Isavuconazole, micafungin, and 8 comparator antifungal agents' susceptibility profiles for common and uncommon opportunistic fungi collected in 2013: temporal analysis of antifungal drug resistance using CLSI species-specific clinical breakpoints and proposed epidemiological cutoff values

Trends in the activity of mold-active azole agents against Aspergillus fumigatus clinical isolates with and without cyp51 alterations from Europe and North America (2017-2021)

Azole resistance in Aspergillus fumigatus (AFM) is increasing and often associated with cyp51 alterations. We evaluated the activity of isavuconazole and other mold-active azoles against 731 AFM isolates causing invasive aspergillosis collected in Europe (EU; n = 449) and North America (NA; n = 282). Isolates were submitted to CLSI susceptibility testing and epidemiological cutoff value (ECV) criteria. A posaconazole ECV of 0.5 mg/L was used as no CLSI ECV was determined. Azole non-wild-type (NWT) isolates were submitted for cyp51 sequencing by whole genome sequencing. Overall, isavuconazole activity (92.7%/94.0% WT in EU/NA) was comparable to other azoles (WT rate range, 90.9%-96.4%/91.8%-98.6%, respectively), regardless of the region. A total of 79 (10.8%) azole NWT isolates were detected, and similar rates of these isolates were noted in EU (10.7%) and NA (11.0%). Although most AFM were WT to azoles, increasing azole NWT rates were observed in NA (from 6.0% in 2017 to 29.3% in 2021). Azole NWT rates varied from 4.9% (2019) to 20.6% (2018) in EU without an observed trend. cyp51 alterations occurred in 56.3%/54.8% of azole NWT from EU/NA, respectively. The cyp51A TR34/L98H alteration was observed only in EU isolates (72.0% of EU isolates), while cyp51A I242V occurred only in NA isolates (58.3%). Isavuconazole remained active (MIC, ≤1 mg/L) against 18.5/47.1% of azole NWT AFM exhibiting cyp51 alterations in EU/NA, along with voriconazole (29.6/82.4%; MIC, ≤1 mg/L) and posaconazole (48.1/88.2%; MIC, ≤0.5 mg/L). Fourteen different cyp51 alterations were detected in 44 of 79 NWT isolates. The in vitro activity of the azoles varied in AFM that displayed cyp51 alterations. IMPORTANCE A few microbiology laboratories perform antifungal susceptibility testing locally for systemically active antifungal agents. The identification of emerging azole-resistant Aspergillus fumigatus is worrisome. As such, there is a critical role for antifungal surveillance in tracking emerging resistance among both common and uncommon opportunistic fungi. Differences in the regional prevalence and antifungal resistance of these fungi render local epidemiological knowledge essential for the care of patients with a suspected invasive fungal infection.

Antifungal Resistance and Genotyping of Clinical Candida parapsilosis Complex in Japan

Non-albicans Candida infections have recently gained worldwide attention due to their intrinsic resistance to different antifungal agents and the limited therapeutic options for treating them. Although the Candida parapsilosis complex is reported to be the second or third most prevalent Candida spp., little information is available on the prevalence of antifungal resistance along with genotyping of the C. parapsilosis complex. In this study, we aimed to evaluate the prevalence of antifungal resistance, the genetic basis of such resistance, and the genotyping of C. parapsilosis complex isolates that were recovered from hospitalized patients in Japan from 2005 to 2019. Our results indicated that, with the exception of one single C. metapsilosis isolate that was dose-dependently susceptible to fluconazole, all other isolates were susceptible or showed wild phenotypes to all tested antifungals, including azoles, echinocandins, amphotericin B, and flucytosine. Molecular analyses for azole and echinocandin resistance via evaluating ERG11 mutation and FKS1 hotspot one (HS1) and hotspot two (HS2) mutations, respectively, confirmed the phenotypic results. Genotyping of our isolates confirmed that they belong to 53 different but closely related genotypes, with a similarity percentage of up to 90%. Our results are of significant concern, since understanding the genetic basis of echinocandin resistance in the C. parapsilosis complex as well their genotyping is essential for directing targeted therapy, identifying probable infection sources, and developing strategies for overcoming epidemic spread.

Chemical composition, antifungal activity, antibiofilm and citotoxicity of the essential oil of Citrus deliciosa tenore

The leaves of Citrus deliciosa Tenore were collected in southern Brazil, dried, and subjected to the hydrodistillation process to obtain the essential oil. The extraction of essential oil yielded 0.97% ± 0.04. The chromatographic profile of this compound revealed 11 substances, being methyl N-methyl-anthranilate (75.1%), γ-terpinene (13.8%), and Limonene (7%) as major substances. The essential oil shows antifungal action against all tested yeasts, with promising action against Cryptococcus neoformans, Cryptococcus gattii, and Trichosporon asahii. This compound was also able to inhibit the biofilm production of Candida albicans, Candida glabrata, Candida parapsilosis, and T. asahii. The essential oil of tangerine showed weak antioxidant action. It did not show cytotoxicity in human mononuclear cells. It is hoped that these results may guide future studies for the production of formulations that can be used in the treatment of biofilms caused by yeasts, as well as in candidiasis, cryptococcosis, and/or trichosporonosis.

Antifungal susceptibility profiles of Cryptococcus neoformans strains clinically isolated from non-HIV-infected patients in Nagasaki, Japan

Data on antifungal susceptibility of Cryptococcus neoformans are limited in Japan. A total of 89 C. neoformans strains isolated from 83 non-human immunodeficiency virus-infected patients with cryptococcosis between 1997 and 2021 in Nagasaki, Japan, were investigated. Using the reference method M27-Ed4 by the Clinical and Laboratory Standards Institute, the minimum inhibitory concentration for 90% of isolates of fluconazole, itraconazole, voriconazole, amphotericin B, and flucytosine were 4, 0.125, 0.06, 0.5, and 4 µg/ml, respectively, which were below the reported epidemiological cutoff values, without any detectable non-wild-type strains. Our findings imply no increasing trend of antifungal-resistant C. neoformans in Nagasaki, Japan.

Susceptibility patterns of amphotericin B, itraconazole, posaconazole, voriconazole and caspofungin for isolates causing invasive mould infections from the SENTRY Antifungal Surveillance Program (2018-2021) and application of single-site epidemiological cutoff values to evaluate amphotericin B activity

We evaluated the activity of amphotericin B, itraconazole, posaconazole, voriconazole and caspofungin against 1468 invasive moulds collected worldwide from 2018 to 2021. Most (>92%) of the Aspergillus spp. isolates were wildtype (WT) to amphotericin B, caspofungin and the azoles. Azole-non-wildtype A. fumigatus rates were higher in Europe (9.5%) and North America (9.1%) than Latin America (0.0%; only 12 isolates) and the Asia-Pacific region (5.3%). Amphotericin B and caspofungin were active against azole-non-wildtype A. fumigatus isolates. Posaconazole and amphotericin B were the most active agents against the Mucorales. Among the less common moulds, several expressed a pan-azole-resistant phenotype; many of these species also showed elevated MIC values (MIC, >2 mg/L) for amphotericin B and caspofungin. Although most isolates of Aspergillus spp. remain WT to the azoles, azole resistance is increasing in both North America and Europe. Amphotericin B and caspofungin exhibit potentially useful activity against azole-resistant A. fumigatus.

Cm-p5 Peptide Dimers Inhibit Biofilms of Candida albicans Clinical Isolates, C. parapsilosis and Fluconazole-Resistant Mutants of C. auris

Antimicrobial peptides (AMPs) represent a promising class of therapeutic biomolecules that show antimicrobial activity against a broad range of microorganisms, including life-threatening pathogens. In contrast to classic AMPs with membrane-disrupting activities, new peptides with a specific anti-biofilm effect are gaining in importance since biofilms could be the most important way of life, especially for pathogens, as the interaction with host tissues is crucial for the full development of their virulence in the event of infection. Therefore, in a previous study, two synthetic dimeric derivatives (parallel Dimer 1 and antiparallel Dimer 2) of the AMP Cm-p5 showed specific inhibition of the formation of Candida auris biofilms. Here we show that these derivatives are also dose-dependently effective against de novo biofilms that are formed by the widespread pathogenic yeasts C. albicans and C. parapsilosis. Moreover, the activity of the peptides was demonstrated even against two fluconazole-resistant strains of C. auris.

