Genetic Mutations in FKS1 Gene Associated with Acquired Echinocandin Resistance in Candida parapsilosis Complex.

Candida parapsilosis complex has recently received special attention due to naturally occurring FKS1 polymorphism associated with high minimal inhibitory concentrations for echinocandin and the increase of clonal outbreaks of strains resistant to commonly used antifungals such as fluconazole. Despite the previous fact, little is known about the genetic mechanism associated with echinocandin resistance. Therefore, the present study was designed to investigate the mechanism of acquired echinocandin resistance in C. parapsilosis complex strains. A total of 15 clinical C. parapsilosis complex isolates were sub-cultured for 30 days at a low concentration of micafungin at ½ the lowest MIC value of the tested isolates (0.12 µg/ml). After culturing, all the isolates were checked phenotypically for antifungal resistance and genotypically for echinocandin resistance by checking FKS1 gene hot spot one (HS1) and HS2 mutations. In vitro induction of echinocandin resistance confirmed the rapid development of resistance at low concentration micafungin, with no difference among C. parapsilosis, C. metapsilosis, and C. orthopsilosis in the resistance development. For the first time we identified different FKS1 HS1 and or HS2 mutations responsible for echinocandin resistance such as R658S and L1376F in C. parapsilosis, S656X, R658X, R658T, W1370X, X1371I, V1371X, and R1373X (corresponding to their location in C. parapsilosis) in C. metapsilosis, and L648F and R1366H in C. orthopsilosis. Our results are of significant concern, since the rapid development of resistance may occur clinically after short-term exposure to antifungals as recently described in other fungal species with the potential of untreatable infections.

An oxylipin signal confers protection against antifungal echinocandins in pathogenic aspergilli.

Aspergillus fumigatus is the leading causative agent of life-threatening invasive aspergillosis in immunocompromised individuals. One antifungal class used to treat Aspergillus infections is the fungistatic echinocandins, semisynthetic drugs derived from naturally occurring fungal lipopeptides. By inhibiting beta-1,3-glucan synthesis, echinocandins cause both fungistatic stunting of hyphal growth and repeated fungicidal lysis of apical tip compartments. Here, we uncover an endogenous mechanism of echinocandin tolerance in A. fumigatus whereby the inducible oxylipin signal 5,8-diHODE confers protection against tip lysis via the transcription factor ZfpA. Treatment of A. fumigatus with echinocandins induces 5,8-diHODE synthesis by the fungal oxygenase PpoA in a ZfpA dependent manner resulting in a positive feedback loop. This protective 5,8-diHODE/ZfpA signaling relay is conserved among diverse isolates of A. fumigatus and in two other Aspergillus pathogens. Our findings reveal an oxylipin-directed growth program-possibly arisen through natural encounters with native echinocandin producing fungi-that enables echinocandin tolerance in pathogenic aspergilli.

A Hadal Streptomyces-Derived Echinocandin Acylase Discovered through the Prioritization of Protein Families.

Naturally occurring echinocandin B and FR901379 are potent antifungal lipopeptides featuring a cyclic hexapeptide nucleus and a fatty acid side chain. They are the parent compounds of echinocandin drugs for the treatment of severe fungal infections caused by the Candida and Aspergilla species. To minimize hemolytic toxicity, the native fatty acid side chains in these drug molecules are replaced with designer acyl side chains. The deacylation of the N-acyl side chain is, therefore, a crucial step for the development and manufacturing of echinocandin-type antibiotics. Echinocandin E (ECE) is a novel echinocandin congener with enhanced stability generated via the engineering of the biosynthetic machinery of echinocandin B (ECB). In the present study, we report the discovery of the first echinocandin E acylase (ECEA) using the enzyme similarity tool (EST) for enzymatic function mining across protein families. ECEA is derived from Streptomyces sp. SY1965 isolated from a sediment collected from the Mariana Trench. It was cloned and heterologously expressed in S. lividans TK24. The resultant TKecea66 strain showed efficient cleavage activity of the acyl side chain of ECE, showing promising applications in the development of novel echinocandin-type therapeutics. Our results also provide a showcase for harnessing the essentially untapped biodiversity from the hadal ecosystems for the discovery of functional molecules.

