Cryptococcus gattii: Emergence in Western North America: Exploitation of a Novel Ecological Niche

A global view on fungal infections in humans and animals: opportunistic infections and microsporidioses

After cardiovascular diseases, infectious diseases are the second most common cause of death worldwide. Although these infections are caused mainly by viruses or bacteria, a systematically growing prevalence of human and animal opportunistic fungal infections is noticeable worldwide. More attention is being paid to this problem, especially due to the growing frequency of recalcitrant and recurrent mycoses. The latter are classically divided into superficial, which are the most common type, subcutaneous, and systemic. This work discusses opportunistic fungal pathogens without proven horizontal transmission between different animal species including humans and microsporidia as spore-forming unicellular parasites related to fungi; however, with a yet undetermined taxonomic position. The review also mentions aetiological agents, risk factors, epidemiology, geographical distribution, and finally symptoms characteristic for individual disease entities. This paper provides insight into fungal infections from a global perspective and simultaneously draws attention to emerging pathogens, whose prevalence is continuously increasing. Finally, this work also takes into consideration the correct nomenclature of fungal disease entities and the importance of secondary metabolites in the pathogenesis of fungal infections.

Multilocus Sequence Typing of Clinical Isolates of Cryptococcus from India

Cryptococcosis is a life-threatening infection caused by Cryptococcus neoformans and C. gattii species complex. In the present study, to understand the molecular epidemiology of 208 clinical isolates of Cryptococcus from different parts of India, multilocus sequence typing (MLST) using ISHAM MLST consensus scheme for C. neoformans/C. gattii species complex was used. MLST analysis yielded a total of 10 Sequence Types (STs)-7 STs for C. neoformans and 3 for C. gattii species complex. The majority of isolates identified as C. neoformans belonged to molecular type VNI with predominant STs 31 and 93. Only 3 isolates of C. gattii species complex were obtained, belonging to ST58 and ST215 of VGI and ST69 of VGIV. Phylogenetic analysis revealed less diversity among the clinical Indian isolates compared to the global MLST database. No association between prevalent STs and HIV status, geographical origin or minimum inhibitory concentration (MIC) could be established.

3-Bromopyruvate as a potent anticancer therapy in honor and memory of the late Professor André Goffeau

3-Bromopyruvate (3BP) is a small, highly reactive molecule formed by bromination of pyruvate. In the year 2000, the antitumor properties of 3BP were discovered. Studies using animal models proved its high efficacy for anticancer therapy with no apparent side effects. This was also found to be the case in a limited number of cancer patients treated with 3BP. Due to the "Warburg effect," most tumor cells exhibit metabolic changes, for example, increased glucose consumption and lactic acid production resulting from mitochondrial-bound overexpressed hexokinase 2. Such alterations promote cell migration, immortality via inhibition of apoptosis, and less dependence on the availability of oxygen. Significantly, these attributes also make cancer cells more sensitive to agents, such as 3BP that inhibits energy production pathways without harming normal cells. This selectivity of 3BP is mainly due to overexpressed monocarboxylate transporters in cancer cells. Furthermore, 3BP is not a substrate for any pumps belonging to the ATP-binding cassette superfamily, which confers resistance to a variety of drugs. Also, 3BP has the capacity to induce multiple forms of cell death, by, for example, ATP depletion resulting from inactivation of both glycolytic and mitochondrial energy production pathways. In addition to its anticancer property, 3BP also exhibits antimicrobial activity. Various species of microorganisms are characterized by different susceptibility to 3BP inhibition. Among tested strains, the most sensitive was found to be the pathogenic yeast-like fungus Cryptococcus neoformans. Significantly, studies carried out in our laboratories have shown that 3BP exhibits a remarkable capacity to eradicate cancer cells, fungi, and algae.

A Call to Arms: Quest for a Cryptococcal Vaccine

Cryptococcosis remains a significant cause of morbidity and mortality world-wide, particularly among AIDS patients. Yet, to date, there are no licensed vaccines clinically available to treat or prevent cryptococcosis. In this review, we provide a rationale to support continued investment in Cryptococcus vaccine research, potential challenges that must be overcome along the way, and a literature review of the current progress underway towards developing a vaccine to prevent cryptococcosis.