The association between <i>Candida albicans</i> sensitivity to antimycotic drugs and the architecture of their microbial community in the oropharynx of HIV infected patients

Relevance. Candida infection remains relevant due to the wide spread of antimycotic-resistant strains of Candida fungi, especially among immunocompromised individuals. It was previously discovered that the Candida spp. microbial community in the biotope of the oropharynx of HIV infected patients is characterized by a certain architecture: they can be present in this biotope in the form of a monoculture or as association of co-isolates. It has been suggested that the architecture of the Candida microbial community may influence their resistance to antimycotic drugs. Purpose a comparative study of the association between the architecture of the C. albicans microbial community in the oropharynx of HIV infected patients with oropharyngeal candidiasis and their sensitivity to antimycotic drugs. Materials and methods. A microbiological study of 52 isolates of Candida fungi (C. albicans, C. glabrata, C. tropicalis and C. krusei) from the oropharynx of 31 HIV infected patients with clinical manifestations of oropharyngeal candidiasis aged 20 to 69 years with almost equal gender distribution was carried out. In the form of monocultures, 18 isolates were isolated, while 34 were identified as co-isolates, which formed 16 homogeneous communities that included strains of the same species, and 18 heterogeneous ones that consisted of fungi of various species. Results. It was found that heterogeneous communities of C. albicans were markedly distinguished by sensitivity to antimycotic drugs, in particular, by low sensitivity to imidazoles. Homogeneous communities practically did not differ from monocultural ones. The general properties of the C. non-albicans population were largely similar to those of C. albicans, but were characterized by lower heterogeneity in response to antimycotic drugs. Conclusion. The architecture of the community of C. albicans isolated from the oropharynx of HIV infected patients with clinical manifestations of oropharyngeal candidiasis affects their sensitivity to antimycotic drugs. When selecting effective antimycotic therapy for such patients, it is necessary to take into account the structure of the Candida spp. community in the oropharynx.

Limosilactobacillus fermentum Limits Candida glabrata Growth by Ergosterol Depletion

Candida glabrata is a human-associated opportunistic fungal pathogen. It shares its niche with Lactobacillus spp. in the gastrointestinal and vaginal tract. In fact, Lactobacillus species are thought to competitively prevent Candida overgrowth. We investigated the molecular aspects of this antifungal effect by analyzing the interaction of C. glabrata strains with Limosilactobacillus fermentum. From a collection of clinical C. glabrata isolates, we identified strains with different sensitivities to L. fermentum in coculture. We analyzed the variation of their expression pattern to isolate the specific response to L. fermentum. C. glabrata-L. fermentum coculture induced genes associated with ergosterol biosynthesis, weak acid stress, and drug/chemical stress. L. fermentum coculture depleted C. glabrata ergosterol. The reduction of ergosterol was dependent on the Lactobacillus species, even in coculture with different Candida species. We found a similar ergosterol-depleting effect with other lactobacillus strains (Lactobacillus crispatus and Lactobacillus rhamosus) on Candida albicans, Candida tropicalis, and Candida krusei. The addition of ergosterol improved C. glabrata growth in the coculture. Blocking ergosterol synthesis with fluconazole increased the susceptibility against L. fermentum, which was again mitigated by the addition of ergosterol. In accordance, a C. glabrata Δerg11 mutant, defective in ergosterol biosynthesis, was highly sensitive to L. fermentum. In conclusion, our analysis indicates an unexpected direct function of ergosterol for C. glabrata proliferation in coculture with L. fermentum. IMPORTANCE The yeast Candida glabrata, an opportunistic fungal pathogen, and the bacterium Limosilactobacillus fermentum both inhabit the human gastrointestinal and vaginal tract. Lactobacillus species, belonging to the healthy human microbiome, are thought to prevent C. glabrata infections. We investigated the antifungal effect of Limosilactobacillus fermentum on C. glabrata strains quantitively in vitro. The interaction between C. glabrata and L. fermentum evokes an upregulation of genes required for the synthesis of ergosterol, a sterol constituent of the fungal plasma membrane. We found a dramatic reduction of ergosterol in C. glabrata when it was exposed to L. fermentum. This effect extended to other Candida species and other Lactobacillus species. Furthermore, fungal growth was efficiently suppressed by a combination of L. fermentum and fluconazole, an antifungal drug which inhibits ergosterol synthesis. Thus, fungal ergosterol is a key metabolite for the suppression of C. glabrata by L. fermentum.

Higher Dose Oral Fluconazole for the Treatment of AIDS-related Cryptococcal Meningitis (HIFLAC)-report of A5225, a multicentre, phase I/II, two-stage, dose-finding, safety, tolerability and efficacy randomised, amphotericin B-controlled trial of the AIDS Clinical Trials Group

BACKGROUND

The WHO recommended 1200mg/day of fluconazole (FCZ) in the induction phase of cryptococcal meningitis (CM) in HIV prior to 2018 in regions where amphotericin-B (AMB) was unavailable. A 2-stage AMB-controlled, dose-escalation study to determine the maximum tolerated dose and the safety/efficacy of an induction-consolidation strategy of higher doses FCZ (1200mg-2000mg/day), adjusted for weight and renal function (eGFR)in adults with CM was undertaken.

METHODS

In Stage-1, three induction doses of FCZ (1200mg/day, 1600mg/day and 2000mg/day) were tested in sequential cohortsand compared with AMB in a 3:1 ratio. A particular dose was not tested in Stage 2 if there were significant predetermined safety or efficacy concerns. In Stage-2, the 1200mg dose was excluded per protocol because of increased mortality, and participants were randomised to 1600mg, 2000mg FCZ or AMB in a 1:1:1 ratio.

FINDINGS

One hundred and sixty eight participants were enrolled with 48, 50, and 48 in the AMB, 1600mg and 2000mg cohorts. The Kaplan Meier proportion for mortality (90% CI) at 10 and 24 weeks for AMB was 17% (10, 29) and 24% (15, 37), compared to 20% (12, 32) and 30% (20, 43) for 1600mg, and 33% (23, 46) and 38% (27, 51) for 2000mg/day FCZ. With the exception of a higher incidence of gastrointestinal side effects in the 2000mg cohort, both induction doses of FCZ were safe and well tolerated. There were no life-threatening changes in electrocardiogram QTc which were similar across all doses of FCZ and AMB. The median (IQR) change in log10 cryptoccal colony forming units (CFU) from week 0 to week 2 was -8(-4.1,-1.9) for AMB; -2.5(-4.0, -1.4) for 1600mg FCZ and -8 (-3.2, -1.0) for 2000mg FCZ. The proportion (90% CI) CSF CM negative at 10 weeks was 81%(71,90) for AMB; 56%(45,69) for 1600mg FCZ and 60%(49,73) for 2000mg FCZ.

INTERPRETATION

Induction phase weight and renal-adjusted doses of 1600mg and 2000mg/day FCZ for CM were safe and well tolerated except for increased GI side effects in the 2000mg/day dose, and had similar times to achieve CSF sterilization, but took significantly longer than AMB. The WHO recommended 1200mg FCZ was associated with a high mortality. While not statistically significant, mortality was numerically lower in the AMB compared to 1600mg and 2000mg FCZ These data make a case for a phase 3 study of higher doses of FZC.

In Silico and In Vitro Analysis of Sulforaphane Anti-Candida Activity

Oropharyngeal candidiasis/candidosis is a common and recurrent opportunistic fungal infection. Fluconazole (FLZ), one of the most used and effective antifungal agents, has been associated with a rise of resistant Candida species in immunocompromised patients undergoing prophylactic therapy. Sulforaphane (SFN), a compound from cruciferous vegetables, is an antimicrobial with yet controversial activities and mechanisms on fungi. Herein, the in silico and antifungal activities of SFN against C. albicans were investigated. In silico analyzes for the prediction of the biological activities and oral bioavailability of SFN, its possible toxicity and pharmacokinetic parameters, as well as the estimates of its gastrointestinal absorption, permeability to the blood-brain barrier and skin, and similarities to drugs, were performed by using different software. SFN in vitro anti-Candida activities alone and in combination with fluconazole (FLZ) were determined by the broth microdilution method and the checkerboard, biofilm and hyphae formation tests. Amongst the identified probable biological activities of SFN, nine indicated an antimicrobial potential. SFN was predicted to be highly absorbable by the gastrointestinal tract, to present good oral availability, and not to be irritant and/or hepatotoxic. SFN presented antifungal activity against C. albicans and prevented both biofilm and hyphae formation by this microorganism. SFN was additive/synergistic to FLZ. Overall, the data highlights the anti-Candida activity of SFN and its potential to be used as an adjuvant therapy to FLZ in clinical settings.

Meyerozyma guilliermondii species complex: review of current epidemiology, antifungal resistance, and mechanisms

Meyerozyma guilliermondii has been accepted as a complex composed of Meyerozyma guilliermondii, Meyerozyma carpophila, and Meyerozyma caribbica. M. guilliermondii is a saprophyte detected on human mucosa and skin. It can lead to serious infections in patients with risk factors like chemotherapy, immunodeficiency, gastrointestinal or cardiovascular surgery, and oncology disorders. Most deaths related to M. guilliermondii infections occur in individuals with malignancy. In recent decades, incidence of M. guilliermondii infections is increased. Sensitivity of this microorganism to conventional antifungals (e.g., amphotericin B, fluconazole, micafungin and anidulafungin) was reduced. Prophylactic and empirical uses of these drugs are linked to elevated minimal inhibitory concentrations (MICs) of M. guilliermondii. Drug resistance has concerned many researchers across the world. They are attempting to discover appropriate solution to combat this challenge. This study reviews the most important mechanisms of resistance to antifungals developed by in M. guilliermondii species complex.