Hydrophobic substrate binding pocket remodeling of echinocandin B deacylase based on multi-dimensional rational design.

Actinoplanes utahensis deacylase (AAC)-catalyzed deacylation of echinocandin B (ECB) is a promising method for the synthesis of anidulafungin, the newest of the echinocandin antifungal agents. However, the low activity of AAC significantly limits its practical application. In this work, we have devised a multi-dimensional rational design strategy for AAC, conducting separate analyses on the substrate-binding pocket's volume, curvature, and length. Furthermore, we quantitatively analyzed substrate properties, particularly on hydrophilic and hydrophobic. Accordingly, we tailored the linoleic acid-binding pocket of AAC to accommodate the extended long lipid chain of ECB. By fine-tuning the key residues, the resulting AAC mutants can accommodate the ECB lipid chain with a lower curvature binding pocket. The D53A/I55F/G57M/F154L/Q661L mutant (MT) displayed 331 % higher catalytic efficiency than the wild-type (WT) enzyme. The MT product conversion was 94.6 %, reaching the highest reported level. Utilizing a multi-dimensional rational design for a customized mutation strategy of the substrate-binding pocket is an effective approach to enhance the catalytic efficiency of enzymes in handling complicated substrates.

Impact of prophylactic echinocandin on the development of neurological complications in patients receiving busulfan-containing conditioning regimens for stem cell transplantation: A single-center retrospective study.

BACKGROUND: Although neurotoxicity is a major adverse event associated with busulfan, little information is available regarding the association between drug interactions and neurological symptoms during busulfan-based regimens. This study evaluated the association between prophylactic echinocandins and neurological complications in patients receiving busulfan-containing conditioning regimens for stem cell transplantation. METHODS: We retrospectively included consecutive patients who administered intravenous busulfan as a conditioning regimen at our facility between 2007 and 2022. Prophylactic echinocandin use was defined as the use of an echinocandin antifungal drug to prevent invasive fungal disease in SCT recipients. The primary outcome was the incidence of neurological complications within 7 days of busulfan initiation and was compared between the echinocandin group (patients received prophylactic echinocandin) and nonechinocandin group (patients received prophylactic antifungal drugs other than echinocandin and those without antifungal prophylaxis). RESULTS: Among the 59 patients included in this study, the incidence of neurological complications in the echinocandin (n = 26) and nonechinocandin groups (n = 33) was 30.8% and 63.6%, respectively. We observed a negative association between prophylactic echinocandin use and the development of neurological complications after adjusting for the propensity score for receiving prophylactic echinocandins (adjusted odds ratio 0.294, 95% confidence interval 0.090 to 0.959). We observed a lower incidence of neurological complications in the echinocandin group than in the nonechinocandin group. CONCLUSION: Our results suggested that the choice of antifungal prophylaxis is associated with busulfan neurotoxicity.

Taxonomy of Candida parapsilosis complex isolated from neonates and the role of Hsp90 inhibitors to enhanced the antifungal activity of micafungin.

