Nosocomial fungal infections: epidemiology, infection control, and prevention

Outbreaks of Fungal Infections in Hospitals: Epidemiology, Detection, and Management

Nosocomial clusters of fungal infections, whilst uncommon, cannot be predicted and are associated with significant morbidity and mortality. Here, we review reports of nosocomial outbreaks of invasive fungal disease to glean insight into their epidemiology, risks for infection, methods employed in outbreak detection including genomic testing to confirm the outbreak, and approaches to clinical and infection control management. Both yeasts and filamentous fungi cause outbreaks, with each having general and specific risks. The early detection and confirmation of the outbreak are essential for diagnosis, treatment of affected patients, and termination of the outbreak. Environmental sampling, including the air in mould outbreaks, for the pathogen may be indicated. The genetic analysis of epidemiologically linked isolates is strongly recommended through a sufficiently discriminatory approach such as whole genome sequencing or a method that is acceptably discriminatory for that pathogen. An analysis of both linked isolates and epidemiologically unrelated strains is required to enable genetic similarity comparisons. The management of the outbreak encompasses input from a multi-disciplinary team with epidemiological investigation and infection control measures, including screening for additional cases, patient cohorting, and strict hygiene and cleaning procedures. Automated methods for fungal infection surveillance would greatly aid earlier outbreak detection and should be a focus of research.

Identification and evaluation of thermotolerance of yeasts from milk in natura exposed to high temperature and slow and fast pasteurization

Milk is considered one of the basic raw materials of animal origin; it must present hygienic quality and physical-chemical properties suitable for processing and human consumption. Thus, the ingestion of milk in natura when not properly treated can be characterized as an opportunistic route of transmission of possible microbial pathogens, which can offer risks to public health. The present study aimed the yeast identification, to analyze the thermo-resistance of yeasts isolated from fresh milk, and to trace the susceptibility profile of the isolates to antifungal agents. For this, 23 samples of fresh milk type B, collected by manual or mechanical milking, were stored in collective refrigeration tanks of farms located in the Metropolitan Region of Natal and nearby, State of Rio Grande do Norte (RN), Brazil. Twenty samples of fresh milk commercially traded in the city of Ceará-Mirim RN were also analyzed. The yeasts were quantified by count of colony-forming units (CFU). All isolated species were treated by slow pasteurization (62-64 °C for 30 min) and fast (72-75 °C for 20 s), as well as by boiling (100 °C). Fifty yeast strains were obtained, and the species were identified as Candida tropicalis (28%), Candida parapsilosis (14%), Candida albicans (12%), Candida glabrata (10%), Candida krusei (10%), Kluyveromyces marxianus (10%), Candida guilliermondii (8%), Candida rugosa (2%), Candida orthopsilosis (2%), Pichia manshurica (2%), and Kodamaea ohmeri (2%). Five isolates showed resistance to the antifungal agents tested. Among all the isolates submitted to heat treatment, 80% were resistant to fast pasteurization and 60% to boiling, but none of them resisted the slow pasteurization. The milk collected through mechanical milking and stored in collective cooling tanks, presented higher rates of yeast contamination, compared to milk samples collected by manual milking and kept under the same storage conditions.

Identification and Elimination of Antifungal Tolerance in Candida auris

Antimicrobial resistance is a global health crisis to which pathogenic fungi make a substantial contribution. The human fungal pathogen C. auris is of particular concern due to its rapid spread across the world and its evolution of multidrug resistance. Fluconazole failure in C. auris has been recently attributed to antifungal “tolerance”. Tolerance is a phenomenon whereby a slow-growing subpopulation of tolerant cells, which are genetically identical to susceptible cells, emerges during drug treatment. We use microbroth dilution and disk diffusion assays, together with image analysis, to investigate antifungal tolerance in C. auris to all three classes of antifungal drugs used to treat invasive candidiasis. We find that (1) C. auris is tolerant to several common fungistatic and fungicidal drugs, which in some cases can be detected after 24 h, as well as after 48 h, of antifungal drug exposure; (2) the tolerant phenotype reverts to the susceptible phenotype in C. auris; and (3) combining azole, polyene, and echinocandin antifungal drugs with the adjuvant chloroquine in some cases reduces or eliminates tolerance and resistance in patient-derived C. auris isolates. These results suggest that tolerance contributes to treatment failure in C. auris infections for a broad range of antifungal drugs, and that antifungal adjuvants may improve treatment outcomes for patients infected with antifungal-tolerant or antifungal-resistant fungal pathogens.

Magnesium impairs Candida albicans immune evasion by reduced hyphal damage, enhanced β-glucan exposure and altered vacuole homeostasis

With a limited arsenal of available antifungal drugs and drug-resistance emergence, strategies that seek to reduce Candida immune evasion and virulence could be a promising alternative option. Harnessing metal homeostasis against C. albicans has gained wide prominence nowadays as a feasible antifungal strategy. Herein, the effect of magnesium (Mg) deprivation on the immune evasion mechanisms of C. albicans is demonstrated. We studied host pathogen interaction by using the THP-1 cell line model and explored the avenue that macrophage-mediated killing was enhanced under Mg deprivation, leading to altered cytokine (TNFα, IL-6 and IL10) production and reduced pyroptosis. Insights into the mechanisms revealed that hyphal damage inside the macrophage was diminished under Mg deprivation. Additionally, Mg deprivation led to cell wall remodelling; leading to enhanced β-1,3-glucan exposure, crucial for immune recognition, along with concomitant alterations in chitin and mannan levels. Furthermore, vacuole homeostasis was disrupted under Mg deprivation, as revealed by abrogated morphology and defective acidification of the vacuole lumen. Together, we demonstrated that Mg deprivation affected immune evasion mechanisms by: reduced hyphal damage, enhanced β-1,3-glucan exposure and altered vacuole functioning. The study establishes that Mg availability is indispensable for successful C. albicans immune evasion and specific Mg dependent pathways could be targeted for therapy.