The Antibiofilm Role of Biotics Family in Vaginal Fungal Infections

“Unity in strength” is a notion that can be exploited to characterize biofilms as they bestow microbes with protection to live freely, escalate their virulence, confer high resistance to therapeutic agents, and provide active grounds for the production of biofilms after dispersal. Naturally, fungal biofilms are inherently resistant to many conventional antifungals, possibly owing to virulence factors as their ammunitions that persistently express amid planktonic transition to matured biofilm state. These ammunitions include the ability to form polymicrobial biofilms, emergence of persister cells post-antifungal treatment and acquisition of resistance genes. One of the major disorders affecting vaginal health is vulvovaginal candidiasis (VVC) and its reoccurrence is termed recurrent VVC (RVVC). It is caused by the Candida species which include Candida albicans and Candida glabrata. The aforementioned Candida species, notably C. albicans is a biofilm producing pathogen and habitually forms part of the vaginal microbiota of healthy women. Latest research has implicated the role of fungal biofilms in VVC, particularly in the setting of treatment failure and RVVC. Consequently, a plethora of studies have advocated the utilization of probiotics in addressing these infections. Specifically, the excreted or released compounds of probiotics which are also known as postbiotics are being actively researched with vast potential to be used as therapeutic options for the treatment and prevention of VVC and RVVC. These potential sources of postbiotics are harnessed due to their proven antifungal and antibiofilm. Hence, this review discusses the role of Candida biofilm formation in VVC and RVVC. In addition, we discuss the application of pro-, pre-, post-, and synbiotics either individually or in combined regimen to counteract the abovementioned problems. A clear understanding of the role of biofilms in VVC and RVVC will provide proper footing for further research in devising novel remedies for prevention and treatment of vaginal fungal infections.

Lung nodules due to Candida parapsilosis in a person with cystic fibrosis

We present the first reported case of Candida parapsilosis pulmonary infection presenting as lung nodules. The patient is a 31-year-old man with cystic fibrosis (CF) colonised with multidrug-resistant Escherichia coli and increased frequency of pulmonary exacerbations in the preceding months. While on intravenous antibiotics for a pulmonary exacerbation, he developed bilateral pulmonary nodules. Bronchoalveolar lavage cultures grew C. parapsilosis He was initially treated with dual antifungal therapy, voriconazole and micafungin. Discontinuation of voriconazole due to transaminitis resulted in the development of new nodules, and isavuconazonium was added. Repeat imaging revealed no progression of disease. Micafungin was eventually discontinued. Monotherapy with isavuconazonium is planned for 1 year post lung transplant. In the CF population, C. parapsilosis may be an opportunistic pathogen. The case highlights that frequent CF exacerbations and antibiotic exposure increase the risk for opportunistic infections including Candida species and the implications for lung transplantation in this setting.

What 'Omics Can Tell Us About Antifungal Adaptation

Invasive candidiasis, the most frequent healthcare-associated invasive fungal infection, is commonly caused by Candida albicans. However, in recent years other antifungal-resistant Candida species—namely Candida glabrata and Candidaauris—have emerged as a serious matter of concern. Much of our understanding of the mechanisms regulating antifungal resistance and tolerance relies on studies utilizing C. albicans, C. glabrataand the model yeast Saccharomyces cerevisiae. ‘Omics studies have been used to describe alterations in metabolic, genomic and transcriptomic expression profiles upon antifungal treatment of fungal cells. The physiological changes identified by these approaches could significantly affect fungal fitness in the host and survival during antifungal challenge, as well as provide further understanding of clinical resistance. Thus, this review aims to comparatively address ‘omics data for C. albicans, C. glabrata andS. cerevisiae published from 2000 to 2021 to identify what these technologies can tell us regarding cellular responses to antifungal therapy. We will also highlight possible effects on pathogen survival and identify future avenues for antifungal research.

Evaluation of bisphenylthiazoles as a promising class for combating multidrug-resistant fungal infections

To minimize the intrinsic toxicity of the antibacterial agent hydrazinyloxadiazole 1, the hydrazine moiety was replaced with ethylenediamine (compound 7). This replacement generated a potent antifungal agent with no antibacterial activity. Notably, use of a 1,2-diaminocyclohexane moiety, as a conformationally-restricted isostere for ethylenediamine, potentiated the antifungal activity in both the cis and trans forms of N-(5-(2-([1,1’-biphenyl]-4-yl)-4-methylthiazol-5-yl)-1,3,4-oxadiazol-2-yl)cyclohexane-1,2-diamine (compounds 16 and 17). Both compounds 16 and 17 were void of any antibacterial activity; nonetheless, they showed equipotent antifungal activity in vitro to that of the most potent approved antifungal agent, amphotericin B. The promising antifungal effects of compounds 16 and 17 were maintained when assessed against an additional panel of 26 yeast and mold clinical isolates, including the Candida auris and C. krusei. Furthermore, compound 17 showed superior activity to amphotericin B in vitro against Candida glabrata and Cryptococcus gattii. Additionally, neither compound inhibited the normal human microbiota, and both possessed excellent safety profiles and were 16 times more tolerable than amphotericin B.

The Inhibition of Non-albicans Candida Species and Uncommon Yeast Pathogens by Selected Essential Oils and Their Major Compounds

The epidemiology of yeast infections and resistance to available antifungal drugs are rapidly increasing, and non-albicans Candida species and rare yeast species are increasingly emerging as major opportunistic pathogens. In order to identify new strategies to counter the threat of antimicrobial resistant microorganisms, essential oils (EOs) have become an important potential in the treatment of fungal infections. EOs and their bioactive pure compounds have been found to exhibit a wide range of remarkable biological activities. We investigated the in vitro antifungal activity of nine commercial EOs such as Thymus vulgaris (thyme red), Origanum vulgare (oregano), Lavandula vera (lavender), Pinus sylvestris (pine), Foeniculum vulgare (fennel), Melissa officinalis (lemon balm), Salvia officinalis (sage), Eugenia caryophyllata (clove) and Pelargonium asperum (geranium), and some of their main components (α-pinene, carvacrol, citronellal, eugenol, γ-terpinene, linalool, linalylacetate, terpinen-4-ol, thymol) against non-albicans Candida strains and uncommon yeasts. The EOs were analyzed by GC-MS, and their antifungal properties were evaluated by minimum inhibitory concentration and minimum fungicidal concentration parameters, in accordance with CLSI guidelines, with some modifications for EOs. Pine exhibited strong antifungal activity against the selected non-albicans Candida isolates and uncommon yeasts. In addition, lemon balm EOs and α-pinene exhibited strong antifungal activity against the selected non-albicans Candida yeasts. Thymol inhibited the growth of all uncommon yeasts. These data showed a promising potential application of EOs as natural adjuvant for management of infections by emerging non-albicans Candida species and uncommon pathogenic yeasts.

Antifungal susceptibilities of opportunistic filamentous fungal pathogens from the Asia and Western Pacific Region: data from the SENTRY Antifungal Surveillance Program (2011-2019)

Antifungal surveillance is an important tool to monitor the prevalence of uncommon fungal species and increasing antifungal resistance throughout the world, but data comparing results across several different Asian countries are scarce. In this study, 372 invasive molds collected in the Asia-Western Pacific region in 2011-2019 were susceptibility tested for mold-active triazoles (isavuconazole, posaconazole, voriconazole, and itraconazole). The collection includes 318 Aspergillus spp. isolates and 53 non-Aspergillus molds. The MIC values using CLSI methods for isavuconazole versus Aspergillus fumigatus ranged from 0.25 to 2 mg l^-1. Isavuconazole, itraconazole, posaconazole, and voriconazole acted similarly against A. fumigatus. The mold-active triazoles exhibited a wildtype phenotype to most of the Aspergillus spp. isolates tested (>94%), but poor activity against Fusarium solani species complex and Lomentospora prolificans. Voriconazole was most active against the Scedosporium spp. and posaconazole was most active against the Mucorales. In summary, isavuconazole displayed excellent activity against most species of Aspergillus and was comparable to other mold-active triazoles against non-Aspergillus molds.

Update on Candida krusei, a potential multidrug-resistant pathogen

Although Candida albicans remains the main cause of candidiasis, in recent years a significant number of infections has been attributed to non-albicans Candida (NAC) species, including Candida krusei. This epidemiological change can be partly explained by the increased resistance of NAC species to antifungal drugs. C. krusei is a diploid, dimorphic ascomycetous yeast that inhabits the mucosal membrane of healthy individuals. However, this yeast can cause life-threatening infections in immunocompromised patients, with hematologic malignancy patients and those using prolonged azole prophylaxis being at higher risk. Fungal infections are usually treated with five major classes of antifungal agents which include azoles, echinocandins, polyenes, allylamines, and nucleoside analogues. Fluconazole, an azole, is the most commonly used antifungal drug due to its low host toxicity, high water solubility, and high bioavailability. However, C. krusei possesses intrinsic resistance to this drug while also rapidly developing acquired resistance to other antifungal drugs. The mechanisms of antifungal resistance of this yeast involve the alteration and overexpression of drug target, reduction in intracellular drug concentration and development of a bypass pathway. Antifungal resistance menace coupled with the paucity of the antifungal arsenal as well as challenges involved in antifungal drug development, partly due to the eukaryotic nature of both fungi and humans, have left researchers to exploit alternative therapies. Here we briefly review our current knowledge of the biology, pathophysiology and epidemiology of a potential multidrug-resistant fungal pathogen, C. krusei, while also discussing the mechanisms of drug resistance of Candida species and alternative therapeutic approaches.