Species from Candida parapsilosis complex are frequently found in neonatal candidemia. The antifungal agents to treat this infection are limited and the occurrence of low in vitro susceptibility to echinocandins such as micafungin has been observed. In this context, the chaperone Hsp90 could be a target to reduce resistance. Thus, the objective of this research was to identify isolates from the C. parapsilosis complex and verify the action of Hsp90 inhibitors associated with micafungin. The fungal identification was based on genetic sequencing and mass spectrometry. Minimal inhibitory concentrations were determined by broth microdilution method according to Clinical Laboratory and Standards Institute. The evaluation of the interaction between micafungin with Hsp90 inhibitors was realized using the checkerboard methodology. According to the polyphasic taxonomy, C. parapsilosis sensu stricto was the most frequently identified, followed by C. orthopsilosis and C. metapsilosis, and one isolate of Lodderomyces elongisporus was identified by genetic sequencing. The Hsp90 inhibitor geladanamycin associated with micafungin showed a synergic effect in 31.25% of the isolates, a better result was observed with radicicol, which shows synergic effect in 56.25% tested yeasts. The results obtained demonstrate that blocking Hsp90 could be effective to reduce antifungal resistance to echinocandins.

Evaluation of the Vitek 2 system for antifungal susceptibility testing of Candida auris using a representative international panel of clinical isolates: overestimation of amphotericin B resistance and underestimation of fluconazole resistance.

Although the Vitek 2 system is broadly used for antifungal susceptibility testing of Candida spp., its performance against Candida auris has been assessed using limited number of isolates recovered from restricted geographic areas. We therefore compared Vitek 2 system with the reference Clinical and Laboratory Standards Institute (CLSI) broth microdilution method using an international collection of 100 C. auris isolates belonging to different clades. The agreement ±1 twofold dilution between the two methods and the categorical agreement (CA) based on the Centers for Disease Control and Prevention's (CDC's) tentative resistance breakpoints and Vitek 2-specific wild-type upper limit values (WT-ULVs) were determined. The CLSI-Vitek 2 agreement was poor for 5-flucytosine (0%), fluconazole (16%), and amphotericin B (29%), and moderate for voriconazole (61%), micafungin (67%), and caspofungin (81%). Significant interpretation errors were recorded using the CDC breakpoints for amphotericin B (31% CA, 69% major errors; MaEs) and fluconazole (69% CA, 31% very major errors; VmEs), but not for echinocandins (99% CA, 1% MaEs for both micafungin and caspofungin) for which the Vitek 2 allowed correct categorization of echinocandin-resistant FKS1 mutant isolates. Discrepancies were reduced when the Vitek 2 WT-ULV of 16 mg/L for amphotericin B (98% CA, 2% MaEs) and of 4 mg/L for fluconazole (96% CA, 1% MaEs, 3% VmEs) were used. In conclusion, the Vitek 2 system performed well for echinocandin susceptibility testing of C .auris. Resistance to fluconazole was underestimated whereas resistance to amphotericin B was overestimated using the CDC breakpoints of ≥32 and ≥2 mg/L, respectively. Vitek 2 minimun inhibitory concentrations (MICs) >4 mg/L indicated resistance to fluconazole and Vitek 2 MICs ≤16 mg/L indicated non-resistance to amphotericin B.

An evaluation of Rezafungin: the latest treatment option for adults with candidemia and invasive candidiasis.

INTRODUCTION: Invasive fungal infections, especially candidemia and invasive candidiasis, continue to cause substantial morbidity and mortality. In addition, the emergence of drug-resistant Candida species, notably C. glabrata and C. auris, along with limitations in available treatments, highlights the urgent need for novel, effective antifungal agents. AREAS COVERED: This review discusses the results of in vitro studies evaluating the spectrum and highlights the pharmacokinetic/pharmacodynamic properties. It also includes discussions on two key clinical studies that assess safety, tolerability, and efficacy. EXPERT OPINION: Rezafungin has demonstrated comparable efficacy to other echinocandins in two clinical studies and exhibits in vitro activity against a broad range of Candida species and Aspergillus spp. It has a favorable safety profile with minimal side effects, and no drug interactions or effects on QT intervals. In contrast to other echinocandins, it demonstrates dose-dependent killing, a prolonged half-life, and low clearance make it suitable for once-weekly dosing, which is supported by clinical trials confirming its efficacy. Rezafungin offers a promising option for the outpatient management of difficult to treat fungal infections. It has become a valuable addition to the antifungal arsenal, with the potential to reduce hospital length of stay and hospitalization costs and combat drug-resistant Candida species.