A Predicted Mannoprotein Participates in Cryptococcus gattii Capsular Structure

The yeast-like pathogen Cryptococcus gattii is an etiological agent of cryptococcosis. The major cryptococcal virulence factor is the polysaccharide capsule, which is composed of glucuronoxylomannan (GXM), galactoxylomannan (GalXM), and mannoproteins (MPs). The GXM and GalXM polysaccharides have been extensively characterized; however, there is little information about the role of mannoproteins in capsule assembly and their participation in yeast pathogenicity. The present study characterized the function of a predicted mannoprotein from C. gattii, designated Krp1. Loss-of-function and gain-of-function mutants were generated, and phenotypes associated with the capsular architecture were evaluated. The null mutant cells were more sensitive to a cell wall stressor that disrupts beta-glucan synthesis. Also, these cells displayed increased GXM release to the culture supernatant than the wild-type strain did. The loss of Krp1 influenced cell-associated cryptococcal polysaccharide thickness and phagocytosis by J774.A1 macrophages in the early hours of interaction, but no difference in virulence in a murine model of cryptococcosis was observed. In addition, recombinant Krp1 was antigenic and differentially recognized by serum from an individual with cryptococcosis, but not with serum from an individual with candidiasis. Taken together, these results indicate that C. gattii Krp1 is important for the cell wall structure, thereby influencing capsule assembly, but is not essential for virulence in vivoIMPORTANCECryptococcus gattii has the ability to escape from the host's immune system through poorly understood mechanisms and can lead to the death of healthy individuals. The role of mannoproteins in C. gattii pathogenicity is not completely understood. The present work characterized a protein, Kpr1, that is essential for the maintenance of C. gattii main virulence factor, the polysaccharide capsule. Our data contribute to the understanding of the role of Kpr1 in capsule structuring, mainly by modulating the distribution of glucans in C. gattii cell wall.

Induction of Broad-Spectrum Protective Immunity against Disparate Cryptococcus Serotypes

Cryptococcosis is a fungal disease caused by multiple Cryptococcus serotypes; particularly C. neoformans (serotypes A and D) and C. gattii (serotypes B and C). To date, there is no clinically available vaccine to prevent cryptococcosis. Mice given an experimental pulmonary vaccination with a C. neoformans serotype A strain engineered to produce interferon-γ, denoted H99γ, are protected against a subsequent otherwise lethal experimental infection with C. neoformans serotype A. Thus, we determined the efficacy of immunization with C. neoformans strain H99γ to elicit broad-spectrum protection in BALB/c mice against multiple disparate Cryptococcus serotypes. We observed significantly increased survival rates and significantly decreased pulmonary fungal burden in H99γ immunized mice challenged with Cryptococcus serotypes A, B, or D compared to heat-killed H99γ (HKH99γ) immunized mice. Results indicated that prolonged protection against Cryptococcus serotypes B or D in H99γ immunized mice was CD4⁺ T cell dependent and associated with the induction of predominantly Th1-type cytokine responses. Interestingly, immunization with H99γ did not elicit greater protection against challenge with the Cryptococcus serotype C tested either due to low overall virulence of this strain or enhanced capacity of this strain to evade host immunity. Altogether, these studies provide “proof-of-concept” for the development of a cryptococcal vaccine that provides cross-protection against multiple disparate serotypes of Cryptococcus.

Methodology for Anti-Cryptococcal Vaccine Development

Cryptococcus neoformans and Cryptococcus gattii, the predominant etiological agents of cryptococcosis, are fungal pathogens that cause disease ranging from a mild pneumonia to life-threatening infections of the central nervous system (CNS). C. neoformans is widely considered an opportunistic fungal pathogen which targets individuals with impaired immune systems, while C. gattii is predominantly associated with fungal infections in immunocompetent individuals. However, C. neoformans and C. gattii have certainly been identified as the causative agent of cryptococcosis in both immune compromised and immune competent individuals. Cell-mediated immunity (CMI) by T-helper (Th) 1-type CD4⁺ T cells is the predominant host defense mechanism against cryptococcosis. Consequently, there has been great interest in identifying cryptococcal antigens that elicit protective CMI against Cryptococcus infection. Although many different cryptococcal proteins have been shown to stimulate potent cellular responses, there remains no standardized vaccine available for the prevention of cryptococcal infections in humans. Several studies have identified immunodominant antigens that may serve as attractive candidates for the development of novel subunit vaccines for the treatment and/or the prevention of cryptococcosis. The purpose of this chapter is to describe one methodology to screen and isolate cryptocococcal proteins that induce protective immune responses against cryptococossis.