Evaluation of bio-aerosols type, density, and modeling of dispersion in inside and outside of different wards of educational hospital

Exposure to bioaerosols in the air of hospitals is associated with a wide range of adverse health effects due to the presence of airborne microorganisms. Intensity and type of health effects depend on many factors such as the type, density, and diversity of bioaerosols in hospital environments. Therefore, identifying and determining their distribution in hospital environment contribute to reduce their adverse effects and maintain the physical health of patients and staff, as well as find the source of infections and possible allergies due to the presence of bioaerosols. Therefore, the present study was conducted to determine the type and concentration of the bacterial and fungal bioaerosols, and their distribution in the indoor and outdoor air of a teaching hospital to establish a reference for future studies or measures. The air samples were collected with a one-stage Anderson sampler and particle mass counter for a period of four months in the fall and winter of 2019. In total, 262 bacterial and fungal samples were collected from the air of the wards of Tohid Hospital, Sanandaj, Iran. Antibiotic resistance test, bacterial identification by PCR method, and modeling the dispersion of concentrations of bio-aerosols were also conducted. In order to identify bacteria and fungi, some biochemical and molecular tests and microscopic and macroscopic characteristic methods were applied, respectively. The results showed that the highest and lowest densities of the bioaerosols were observed in lung and operating wards (336.67 and 15.25 CFU/m3). Moreover, the highest and least concentrations of particles were seen in the emergency and operating wards, respectively. The most common fungi isolated from the hospital air were Penicillium (24.7%), Cladosporium (23. 4%), Aspergillus niger (13.3%), and Aspergillus Flavus (11.4%). Furthermore, the highest concentration of the isolated bacterium was Staphylococcus hemolyticus (31.84%). Most bacteria showed the highest resistance to gentamicin. The overall average hospital air pollution to bioaerosols was slightly higher than the standards proposed by international organizations. Due to the high concentration of bioaerosols and particles in the studied hospital, providing suitable conditions such as temperature, humidity, proper ventilation, and intelligent air conditioning system using efficient ventilation systems, and restricting the entrance of wards can reduce airborne particles in hospital environment.

Evaluation of a stewardship program of antifungal use at a Brazilian tertiary care hospital

Introduction

Stewardship programs have been developed to optimize the use of antibiotics, but programs focusing on antifungal agents are less frequent.

Objective

To evaluate the quality of antifungal prescriptions in a tertiary care hospital, and to test if a simple educational activity could improve the quality of prescriptions.

Methods

The study comprised three phases: 1) Retrospective audit of all antifungal prescriptions in a 6-month period, applying a score based on six parameters: indication, drug, dosage, route of administration, microbiologic adequacy after results of cultures, switching to an oral agent, and duration of treatment; 2) Creation of text boxes in the electronic medical records with information about antifungal agents, shown during prescription; 3) Retrospective audit of all antifungal prescriptions in a 6-month period, applying the same 6-parameters score, and comparison between the two periods.

Results

Among 333 prescriptions, fluconazole was the most frequently (80.5%) prescribed agent. Hematology (26.7%), Infectious Diseases Department (22.8%), Internal Medicine (15.9%) and Intensive Care Unit (14.4%) were the units with most antifungal prescriptions. The median score for the 333 prescriptions was 8.0 (range 0 – 10), and 72.7% of prescriptions were considered inappropriate. The median and mean scores in the first and second audit were 8.0 and 6.9, and 8.0 and 7.9, respectively (p<0.001). All items that comprised the score improved from the first to the second audit. Likewise, there was a reduction of inappropriate prescriptions (80.2% in the first audit vs. 64.6% in the second audit, p=0.001).

Conclusions

A large proportion of inappropriate prescriptions was observed, which improved with the implementation of simple educational activities.

Functionalized niosomes as a smart delivery device in cancer and fungal infection

Various diseases remain untreated due to lack of suitable therapeutic moiety or a suitable drug delivery device, especially where toxicities and side effects are the primary reason for concern. Cancer and fungal infections are diseases where treatment schedules are not completed due to severe side effects or lengthy treatment protocols. Advanced treatment approaches such as active targeting and inhibition of angiogenesis may be preferred method for the treatment for malignancy over the conventional method. Niosomes may be a better alternative drug delivery carrier for various therapeutic moieties (either hydrophilic or hydrophobic) and also due to ease of surface modification, non-immunogenicity and economical. Active targeting approach may be done by targeting the receptors through coupling of suitable ligand on niosomal surface. Moreover, various receptors (CD44, folate, epidermal growth factor receptor (EGFR) & Vascular growth factor receptor (VGFR)) expressed by malignant cells have also been reviewed. The preparation of suitable niosomal formulation also requires considerable attention, and its formulation depends upon various factors such as selection of non-ionic surfactant, method of fabrication, and fabrication parameters. A combination therapy (dual drug and immunotherapy) has been proposed for the treatment of fungal infection with special consideration for surface modification with suitable ligand on niosomal surface to sensitize the receptors (C-type lectin receptors, Toll-like receptors & Nucleotide-binding oligomerization domain-like receptors) present on immune cells involved in fungal immunity. Certain gene silencing concept has also been discussed as an advanced alternative treatment for cancer by silencing the mRNA at molecular level using short interfering RNA (si-RNA).

Cationic Polymeric Nanoparticles for Improved Ocular Delivery and Antimycotic Activity of Terconazole

Terconazole (TCZ) is a broad-spectrum antifungal triazole that is particularly active against Candida species, but its poor water solubility hinders its ocular absorption and restricts its application. This study aims to fabricate TCZ-loaded cationic polymeric nanoparticles to enhance the ocular delivery and antimycotic activity of terconazole. TCZ-loaded nanoparticles were developed by nanoprecipitation method employing Eudragit RLPO®. They were characterized by entrapment efficiency (EE%), particle size (PS), zeta potential (ZP), morphology, Fourier transform infrared spectroscopy (FT-IR), and X-ray powder diffraction (XRPD). In-vitro antimycotic activity was evaluated by measuring zone of inhibition (ZI), minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). The developed nanoparticles were spherical with moderate to high EE% (44.03-71.14%), a nanometric PS (49.41-78.72 nm), and a positively charged ZP (≥ +21.47). In-vitro release studies revealed sustained release of drug up to 24 h. FT-IR of TCZ-loaded nanoparticles revealed distinctive peaks for Eudragit RLPO® and Poloxamer-188, with disappearance of the TCZ characteristic peaks. XRPD revealed the amorphous state of TCZ within the polymer matrix. Mucoadhesive studies proved the mucoadhesive property of the developed TCZ nanoparticles. In-vitro antimycotic studies, assessed by ZI, MIC and MFC, revealed enhanced antimycotic activity of TCZ-loaded nanoparticles against Candida albicans, relative to plain TCZ. No irritation or abnormal changes to the rabbits' eyes for plain and medicated polymeric nanoparticles were found by the in-vivo Draize test. These findings reveal that the cationic polymeric nanoparticles can be regarded as a potential drug delivery system for enhancing the ocular antimycotic activity of TCZ.

Secondary Infections After Diagnosis of Severe Radiation Pneumonitis (SRP) Among Patients With Non-small Cell Lung Cancer: Pathogen Distributions, Choice of Empirical Antibiotics, and the Value of Empirical Antifungal Treatment

PURPOSE

This study aimed to assess pathogen distributions and antimicrobial sensitivity characteristics in patients with non-small cell lung cancer (NSCLC) with severe radiation pneumonitis (SRP) and secondary infections.