Susceptibility in vitro of clinical Candida albicans isolates to the selected azoles

Candida spp. is the most prevalent cause of fungal infection worldwide, and their increasing resistance to anti-fungal agents, especially to azoles, has become problematic. The aim of this work was to establish the susceptibility to fluconazole, itraconazole, voriconazole and posaconazole of 50 clinical C. albicans isolates from hematooncological patients. This has been evaluated using the following parameters: MIC (Minimum Inhibitory Concentration), MIC50 (MIC required to inhibit the growth of 50% of organisms), as well as MIC90 (MIC required to inhibit the growth of 90% of organisms). Susceptibility of the studied clinical isolates to all azoles was high, being 86% for itraconazole, 90% for fluconazole and posaconazole and 92% for voriconazole. The resistance rates ranged from 8% (voriconazole), to 12% (itraconazole). The emergence of azole-resistant yeast strains creates a necessity to determine and monitor the sensitivity of the isolated Candida spp., including C. albicans, especially in patients predisposed to life-threating fungal invasive disease.

In vitro activity of posaconazole and comparators versus opportunistic filamentous fungal pathogens globally collected during 8 years

The epidemiology of invasive filamentous fungal diseases requires monitoring due to changes in susceptibility patterns of new and established antifungal agents that may affect clinical practices. We evaluated the activity of posaconazole against 2,157 invasive moulds collected worldwide from 2010-2017. The isolates included 1,775 Aspergillus spp. and 382 non-Aspergillus moulds, including 81 Fusarium spp., 62 Mucorales group, and 57 Scedosporium spp. Isolates were tested using the CLSI reference broth microdilution method. Posaconazole showed similar activity to itraconazole and voriconazole against A. fumigatus. Applying published ECV, 98.0% of the A. fumigatus and 97.7% to 100.0% of other common Aspergillus species were wildtype to posaconazole. Categorical agreement between posaconazole and the other azoles tested against A. fumigatus was 98.7%. Notably, most of the Aspergillus spp. isolates recovered from this large collection were wildtype to echinocandins and all azoles. Posaconazole non-wildtype rates of A. fumigatus varied across the different geographic regions, with 2.1% in Europe, 2.2% in North America, 1.8% in Latin America, and 0.7% in the Asia-Pacific region. The frequency of azole non-wildtype A. fumigatus isolates from Europe increased steadily from 2010-2017 for all 3 triazoles (0.0%-5.0%). The azole non-wildtype A. fumigatus rates from the other geographic areas were stable over time. Fusarium and/or Scedosporium spp. isolates were highly resistant to azoles and echinocandins. Posaconazole and amphotericin B were the most active agents against the Mucorales. Posaconazole was very active against most species of Aspergillus and was comparable to itraconazole and voriconazole against the less common moulds. Posaconazole should provide a useful addition to the anti-mould grouping of antifungal agents.

Molecular and genetic basis of azole antifungal resistance in the opportunistic pathogenic fungus Candida albicans

Candida albicans is an opportunistic yeast and the major human fungal pathogen in the USA, as well as in many other regions of the world. Infections with C. albicans can range from superficial mucosal and dermatological infections to life-threatening infections of the bloodstream and vital organs. The azole antifungals remain an important mainstay treatment of candidiasis and therefore the investigation and understanding of the evolution, frequency and mechanisms of azole resistance are vital to improving treatment strategies against this organism. Here the organism C. albicans and the genetic changes and molecular bases underlying the currently known resistance mechanisms to the azole antifungal class are reviewed, including up-regulated expression of efflux pumps, changes in the expression and amino acid composition of the azole target Erg11 and alterations to the organism's typical sterol biosynthesis pathways. Additionally, we update what is known about activating mutations in the zinc cluster transcription factor (ZCF) genes regulating many of these resistance mechanisms and review azole import as a potential contributor to azole resistance. Lastly, investigations of azole tolerance in C. albicans and its implicated clinical significance are reviewed.

Cryptococcal meningitis: a review for emergency clinicians

INTRODUCTION

Cryptococcal Meningitis (CM) remains a high-risk clinical condition, and many patients require emergency department (ED) management for complications and stabilization.

OBJECTIVE

This narrative review provides an evidence-based summary of the current data for the emergency medicine evaluation and management of CM.

DISCUSSION

This review evaluates the diagnosis, management, and empiric treatment of suspected CM in the ED. CM can easily evade diagnosis with a subacute presentation, and should be considered in any patient with a headache, neurological deficit, or who is immunocompromised. As a definitive diagnosis of CM will not be made in the ED, management of a patient with suspected CM includes prompt diagnostic testing and initiation of empiric treatment. Multiple types of newer Cryptococcal antigen tests provide high sensitivity and specificity both in serum and cerebrospinal fluid (CSF). Patients should be treated empirically for bacterial, fungal, and viral meningitis, specifically with amphotericin B and flucytosine for presumed CM. Additionally, appropriate resuscitation and supportive care, including advanced airway management, management of increased intracranial pressure (ICP), antipyretics, intravenous fluids, and isolation, should be initiated. Antiretroviral therapy (ART) should not be initiated in the ED for those found or known to be HIV-positive for risk of immune reconstitution inflammatory syndrome (IRIS).

CONCLUSIONS

CM remains a rare clinical presentation, but carries significant morbidity and mortality. Physicians must rapidly diagnose these patients while evaluating for other diseases and complications. Early consultation with an infectious disease specialist is imperative, as is initiating symptomatic care.

Underlying mechanisms of the effect of minocycline against Candida albicans biofilms

Minocycline (MH) is a broad-spectrum antimicrobial agent and semisynthetic tetracycline derivative, which has been widely used in the clinic due to its efficacy. Having the strongest anti-microbial effect, MH exceeded the traditional scope of antibiotics and its previously unknown antifungal activity is also gradually being discovered. To preliminarily investigate the inhibitory effect of MH on Candida albicans (C. albicans), changes of cell growth, hyphal formation and transition, biofilm production and signaling pathway gene expression of C. albicans in the presence of MH were assessed in the present study. An XTT reduction assay was performed to quantitatively detect the metabolic activity of biofilms and evaluate the inhibition of MH on this. The results suggested that biofilm formation was clearly inhibited by 67% (P<0.0001) in the presence of 250 µg/ml MH, while mature biofilms were not significantly affected. In addition, MH inhibited the transition from yeast to hypha in a dose-dependent manner. Furthermore, reverse transcription-quantitative PCR revealed that several hyphae- and adhesion-specific genes associated with the Ras/cyclic (c)AMP/protein kinase A (PKA) pathway were differentially expressed following MH treatment, including downregulation of ras family GTPase (RAS1), adenylyl cyclase-associated protein 1 (CAP1), thiamin pyrophosphokinase 1 (TPK1), adenylate cyclase (CDC35), transcription factor (TEC1), agglutinin-like protein 3 (ALS3) and hyphal wall protein 1 (HWP1) and upregulation of EFG1 (enhanced filamentous growth protein 1 gene) and PDE2 (high-affinity phosphodiesterase gene). The most obviously changed genes were TPK1, HWP1 and RAS1, downregulated by 0.33-, 0.48- and 0.55-fold, respectively. It was suggested that MH is associated with alterations in the morphology of C. albicans, such as the repression of hypha and biofilm formation of cells, and MH affected the Ras/cAMP pathway to regulate the expression of cAMP-associated genes.

Vaccination with Secreted Aspartyl Proteinase 2 Protein from Candida parapsilosis Can Enhance Survival of Mice during C. tropicalis-Mediated Systemic Candidiasis

The rising incidence of non-albicans Candida species globally, along with the emergence of drug resistance, is a cause for concern. This study investigated the protective efficacy of secreted aspartyl proteinase 2 (Sap2) in systemic C. tropicalis infection. Vaccination with recombinant Sap2 (rSap2) protein from C. parapsilosis enhanced survival of mice compared to rSap2 vaccinations from C. albicans (P = 0.02), C. tropicalis (P = 0.06), and sham immunization (P = 0.04). Compared to sham-immunized mice, the fungal CFU number was significantly reduced in organs of Sap2-parapsilosis-immunized mice. Histopathologically, increased neutrophilic recruitment was observed in Sap2-parapsilosis- and Sap2-tropicalis-immunized mice. Among different rSap2 proteins, Sap2-parapsilosis vaccination induced increased titers of Sap2-specific Ig, IgG, and IgM antibodies, which could bind whole fungus. Between different groups, sera from Sap2-parapsilosis-vaccinated mice exhibited increased C. tropicalis biofilm inhibition ability in vitro and enhanced neutrophil-mediated fungal killing. Passive transfer of anti-Sap2-parapsilosis immune serum in naive mice significantly reduced fungal burdens compared to those in mice receiving anti-sham immune serum. Higher numbers of plasma cells and Candida-binding B cells in Sap2-vaccinated mice suggest a role of B cells during early stages of Sap2-mediated immune response. Additionally, increased levels of Th1/Th2/Th17 cytokines observed in Sap2-parapsilosis-vaccinated mice indicate immunomodulatory properties of Sap2. Epitope analysis performed using identified B-cell epitopes provides a basis to understand differences in immunogenicity observed among Sap2-antigens and can aid the development of a multivalent or multiepitope anti-Candida vaccine(s). In summary, our results suggest that Sap2-parapsilosis vaccination can improve mouse survival during C. tropicalis infection by inducing both humoral and cellular immunity, and higher titers of Sap2-induced antibodies are beneficial during systemic candidiasis.

