Clinical Characteristics of Candidemia Due to Candida parapsilosis with Serial Episodes: Insights from 5-Year Data Collection at a Tertiary Hospital in Korea.

Candida parapsilosis is a common cause of non-albicans Candida species causing candidemia, particularly invasive candidiasis. This study aimed to characterize candidemia due to the C. parapsilosis complex with serial episodes, including clinical and mycological features. METHODS: Blood isolates of the C. parapsilosis complex were collected from February 2019 to January 2023 at a tertiary Korean hospital. Species identification was performed using Vitek 2 or matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and antifungal susceptibility testing was performed using the Sensititre YeastOne® system. Clinical information was collected, and characteristics were analyzed according to single or serial isolates. RESULTS: A total of 586 blood isolates of the C. parapsilosis complex were recovered from 68 candidemia patients during the study period. Of them, only the first isolate per patient was investigated. The only two isolates were resistant to fluconazole and no isolate was resistant to echinocandins, amphotericin B, or 5-FC. A single episode of candidemia occurred in 35 patients, while serial episodes occurred in 33 patients. Underlying liver diseases, use of vasopressors, ICU admission, severe sepsis, and CVC use were more frequent in patients with serial episodes. There was no significant difference in the median MIC values of antifungal agents or the use of azoles or amphotericin B between single and serial episodes. However, patients with serial episodes more frequently received echinocandin therapy. Overall, there was no significant difference in the 30-day mortality rate between patients with single and serial episodes. CONCLUSION: Our data indicate that several factors related to the underlying conditions of the patients are associated with C. parapsilosis candidemia with serial episodes, rather than the characteristics of Candida itself.

Evaluation of clinical outcomes of anidulafungin for the treatment of candidemia in hospitalized critically ill patients with obesity: A multicenter, retrospective cohort study.

OBJECTIVES: To evaluate the clinical outcomes of anidulafungin for candidemia treatment in critically ill obese patients. METHOD: A multicenter, retrospective cohort study was conducted in Saudi Arabia for critically ill adults with candidemia who received anidulafungin. Patients with obesity have a body mass index ≥ 30 kg/m2. The primary outcome was the clinical cure rate. RESULTS: 146 patients were included, 64 of whom were obese. There were no statistically significant differences in the clinical cure rate (P=0.63), microbiological cure rate (P=0.27), or the median time for a clinical cure (P=0.13) for patients with obesity compared to non-obese. The median time for a microbiological cure was longer in non-obese patients than in patients with obesity (P=0.04). The median hospital length of stay (LOS) and the median mechanical ventilation (MV) durations were numerically longer in obese patients. CONCLUSION: Clinical and microbiological cure rates and time for clinical cure were statistically similar for both groups. Considering the study's limitations (especially with a small sample size), it is uncertain if patients with obesity have similar effectiveness to non-obese patients. Future studies with larger sample sizes are warranted to evaluate if obesity negatively impacts anidulafungin's clinical outcomes for candidemia.

Comparative evaluation of Sensititre YeastOne and CLSI M38-Ed3 reference method for determining echinocandin minimum effective concentrations against Aspergillus isolates.

The minimum inhibitory concentration (MIC) of echinocandins against Aspergillus spp. does not represent the actual inhibition threshold of echinocandins. Therefore, the recommended method to evaluate their activity is determining the minimum effective concentration (MEC) in broth microdilution, a method that is less common in clinical settings. This study aimed to assess a user-friendly commercial method, Sensititre YeastOne (SYO), to determine the effectiveness of echinocandins (caspofungin, anidulafungin and micafungin) against Aspergillus spp. Echinocandins MEC was determined against 23 isolates of Aspergillus spp. using SYO and the reference Clinical and Laboratory Standards Institute (CLSI) method. MECs were read with an inverted microscope and a reading mirror. Essential agreement (EA) between the tested methods was defined as a ±twofold dilution difference. There was a high EA (91%-100%) between the reference method and SYO in determining echinocandins MEC against Aspergillus isolates using inverted microscopy. A high EA was also observed between SYO MEC determined by inverted microscopy and a reading mirror, but different incubation times were required. SYO is a reliable, simple method for determining the MEC of echinocandins against Aspergillus isolates, preferably with an inverted microscope, and can be easily used in clinical laboratories when echinocandin susceptibility testing is required.IMPORTANCEUsing a commercial method such as Sensititre YeastOne (SYO) to determine the minimum effective concentration (MEC) of echinocandins against Aspergillus spp. has been shown to be a reliable alternative to the Clinical and Laboratory Standards Institute (CLSI) reference method. This makes it more suitable for high-volume clinical laboratories. SYO provides accurate results comparable to the standard method and could potentially improve patient care by guiding more optimal antifungal treatment choices for patients with Aspergillus infections.