Targeting Fks1 proteins for novel antifungal drug discovery.

Fungal infections are a major threat to human health. The limited availability of antifungal drugs, the emergence of drug resistance, and a growing susceptible population highlight the critical need for novel antifungal agents. The enzymes involved in fungal cell wall synthesis offer potential targets for antifungal drug development. Recent studies have enhanced our focus on the enzyme Fks1, which synthesizes ß-1,3-glucan, a critical component of the cell wall. These studies provide a deeper understanding of Fks1's function in cell wall biosynthesis, pathogenicity, structural biology, evolutionary conservation across fungi, and interaction with current antifungal drugs. Here, we discuss the role of Fks1 in the survival and adaptation of fungi, guided by insights from evolutionary and structural analyses. Furthermore, we delve into the dynamics of Fks1 modulation with novel antifungal strategies and assess its potential as an antifungal drug target.

Echinocandin persistence directly impacts the evolution of resistance and survival of the pathogenic fungus Candida glabrata.

Recent epidemiological studies documented an alarming increase in the prevalence of echinocandin-resistant (ECR) Candida glabrata blood isolates. ECR isolates are known to arise from a minor subpopulation of a clonal population, termed echinocandin persisters. Although it is believed that isolates with a higher echinocandin persistence (ECP) are more likely to develop ECR, the implication of ECP needs to be better understood. Moreover, replacing laborious and time-consuming traditional approaches to determine ECP levels with rapid, convenient, and reliable tools is imperative to advance our understanding of this emerging concept in clinical practice. Herein, using extensive ex vivo and in vivo systemic infection models, we showed that high ECP isolates are less effectively cleared by micafungin treatment and exclusively give rise to ECR colonies. Additionally, we developed a flow cytometry-based tool that takes advantage of a SYTOX-based assay for the stratification of ECP levels. Once challenged with various collections of echinocandin-susceptible blood isolates, our assay reliably differentiated ECP levels in vitro and predicted ECP levels in real time under ex vivo and in vivo conditions when compared to traditional methods relying on colony-forming unit counting. Given the high and low ECP predictive values of 92.3% and 82.3%, respectively, our assay showed a high agreement with traditional approach. Collectively, our study supports the concept of ECP level determination in clinical settings and provides a robust tool scalable for high-throughput settings. Application of this tool facilitates the interrogation of mutant and drug libraries to further our understanding of persister biology and designing anti-persister therapeutics. IMPORTANCE: Candida glabrata is a prevalent fungal pathogen able to replicate inside macrophages and rapidly develop resistance against frontline antifungal echinocandins. Multiple studies have shown that echinocandin resistance is fueled by the survival of a small subpopulation of susceptible cells surviving lethal concentrations of echinocandins. Importantly, bacterial pathogens that exhibit high antibiotic persistence also impose a high burden and generate more antibiotic-resistant colonies. Nonetheless, the implications of echinocandin persistence (ECP) among the clinical isolates of C. glabrata have not been defined. Additionally, ECP level determination relies on a laborious and time-consuming method, which is prone to high variation. By exploiting in vivo systemic infection and ex vivo models, we showed that C. glabrata isolates with a higher ECP are associated with a higher burden and more likely develop echinocandin resistance upon micafungin treatment. Additionally, we developed an assay that reliably determines ECP levels in real time. Therefore, our study identified C. glabrata isolates displaying high ECP levels as important entities and provided a reliable and convenient tool for measuring echinocandin persistence, which is extendable to other fungal and bacterial pathogens.

Efficacy and safety of caspofungin for the treatment of invasive pulmonary aspergillosis in patients with chronic obstructive pulmonary disease.