Genome-Scale Metabolic Model of the Human Pathogen Candida albicans: A Promising Platform for Drug Target Prediction

Candida albicans is one of the most impactful fungal pathogens and the most common cause of invasive candidiasis, which is associated with very high mortality rates. With the rise in the frequency of multidrug-resistant clinical isolates, the identification of new drug targets and new drugs is crucial in overcoming the increase in therapeutic failure. In this study, the first validated genome-scale metabolic model for Candida albicans, iRV781, is presented. The model consists of 1221 reactions, 926 metabolites, 781 genes, and four compartments. This model was reconstructed using the open-source software tool merlin 4.0.2. It is provided in the well-established systems biology markup language (SBML) format, thus, being usable in most metabolic engineering platforms, such as OptFlux or COBRA. The model was validated, proving accurate when predicting the capability of utilizing different carbon and nitrogen sources when compared to experimental data. Finally, this genome-scale metabolic reconstruction was tested as a platform for the identification of drug targets, through the comparison between known drug targets and the prediction of gene essentiality in conditions mimicking the human host. Altogether, this model provides a promising platform for global elucidation of the metabolic potential of C. albicans, possibly guiding the identification of new drug targets to tackle human candidiasis.

Bio- and Nanotechnology as the Key for Clinical Application of Salivary Peptide Histatin: A Necessary Advance

Candida albicans is a common microorganism of human’s microbiota and can be easily found in both respiratory and gastrointestinal tracts as well as in the genitourinary tract. Approximately 30% of people will be infected by C. albicans during their lifetime. Due to its easy adaptation, this microorganism started to present high resistance to antifungal agents which is associated with their indiscriminate use. There are several reports of adaptive mechanisms that this species can present. Some of them are intrinsic alteration in drug targets, secretion of extracellular enzymes to promote host protein degradation and efflux receptors that lead to a diminished action of common antifungal and host’s innate immune response. The current review aims to bring promising alternatives for the treatment of candidiasis caused mainly by C. albicans. One of these alternatives is the use of antifungal peptides (AFPs) from the Histatin family, like histatin-5. Besides that, our focus is to show how nanotechnology can allow the application of these peptides for treatment of this microorganism. In addition, our intention is to show the importance of nanoparticles (NPs) for this purpose, which may be essential in the near future.

Treatment of invasive fungal diseases in cancer patients-Revised 2019 Recommendations of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Oncology (DGHO)

BACKGROUND

Invasive fungal diseases remain a major cause of morbidity and mortality in cancer patients undergoing intensive cytotoxic therapy. The choice of the most appropriate antifungal treatment (AFT) depends on the fungal species suspected or identified, the patient's risk factors (eg length and depth of granulocytopenia) and the expected side effects.

OBJECTIVES

Since the last edition of recommendations for 'Treatment of invasive fungal infections in cancer patients' of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO) in 2013, treatment strategies were gradually moving away from solely empirical therapy of presumed or possible invasive fungal diseases (IFDs) towards pre-emptive therapy of probable IFD.

METHODS

The guideline was prepared by German clinical experts for infections in cancer patients in a stepwise consensus process. MEDLINE was systematically searched for English-language publications from January 1975 up to September 2019 using the key terms such as 'invasive fungal infection' and/or 'invasive fungal disease' and at least one of the following: antifungal agents, cancer, haematological malignancy, antifungal therapy, neutropenia, granulocytopenia, mycoses, aspergillosis, candidosis and mucormycosis.

RESULTS

AFT of IFDs in cancer patients may include not only antifungal agents but also non-pharmacologic treatment. In addition, the armamentarium of antifungals for treatment of IFDs has been broadened (eg licensing of isavuconazole). Additional antifungals are currently under investigation or in clinical trials.

CONCLUSIONS

Here, updated recommendations for the treatment of proven or probable IFDs are given. All recommendations including the levels of evidence are summarised in tables to give the reader rapid access to key information.

A Single-Center, Open-Label Trial of Isavuconazole Prophylaxis against Invasive Fungal Infection in Patients Undergoing Allogeneic Hematopoietic Cell Transplantation

Isavuconazole is a broad-spectrum triazole approved for treatment of invasive fungal infections (IFIs). In this open-label, single-arm study, we evaluated isavuconazole for antifungal prophylaxis after allogeneic hematopoietic cell transplantation (HCT). Adult patients admitted for first HCT received micafungin 150 mg i.v. daily from admission through day +7 (D+7) post-transplantation (±2 days) followed by isavuconazole prophylaxis (i.v./p.o. 372 mg every 8 hours for 6 doses and then 372 mg daily) through maximum D+98 post-HCT. Patients were followed through D+182. The primary endpoint was prophylaxis failure, defined as discontinuation of prophylaxis for proven/probable IFI; systemic antifungal therapy for >14 days for suspected IFI; toxicity leading to discontinuation; or an adverse event. Between June 2017 and October 2018, 99 patients were enrolled in the study, of whom 95 were included in our analysis. The median patient age was 57 years (interquartile range [IQR], 50 to 66 years). Sixty-four (67%) patients received peripheral blood, 17(18%) received bone marrow, and 14 (15%) received a cord blood allograft for acute leukemia (55%), lymphoma (17%), myelodysplastic syndrome (16%), or another hematologic disease (14%). One-third (n = 31; 33%) of patients underwent CD34⁺-selected HCT. Isavuconazole prophylaxis was given for a median of 90 days (IQR, 87 to 91 days). Ten patients (10.7%) met the primary endpoint. Candidemia occurred in 3 patients (3.1%), 1 of whom had grade III skin acute graft-versus-host disease (GVHD). Toxicity leading to discontinuation occurred in 7 patients (7.4%). The most common toxicity was liver function abnormalities in 5 patients, including grade 1 transaminitis in 2 patients and grade 3 hyperbilirubinemia in 3 patients. Four patients (4.2%) had early discontinuation of isavuconazole for reasons not meeting the primary study endpoint. Six patients died during the study period, including 3 during prophylaxis and 3 during follow-up. No deaths were attributed to isavuconazole. The majority (85%) of allogeneic HCT recipients completed isavuconazole prophylaxis according to protocol. The rate of breakthrough candidemia was 3.1%, and there were no invasive mold infections. Our data support the utility of isavuconazole for antifungal prophylaxis after HCT.

In vitro activity of four triazole antifungal drugs against clinically common and uncommon yeast species

Background and Purpose:

Incidence of fungal infections caused by opportunistic fungal pathogens, such as yeasts and yeast-like species, has undergone an increase in otherwise healthy individuals. These pathogens account for high mortality and show reduced susceptibility to the routine antifungal drugs. Accordingly, antifungal susceptibility testing is an urgent need in the determination of the susceptibility spectrum of antifungals and selection of appropriate antifungal agents for the management of patients with fungal infection.

Materials and Methods:

The present study was conducted on 110 yeast strains belonging to 15 species recovered from clinical specimens. Susceptibility of the isolates to four antifungal drugs (i.e., fluconazole, itraconazole, voriconazole, and posaconazole) was tested according to the Clinical and Laboratory Standards Institute guidelines M27-A3 and M27-S4.

Results:

Fluconazole exhibited no activity against 4.3% (n=2) of C. albicans isolates, whereas the remaining 44 isolates had a minimum inhibitory concentration (MIC) range of 0.125-4 μg/ml. Voriconazole had the lowest geometric mean MIC (0.03 µg/ml) against all isolated yeast species, followed by posaconazole (0.07 µg/ml), itraconazole (0.10 µg/ml), and fluconazole (0.60 µg/ml). Overall, all of the isolates had reduced voriconazole MICs with a MIC range of 0.016-0.5 μg/ml, except for one isolate of C. albicans that had a MIC of 1 μg/ml. Candida haemulonii as a multidrug-resistant fungus showed a fluconazole MIC of > 64 μg/ml.

Conclusion:

The current study provides insight into the antifungal susceptibility profiles of clinically common and uncommon yeast species to four triazole antifungal agents. According to our findings, voriconazole was the most active agent. Awareness about antifungal susceptibility patterns is highly helpful in the selection of appropriate antifungal drugs and identification of the efficiency of the currently used agents.