Genotypes of Clinical and Environmental Isolates of Cryptococcus neoformans and Cryptococcus gattii in Korea

Multilocus sequence typing analysis was applied to determine the genotypes of 147 (137 clinical and 10 environmental) Cryptococcus neoformans and three clinical Cryptococcus gattii isolates from 1993 to 2014 in Korea. Among the 137 clinical isolates of C. neoformans, the most prevalent genotype was ST5 (n = 131), followed by ST31 (n = 5) and ST127 (n = 1). Three C. gattii strains were identified as ST57, ST7, and ST113. All environmental isolates were identified as C. neoformans with two genotypes, ST5 (n = 7) and ST31 (n = 3). Our results show that C. neoformans isolates in Korea are genetically homogeneous, and represent a close genetic relationship between clinical and environmental isolates.

Vaccine-mediated immune responses to experimental pulmonary Cryptococcus gattii infection in mice

Cryptococcus gattii is a fungal pathogen that can cause life-threatening respiratory and disseminated infections in immune-competent and immune-suppressed individuals. Currently, there are no standardized vaccines against cryptococcosis in humans, underlying an urgent need for effective therapies and/or vaccines. In this study, we evaluated the efficacy of intranasal immunization with C. gattii cell wall associated (CW) and/or cytoplasmic (CP) protein preparations to induce protection against experimental pulmonary C. gattii infection in mice. BALB/c mice immunized with C. gattii CW and/or CP protein preparations exhibited a significant reduction in pulmonary fungal burden and prolonged survival following pulmonary challenge with C. gattii. Protection was associated with significantly increased pro-inflammatory and Th1-type cytokine recall responses, in vitro and increased C. gattii-specific antibody production in immunized mice challenged with C. gattii. A number of immunodominant proteins were identified following immunoblot analysis of C. gattii CW and CP protein preparations using sera from immunized mice. Immunization with a combined CW and CP protein preparation resulted in an early increase in pulmonary T cell infiltrates following challenge with C. gattii. Overall, our studies show that C. gattii CW and CP protein preparations contain antigens that may be included in a subunit vaccine to induce prolonged protection against pulmonary C. gattii infection.

Clinical and microbiological characteristics of cryptococcosis in Singapore: predominance of Cryptococcus neoformans compared with Cryptococcus gattii

OBJECTIVES

To describe the clinical features, treatments, outcomes, and subtype prevalence of cryptococcosis in Singapore.

METHODS

All patients with laboratory confirmed cryptococcal infections admitted from 1999 to 2007 to a teaching hospital in Singapore were reviewed retrospectively. Identification and molecular types of Cryptococcus neoformans variants and Cryptococcus gattii were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Serotypes were inferred with a multiplex PCR method.

RESULTS

Of 62 patients with cryptococcosis, C. neoformans var. grubii was the predominant subtype (in 95%), affecting mainly immunocompromised hosts (91%) with HIV infection (80%). Patients with HIV were younger (median age 36.5 vs. 49.5 years, p=0.006) and less likely to present with an altered mental status (14% vs. 50%, p=0.013). In contrast, delayed treatment (median 7 days vs. 2 days, p=0.03), pulmonary involvement (58% vs. 14%, p=0.03), and initial treatment with fluconazole (25% vs. 2%, p=0.02) were more common in HIV-negative patients. C. gattii was uncommon, affecting only three patients, all of whom were immunocompetent and had disseminated disease with pulmonary and neurological involvement. All C. gattii were RFLP type VG II, serotype B and all C. neoformans var. grubii were RFLP type VN I, serotype A, except for one that was RFLP type VN II.

CONCLUSION

C. neoformans var. grubii, subtype VN I, was the predominant subtype in Singapore, infecting younger, mainly immunocompromised hosts with HIV. C. gattii was uncommon, causing pulmonary manifestations in older, immunocompetent patients and were RFLP type VG II.

Cryptococcus antigens and immune responses: implications for a vaccine

Cryptococcosis is a fungal disease primarily occurring in immunocompromised individuals, such as AIDS patients, and is associated with high morbidity and mortality. However, cryptococcosis can occur within immunocompetent populations as observed during an outbreak in Vancouver Island, British Columbia, Canada, the Pacific Northwest and other regions of the USA and in Mediterranean Europe. Mortality rates due to cryptococcosis have significantly declined in economically developed countries since the widespread implementation of highly active antiretroviral therapy. However, the incidence and mortality of this disease remains high in economically undeveloped areas in Africa and Asia where HIV infections are high and availability of HAART is limited. The continuing AIDS epidemic coupled with the increased usage of immunosuppressive drugs to prevent organ transplant rejection or to treat autoimmune diseases has resulted in an increase in individuals at risk for developing cryptococcosis. The purpose of this review is to discuss the need, challenges and potential for developing vaccines against cryptococcosis.