OBJECTIVES: We assessed the efficacy of a 3-week primary or salvage caspofungin regimen in patients with chronic obstructive pulmonary disease (COPD) and concomitant proven or suspected invasive pulmonary aspergillosis (IPA). METHODS: Forty-four patients were treated with an initial loading caspofungin dose of 70 mg, followed by a daily dose of 50 mg for 20 days. The main efficacy endpoint was clinical effectiveness. Secondary endpoints included the clinical efficacy of caspofungin after 1 week, therapeutic efficacy based on the European Organization for Research and Treatment of Cancer and Mycoses Study Group Education and Research Consortium (EORTC/MSG) criteria, the sensitivity of different Aspergillus strains to caspofungin in vitro, and the safety of caspofungin. RESULTS: An assessment of 42 patients in the intention-to-treat group revealed efficacy rates of 33.33% within 1 week and 38.10% within 3 weeks. According to the EORTC/MSG criteria, the treatment success rate was 38.10%. The success rate of first-line treatment was 54.76%, whereas salvage treatment had a success rate of 45.24%. No adverse events were reported among the participants. CONCLUSIONS: Caspofungin is effective and safe as an initial or salvage treatment for patients with IPA and COPD.

Rapid identification,fluconazole and micafungin susceptibility testing of Candida species from blood culture by a short incubation method.

This study aimed to develop and validate a rapid method for identification by MALDI-TOF system and determination of the susceptibility to Fluconazole and Micafungin by broth microdilution among Candidaspecies causing bloodstream infections. Subcultures from blood culture bottles were incubated for 5 hours (+/- 1h) and used to perform the tests, so that the turnaround time of rapid identification and susceptibility profile was about 5 and 24 hours, respectively. The rapid identification showed agreement of 92.05 %. Regarding the rapid broth microdilution for Fluconazole and Micafungin, the agreement was 97.06 % (p<0.001) and 100 % (p<0.001), and the Kappa coefficient was 0.91 (p<0.001) and 1.0 (p<0.001), respectively. To conclude, both rapid methods showed to be reproducible, inexpensive, easy to perform and time-saving. Thus, these methodologies could be useful to guide and adjust empirical antifungal therapy.

Clinical evaluation of antifungal de-escalation in Candida infections: A systematic review and meta-analysis.

OBJECTIVES: De-escalation (DES) from echinocandins to azoles is recommended by several medical societies in Candida infections. We summarise the evidence of DES on clinical and microbiological cure and 30-day survival and compare it with continuing the treatment with echinocandins (non-DES). METHODS: We searched MEDLINE, Embase, Web of Science and Scopus. Studies describing DES in inpatients and reporting any of the outcomes evaluated were included. Pooled estimates of the tree outcomes were calculated with a fixed or random-effects model. Heterogeneity was explored stratifying by subgroups and via meta-regression. This systematic review is registered with PROSPERO (CRD42023475486). RESULTS: Of 1853 records identified, 9 studies were included, totalling 1575 patients. Five studies stepped-down to fluconazole; one to voriconazole and three to any of azoles. The mean day of DES was 5.2 (4.6-6.5) days. The clinical cure OR was 1.29 (95% CI: 0.88-1.88); the microbiological cure 1.62 (95% CI: 0.71-3.71); and 30-day survival 2.17 (95% CI: 1.09-4.32). The 30-day survival data into subgroups showed higher effect on critically ill patients and serious-risk bias studies. Meta-regression did not identify significant effect modifiers. CONCLUSIONS: DES is a safe strategy; it showed no higher 30-day mortality and a trend towards greater clinical and microbiological cure.

Outcomes by Candida spp. in the ReSTORE Phase 3 trial of rezafungin versus caspofungin for candidemia and/or invasive candidiasis.