METHODS AND MATERIALS

Data from 1746 patients with NSCLC and SRP after thoracic radiation therapy from January 2009 to December 2020 were retrospectively analyzed. Pneumonia incidence, causative pathogens, and antibiotic resistance characteristics in patients with secondary lung infections were analyzed. Risk factors associated with mortality were identified through univariate and multivariate analyses. Antifungal drug efficacy and duration-related effects were assessed with Forest plots and receiver operating characteristic curves.

RESULTS

Overall, 44.5% of patients with NSCLC and SRP (777 of 1746 patients) were diagnosed with secondary lung infections. In total, 899 bacterial strains were isolated from these patients, with Acinetobacter baumannii (n = 206; 27%), Klebsiella pneumonia (n = 200; 26.2%), and Pseudomonas aeruginosa (n = 104; 13.6%) being the most common. Carbapenems and cefoperazone-sulbactam resistance rates of 52.7% and 32.2%, 28.8% and 26.4%, and 23.7% and 20.2% were observed for these isolates, respectively. Infection-related deaths occurred in 22.4% of patients with SRP. Independent risk factors for infection-related death included poor performance status scores, inappropriate empirical antimicrobial treatment, bacteria/fungal coinfection, and lack of empirical antifungal treatment. Receiver operating characteristic curves showed that the cutoff value of empirical antifungal treatment duration was 9 (area under the curve: 0.819).

CONCLUSIONS

For patients with SRP and secondary lung infections, appropriate empirical antimicrobial treatment could decrease infection-related mortality, and cefoperazone-sulbactam may be an appropriate antibacterial drug. Empirical antifungal treatment for a minimum of 9 days might contribute to better outcomes. Although this represents a promising treatment approach for patients with SRP and secondary lung infections before antibacterial susceptibility testing, further prospective validation is essential.

Performance of the new ID-fungi plate using two types of reference libraries (Bruker and MSI) to identify fungi with the Bruker MALDI Biotyper

During the last decade, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has revolutionized the diagnosis of fungal infections. Recently, a new Conidia ID-fungi plate (IDFP) medium was introduced to facilitate growth and sampling of fungi. This study aimed to evaluate the IDFP for fungal MALDI-TOF MS identification by comparison with a standard fungal growth medium using two reference libraries. A total of 75 filamentous fungal isolates (including 32 dermatophytes) were inoculated on IDFP and Sabouraud-gentamicin-chloramphenicol (SGC) agar and identified by MALDI-TOF MS using formic acid/acetonitrile extraction. Both the commercially available Bruker library (version 2.0) and the public available MSI web application (version 2018) were applied. For 15% of the isolates, a faster growth was noticed on IDFP compared to SGC. IDFP enhanced the performance of fungal identification compared to SGC for both MSI (increase of 16% identifications to genus and 5% to species level) and Bruker library (increase of 22% identifications to genus and 8% to species level). In total, only 73% of the tested isolates were present in the Bruker library compared to 92% for MSI library. No significant difference (P = 0.46) in MALDI score between IDFP and SGC was observed for the MSI library, but scores were significantly (P = 0.03) higher for IDFP when using Bruker library, potentially explained by the prevention of agar contamination by using IDFP since the Bruker database was created from liquid media. IDFP is a promising alternative growth medium for MALDI-TOF MS fungal identification which would strongly benefit from optimizing the Bruker reference library.

Microalgal Cell Biofactory-Therapeutic, Nutraceutical and Functional Food Applications

Microalgae are multifaceted photosynthetic microorganisms with emerging business potential. They are present ubiquitously in terrestrial and aquatic environments with rich species diversity and are capable of producing significant biomass. Traditionally, microalgal biomass is being used as food and feed in many countries around the globe. The production of microalgal-based bioactive compounds at an industrial scale through biotechnological interventions is gaining interest more recently. The present review provides a detailed overview of the key algal metabolites, which plays a crucial role in nutraceutical, functional foods, and animal/aquaculture feed industries. Bioactive compounds of microalgae known to exhibit antioxidant, antimicrobial, antitumor, and immunomodulatory effects were comprehensively reviewed. The potential microalgal species and biological extracts against human pathogens were also discussed. Further, current technologies involved in upstream and downstream bioprocessing including cultivation, harvesting, and cell disruption were documented. Establishing microalgae as an alternative supplement would complement the sustainable and environmental requirements in the framework of human health and well-being.

The implementation of an infection control bundle within a Total Care Burns Unit

AIM

To evaluate the impact of the implementation of a best practice infection prevention and control bundle on healthcare associated burn wound infections in a paediatric burns unit.

BACKGROUND

Burn patients are vulnerable to infection. For this patient population, infection is associated with increased morbidity and mortality, thereby representing a significant challenge for burns clinicians who care for them.

METHODS

An interrupted time series was used to compare healthcare associated burn wound infections in paediatric burn patients before and after implementation of an infection prevention and control bundle. Prospective surveillance of healthcare associated burn wound infections was conducted from 2012 to 2014. Other potential healthcare associated infection rates were also reviewed over the study period, including urinary tract infections, pneumonia, upper respiratory tract infections and sepsis. An infection prevention and control bundle developed in collaboration between the paediatric burn unit and infection control clinicians was implemented in 2013 in addition to previous standard practice.

RESULTS

During the study period a total of 626 patients were admitted to the paediatric burns unit. Healthcare associated burn wound infections reduced from 34 in 2012 to 0 in 2014 following the implementation of the infection prevention and control bundle. Pneumonia and sepsis also reduced to 0 in 2013 and 2014, however one upper respiratory tract infection occurred in 2013 and urinary tract infections persisted in 2013.

CONCLUSION

The implementation of an infection prevention and control bundle was effective in reducing healthcare associated burn wound infections, pneumonia and sepsis within our paediatric burns unit. Urinary tract infections remain a challenge for future improvement.

Azole-triphenylphosphonium conjugates combat antifungal resistance and alleviate the development of drug-resistance

Azole antifungals are commonly used to treat fungal infections but have resulted in the occurrence of drug resistance. Therefore, developing azole derivatives (AZDs) that can both combat established drug-resistant fungal strains and evade drug resistance is of great importance. In this study, we synthesized a series of AZDs with a fluconazole (FLC) skeleton conjugated with a mitochondria-targeting triphenylphosphonium cation (TPP⁺). These AZDs displayed potent activity against both azole-sensitive and azole-resistant Candida strains without eliciting obvious resistance. Moreover, two representative AZDs, 20 and 25, exerted synergistic antifungal activity with Hsp90 inhibitors against C. albicans strains resistant to the combination treatment of FLC and Hsp90 inhibitors. AZD 25, which had minimal cytotoxicity, was effective in preventing C. albicans biofilm formation. Mechanistic investigation revealed that AZD 25 inhibited the biosynthesis of the fungal membrane component ergosterol and interfered with mitochondrial function. Our findings provide an alternative approach to address fungal resistance problems.