An alarming rise of non-albicans Candida species and uncommon yeasts in the clinical samples; a combination of various molecular techniques for identification of etiologic agents

OBJECTIVE

Yeasts are unicellular microorganisms may cause systemic infection in immunocompromised patients. The aim of this study was to identify yeast strains isolated from clinical specimens using molecular techniques.

RESULTS

A total of 202 yeast strains isolated from 341 clinical samples between February 2017 and May 2019. All clinical isolates were identified using phenotypic and molecular tests including PCR-RFLP, duplex-PCR, multiplex-PCR, and PCR-sequencing. The most yeast fungal isolates were obtained from urine (66.8%), nail (9.4%), skin lesion (7.9%), bronchoalveolar lavage (5.9%), and blood (3.9%). One hundred and twenty-one Candida species were identified as non-albicans versus 76 Candida albicans. Trichosporon asahii, and Pichia terricola were uncommon non-Candida yeasts isolated from urine samples. For the first time, we isolated P. terricola as etiological agent of urinary tract infection in a pregnant female. Since Candida species show different levels of resistance to antifungal agents, precise identification of clinical isolates is critical for better treatment of infection.

The role of Lactobacillus species in the control of Candida via biotrophic interactions

Microbial communities have an important role in health and disease. Candida spp. are ubiquitous commensals and sometimes opportunistic fungal pathogens of humans, colonizing mucosal surfaces of the genital, urinary, respiratory and gastrointestinal tracts and the oral cavity. They mainly cause local mucosal infections in immune competent individuals. However, in the case of an ineffective immune defense, Candida infections may become a serious threat. Lactobacillus spp. are part of the human microbiome and are natural competitors of Candida in the vaginal environment. Lactic acid, low pH and other secreted metabolites are environmental signals sensed by fungal species present in the microbiome. This review briefly discusses the ternary interaction between host, Lactobacillus species and Candida with regard to fungal infections and the potential antifungal and fungistatic effect of Lactobacillus species. Our understanding of these interactions is incomplete due to the variability of the involved species and isolates and the complexity of the human host.

Saprochaete clavata Invasive Infections - A New Threat to Hematological-Oncological Patients

Background

Saprochaete clavata (formerly Geotrichum clavatum, now proposed as Magnusiomyces clavatus) is a filamentous yeast-like fungus that has recently been described as an emerging pathogen mostly in patients with acute leukemia.

Methods

This is a retrospective study of patients diagnosed with proven and probable S. clavata infection at the University Hospital, Hradec Králové, Czechia between March 2005 and December 2017. Previous cases were identified from the literature and FungiScope^® database.

Results

Six new cases (5 females, 1 male) of blood-stream S. clavata infections at the hemato-oncological department were described including epidemiological data of additional 48 patients colonized with the species. Overall, 116 strains of S. clavata were isolated from different clinical specimens of 54 patients; most of them belonged to the respiratory tract (60.3%). S. clavata was the most frequent species among arthroconidial yeasts (Trichosporon, Galactomyces, Magnusiomyces) recovered from the blood. All our patients with S. clavata infection had profound neutropenia, a central venous catheter, broad-spectrum antibiotics and antifungal prophylaxis; four had a history of a biliary tract system disease. The diagnosis was based on a positive blood culture in all patients. Four patients died of multiorgan failure and sepsis despite treatment with lipid-based amphotericin B and/or voriconazole. From the literature and FungiScope database, 67 previous cases of S. clavata infections were evaluated in context of our cases.

Conclusion

Saprochaete clavata infection represents a life-threatening mycosis in severely immunocompromised patients. The successful outcome of treatment seems to be critically dependent on the early diagnosis and the recovery of underlying conditions associated with immune dysfunction or deficiency.

Isavuconazole and voriconazole inhibition of sterol 14α-demethylases (CYP51) from Aspergillus fumigatus and Homo sapiens

Here we report the first evaluation of isavuconazole inhibition of Aspergillus fumigatus CYP51 and thus sterol biosynthesis in the fungus. Voriconazole and isavuconazole both bound tightly to recombinant A. fumigatus CYP51 isoenzymes A and B (AfCYP51A and AfCYP51B) isolated in Escherichia coli membranes. CYP51 reconstitution assays confirmed that AfCYP51A and AfCYP51B as well as three AfCYP51A mutants known to confer azole resistance (G54W, L98H and M220K) were strongly inhibited by both triazoles. Voriconazole bound relatively weakly to purified Homo sapiens CYP51 (HsCYP51), unlike isavuconazole that bound tightly. However, isavuconazole was a relatively poor inhibitor of HsCYP51 activity, with an IC₅₀ value (half-maximal inhibitory concentration) of 25 µM, which was 55- to 120-fold greater than those observed for the A. fumigatus CYP51 enzymes, albeit not as poor an inhibitor of HsCYP51 as voriconazole with an IC₅₀ value of 112 µM. Sterol analysis of triazole-treated A. fumigatus Af293 cells confirmed that isavuconazole and voriconazole both inhibited cellular CYP51 activity with the accumulation of 14-methylated sterol substrates and depletion of ergosterol levels. Isavuconazole elicited a stronger perturbation of the sterol composition in A. fumigatus Af293 than voriconazole at 0.0125 µg/mL, indicating increased potency. However, complementation studies in Saccharomyces cerevisiae using strains containing AfCYP51A and AfCYP51B showed isavuconazole to be equally as effective at inhibiting CYP51 activity as voriconazole. These in vitro studies suggest that isavuconazole is an effective alternative to voriconazole as an antifungal agent against the target CYP51 in A. fumigatus.

Comparison of fks gene mutations and minimum inhibitory concentrations for the detection of Candida glabrata resistance to micafungin: A systematic review and meta-analysis

Candida resistance to antifungals impaired invasive candidiasis outcome. In a context of echinocandin resistance development, we aimed to evaluate the association between phenotypic resistance to micafungin and fks mutations of Candida glabrata. For this systematic review and meta-analysis, we searched MEDLINE, Scopus and Web of Science for reports published up to December 2017. Studies of C glabrata candidiasis with minimum inhibitory concentrations (MIC) determination of micafungin and fks genotyping were included. Reviews, studies not using reference methods, non-glabrata Candida, experimental isolates and undetailed mutations were excluded. Two authors independently assessed the eligibility of articles and extracted data. The main outcome was the diagnostic accuracy of fks mutations compared to micafungin MIC for C glabrata, measured as fixed-effect odd ratio. Heterogeneity was calculated with the I² statistic. This study is registered with PROSPERO (CRD42018082023). Twenty-four studies were included in the meta-analysis. Pooled analysis found that S663P (OR 7.25, 95% CI 3.50-15.00; P < 0.00001), S629P (OR 3.70, 1.64-8.33; P = 0.002) and F659del (OR 5.66, 1.22-26.18; P = 0.03) were associated with increased risk of having a resistant isolate according to authors' interpretation of MICs. In sensitivity analysis based on new CLSI clinical breakpoints, the ORs for S663P and S629P remained significant. Genotyping of isolates of C glabrata for S663P and S629P mutations is an effective alternative to micafungin susceptibility tests. Relevant molecular markers of drug resistance will significantly improve the management of C glabrata infections.

K21 Compound, a Potent Antifungal Agent: Implications for the Treatment of Fluconazole-Resistant HIV-Associated Candida Species

Background/Objectives: With mucocutaneous candidiasis being highly prevalent in HIV patients, the emergence of fluconazole-resistant Candida species forms a major challenge in treating and eradicating these infections. The objective of this study was to establish the antifungal activity of K21, a membrane-rupturing antimicrobial compound derived from a silica quaternary ammonium compound (SiQAC) with tetraethoxysilane (TEOS). Methods: The study sample included 81 Candida species of which 9 were type strains and 72 were clinical isolates. Minimum inhibitory concentrations, synergy, fractional inhibitory concentration index (FICI), and time kill assays were determined by broth microdilution. Electron microscopy (EM) was used to determine the qualitative changes brought about after treatment with K21. Results: K21 inhibited the growth of all fluconazole-resistant and susceptible Candida strains with only 2 h of exposure required to effectively kill 99.9% of the inoculum, and a definite synergistic effect was observed with a combination of K21 and fluconazole. EM demonstrated the presence of two forms of extracellular vesicles indicative of biofilm formation and cell lysis. Conclusion: The study established the efficacy of K21 as an antifungal agent and with fluconazole-resistant candidiasis on the increase, the development of K21 can provide a promising alternative to combat acquired drug resistance.

Drugs in Clinical Development for Fungal Infections

Despite increasing rates of invasive fungal infections being reported globally, only a single antifungal drug has been approved during the last decade. Resistance, toxicity, drug interactions and restricted routes of administration remain unresolved issues. This review focuses on new antifungal compounds which are currently in various clinical phases of development. We discuss two azoles with a tetrazole moiety that allows selective activity against the fungal CYP: VT-1161 for Candida infections and VT-1129 for cryptococcal meningoencephalitis. We also discuss two glucan synthesis inhibitors: CD101, an echinocandin with an increased half-life, and SCY-078 with oral bioavailability and increased activity against echinocandin-resistant isolates. Among the polyenes, we discuss MAT023, an encochleated amphotericin B formulation that allows oral administration. Two novel classes of antifungal drugs are also described: glycosylphosphatidylinositol inhibitors, and the leading drug APX001, which disrupt the integrity of the fungal wall; and the orotomides, inhibitors of pyrimidine synthesis with the leading drug F901318. Finally, a chitin synthesis inhibitor and progress on human monoclonal antifungal antibodies are discussed.