Rezafungin is a long-acting, intravenously administered echinocandin for the treatment of candidemia and invasive candidiasis (IC). Non-inferiority of rezafungin vs caspofungin for the treatment of adults with candidemia and/or IC was demonstrated in the Phase 3 ReSTORE study based on the primary endpoints of day 14 global cure and 30-day all-cause mortality. Here, an analysis of ReSTORE data evaluating efficacy outcomes by baseline Candida species is described. Susceptibility testing was performed for Candida species using the Clinical and Laboratory Standards Institute reference broth microdilution method. There were 93 patients in the modified intent-to-treat population who received rezafungin; 94 received caspofungin. Baseline Candida species distribution was similar in the two treatment groups; C. albicans (occurring in 41.9% and 42.6% of patients in the rezafungin and caspofungin groups, respectively), C. glabrata (25.8% and 26.6%), and C. tropicalis (21.5% and 18.1%) were the most common pathogens. Rates of global cure and mycological eradication at day 14 and day 30 all-cause mortality by Candida species were comparable in the rezafungin and caspofungin treatment groups and did not appear to be impacted by minimal inhibitory concentration (MIC) values for either rezafungin or caspofungin. Two patients had baseline isolates with non-susceptible MIC values (both in the rezafungin group: one non-susceptible to rezafungin and one to caspofungin, classified as intermediate); both were candidemia-only patients in whom rezafungin treatment was successful based on the day 30 all-cause mortality endpoint. This analysis of ReSTORE demonstrated the efficacy of rezafungin for candidemia and IC in patients infected with a variety of Candida species.

Pulmonary surfactant impacts in vitro activity of selected antifungal drugs against Candida krusei and Candida albicans.

PURPOSE: This study investigates how surfactants affect the in-vitro anti-infective efficacy of micafungin, caspofungin, anidulafungin, and amphotericin B in treating pulmonary mycoses. METHODS: MIC values for antifungal agents were determined against Candida krusei (now Pichia kudriavzevii) ATCC 6258, Candida albicans ATCC 90028, and 18 clinical isolates using the broth microdilution method in RPMI medium, following EUCAST recommendations. MIC assays included testing with and without Curosurf® surfactant at 1 mg/mL for C. krusei ATCC 6258 and all C. krusei isolates. Subsequent Time-kill studies in Sabouraud broth involved testing both C. albicans ATCC 90028 and C. krusei ATCC 6258 strains at concentrations equal their respective MIC values, with and without surfactant, using all four antifungals. CFU/mL were assessed at multiple time points up to 24 h. TKCs with different surfactant concentrations for C. krusei ATCC 6258 and mini-TKCs at various concentrations relative to the MIC of C. krusei isolates and the reference strain were conducted with micafungin, anidulafungin, and caspofungin. RESULTS: MIC results showed that 1 µg/mL surfactant reduced killing of micafungin and anidulafungin against C. krusei, while caspofungin was unaffected. Amphotericin B's MIC decreased by half. TKCs demonstrated significant effects of surfactant on micafungin and anidulafungin against C. krusei, with complete abolition of anidulafungin's activity against C. albicans. CONCLUSION: This in-vitro study highlights the concentration-dependent inhibitory effect of surfactant on antifungal activity against C. krusei and, to some extent, C. albicans, necessitating further clinical validation for invasive lung mycoses treatment.

Comparative assessment of Sensititre YeastOne and Micronaut-AM EUCAST for antifungal susceptibility testing in candidaemia isolates.