Bursting the Virulence Traits of MDR Strain of Candida albicans Using Sodium Alginate-based Microspheres Containing Nystatin-loaded MgO/CuO Nanocomposites

INTRODUCTION

Candida albicans is a major opportunistic pathogen that causes a wide range of human infections. Currently available therapeutic agents are limited for treating these fungal infections due to multidrug resistance as well as their nonbiodegradability, poor biocompatibility and toxicity. In order to battle these limitations, we have synthesized a polymeric system as microcarriers to deliver the antifungal drug. The objective of the present study was to immobilize MgO/CuO nanocomposite and nystatin-loaded MgO/CuO nanocomposites in nontoxic, nonimmunogenic, biodegradable and biocompatible sodium alginate microspheres for the first time.

MATERIALS AND METHODS

Nanoparticle-loaded sodium alginate microspheres were prepared by ionotropic gelation technique using calcium chloride as a cross-linker. Synthesized microspheres were characterized using standard characterization techniques and were evaluated for biological activity against MDR strain of C. albicans.

RESULTS

Characterization of microspheres by Fourier-transform infrared spectroscopy confirmed loading of Nys-MgO/CuO NPs, scanning electron microscopy (SEM) revealed rough spherical beads with a highly porous surface having an average size in the range of 8-10 µm. X-ray diffraction (XRD) analyzed its semicrystalline structure. Entrapment efficiency of Nys-MgO/CuO NPs was 80% and release kinetic study revealed sustained and prolonged release of drug in pH 5.5. Flow cytometry analysis showed yeast cell death caused by Nys-MgO/CuO MS exhibits late apoptotic features. In cytotoxicity assay 5-14 mg of microspheres did not cause hemolysis. Microspheres reduced virulence traits of C. albicans such as germ tube and biofilm formation were compromised at concentration of 5 mg/mL. Antimicrobial assessment results revealed a pronounced inhibitory effect against C. albicans.

CONCLUSION

The in vitro experiments have shown promising results based on good stability, Nys-MgO/CuO NP-encapsulated microspheres can be used as a prolonged controlled release system against MDR pathogenic C. albicans.

Catheter-related blood stream infections: prevalence, risk factors and antimicrobial resistance pattern

Background

Intravascular devices have significant potential for producing iatrogenic diseases resulting in catheter-related blood stream infections (CRBSIs). A study was undertaken to find the prevalence of CRBSI among patients in acute wards and to analyze the associated risk factors, causative pathogens with their antibiotic susceptibility (ABST) patterns.

Methods

Randomly ten days per month were chosen, for a period of two years. All the acute wards patients who were on indwelling blood catheters were identified. Those fulfilling the CRBSI criteria were further worked up for confirmation of diagnosis by differential time to positivity. The catheter tip was cultured by Maki's semiquantitative method. ABST of the isolates obtained was performed by Kirby-Bauer disk diffusion method.

Results

The prevalence of CRBSI was found to be 39.25% with the most common organism isolate being Serratia marcescens (23.81%). The immunocompromised status of the patients and catheterisation time were significant risk factors. Methicillin resistance was found to be 33.33% in coagulase-negative staphylococci. The resistance to vancomycin among the Entercoccus faecium isolates was found to be 33.33%. Among the gram negatives, resistance to aminoglycosides, fluoroquinolones and third-generation cephalosporins was high.

Conclusion

The study highlights the importance of regular surveillance programs, an efficient infection control program, strict adherence to antiseptic measures and use of a rational antibiotic policy for the early diagnosis and better management of CRBSI.

Broad-Spectrum Antifungal Agents: Fluorinated Aryl- and Heteroaryl-Substituted Hydrazones

Fluorinated aryl- and heteroaryl-substituted monohydrazones displayed excellent broad-spectrum activity against various fungal strains, including a panel of clinically relevant Candida auris strains relative to a control antifungal agent, voriconazole (VRC). These monohydrazones displayed less hemolysis of murine red blood cells than that of VRC at the same concentrations, possessed fungicidal activity in a time-kill study, and exhibited no mammalian cell cytotoxicity. In addition, these monohydrazones prevented the formation of biofilms that otherwise block antibiotic effectiveness and did not trigger the development of resistance when exposed to C. auris AR Bank # 0390 over 15 passages.

Azole-Resistant Aspergillus fumigatus Harboring the TR34/L98H Mutation: First Report in Portugal in Environmental Samples

Introduction: The frequency in detection of azole-resistant Aspergillus fumigatus isolates has increased since 2010. In Portugal, the section Fumigati is one of the most frequent, and resistant strains to have been found in clinical and environmental contexts. Although several cryptic species within the Fumigati section show intrinsic resistance to azoles, one factor driving (acquired) resistance is selective pressure deriving from the extensive use of azoles. This is particularly problematic in occupational environments where high fungal loads are expected, and where there is an increased risk of human exposure and infection, with impact on treatment success and disease outcome. The mechanisms of resistance are diverse, but mainly associated with mutations in the cyp51A gene. Despite TR₃₄/L98H being the most frequent mutation described, it has only been detected in clinical specimens in Portugal. Methods: We analyzed 99 A. fumigatus isolates from indoor environments (healthcare facilities, spas, one dairy and one waste sorting unit) collected from January 2018 to February 2019 in different regions of Portugal. Isolates were screened for resistance to itraconazole, voriconazole and posaconazole by culture, and resistance was confirmed by broth microdilution. Sequencing of the cyp51A gene and its promoter was performed to detect mutations associated with resistance. Results: Overall, 8.1% of isolates were able to grow in the presence of at least one azole, and 3% (isolated from the air in a dairy and from filtering respiratory protective devices in a waste sorting industry) were pan-azole-resistant, bearing the TR₃₄/L98H mutation. Conclusion: For the first time in Portugal, we report environmental isolates bearing the TR₃₄/L98H mutation, isolated from occupational environments. Environmental surveillance of the emergence of azole-resistant A. fumigatus sensu stricto strains is needed, to ensure proper and timely implementation of control policies that may have a positive impact on public and occupational health.

Machaerium acutifolium lectin alters membrane structure and induces ROS production in Candida parapsilosis

Lectins are a group of widely distributed and structurally heterogeneous proteins of nonimmune origin. These proteins have the ability to interact with glycans present on cell surfaces and elicit diverse biological activities. Machaerium acutifolium lectin (MaL) is an N-acetyl-D-glucosamine-binding lectin that exhibits antinociceptive activity via transient receptor potential cation channel subfamily V member 1 (TRPV1). Lectins that have the ability to recognize and interact with N-acetyl-D-glucosamine residues are potential candidates for studies of fungicidal activity. In this work, we show that MaL has antifungal activity against Candida species, and we describe its mode of action towards Candida parapsilosis. MaL inhibited the growth of C. albicans and C. parapsilosis. However, MaL was more potent against C. parapsilosis. The candidacidal mode of action of MaL on C. parapsilosis involves enhanced cell permeabilization, alteration of the plasma membrane proton-pumping ATPase function (H+-ATPase), induction of oxidative stress, and DNA damage. MaL also exhibited antibiofilm activity and noncytotoxicity to Vero cells. These results indicate that MaL is a promising candidate for the future development of a new, natural, and safe drug for the treatment of infections caused by C. parapsilosis.