Trimethoprim-sulfamethoxazole combined with echinocandins versus trimethoprim-sulfamethoxazole alone for Pneumocystis pneumonia in patients without human immunodeficiency virus infection: A nationwide retrospective cohort study.

BACKGROUND: Although combination therapy of echinocandins with trimethoprim-sulfamethoxazole (TMP-SMX) has been reported for patients with Pneumocystis jirovecii pneumonia (PCP), the effectiveness of this combination therapy in patients with PCP without human immunodeficiency virus (HIV) infection remains unknown. METHODS: Data from the Japanese Diagnosis Procedure Combination inpatient database was used to identify non-HIV patients who underwent their first hospitalisation for PCP between April 2012 and March 2022. The patients were divided into those treated with TMP-SMX alone and those treated with TMP-SMX combined with echinocandins. We performed propensity-score overlap-weighting analysis to estimate in-hospital mortality. RESULTS: Among the 1324 eligible patients, 122 received TMP-SMX plus echinocandins, while 1202 received TMP-SMX alone. The propensity-score overlap-weighting analysis showed that the combination therapy was not associated with reduced in-hospital mortality in comparison with TMP-SMX alone (22.2 % vs. 26.9 %; risk difference, 4.6 %; 95 % confidence interval, -6.1 %-15.3 %; P = 0.398). CONCLUSIONS: Echinocandins combined with TMP-SMX may not improve in-hospital mortality due to PCP in patients without HIV infection.

Treatment Outcomes Among Patients With a Positive Candida Culture Close to Randomization Receiving Rezafungin or Caspofungin in the ReSTORE Study.

BACKGROUND: Rezafungin, a novel, once-weekly echinocandin for the treatment of candidemia and/or invasive candidiasis (IC) was noninferior to caspofungin for day 30 all-cause mortality (ACM) and day 14 global cure in the phase 3 ReSTORE trial (NCT03667690). We conducted preplanned subgroup analyses for patients with a positive culture close to randomization in ReSTORE. METHODS: ReSTORE was a multicenter, double-blind, double-dummy, randomized trial in patients aged ≥18 years with candidemia and/or IC treated with once-weekly intravenous rezafungin (400 mg/200 mg) or once-daily intravenous caspofungin (70 mg/50 mg). This analysis comprised patients with a positive blood culture drawn between 12 hours before and 72 hours after randomization or a positive culture from another normally sterile site sampled between 48 hours before and 72 hours after randomization. Efficacy endpoints included day 30 ACM, day 14 global cure rate, and day 5 and 14 mycological response. Adverse events were evaluated. RESULTS: This analysis included 38 patients randomized to rezafungin and 46 to caspofungin. In the rezafungin and caspofungin groups, respectively, day 30 ACM was 26.3% and 21.7% (between-group difference [95% confidence interval], 4.6% [-13.7%, 23.5%]), day 14 global response was 55.3% and 50.0% (between-group difference, 5.3% [-16.1%, 26.0%]), and day 5 mycological eradication was 71.1% and 50.0% (between-group difference, 21.1% [-0.2%, 40.2%]). Safety was comparable between treatments. CONCLUSIONS: These findings support the efficacy and safety of rezafungin compared with caspofungin for the treatment of candidemia and/or IC in patients with a positive culture close to randomization, with potential early treatment benefits for rezafungin.

Evolutionary accumulation of FKS1 mutations from clinical echinocandin-resistant Candida auris.

INTRODUCTION: Drug resistance to echinocandins, first-line drugs used to treat Candida auris infection, is rapidly emerging. However, the accumulation of mutations in genes other than FKS1 (before an isolate develops to resistance via FKS1 mutations), remains poorly understood. Methods: Four clinical cases and 29 isolates associated with the incremental process of echinocandin resistance were collected and analyzed using antifungal drug susceptibility testing and genome sequencing to assess the evolution of echinocandin resistance. FINDINGS: Six echinocandin minimum inhibitory concentration (MIC)-elevated C. auris strains and seven resistant strains were isolated from the urinary system of patients receiving echinocandin treatment. Meanwhile, phylogenetic analyses illustrated that the echinocandin-resistant strains were closely related to other strains in the same patient. Genomic data revealed that the echinocandin-resistant strains had FKS1 mutations. Furthermore, three categories (ECN-S/E/R) of non-synonymous mutant SNP genes (such as RBR3, IFF6, MKC1, MPH1, RAD2, and MYO1) in C. auris appeared to be associated with the three-stage-evolutionary model of echinocandin resistance in C. glabrata: cell wall stress, drug adaptation, and genetic escape (FKS mutation). INTERPRETATION: Echinocandin-resistant C. auris undergoes spatial and temporal phase changes closely related to echinocandin exposure, particularly in the urinary system. These findings suggest that FKS1 mutations mediate an evolutionary accumulation of echinocandin resistance followed by modulation of chromosome remodelling and DNA repair processes that ultimately lead to FKS1 hot spot mutations and the development of drug resistance. This study provides an in-depth exploration of the molecular pathways involved in the evolution of Candida auris echinocandin resistance.