Molecular Epidemiology of Clinical Cryptococcus neoformans Isolates in Seoul, Korea

Cryptococcal infection is primarily caused by two species, Cryptococcus neoformans and C. gattii. Between the two species, C. neoformans var. grubii is the major causative agent of cryptococcosis in Asia. We investigated the molecular characteristics of 46 isolates of C. neoformans from patients with cryptococcosis between 2008 and 2012 in Seoul, Korea. All the isolates were determined to be C. neoformans var. grubii (serotype A), mating type MATα, and molecular type VNI by PCR-restriction fragment length polymorphism of the URA5 gene. Multilocus sequencing type (MLST) analysis using the International Society of Human and Animal Mycoses (ISHAM) consensus MLST scheme identified two sequence types (ST). Out of the 46 strains, 44 (95.7%) were identified as ST5, and remaining 2 were identified as ST31. Our study revealed that the clinical strains of C. neoformans in Korea are genetically homogeneous with the VNI/ST5 genotypes, and new appearance of VNI/ST31 genotype may serve as an important indicator of global genetic analysis.

Cryptococcosis as an emerging systemic mycosis in dogs

OBJECTIVE

To review the etiology, pathogenesis, and clinical presentations of canine cryptococcosis that are of relevance to veterinary emergency and critical care veterinarians. Diagnosis, treatment, and public health considerations of the disease will also be discussed.

ETIOLOGY

Cryptococcosis is a multisystemic disease of dogs, with a predilection for the CNS, caused by encapsulated yeast species of the genus Cryptococcus. The 2 main pathogenic species are Cryptococcus neoformans and Cryptococcus gattii (previously known as C. neoformans var. gattii). Cryptococcosis is an emerging disease in North America, with C. gattii gaining prominence as a cause of serious veterinary and human disease.

DIAGNOSIS

Definitive diagnosis is made by serologic (antigen) testing, culture, and identification of the organism using light microscopy. False negatives and false positives, while uncommon, can occur in dogs using commercially available antigen tests. Cytological examination demonstrates the organism in a majority of cases, although culture is more sensitive. Specific media are required to differentiate between C. neoformans and C. gattii.

THERAPY

The most commonly used antifungal drugs to treat canine cryptococcosis are azole antifungals and amphotericin B. Some strains of Cryptococcus are resistant to antifungal drugs, especially fluconazole. Cautious use of glucocorticoids in critically affected dogs with CNS presentations can improve outcome.

PROGNOSIS

Prognosis is variable and depends on the severity of disease, underlying host immunocompetence, and financial constraints of the owner. Altered mental status in dogs with CNS cryptococcosis is a negative prognostic indicator.

Vaccine and immunotherapeutic approaches for the prevention of cryptococcosis: lessons learned from animal models

Cryptococcus neoformans and C. gattii, the predominant etiological agents 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 C. neoformans remains the third most common invasive fungal infection among organ transplant recipients. Current anti-fungal drug therapies are oftentimes rendered ineffective due to drug toxicity, the emergence of drug resistant organisms, and/or the inability of the host's immune defenses to assist in eradication of the yeast. Therefore, there remains an urgent need for the development of immune-based therapies and/or vaccines to combat cryptococcosis. Studies in animal models have demonstrated the efficacy of various vaccination strategies and immune therapies to induce protection against cryptococcosis. This review will summarize the lessons learned from animal models supporting the feasibility of developing immunotherapeutics and vaccines to prevent cryptococcosis.

Ten challenges on Cryptococcus and cryptococcosis

Cryptococcosis has become a significant public global health problem worldwide. Caused by two species, Cryptococcus neoformans or Cryptococcus gattii, this life-threatening infection afflicts not only immunocompromised individuals but also apparently immunocompetent subjects. Hence, cryptococcosis should no longer be considered merely an opportunistic infection. In this article, we focus on ten unanswered questions/topics in this field with the hope to stimulate discussion and research on these topics that would lead not only to a better understanding of the physiopathology of this disease but also to a better diagnosis and prognosis.