Ethnobotanical survey on plants used in the treatment of candidiasis in traditional markets of southern Benin

BACKGROUND

Candidiasis, an opportunistic cosmopolitan disease is nowadays like bacterial infections which is a real public health problem. In view of the emergence of Candida strains resistant to existing antifungal agents, alternative solutions should be considered. This is the purpose of this ethnobotanical survey, which aims to identify the medicinal plant species traditionally used to treat candidiasis in traditional markets of southern Benin.

METHODS

The study was performed from October 2015 to January 2018 in the traditional markets of Southern-Benin. Data were collected by two complementary methods: triplet purchase of medicinal recipes (ATRM) from herbalists markets and semi-structured interview (ISS) from traditional healers.

RESULTS

A total of 109 species of medicinal plants belonging to 44 families have been listed and identified. The most frequently cited species were Pteleopsis suberosa Engl. & Diels, Lantana camara L., Cyanthillium cinereum (L.) H. Rob, Ocimum gratissimum L. and Lippia multiflora Moldenke with respectively 43.84, 39.73 and 34.25% citation frequencies for the last three species respectively. Leguminosae (20.18%), Euphorbiaceae (5.50%) and Apocynaceae (5.50%) were the most represented botanical families. Leafy stems were more used than other plant organs. The decoction and the oral route were the most appropriate methods of preparation and administration reported by traditional healers.

CONCLUSION

Benin's plant cover is made up of a wide variety of medicinal plant species used in the traditionnal treatment of candidiasis and which may constitute new sources of medicines to be developed.

The antifungal activities and biological consequences of BMVC-12C-P, a carbazole derivative against Candida species

Fungal infections, particularly Candida species, have increased worldwide and caused high morbidity and mortality rates. The toxicity and development of resistance in present antifungal drugs justify the need of new drugs with different mechanism of action. BMVC-12C-P, a carbazole-type compound, has been found to dysfunction mitochondria. BMVC-12C-P displayed the strongest antifungal activities among all of the BMVC derivatives. The minimal inhibitory concentration (MIC) of BMVC-12C-P against Candida species ranged from 1 to 2 μg/ml. Fluconazole-resistant clinical isolates of Candida species were highly susceptible to BMVC-12C-P. The potent fungicidal activity of BMVC-12C-P relates to its impairing mitochondrial function. Furthermore, we found that the hyphae growth and biofilm formation were suppressed in C. albicans survived from BMVC-12C-P treatment. This study demonstrates the potential of BMVC-12C-P as an antifungal agent for treating Candida infections.

Broad-spectrum antifungal activities and mechanism of drimane sesquiterpenoids

Eight drimane sesquiterpenoids including (-)-drimenol and (+)-albicanol were synthesized from (+)-sclareolide and evaluated for their antifungal activities. Three compounds, (-)-drimenol, (+)-albicanol, and (1R,2R,4aS,8aS)-2-hydroxy-2,5,5,8a-tetramethyl-decahydronaphthalene-1-carbaldehyde (4) showed strong activity against C. albicans. (-)-Drimenol, the strongest inhibitor of the three, (at concentrations of 8 – 64 µg/ml, causing 100% death of various fungi), acts not only against C. albicans in a fungicidal manner, but also inhibits other fungi such as Aspergillus, Cryptococcus, Pneumocystis, Blastomyces, Saksenaea and fluconazole resistant strains of C. albicans, C. glabrata, C. krusei, C. parapsilosis and C. auris. These observations suggest that drimenol is a broad-spectrum antifungal agent. At a high concentration (100 μg/ml) drimenol caused rupture of the fungal cell wall/membrane. In a nematode model of C. albicans infection, drimenol rescued the worms from C. albicans-mediated death, indicating drimenol is tolerable and bioactive in metazoans. Genome-wide fitness profiling assays of both S. cerevisiae (nonessential homozygous and essential heterozygous) and C. albicans (Tn-insertion mutants) collections revealed putative genes and pathways affected by drimenol. Using a C. albicans mutant spot assay, the Crk1 kinase associated gene products, Ret2, Cdc37, and orf19.759, orf19.1672, and orf19.4382 were revealed to be involved in drimenol's mechanism of action. The three orfs identified in this study are novel and appear to be linked with Crk1 function. Further, computational modeling results suggest possible modifications of the structure of drimenol, including the A ring, for improving the antifungal activity.

Limited Positive Predictive Value of β-d-Glucan in Hematologic Patients Receiving Antimold Prophylaxis

Background

Diagnostic value of β-d-glucan (BDG) in populations with low prevalence of invasive fungal infection (IFI), such as hematologic patients receiving antimold prophylaxis, should be re-evaluated.

Methods

We retrospectively reviewed episodes with BDG results in hematologic patients receiving antimold prophylaxis from January 2017 to August 2019 in a tertiary hospital. The episodes were classified as true positive ([TP] positive BDG with IFI), true negative ([TN] negative BDG without IFI), false positive ([FP] positive BDG without IFI), false negative ([FN] negative BDG with IFI), and nonevaluable.

Results

A total of 203 episodes were analyzed: 101 episodes (49.8%) were from stem cell transplants, 89 (43.8%) were from induction chemotherapy, and 13 (6.4%) were from graft-versus-host disease treatment. There were 62 nonevaluable episodes. Among 141 evaluable ones, there were 8 (5.7%) episodes of probable/proven IFI. True positive, TN, FP, and FN cases were 4 (2.8%), 112 (79.4%), 21 (14.9%), and 4 (2.8%) episodes, respectively. Sensitivity, specificity, positive predictive value, and negative predictive value were 50.0%, 84.2%, 16.1%, and 96.5%, respectively. Positive predictive value was 26.7% and 0.0% in diagnostic and surveillance episodes, respectively.

Conclusions

β-d-glucan test should be used to exclude IFI rather than for diagnosis in these patients.

Drug resistance and tolerance in fungi

Systemic fungal infections pose a serious clinical problem. Treatment options are limited, and antifungal drug resistance is increasing. In addition, a substantial proportion of patients do not respond to therapy despite being infected with fungi that are susceptible to the drug. The discordance between overall treatment outcome and low levels of clinical resistance may be attributable to antifungal drug tolerance. In this Review, we define and distinguish resistance and tolerance and discuss the current understanding of the molecular, genetic and physiological mechanisms that contribute to those phenomena. Distinguishing tolerance from resistance might provide important insights into the reasons for treatment failure in some settings.