Safety, tolerability, and pharmacokinetics of HRS9432(A) injection in healthy Chinese subjects: a phase-I randomized, double-blind, dose escalation, placebo-controlled study.

HRS9432(A) is a long-acting echinocandin antifungal medication primarily used to treat invasive fungal infections, particularly invasive candidiasis. The safety, tolerability, and pharmacokinetic characteristics of HRS9432(A) injection were investigated in a randomized, double-blind, placebo-controlled, single- and multiple-ascending-dose Phase I study involving 56 healthy adult subjects. Doses ranging from 200 to 1200 mg were administered. Safety was continually monitored, including adverse events, clinical laboratory examinations, vital signs, 12-lead electrocardiograms, and physical examinations, while the pharmacokinetic profile within the body was evaluated. The results indicated that concentrations of HRS9432 peaked immediately after infusion, demonstrating essentially linear pharmacokinetic characteristics within the dosage range of 200-1,200 mg. It exhibited a low clearance rate and an extended half-life, with a clearance of approximately 0.2 L/h, a volume of distribution of around 40 L, and a half-life of approximately 140h following a single dose. The accumulation index for AUC0-τ after multiple doses ranged from 1.41 to 1.75. No severe adverse events occurred during the study, and the severity of all adverse events was mild or moderate. Therefore, the intravenous administration of HRS9432(A) in healthy Chinese adult subjects, either as multiple infusions of 200 to 600 mg (once a week, four doses) or as a single infusion of 900-1,200 mg, demonstrated overall good safety and tolerability. The pharmacokinetic exhibited essentially linear characteristics in the body, supporting a weekly dosing frequency for clinical applications and providing additional options for the treatment or prevention of invasive fungal infections. CLINICAL TRIALS: This study is registered with the International Clinical Trials Registry Platform as ChiCTR2300073525.

Antifungal resistance: why are we losing this battle?

The emergence of fungal pathogens and changes in the epidemiological landscape are prevalent issues in clinical mycology. Reports of resistance to antifungals have been reported. This review aims to evaluate molecular and nonmolecular mechanisms related to antifungal resistance. Mutations in the ERG genes and overexpression of the efflux pump (MDR1, CDR1 and CDR2 genes) were the most reported molecular mechanisms of resistance in clinical isolates, mainly related to Azoles. For echinocandins, a molecular mechanism described was mutation in the FSK genes. Furthermore, nonmolecular virulence factors contributed to therapeutic failure, such as biofilm formation and selective pressure due to previous exposure to antifungals. Thus, there are many public health challenges in treating fungal infections.

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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.

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.

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.

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.

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.

Necrotizing pancreatitis with invasive candidiasis and candidemia due to Candida albicans and pan-echinocandin-resistant Candidaglabrata.

We report on a 64-year-old man with necrotizing pancreatitis related, invasive candidiasis, and candidemia. Despite a multidisciplinary management including antifungal therapy, endoscopic interventions and surgery, the patients' infection progressed and lead to colon perforation, retroperitoneal abscess formation, and polymicrobial bloodstream infections. Resistance to echinocandins in Candida glabrata further complicated the course. This report emphasizes the need for vigilant monitoring and exploring alternative therapeutic approaches for patients in critical conditions.

Candida albicans Genes Modulating Echinocandin Susceptibility of Caspofungin-Adapted Mutants Are Constitutively Expressed in Clinical Isolates with Intermediate or Full Resistance to Echinocandins.

The opportunistic fungus Candida albicans is the leading cause of invasive candidiasis in immune-compromised individuals. Drugs from the echinocandin (ECN) class, including caspofungin, are used as a first line of therapy against invasive candidiasis. The only known mechanism of clinical resistance to ECNs is point mutations in the FKS1 gene, which encodes the drug target. However, many clinical isolates developed decreased ECN susceptibilities in the absence of resistance-associated FKS1 mutations. We have identified 15 C. albicans genes that contribute to decreased drug susceptibility. We explored the expression of these 15 genes in clinical isolates with different levels of ECN susceptibility. We found that these 15 genes are expressed in clinical isolates with or without FKS1 mutations, including those strains that are less susceptible to ECNs. In addition, FKS1 expression was increased in such less susceptible isolates compared to highly susceptible isolates. Similarities of gene expression patterns between isolates with decreased ECN susceptibilities in the absence of FKS1 mutations and clinically resistant isolates with mutations in FKS1 suggest that clinical isolates with decreased ECN susceptibilities may be a precursor to development of resistance.