Surfactant protein D facilitates Cryptococcus neoformans infection

Concurrent with the global escalation of the AIDS pandemic, cryptococcal infections are increasing and are of significant medical importance. Furthermore, Cryptococcus neoformans has become a primary human pathogen, causing infection in seemingly healthy individuals. Although numerous studies have elucidated the virulence properties of C. neoformans, less is understood regarding lung host immune factors during early stages of fungal infection. Based on our previous studies documenting that pulmonary surfactant protein D (SP-D) protects C. neoformans cells against macrophage-mediated defense mechanisms in vitro (S. Geunes-Boyer et al., Infect. Immun. 77:2783-2794, 2009), we postulated that SP-D would facilitate fungal infection in vivo. To test this hypothesis, we examined the role of SP-D in response to C. neoformans using SP-D⁻/⁻ mice. Here, we demonstrate that mice lacking SP-D were partially protected during C. neoformans infection; they displayed a longer mean time to death and decreased fungal burden at several time points postinfection than wild-type mice. This effect was reversed by the administration of exogenous SP-D. Furthermore, we show that SP-D bound to the surface of the yeast cells and protected the pathogenic microbes against macrophage-mediated defense mechanisms and hydrogen peroxide (H₂O₂)-induced oxidative stress in vitro and in vivo. These findings indicate that C. neoformans is capable of coopting host SP-D to increase host susceptibility to the yeast. This study establishes a new paradigm for the role played by SP-D during host responses to C. neoformans and consequently imparts insight into potential future preventive and/or treatment strategies for cryptococcosis.

Cryptococcus gattii: where do we go from here?

Infections caused by the emerging pathogen Cryptococcus gattii are increasing in frequency in North America. During the past decade, interest in the pathogen has continued to grow, not only in North America but also in other areas of the world where infections have recently been documented. This review synthesizes existing data and raises issues that remain to be addressed.

The Outbreak of Cryptococcus gattii in Western North America: Epidemiology and Clinical Issues

Over the previous decade, we observed the emergence of the fungal pathogen, Cryptococcus gattii, as a cause of disease in humans and animals in a temperate climate. This outbreak, first documented on Vancouver Island, has since expanded throughout Western North America, with non-travel-associated cases now in British Columbia, Washington, Oregon, and California. Additionally, a secondary outbreak, originating in and still restricted to Oregon, has also occurred. During the past several years, several studies detailing molecular typing, virulence, antifungal susceptibilities, epidemiology, and clinical issues have been published. These studies begin to address the complex dynamics of this novel emergence of a rare and fatal fungus, outline clinical characteristics of human cases, and also opened several new areas that should be explored in the upcoming years.

Global VGIIa isolates are of comparable virulence to the major fatal Cryptococcus gattii Vancouver Island outbreak genotype

The ongoing cryptococcosis outbreak on Vancouver Island, BC, Canada, is caused by two VGII sub-genotypes of the primary pathogen, Cryptococcus gattii: VGIIa isolates predominate, whereas VGIIb isolates are rare. Although higher virulence of the VGIIa genotype has been proposed, an unresolved key question is whether VGIIa isolates from other regions are also more virulent than VGIIb isolates. We report the relationship between genotype and virulence for a global collection of C. gattii VGIIa and VGIIb isolates (from Australia, Argentina, Brazil, Canada, Thailand and the USA). In vitro and in vivo virulence studies were conducted. At 37°C, growth [at 18 h: 0.2 optical density (OD) difference, p 0.026; at 36 h: 0.6 OD difference, p 0.036) and mean melanin production (OD = 0.25 vs. OD = 0.15, p 0.059] of VGIIa isolates was greater than that of VGIIb isolates. The inhibitory effect of high temperature on melanin production of VGIIa isolates was less than that of VGIIb isolates (OD = 0.36 vs. OD = 0.69; p 0.001). Capsule production at 37°C of VGIIa isolates was less than that of VGIIb isolates. All VGIIa isolates were fertile, whereas only 17% of VGIIb isolates were fertile (p <0.001). In vivo virulence studies using the BALB/c mice nasal inhalation model revealed that VGIIa isolates were more virulent than VGIIb isolates (p <0.001) independent of their clinical (p 0.003) or environmental origin (p <0.001). This study established a clear association between genotype and virulence of the primary fungal pathogen, C. gattii.