Signaling C-Type Lectin Receptors in Antifungal Immunity

We are all exposed to fungal organisms daily, and although many of these organisms are not harmful, billions of people a year contract a fungal infection. Most of these infections are not fatal and can be cleared by the host immune response. However, due to an increase in high-risk populations, the global fungal burden has increased, with more than 1.5 million deaths per year caused by invasive fungal infections. The fungal cell wall is an important surface for interacting with the host immune system as it contains pathogen-associated molecular patterns (PAMPs) which are detected as being foreign by the host pattern recognition receptors (PRRs). C-type lectin receptors are a group of PRRs that play a central role in the protection against invasive fungal infections. Following the recognition of fungal PAMPs, CLRs trigger various innate and adaptive immune responses. In this chapter, we specifically focus on C-type lectin receptors capable of activating downstream signaling pathways, resulting in protective antifungal immune responses. The current roles that these signaling CLRs play in protection against four of the most prevalent fungal infections affecting humans are reviewed. These include Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans and Pneumocystis jirovecii.

Construction of antifungal dual-target (SE, CYP51) pharmacophore models and the discovery of novel antifungal inhibitors

Fungal infections and drug-resistance are rapidly increasing with the deterioration of the external environment. Squalene cyclooxygenase (SE) and 14α-demethylase (CYP51) are considered to be important antifungal targets, and the corresponding pharmacophore models can be used to design and guide the discovery of novel inhibitors. Therefore, the common feature pharmacophore model (SE inhibitor) and structure-based pharmacophore model (CYP51 receptor) were constructed using different methods in this study. Then, appropriate organic fragments were selected and superimposed onto the pharmacophore features, and compounds 5, 6 and 8 were designed and produced by linking these organic fragments. It is noteworthy that compound 8 can simultaneously match the features of both the SE and CYP51 pharmacophores. Further analysis found that these compounds exhibit a potent antifungal activity. Preliminary mechanistic studies revealed that compound 8 could undergo dual-target inhibition (SE and CYP51) of Candida albicans. This study proved the rationale of pharmacophore models (SE and CYP51), which can guide the design and discovery of new antifungal inhibitors.

Dependence on Dectin-1 Varies With Multiple Candida Species

Four Candida spp. (albicans, glabrata, tropicalis, parapsilosis) cause >95% of invasive Candida infections. C. albicans elicits immune responses via pathogen recognition receptors including C-type lectin-like receptors (CLRs). The CLR, Dectin-1 is important for host immunity to C. albicans and C. glabrata, however, whether Dectin-1 is important for host defense against C. tropicalis or C. parapsilosis is unknown. Therefore, we compared the involvement of Dectin-1 in response to these four diverse Candida spp. We found that Dectin-1 mediates innate cytokine responses to these Candida spp. in a species- and cell-dependent manner. Dectin-1 KO mice succumbed to infection with highly virulent C. albicans while they mostly survived infection with less virulent Candida spp. However, Dectin-1 KO mice displayed increased fungal burden following infection with each Candida spp. Additionally, T cells from Dectin-1 KO mice displayed enhanced effector functions likely due to the inability of Dectin-1 KO mice to clear the infections. Together, these data indicate that Dectin-1 is important for host defense to multiple Candida spp., although the specific roles for Dectin-1 varies with different Candida spp.

Antifungal Activity and Potential Mechanism of N-Butylphthalide Alone and in Combination With Fluconazole Against Candida albicans

Candida albicans is a common opportunistic fungal pathogen that may cause nosocomial fungal infections. The resistance of Candida albicans to traditional antifungal drugs has been increasing rapidly in recent years, and it brings a great challenge in clinical treatment. N-butylphthalide is originally extracted from the seed of Apium graveolens and is currently used for the treatment of ischemic stroke in the clinic. This study demonstrated that n-butylphthalide exhibited antifungal activity against Candida albicans with minimum inhibitory concentrations of 128 μg/ml; moreover, n-butylphthalide combined with fluconazole showed synergistic antifungal effects against resistant Candida albicans, resulting in a decrease in the minimum inhibitory concentrations of fluconazole from >512 to 0.25–1 μg/ml. Time-killing curves verified the antifungal activity in dynamic. Besides, n-butylphthalide exhibited anti-biofilm activity against Candida albicans, biofilms preformed <12 h with sessile minimum inhibitory concentrations of 128–256 μg/ml and synergism was observed when n-butylphthalide combined with fluconazole against resistant Candida albicans biofilms preformed <12 h, resulting in a decrease in the sessile minimum inhibitory concentrations of fluconazole from >1,024 to 0.5–8 μg/ml. Furthermore, in vitro antifungal effects of n-butylphthalide were confirmed in vivo. N-butylphthalide prolonged survival rate of larvae infected by Candida albicans, reduced the fungal burden in larvae and caused less damage to larval tissues. Notably, n-butylphthalide inhibited hyphal growth and induced intracellular reactive oxygen species accumulation and a loss in mitochondrial membrane potential, which was a potential antifungal mechanism. Besides, the synergistic effects between n-butylphthalide and fluconazole potentially relied on the mechanism that n-butylphthalide significantly promoted drug uptake, and suppressed drug efflux via down-regulating the drug transporter encoding genes CDR1 and CDR2. These findings demonstrated the antifungal effects and mechanisms of n-butylphthalide against Candida albicans for the first time, which might provide broad prospects for the identification of new potential antifungal targets.

The protective effect of inflammatory monocytes during systemic C. albicans infection is dependent on collaboration between C-type lectin-like receptors

Invasive candidiasis, mainly caused by Candida albicans, is a serious healthcare problem with high mortality rates, particularly in immunocompromised patients. Innate immune cells express pathogen recognition receptors (PRRs) including C-type lectin-like receptors (CLRs) that bind C. albicans to initiate an immune response. Multiple CLRs including Dectin-1, Dectin-2 and Mincle have been proposed individually to contribute to the immune response to C. albicans. However how these receptors collaborate to clear a fungal infection is unknown. Herein, we used novel multi-CLR knockout (KO) mice to decipher the individual, collaborative and collective roles of Dectin-1, Dectin-2 and Mincle during systemic C. albicans infection. These studies revealed an unappreciated and profound role for CLR co-operation in anti-fungal immunity. The protective effect of multiple CLRs was markedly greater than any single receptor, and was mediated through inflammatory monocytes via recognition and phagocytosis of C. albicans, and production of C. albicans-induced cytokines and chemokines. These CLRs were dispensable for mediating similar responses from neutrophils, likely due to lower expression of these CLRs on neutrophils compared to inflammatory monocytes. Concurrent deletion of Dectin-1 and Dectin-2, or all three CLRs, resulted in dramatically increased susceptibility to systemic C. albicans infection compared to mice lacking a single CLR. Multi-CLR KO mice were unable to control fungal growth due to an inadequate early inflammatory monocyte-mediated response. In response to excessive fungal growth, the multi-CLR KO mice mounted a hyper-inflammatory response, likely leading to multiple organ failure. Thus, these data reveal a critical role for CLR co-operation in the effective control of C. albicans and maintenance of organ function during infection.