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.

Candida glabrata hospital isolate from Lebanon reveals micafungin resistance associated with increased chitin and resistance to a cell-surface-disrupting agent.

OBJECTIVES: This study aimed to identify the resistance mechanisms to micafungin and fluconazole in a clinical isolate of Candida glabrata. METHODS: The isolate was whole-genome sequenced to identify amino acid changes in key proteins involved in antifungal resistance, and the isolate was further characterised by pathogenicity-related phenotypic assays that supported the sequencing results. RESULTS: Amino acid substitutions were detected in 8 of 17 protein candidates. Many of these substitutions were novel, including in CHS3, CHS3B, and KRE5, which are involved in the development of micafungin resistance. Regarding fluconazole resistance, overexpression of efflux pumps was observed. Our isolate did not exhibit an increased virulence potential compared with the control strain; however, a significant increase in chitin content and potential to resist the cell surface disruptant sodium dodecyl sulphate was observed. CONCLUSIONS: This clinical Candida glabrata isolate experienced a change in cell wall architecture, which correlates with the development of micafungin resistance.

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.

Therapeutic drug monitoring of antifungal therapies: do we really need it and what are the best practices?

INTRODUCTION: Despite advancements, invasive fungal infections (IFI) still carry high mortality rates, often exceeding 30%. The challenges in diagnosis, coupled with limited effective antifungal options, make managing IFIs complex. Antifungal drugs are essential for IFI management, but their efficacy can be diminished by drug-drug interactions and pharmacokinetic variability. Therapeutic Drug Monitoring (TDM), especially in the context of triazole use, has emerged as a valuable strategy to optimize antifungal therapy. AREAS COVERED: This review provides current evidence regarding the potential benefits of TDM in IFI management. It discusses how TDM can enhance treatment response, safety, and address altered pharmacokinetics in specific patient populations. EXPERT OPINION: TDM plays a crucial role in achieving optimal therapeutic outcomes in IFI management, particularly for certain antifungal agents. Preclinical studies consistently show a link between therapeutic drug levels and antifungal efficacy. However, clinical research in mycology faces challenges due to patient heterogeneity and the diversity of fungal infections. TDM's potential advantages in guiding Echinocandin therapy for critically ill patients warrant further investigation. Additionally, for drugs like Posaconazole, assessing whether serum levels or alternative markers like saliva offer the best measure of efficacy is an intriguing question.

In vitro activity of ibrexafungerp against clinically relevant echinocandin-resistant Candida strains.

Invasive candidiasis is a major hospital-acquired infection. Usually, echinocandins are considered first-line treatment. However, resistant phenotypes have emerged. Ibrexafungerp (IBX) is a new antifungal substance with potent anti-Candida activity. We challenged IBX with a library of 192 pheno-/genotypically echinocandin-resistant Candida isolates, focusing on the substance susceptibility, its activity on certain FKS hotspot (HS) mutated strains, and applying WTULs (wild-type upper limits). Therefore, a 9-year-old strain and patient data collection provided by the German National Reference Center for Invasive Fungal Infections were analyzed. Species identification was confirmed through ITS-sequencing. Molecular susceptibility testing was performed by sequencing HS of the FKS gene. Anidulafungin (AND) and IBX EUCAST-broth-microdilution was conducted. The four most common echinocandin-resistance mediating mutations were found in Candida glabrata [112/192 isolates; F659-(43×) and S663-(48×)] and Candida albicans [63/192 isolates; F641-(15×) and S645-(39×)]. Mutations at the HS-start sequence were associated with higher IBX MIC-values (F659 and F641 (MIC 50/90 mg/L: >4/>4 and 2/4 mg/L) in comparison to AND (F659 and F641 (MIC 50/90: 1/4 and 0.25/1 mg/L). MIC-values in HS-center mutations were almost equal [MIC50/90 in S663: 2/4 (AND and IBX); in S645: 0.5/1 (AND) and 0.25/1 (IBX) mg/L]. In total, 61 vs 78 of 192 echinocandin-resistant isolates may be classified as IBX wild type by applying WTULs, whereas the most prominent effect was seen in C. albicans [48% (30/63) vs 70% (44/63)]. IBX shows in vitro activity against echinocandin-resistant Candida and thus is an addition to the antifungal armory. However, our data suggest that this effect is more pronounced in C. albicans and strains harboring mutations, affecting the HS-center.