PURPOSE: Antifungal susceptibility testing (AFST) is essential to ensure appropriate antifungal therapy in candidaemia. This study compared two commercial colorimetric broth microdilution tests: Sensititre YeastOne (SYO; Thermo Scientific) and Micronaut-AM EUCAST AFST (M-AM; Bruker) for the AFST of Candida spp. MATERIAL AND METHODS: A total of 74 yeast strains, including C. albicans (n = 40) and non-albicans Candida species (NACS) (n = 34), were obtained from blood cultures of patients admitted to a tertiary care hospital in Belgium from 2017 to 2022. AFST by SYO and by M-AM were performed according to the manufacturers' protocols and interpreted using CLSI and EUCAST guidelines, respectively. Essential and categorical agreements (EA and CA), very major, major and minor discrepancies were calculated for amphotericin B, echinocandins and azoles considering SYO as the reference method. RESULTS: In total, 441 and 392 isolate-antifungal results were evaluable for EA and CA, respectively. SYO and M-AM, showed a high level of concordance for C. albicans strains, with an EA and CA ≥90 % for all tested antifungals. However, we noted significant discordances for NACS, the lowest EA were observed with micafungin (50 %) and voriconazole (58.8 %). These discrepancies were likely due to differences in the raw MIC values obtained by the two methods and the different interpretation breakpoints used by CLSI and EUCAST. CONCLUSION: Our study showed excellent agreement between SYO and M-AM for AFST of C. albicans, while the equivalency was lower for NACS. AFST method should be carefully selected, considering the results might impact the choice of antifungals for non-albicans candidaemia.

MOB-mediated regulation of septation initiation network (SIN) signaling is required for echinocandin-induced hyperseptation in Aspergillus fumigatus.

Aspergillus fumigatus is a major invasive mold pathogen and the most frequent etiologic agent of invasive aspergillosis. The currently available treatments for invasive aspergillosis are limited in both number and efficacy. Our recent work has uncovered that the ß-glucan synthase inhibitors, the echinocandins, are fungicidal against strains of A. fumigatus with defects in septation initiation network (SIN) kinase activity. These drugs are known to be fungistatic against strains with normal septation. Surprisingly, SIN kinase mutant strains also failed to invade lung tissue and were significantly less virulent in immunosuppressed mouse models. Inhibiting septation in filamentous fungi is therefore an exciting therapeutic prospect to both reduce virulence and improve current antifungal therapy. However, the SIN remains understudied in pathogenic fungi. To address this knowledge gap, we characterized the putative regulatory components of the A. fumigatus SIN. These included the GTPase, SpgA, it's two-component GTPase-activating protein, ByrA/BubA, and the kinase activators, SepM and MobA. Deletion of spgA, byrA, or bubA resulted in no overt septation or echinocandin susceptibility phenotypes. In contrast, our data show that deletion of sepM or mobA largely phenocopies disruption of their SIN kinase binding partners, sepL and sidB, respectively. Reduced septum formation, echinocandin hypersusceptibility, and reduced virulence were generated by loss of either gene. These findings provide strong supporting evidence that septa are essential not only for withstanding the cell wall disrupting effects of echinocandins but are also critical for the establishment of invasive disease. Therefore, pharmacological SIN inhibition may be an exciting strategy for future antifungal drug development.IMPORTANCESepta are important structural determinants of echinocandin susceptibility and tissue invasive growth for the ubiquitous fungal pathogen Aspergillus fumigatus. Components of the septation machinery therefore represent promising novel antifungal targets to improve echinocandin activity and reduce virulence. However, little is known about septation regulation in A. fumigatus. Here, we characterize the predicted regulatory components of the A. fumigatus septation initiation network. We show that the kinase activators SepM and MobA are vital for proper septation and echinocandin resistance, with MobA playing an essential role. Null mutants of mobA displayed significantly reduced virulence in a mouse model, underscoring the importance of this pathway for A. fumigatus pathogenesis.

Promising immunotherapeutic targets for treating candidiasis.

In the last twenty years, there has been a significant increase in invasive fungal infections, which has corresponded with the expanding population of individuals with compromised immune systems. As a result, the mortality rate linked to these infections remains unacceptably high. The currently available antifungal drugs, such as azoles, polyenes, and echinocandins, face limitations in terms of their diversity, the escalating resistance of fungi and the occurrence of significant adverse effects. Consequently, there is an urgent need to develop new antifungal medications. Vaccines and antibodies present a promising avenue for addressing fungal infections due to their targeted antifungal properties and ability to modulate the immune response. This review investigates the structure and function of cell wall proteins, secreted proteins, and functional proteins within C. albicans. Furthermore, it seeks to analyze the current advancements and challenges in macromolecular drugs to identify new targets for the effective management of candidiasis.