Fungal infections including invasive candidiasis are a serious healthcare problem particularly for immunocompromised patients. Mortality rates for invasive candidiasis are very high and complex anti-fungal immune responses are poorly understood, hindering the development of novel immunotherapies. Dectin-1, Dectin-2 and Mincle are three cell surface receptors that are proposed to be involved in the immune response to fungal pathogens. However, if or how these receptors work together during infection is currently unknown. Here we demonstrate that these receptors, in particular Dectin-1 and Dectin-2, work together to promote fungal clearance by a group of innate immune cells called inflammatory monocytes. Furthermore, we found that mice lacking these three receptors are dramatically susceptible to systemic Candida albicans infection due to defective early innate immune responses. These mice develop hyper-inflammation to try to control excessive fungal growth likely resulting in multi-organ failure. Our work helps explain how these receptors work together to clear/control invasive candidiasis. Our improved knowledge of the interactions between these receptors could be used to help design novel anti-fungal immunotherapies.

Impact of automatic infectious diseases consultation on the management of fungemia at a large academic medical center

PURPOSE

The impact of automatic infectious diseases (ID) consultation for inpatients with fungemia at a large academic medical center was studied.

METHODS

In this single-center, retrospective study, the time to appropriate antifungal therapy before and after implementing a policy requiring automatic ID consultation for the management of fungemia for all patients with an inpatient positive blood culture for fungus was examined. The rates of ID consultation; the likelihood of receiving appropriate antifungal therapy; central venous catheter (CVC) removal rates; performance of ophthalmologic examinations; infection-related length of stay (LOS); rates of all-cause inhospital mortality, death, or transfer to an intensive care unit within 7 days of first culture; and inpatient cost of antifungals were also evaluated.

RESULTS

A total of 173 unique episodes (94 and 79 in the control and intervention groups, respectively) were included. Candida species were the most frequently cultured organisms, isolated from over 90% of patients in both groups. No differences were observed between the control and intervention groups in time to appropriate therapy, infection-related LOS, or time to CVC removal. However, patients in the intervention group were more likely than those in the control group to receive appropriate antifungal therapy (p = 0.0392), undergo ophthalmologic examination (p = 0.003), have their CVC removed (p = 0.0038), and receive ID consultation (p = 0.0123). Inpatient antifungal costs were significantly higher in the intervention group (p = 0.0177).

CONCLUSION

While automatic ID consultation for inpatients with fungemia did not affect the time to administration of appropriate therapy, improvement was observed for several process indicators, including rates of appropriate antifungal therapy selection, time to removal of CVCs, and performance of ophthalmologic examinations.

The fungal cell wall as a target for the development of new antifungal therapies

In the past three decades invasive mycoses have globally emerged as a persistent source of healthcare-associated infections. The cell wall surrounding the fungal cell opposes the turgor pressure that otherwise could produce cell lysis. Thus, the cell wall is essential for maintaining fungal cell shape and integrity. Given that this structure is absent in host mammalian cells, it stands as an important target when developing selective compounds for the treatment of fungal infections. Consequently, treatment with echinocandins, a family of antifungal agents that specifically inhibits the biosynthesis of cell wall (1-3)β-D-glucan, has been established as an alternative and effective antifungal therapy. However, the existence of many pathogenic fungi resistant to single or multiple antifungal families, together with the limited arsenal of available antifungal compounds, critically affects the effectiveness of treatments against these life-threatening infections. Thus, new antifungal therapies are required. Here we review the fungal cell wall and its relevance in biotechnology as a target for the development of new antifungal compounds, disclosing the most promising cell wall inhibitors that are currently in experimental or clinical development for the treatment of some invasive mycoses.

Infection control measures to prevent hospital transmission of candida

Invasive candida infections are the most important causes of nosocomial infections in intensive care units and in risky groups such as immunosuppressed patients. These infections lead to undesirable consequences such as increased morbidity and mortality in patients, prolongation of hospital stay, and increased hospital costs. In recent years, the incidence of non-albicans Candida spp.'s has increased. Unfortunately, some of these species are naturally resistant to first-line antifungals. In addition, biofilm formation on the central venous catheter and invasive devices may cause treatment failure. The age of the patients, co-morbid diseases, the units where they are treated, the antibiotics and antifungals that are used for the treatment, and invasive devices are risk factors for invasive candida infections. Some of these risk factors can be reduced by the behavior of health-care workers. The most important goal is to take precautions before the occurrence of invasive candida infections. Infection control measures to prevent hospital transmission of candida are very important. Compliance with hand hygiene before and after contact with the patient is the most important step to prevent the spreading of Candida spp. Observation of maximal barrier precautions during invasive catheterization is another important clause of this aim. Avoiding unnecessary invasive devices, antibiotics, and parenteral nutrition are also important to reduce the colonization of candida.

Retrospective cohort study comparing the risk of severe hepatotoxicity in hospitalized patients treated with echinocandins for invasive candidiasis in the presence of confounding by indication

Background

To compare the risk of severe hepatotoxicity with anidulafungin versus caspofungin and micafungin in hospitalized adults.

Methods

This retrospective cohort study combined data from two large US- based hospital electronic medical record databases. Severe hepatotoxicity was a Grade ≥ 3 liver function test (LFT) post-echinocandin initiation. Adjusted incidence rate ratios (IRRs) were estimated for anidulafungin versus caspofungin and micafungin, overall and in patients with normal baseline LFT (Grade 0).

Results

Treatments included anidulafungin (n = 1700), caspofungin (n = 4431), or micafungin (n = 6547). The proportions with LFT Grade ≥ 3 pre-echinocandin initiation were: anidulafungin 40.4% versus caspofungin 25.9% (p <  0.001) and micafungin 25.6% (p <  0.001). Rates of severe underlying diseases or comorbidities were: critical care admissions: 75.3% versus 52.6 and 48.6%; and organ failures: 69.4% versus 46.7 and 51.5%. Adjusted IRRs of severe hepatotoxicity for anidulafungin versus caspofungin and micafungin were 1.43 (p = 0.002) and 1.19 (p = 0.183) overall, and 0.88 (P = 0.773) and 0.97 (P = 0.945) for normal baseline LFT, respectively.

Conclusions

Accounting for confounders, severe hepatotoxicity risk was not significantly different across echinocandins in this real-world head-to-head study. Anidulafungin was used more frequently in patients with more comorbidities. Those with normal baseline LFT (least susceptible to confounding by indication), showed no elevated hepatotoxicity risk for anidulafungin.