Antimicrobial Resistance Surveillance and New Drug Development

Surveillance represents an important informational tool for planning actions to monitor emerging antimicrobial resistance. Antimicrobial resistance surveillance (ARS) programs may have many different designs and can be grouped in 2 major categories based on their main objectives: (1) public health ARS programs and (2) industry-sponsored/product-oriented ARS programs. In general, public health ARS programs predominantly focus on health care and infection control, whereas industry ARS programs focus on an investigational or recently approved molecule(s). We reviewed the main characteristics of industry ARS programs and how these programs contribute to new drug development. Industry ARS programs are generally performed to comply with requirements from regulatory agencies responsible for commercial approval of antimicrobial agents, such as the US Food and Drug Administration, European Medicines Agency, and others. In contrast to public health ARS programs, which typically collect health care and diverse clinical data, industry ARS programs frequently collect the pathogens and perform the testing in a central laboratory setting. Global ARS programs with centralized testing play an important role in new antibacterial and antifungal drug development by providing information on the emergence and dissemination of resistant organisms, clones, and resistance determinants. Organisms collected by large ARS programs are extremely valuable to evaluate the potential of new agents and to calibrate susceptibility tests once a drug is approved for clinical use. These programs also can provide early evaluations of spectrum of activity and postmarketing trends required by regulatory agencies, and the programs may help drug companies to select appropriate dosing regimens and the appropriate geographic regions in which to perform clinical trials. Furthermore, these surveillance programs provide useful information on the potency and spectrum of new antimicrobial agents against indications and organisms in which clinicians have little or no experience. In summary, large ARS programs, such as the SENTRY Antimicrobial Surveillance Program, contribute key data for new drug development.

Twenty Years of the SENTRY Antifungal Surveillance Program: Results for Candida Species From 1997-2016

Background

The emergence of antifungal resistance threatens effective treatment of invasive fungal infection (IFI). Invasive candidiasis is the most common health care–associated IFI. We evaluated the activity of fluconazole (FLU) against 20 788 invasive isolates of Candida (37 species) collected from 135 medical centers in 39 countries (1997–2016). The activity of anidulafungin, caspofungin, and micafungin (MCF) was evaluated against 15 308 isolates worldwide (2006–2016).

Methods

Species identification was accomplished using phenotypic (1997–2001), genotypic, and proteomic methods (2006–2016). All isolates were tested using reference methods and clinical breakpoints published in the Clinical and Laboratory Standards Institute documents.

Results

A decrease in the isolation of Candida albicans and an increase in the isolation of Candida glabrata and Candida parapsilosis were observed over time. Candida glabrata was the most common non–C. albicans species detected in all geographic regions except for Latin America, where C. parapsilosis and Candida tropicalis were more common. Six Candida auris isolates were detected: 1 each in 2009, 2013, 2014, and 2015 and 2 in 2016; all were from nosocomial bloodstream infections and were FLU-resistant (R). The highest rates of FLU-R isolates were seen in C. glabrata from North America (NA; 10.6%) and in C. tropicalis from the Asia-Pacific region (9.2%). A steady increase in isolation of C. glabrata and resistance to FLU was detected over 20 years in the United States. Echinocandin-R (EC-R) ranged from 3.5% for C. glabrata to 0.1% for C. albicans and C. parapsilosis. Resistance to MCF was highest among C. glabrata (2.8%) and C. tropicalis (1.3%) from NA. Mutations on FKS hot spot (HS) regions were detected among 70 EC-R isolates (51/70 were C. glabrata). Most isolates harboring FKS HS mutations were resistant to 2 or more ECs.

Conclusions

EC-R and FLU-R remain uncommon among contemporary Candida isolates; however, a slow and steady emergence of resistance to both antifungal classes was observed in C. glabrata and C. tropicalis isolates.

Detection of ERG11 point mutations in Iranian fluconazole-resistant Candida albicans isolates

Background and Purpose

Candidiasis is referred to a group of superficial and deep-tissue fungal infections often caused by Candida albicans. The superficial infections affect the oral, oropharynx, esophagus, and vaginal mucosa. The treatment of choice for these infections is the use of azoles, such as fluconazole. However, the increased use of these antifungal agents has led to the emergence of azole-resistant isolates of C. albicans. Different mechanisms have been suggested for the development of drug resistance, such as mutations in the encoding gene ERG11. Mutations in ERG11 result in changes in the ERG11p spatial construction and reduce the affinity between the protein and azole. This study aimed to determine the susceptibility profile of C. albicans clinical isolates to fluconazole using microdilution method. The present research was also targeted toward the detection of mutations that might be related to fluconazole resistance by the amplification and sequencing of ERG11 gene.

Materials and Methods

This study was conducted on a total of 216 clinical isolates obtained from Mashhad, Isfahan, and Tehran cities in Iran, during 2016-2018. The clinical isolates were identified using molecular techniques. Furthermore, minimum inhibitory concentration (MICs) was determined according to the clinical and laboratory standards institute M27-A3 and M27-S4 documents. The concentration range for fluconazole was obtained as 0.063-64 μg/ml. In the resistant strains, ERG11 genes were amplified by specific primers. Subsequently, cycle sequencing reactions were performed on purified polymerase chain reaction (PCR) products in forward and reverse directions. Finally, the results were analyzed by MEGA (version 7) and Gene Runner software (version 6.5.30).

Results

Out of 216 strains, 100 (46.3%) species were identified as C. albicans. The MIC values for fluconazole had a range of 0.125-16 μg/ml with the MIC50 and MIC90 values of 0.5 and 1 μg/ml, respectively. Totally, 41 nucleotide changes were detected among 4 resistant isolates. In this regard, 4 out of 41 mutations in codons caused changes in ERG11p; however, these mutations did not lead to fluconazole resistance.

Conclusion

Fluconazole resistance among clinical isolates is not merely due to the changes in ERG11p. This resistance may be also related to some other mechanisms, such as the prevention of the intracellular accumulation of the antifungal agent and alteration of the target enzyme to diminish drug binding.

2-Acryloyl-4,5-methylenedioxyphenol: A Small Molecule Endowed with Antidermatophytic Activity

Background:

Superficial fungal infections are the most common fungal diseases in humans, affecting more than 25% of the population worldwide.

Methods:

In the present study, we have investigated the activity of kakuol, a natural compound isolated from the rhizomes of Asarum sieboldii, and some analogues, against various dermatophytes and pharmacologically relevant yeasts.

Results:

One of the tested compounds, 2-acryloyl-4,5-methylenedioxyphenol, showed a broadspectrum activity against most of the fungal species assayed, resulting particularly effective against dermatophyte strains (MIC values in the range of 0.25-0.5 &#181;g/mL, two/four-fold lower than the positive control miconazole).

Conclusion:

The results suggest that this molecule can be considered a promising starting point for the development of new antifungal compounds.

Candida parapsilosis: from Genes to the Bedside

Patients with suppressed immunity are at the highest risk for hospital-acquired infections. Among these, invasive candidiasis is the most prevalent systemic fungal nosocomial infection. Over recent decades, the combined prevalence of non-albicans Candida species outranked Candida albicans infections in several geographical regions worldwide, highlighting the need to understand their pathobiology in order to develop effective treatment and to prevent future outbreaks. Candida parapsilosis is the second or third most frequently isolated Candida species from patients. Besides being highly prevalent, its biology differs markedly from that of C. albicans, which may be associated with C. parapsilosis' increased incidence. Differences in virulence, regulatory and antifungal drug resistance mechanisms, and the patient groups at risk indicate that conclusions drawn from C. albicans pathobiology cannot be simply extrapolated to C. parapsilosis Such species-specific characteristics may also influence their recognition and elimination by the host and the efficacy of antifungal drugs. Due to the availability of high-throughput, state-of-the-art experimental tools and molecular genetic methods adapted to C. parapsilosis, genome and transcriptome studies are now available that greatly contribute to our understanding of what makes this species a threat. In this review, we summarize 10 years of findings on C. parapsilosis pathogenesis, including the species' genetic properties, transcriptome studies, host responses, and molecular mechanisms of virulence. Antifungal susceptibility studies and clinician perspectives are discussed. We also present regional incidence reports in order to provide an updated worldwide epidemiology summary.