Cryptococcus gattii virulence composite: candidate genes revealed by microarray analysis of high and less virulent Vancouver island outbreak strains

Human and animal cryptococcosis due to an unusual molecular type of Cryptococcus gattii (VGII) emerged recently on Vancouver Island, Canada. Unlike C. neoformans, C. gattii causes disease mainly in immunocompetent hosts, despite producing a similar suite of virulence determinants. To investigate a potential relationship between the regulation of expression of a virulence gene composite and virulence, we took advantage of two subtypes of VGII (a and b), one highly virulent (R265) and one less virulent (R272), that were identified from the Vancouver outbreak. By expression microarray analysis, 202 genes showed at least a 2-fold difference in expression with 108 being up- and 94 being down-regulated in strain R265 compared with strain R272. Specifically, expression levels of genes encoding putative virulence factors (e.g. LAC1, LAC2, CAS3 and MPK1) and genes encoding proteins involved in cell wall assembly, carbohydrate and lipid metabolism were increased in strain R265, whereas genes involved in the regulation of mitosis and ergosterol biosynthesis were suppressed. In vitro phenotypic studies and transcription analysis confirmed the microarray results. Gene disruption of LAC1 and MPK1 revealed defects in melanin synthesis and cell wall integrity, respectively, where CAS3 was not essential for capsule production. Moreover, MPK1 also controls melanin and capsule production and causes a severe attenuation of the virulence in a murine inhalational model. Overall, this study provides the basis for further genetic studies to characterize the differences in the virulence composite of strains with minor evolutionary divergences in gene expression in the primary pathogen C. gattii, that have led to a major invasive fungal infection outbreak.

Common and emerging fungal pulmonary infections

Fungal pulmonary infections are becoming more prevalent as a consequence of the rising prevalence of immunocompromised patients. Besides ubiquitous opportunistic fungi such as Aspergillus spp and geographically delimited mycoses, fungi that were previously thought to be of uncertain pathogenicity, such as hyaline and dematiaceous molds, are increasingly being diagnosed as the causes of invasive disease in profoundly immunosuppressed hosts. Overall progress in the clinical management of fungal pulmonary infections has been slow compared with other areas of infectious diseases. However, recent encouraging advances in fungal diagnostics and therapeutics have resulted in improved clinical outcomes, particularly in vulnerable patient populations such as solid organ or allogeneic hematopoietic stem cell transplant recipients. This article provides an overview of endemic mycoses and other emerging fungal pulmonary infections. Recent developments in terms of the diagnosis and clinical management of these infections are also discussed.

Projecting global occurrence of Cryptococcus gattii

This pathogen likely has wider distribution than is currently recognized.

Cryptococcus gattii and C. neoformans cause pulmonary and systemic cryptococcosis. Recently, C. gattii was recognized as a distinct pathogen of humans and animals. We analyzed information from 400 publications (1948–2008) to examine whether the fungus occurs globally. Known distribution of C. gattii is possibly limited because specialized reagents for differentiation from C. neoformans are not readily available and not always used, and environmental surveys are patchy. However, autochthonous reports of C. gattii cryptococcosis have now been recognized from tropical and temperate regions. An ongoing outbreak in western Canada strengthens the case that the range of the pathogen has expanded. A few studies have highlighted differences in cryptococcosis between C. gattii and C. neoformans. More than 50 tree species have yielded C. gattii especially from decayed hollows suggesting a possible ecologic niche. This pathogen merits more attention so its environmental occurrence and role in cryptococcosis can be accurately determined.

Coordination to gallium(III) strongly enhances the potency of 2-pyridineformamide thiosemicarbazones against Cryptococcus opportunistic fungi

A family of 2-pyridineformamide-derived thiosemicarbazones and their gallium(III) complexes were tested against several isolates of pathogenic Cryptococcus strains. On complexation the antifungal activity significantly increases, suggesting coordination to gallium(III) to be an interesting strategy of antifungal dose reduction.

Rapid detection of pathogenic fungi using loop-mediated isothermal amplification, exemplified by Fonsecaea agents of chromoblastomycosis

Loop-mediated isothermal amplification (LAMP) was developed for rapid detection of pathogenic or allergenic fungal in the environment. Primers applied were derived from the rDNA Internal Transcribed Spacer and the 5.8S rRNA gene. The assay enabled amplification of target fungi at the level of genus or closely related species using pure cultures after 1h reaction at 65 degrees C in a water bath. No cross-reactivity to related species was observed. The DNA detection limit was 0.2fg. The method also proved to work well with fungi on non-sterile adhesive tape. Amplification products were detected by visual inspection using SYBR Green I as well as by electrophoresis on agarose gels. As a model organism we selected Fonsecaea, a fungal genus containing etiologic agents of chromoblastomycosis, a widely distributed tropical and subtropical skin disease in otherwise healthy patients and supposed to be acquired by environmental inoculation. It is suggested that LAMP can also be used for rapid clinical diagnosis, for environmental detection, and for retrospective studies in archived clinical samples.