Clonal Spread of Candida glabrata Bloodstream Isolates and Fluconazole Resistance Affected by Prolonged Exposure: a 12-Year Single-Center Study in Belgium

Candida glabrata is a major cause of candidemia in immunocompromised patients and is characterized by a high-level of fluconazole resistance. In the present study, the acquisition of antifungal resistance and potential clonal spread of C. glabrata were explored at a single center over a 12-year period by analyzing 187 independent clinical C. glabrata bloodstream isolates. One strain was found to be micafungin resistant due to a mutation in the FKS2 gene. Fluconazole resistance remained stable throughout the period and was observed in 20 (10.7%) of the isolates. An analysis of the antifungal consumption data revealed that recent prior exposure to fluconazole increased the risk to be infected by a resistant strain. In particular, the duration of the treatment was significantly longer for patients infected by a resistant isolate, while the total and mean daily doses received did not impact the acquisition of resistance in C. glabrata No link between genotype and resistance was found. However, multilocus variable-number tandem-repeat analyses indicated a potential intrahospital spread of some isolates between patients. These isolates shared the same genetic profiles, and infected patients were hospitalized in the same unit during an overlapping period. Finally, quantitative real-time PCR analyses showed that, unlike that for other ABC efflux pumps, the expression of CgCDR1 was significantly greater in resistant strains, suggesting that it would be more involved in fluconazole (FLC) resistance. Our study provides additional evidence that the proper administration of fluconazole is required to limit resistance and that strict hand hygiene is necessary to avoid the possible spreading of C. glabrata isolates between patients.

Reduction in Percentage of Clusters of Candida albicans and Candida parapsilosis Causing Candidemia in a General Hospital in Madrid, Spain

The presence of clusters in units with a high incidence of candidemia suggests the need for the prevention of candidemia. We analyzed the percentage of patients involved in clusters and its evolution over a large period of time in a tertiary hospital. We studied 432 patients admitted to Gregorio Marañón Hospital with candidemia caused by Candida albicans (n = 276) or Candida parapsilosis (n = 156) between January 2007 and December 2014. Incident isolates were genotyped. A cluster was defined as a group of ≥2 patients infected by an identical genotype; we considered clusters to be "tracking clusters" when the patients involved in the cluster were admitted to the same ward within a period of 24 months. The study period was split into two periods, 2007 to 2010 (period 1) and 2011 to 2014 (period 2). The number of episodes of C. albicans and C. parapsilosis candidemia (n = 262 versus n = 170, respectively), the mean incidence (1.62 versus 1.36 episodes per 1,000 admissions, respectively), and the percentage of episodes caused by clusters (overall clusters [40% versus 12%] and tracking clusters [18% versus 3%], respectively) were significantly lower in period 2 than in period 1. Linear regression analysis showed a positive correlation between the overall number of episodes of candidemia and episodes caused by clusters (r² = 0.89). We found a reduction in the number of episodes of candidemia caused by C. albicans and C. parapsilosis and a decrease in the percentage of episodes caused by clusters over time. Interestingly, the reduction was accompanied by the implementation of a campaign to reduce the number of catheter-related infections.

Structure-based virtual screening and ADME/T-based prediction analysis for the discovery of novel antifungal CYP51 inhibitors

With the increasing incidence of pathogenic fungi and drug-resistant fungi in clinic, it has become very important to develop the novel rate-limiting enzyme 14α-demethylase (CYP51) as an antifungal inhibitor. In this study, a method involving structure-based virtual screening was employed. First, a publicly available database was obtained from the Dow Chemical Company, and the database was screened by the designed pharmacophore model of CYP51 inhibitors. Then, the pharmacophore search hits were docked into the CYP51 crystal structure. Finally, sixteen compounds were selected for in vitro antifungal inhibition assay, and most of the compounds showed a certain degree of antifungal activity. In particular, compounds 3, 4, and 9 exhibited significant antifungal and anti-drug resistance activities by blocking the synthesis of ergosterol. The molecular docking and ADME/T properties of the compounds 3, 4, and 9 were further predicted, and the results indicated that they can form hydrophobic and coordination interactions with the active sites of CYP51. At the same time, compounds 4 and 9 showed promising drug-like properties. This study reveals that the compounds can be further optimized and developed as lead compounds.

In vitro photodynamic inactivation effects of benzylidene cyclopentanone photosensitizers on clinical fluconazole-resistant Candida albicans

BACKGROUND

The incidence of Candida infections has increased for various reasons, including, the more frequent use of immunosuppresants or broad-spectrum antibiotics. Photodynamic inactivation (PDI) is a promising approach for treating localized Candida infections.

METHODS

The PDI efficacies of three benzylidene cyclopentanone-based (BCB) photosensitizers (PSs: P1, P2 and Y1) against three fluconazole-resistant C. albicans (cal-1, cal-2, and cal-3) and one control C. albicans (ATCC 90028), respectively, were evaluated using an established plate dilution method. The binding of PSs to C. albicans was determined by fluorescence spectroscopy. The mechanism of antifungal PDI was investigated using confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM).

RESULTS

Three BCB PSs all bound rapidly to C. albicans. After incubation with PSs for 30 min and irradiation with a 532 nm laser for 10 min (40 mW cm^-2, 24 J cm^-2), the fungicidal activity was achieved as 7.5 μM for P1 and P2, and 25 μM for Y1. CLSM confirmed that P1 and Y1 were located in intracellular components, including mitochondria, while P2 bound to the protoplast exterior and failed to enter the cells. TEM revealed the damage of mitochondria ultrastructures after P1- or Y1-mediated PDI, consistenting with the CLSM results. However, most cells became edematous, enlarged or deformation after P2-mediated PDI.

CONCLUSIONS

The three BCB PSs all have remarkable PDI effects on C. albicans. The best effect is obtained by P1, which has one cationic charge with a proper lipophilicity. The respective subcellular localization of the three PSs led to different PDI mechanisms.

Pattern recognition receptors in fungal immunity

Over the last decade, invasive fungal infections have emerged as a growing threat to human health worldwide and novel treatment strategies are urgently needed. In this context, investigations into host-pathogen interactions represent an important and promising field of research. Antigen presenting cells such as macrophages and dendritic cells are strategically located at the frontline of defence against potential invaders. Importantly, these cells express germline encoded pattern recognition receptors (PRRs), which sense conserved entities from pathogens and orchestrate innate immune responses. Herein, we review the latest findings regarding the biology and functions of the different classes of PRRs involved in pathogenic fungal recognition. We also discuss recent literature on PRR collaboration/crosstalk and the mechanisms involved in inhibiting/regulating PRR signalling. Finally, we discuss how the accumulated knowledge on PRR biology, especially Dectin-1, has been used for the design of new immunotherapies against fungal infections.