文献
19.
Daniel Paiva Barros de Abreu Carlos Henrique Machado Mário Tatsuo Makita Camila Flávia Magalhães Botelho Fernanda Gomes Oliveira Cristiano Chaves Pessoa da Veiga Marilena dos Anjos Martins Francisco de Assis Baroni 《Mycopathologia》2017,182(5-6):597-602
Cryptococcosis is a mycosis caused by yeasts of genus Cryptococcus, mainly the species C. neoformans and C. gattii that can affect humans and animals. These yeasts are widely distributed in the environment and are typically associated with avian droppings and decaying wood. Most infections are related to the respiratory tract, but the central nervous system and cutaneous lesions are also reported in the literature. The present report is a case of cryptococcosis in an 18-month-old unspayed female English Bulldog with the main complaint of weight loss and diarrhea. The presence of two large masses observed in an ultrasound examination leads us to perform an exploratory laparotomy. Considering the size of the lesion and the impossibility of owner to provide intensive care, the consent for euthanasia was requested. The postmortem diagnosis of cryptococcosis was revealed by cytological evaluation, and the involvement of C. gattii VGII was confirmed by isolation and identification tests as well as by the detection of the URA5 gene restriction fragment length polymorphism PCR analysis. Reports in the literature of the involvement of Cryptococcus in gastrointestinal lesions are rare in both human and veterinary medicine. Data about different forms of cryptococcosis are important to provide more knowledge of uncommon clinical presentations of this yeast and therefore improve the diagnoses and decisions for the best therapy. 相似文献