Structure-based design of δ-lactones for new antifungal drug development: susceptibility, mechanism of action, and toxicity

Dermatophytes are the etiological agents of cutaneous mycoses, including the prevalent nail infections and athlete's foot. Candida spp. are opportunistic and emerging pathogens, causing superficial to deeper infections related to high mortality rates. As a consequence of prolonged application of antifungal drugs, the treatment failures combined with multidrug-resistance have become a serious problem in clinical practice. Therefore, novel alternative antifungals are required urgently. δ-Lactones have attracted great interest owing to their wide range of biological activity. This article describes the antifungal activity of synthetic δ-lactones against yeasts of the genus Candida spp. and dermatophytes (through the broth microdilution method), discusses the pathways by which the compounds exert this action (toward the fungal cell wall and/or membrane), and evaluates the toxicity to human leukocytes and chorioallantoic membrane (by the hen's egg test-chorioallantoic membrane). Two of the compounds in the series presented broader spectrum of antifungal activity, including against resistant fungal species. The mechanism of action was related to damage in the fungal cell wall and membrane, with specific target action dependent on the type of substituent present in the δ-lactone structure. The damage in the fungal cell was corroborated by electron microscopy images, which evidenced lysed and completely altered cells after in vitro treatment with δ-lactones. Toxicity was dose dependent for the viability of human leukocytes, but none of the compounds was mutagenic, genotoxic, or membrane irritant when evaluated at higher concentrations than MIC. In this way, δ-lactones constitute a class with excellent perspectives regarding their potential applications as antifungals.

[Current therapeutic options in invasive mycosis and potential therapeutic role of isavuconazole]

The treatment of invasive fungal infections has deeply evolved in recent years with the inclusion of new antifungals to the therapeutic treatment arsenal. A new azole, isavuconazole, has been recently approved. This review focuses on the role of isavuconazole for treating the most important invasive fungal infections: invasive candidiasis, aspergillosis, mucormicosis, infections caused by other filamentous fungi and those caused by dimorphic fungi.

Isavuconazole for treatment of rare invasive fungal diseases

Data regarding treatment of rare invasive fungal diseases (IFDs) are scarce. We documented the efficacy and safety of isavuconazole for treatment of uncommonly diagnosed IFDs. VITAL was a single-arm, international, open-label study evaluating the efficacy and safety of isavuconazole (200 mg orally or intravenously every 8 hours for 48 hours, then once daily). The primary outcome was overall response at Day 42; key secondary outcomes were overall responses at Day 84 and end of treatment (EOT), mortality at Days 42 and 84, and safety. This analysis includes patients with IFD caused by rare or unidentified pathogens. Twenty-six patients with IFDs caused by rare moulds (n = 17), non-Candida yeasts (n = 2), or unidentified moulds (n = 7) were enrolled (median treatment duration [range], 114.5 [1-496]) days. Overall treatment success was observed in 11/26 (42.3%), 10/26 (38.5%), and 15/26 (57.7%) patients at Days 42, 84, and EOT, respectively. All-cause mortality rates were 2/26 patients (7.7%) at Day 42 and 4/26 patients (15.4%) at Day 84; another two patients died after Day 84. All patients had ≥1 treatment-emergent adverse event (TEAE); 15 patients (57.7%) had serious TEAEs, and TEAEs led to discontinuation of isavuconazole in four patients (15.4%). Isavuconazole may be efficacious for treatment of a range of rare IFDs.

Advances in the Treatment of Mycoses in Pediatric Patients

The main indications for antifungal drug administration in pediatrics are reviewed as well as an update of the data of antifungal agents and antifungal policies performed. Specifically, antifungal therapy in three main areas is updated as follows: a) Prophylaxis of premature neonates against invasive candidiasis; b) management of candidemia and meningoencephalitis in neonates; and c) prophylaxis, empiric therapy, and targeted antifungal therapy in children with primary or secondary immunodeficiencies. Fluconazole remains the most frequent antifungal prophylactic agent given to high-risk neonates and children. However, the emergence of fluconazole resistance, particularly in non-albicans Candida species, should be considered during preventive or empiric therapy. In very-low birth-weight neonates, although fluconazole is used as antifungal prophylaxis in neonatal intensive care units (NICU's) with relatively high incidence of invasive candidiasis (IC), its role is under continuous debate. Amphotericin B, primarily in its liposomal formulation, remains the mainstay of therapy for treating neonatal and pediatric yeast and mold infections. Voriconazole is indicated for mold infections except for mucormycosis in children >2 years. Newer triazoles-such as posaconazole and isavuconazole-as well as echinocandins, are either licensed or under study for first-line or salvage therapy, whereas combination therapy is kept for refractory cases.

In Vitro Activity of Isavuconazole against Opportunistic Fungal Pathogens from Two Mycology Reference Laboratories

Monitoring antifungal susceptibility patterns for new and established antifungal agents seems prudent given the increasing prevalence of uncommon species associated with higher antifungal resistance. We evaluated the activity of isavuconazole against 4,856 invasive yeasts and molds collected worldwide. The 4,856 clinical fungal isolates, including 2,351 Candida species isolates, 97 non-Candida yeasts, 1,972 Aspergillus species isolates, and 361 non-Aspergillus molds, including 292 Mucorales isolates collected in 2015 to 2016, were tested using CLSI methods. The MIC values for isavuconazole versus Aspergillus ranged from 0.06 to ≥16 μg/ml. The modal MIC for isavuconazole was 0.5 μg/ml (range, 0.25 [A. nidulans and A. terreus species complex] to 4 μg/ml [A. calidoustus and A. tubingensis]). Eight A. fumigatus isolates had elevated isavuconazole MIC values at ≥8 μg/ml (non-wild type). Isavuconazole showed comparable activity to itraconazole against the Mucorales The lowest modal isavuconazole MIC values were seen for Rhizopus spp., R. arrhizus var. arrhizus, and R. microsporus (all 1 μg/ml). Candida species isolates were inhibited by ≤0.25 μg/ml of isavuconazole (range, 96.1% [C. lusitaniae] to 100.0% [C. albicans, C. dubliniensis, C. kefyr, and C. orthopsilosis]). MIC values were ≤1 μg/ml for 95.5% of C. glabrata isolates and 100.0% of C. krusei isolates. Isavuconazole was active against the non-Candida yeasts, including Cryptococcus neoformans (100.0% at ≤0.5 μg/ml). Isavuconazole exhibited excellent activity against most species of Candida and Aspergillus Isavuconazole was comparable to posaconazole and voriconazole against the less common yeasts and molds. Isavuconazole was generally less active than posaconazole and more active than voriconazole against the 292 Mucorales isolates. We confirm the potentially useful activity of isavuconazole against species of Rhizopus as determined by CLSI methods.

Evolutionary Emergence of Drug Resistance in Candida Opportunistic Pathogens

Fungal infections, such as candidiasis caused by Candida, pose a problem of growing medical concern. In developed countries, the incidence of Candida infections is increasing due to the higher survival of susceptible populations, such as immunocompromised patients or the elderly. Existing treatment options are limited to few antifungal drug families with efficacies that vary depending on the infecting species. In this context, the emergence and spread of resistant Candida isolates are being increasingly reported. Understanding how resistance can evolve within naturally susceptible species is key to developing novel, more effective treatment strategies. However, in contrast to the situation of antibiotic resistance in bacteria, few studies have focused on the evolutionary mechanisms leading to drug resistance in fungal species. In this review, we will survey and discuss current knowledge on the genetic bases of resistance to antifungal drugs in Candida opportunistic pathogens. We will do so from an evolutionary genomics perspective, focusing on the possible evolutionary paths that may lead to the emergence and selection of the resistant phenotype. Finally, we will discuss the potential of future studies enabled by current developments in sequencing technologies, in vitro evolution approaches, and the analysis of serial clinical isolates.

Moonlighting proteins induce protection in a mouse model against Candida species

In recent years, C. albicans and C. glabrata have been identified as the main cause of candidemia and invasive candidiasis in hospitalized and immunocompromised patients. In order to colonize the human host, these fungi express several virulence factors such as the response to oxidative stress and the formation of biofilms. In the expression of these virulence factors, the cell wall of C. albicans and C. glabrata is of fundamental importance. As the outermost structure of the yeast, the cell wall is the first to come in contact with the reactive oxygen species (ROS) generated during the respiratory outbreak, and in the formation of biofilms, it is the first to adhere to organs or medical devices implanted in the human host. In both processes, several cell wall proteins (CWP) are required, since they promote attachment to human cells or abiotic surfaces, as well as to detoxify ROS. In our working group we have identified moonlighting CWP in response to oxidative stress as well as in the formation of biofilms. Having identified moonlighting CWP in Candida species in response to two virulence factors indicates that these proteins may possibly be immunodominant. The aim of the present work was to evaluate whether proteins of this type such as fructose-bisphosphate aldolase (Fba1), phosphoglycerate kinase (Pgk) and pyruvate kinase (Pk), could confer protection in a mouse model against C. albicans and C. glabrata. For this, recombinant proteins His₆-Fba1, His₆-Pgk and His₆-Pk were constructed and used to immunize several groups of mice. The immunized mice were infected with C. albicans or C. glabrata, and subsequently the liver, spleen and kidney were extracted and the number of CFU was determined. Our results showed that Pk confers immunity to mice against C. albicans, while Fba1 to C. glabrata. This data allows us to conclude that the moonlighting CWP, Fba1 and Pk confer in vivo protection in a specific way against each species of Candida. This makes them promising candidates for developing specific vaccines against these pathogens.