Evaluation of outbreak persistence caused by multidrug-resistant and echinocandin-resistant Candida parapsilosis using multidimensional experimental and epidemiological approaches.

Candida parapsilosis is known to cause severe and persistent outbreaks in clinical settings. Patients infected with multidrug-resistant C. parapsilosis (MDR Cp) isolates were identified in a large Turkish hospital from 2017-2020. We subsequently identified three additional patients infected with MDR Cp isolates in 2022 from the same hospital and two echinocandin-resistant (ECR) isolates from a single patient in another hospital. The increasing number of MDR and ECR isolates contradicts the general principle that the severe fitness cost associated with these phenotypes could prevent their dominance in clinical settings. Here, we employed a multidimensional approach to systematically assess the fitness costs of MDR and ECR C. parapsilosis isolates. Whole-genome sequencing revealed a novel MDR genotype infecting two patients in 2022. Despite severe in vitro defects, the levels and tolerances of the biofilms of our ECR and MDR isolates were generally comparable to those of susceptible wild-type isolates. Surprisingly, the MDR and ECR isolates showed major alterations in their cell wall components, and some of the MDR isolates consistently displayed increased tolerance to the fungicidal activities of primary human neutrophils and were more immunoevasive during exposure to primary human macrophages. Our systemic infection mouse model showed that MDR and ECR C. parapsilosis isolates had comparable fungal burden in most organs relative to susceptible isolates. Overall, we observed a notable increase in the genotypic diversity and frequency of MDR isolates and identified MDR and ECR isolates potentially capable of causing persistent outbreaks in the future.

Molecular epidemiology and antimicrobial resistance of vaginal Candida glabrata isolates in Namibia.

Candida glabrata is the most common non-albicans Candida species that causes vulvovaginal candidiasis (VVC). Given the intrinsically low susceptibility of C. glabrata to azole drugs, investigations into C. glabrata prevalence, fungal susceptibility profile, and molecular epidemiology are necessary to optimise the treatment of VVC. This molecular epidemiological study was conducted to determine antifungal drug profile, single nucleotide polymorphisms (SNPs) associated with phenotypic antifungal resistance and epidemic diversity of C. glabrata isolates from women with VVC in Namibia. Candida glabrata isolates were identified using phenotypic and molecular methods. Antifungal susceptibility of strains was determined for fluconazole, itraconazole, amphotericin B, and anidulafungin. Whole genome sequencing was used to determine SNPs in antifungal resistance genes and sequence type (ST) allocation. Among C. glabrata isolates, all (20/20; 100%) exhibited phenotypic resistance to the azole class antifungal drug, (fluconazole), and phenotypic susceptibility to the polyene class (amphotericin B), and the echinocandins (anidulafungin). Non-synonymous SNPs were identified in antifungal resistance genes of all fluconazole-resistant C. glabrata isolates including ERG6 (15%), ERG7 (15%), CgCDR1 (25%), CgPDR1 (60%), SNQ2 (10%), FKS1 (5.0%), FKS2 (5.0%), CgFPS1 (5.0%), and MSH2 (15%). ST15 (n = 8/20, 40%) was predominant. This study provides important insight into phenotypic and genotypic antifungal resistance across C. glabrata isolates from women with VVC in Namibia. In this study, azole resistance is determined by an extensive range of SNPs, while the observed polyene and echinocandin resistance-associated SNPs despite phenotypic susceptibility require further investigation.

Candida glabrata is inherently resistant to azole drugs. In this study, we identified a clone that was predominant in women with vulvovaginal candidiasis in Namibia, and that harboured various mutations in resistance-associated genes. This study provides important insight into antifungal resistance across C. glabrata isolates in a sub-Sahara African setting.