Regulatory Considerations in the Approval of Rezafungin (REZZAYO) for the Treatment of Candidemia and Invasive Candidiasis in Adults.

On March 22, 2023, the FDA approved rezafungin (REZZAYO) for the treatment of candidemia and invasive candidiasis in adults with limited or no alternative treatment options. Rezafungin is an echinocandin that supports weekly dosing, enabling outpatient parenteral treatment that potentially avoids the need for a central venous catheter. Approval of rezafungin was based on a single adequate and well-controlled phase 3 study designed with a Day 30 all-cause mortality primary endpoint and 20% noninferiority margin, which demonstrated that rezafungin is noninferior to the comparator echinocandin. Nonclinical studies of rezafungin in non-human primates identified a neurotoxicity safety signal; however, rezafungin's safety profile in the completed clinical studies was similar to other FDA-approved echinocandins. Here we describe the rationale for this approval and important considerations during the review process for a flexible development program intended to expedite the availability of antimicrobial therapies to treat serious infections in patients with limited treatment options.

Comparative efficacies of the three echinocandins for Candida auris candidemia: real world evidence from a tertiary centre in India.

Though echinocandins are the first line of therapy for C. auris candidemia, there is little clinical data to guide the choice of therapy within this class. This was the first study to compare the three echinocandins in terms of efficacy and outcomes for C. auris candidemia. This was a retrospective analysis of 82 episodes of candidemia caused by C. auris comparing outcomes across the three echinocandins. Majority patients in our study were treated with micafungin. Susceptibility rates were the lowest for caspofungin (35.36% resistance), with no resistance reported for the other two echinocandins. When a susceptible echinocandin was chosen, caspofungin resistance was not a factor significantly associated with mortality. Also, when a susceptible echinocandin was used for therapy, the choice within the class did not affect clinical cure, microbiological cure, or mortality (P > 0.05 for all). Failure to achieve microbiological cure (P = 0.018) and receipt of immune-modulatory therapy (P = 0.01) were significantly associated with increased mortality. Significant cost variation was noted among the echinocandins. Considering the significant cost variation, comparable efficacies can be reassuring for the prescribing physician.

This is the first study comparing efficacy of the three echinocandins in C. auris candidemia. The clinical efficacy of the three echinocandins was found to be comparable. Micafungin and anidulafungin had lower minimum inhibitory concentrations. A significant cost variation was noted.

Candidemia in Adult Patients in the ICU: A Reappraisal of Susceptibility Testing and Antifungal Therapy.

OBJECTIVE: To provide updates on the epidemiology and recommendations for management of candidemia in patients with critical illness. DATA SOURCES: A literature search using the PubMed database (inception to March 2023) was conducted using the search terms "invasive candidiasis," "candidemia," "critically ill," "azoles," "echinocandin," "antifungal agents," "rapid diagnostics," "antifungal susceptibility testing," "therapeutic drug monitoring," "antifungal dosing," "persistent candidemia," and "Candida biofilm." STUDY SELECTION/DATA EXTRACTION: Clinical data were limited to those published in the English language. Ongoing trials were identified through ClinicalTrials.gov. DATA SYNTHESIS: A total of 109 articles were reviewed including 25 pharmacokinetic/pharmacodynamic studies and 30 studies including patient data, 13 of which were randomized controlled clinical trials. The remaining 54 articles included fungal surveillance data, in vitro studies, review articles, and survey data. The current 2016 Infectious Diseases Society of America (IDSA) Clinical Practice Guideline for the Management of Candidiasis provides recommendations for selecting empiric and definitive antifungal therapies for candidemia, but data are limited regarding optimized dosing strategies in critically ill patients with dynamic pharmacokinetic changes or persistent candidemia complicated. RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE: Outcomes due to candidemia remain poor despite improved diagnostic platforms, antifungal susceptibility testing, and antifungal therapy selection for candidemia in critically ill patients. Earlier detection and identification of the species causing candidemia combined with recognition of patient-specific factors leading to dosing discrepancies are crucial to improving outcomes in critically ill patients with candidemia. CONCLUSIONS: Treatment of candidemia in critically ill patients must account for the incidence of non-albicans Candida species and trends in antifungal resistance as well as overcome the complex pathophysiologic changes to avoid suboptimal antifungal exposure.

Natural history and prognostic factors of candidemia in kidney transplant recipients: A retrospective, multinational study.

BACKGROUND: The natural history of candidemia in kidney transplant recipients (KTR) remains poorly understood. This study aimed to evaluate mortality, prognostic factors and overall graft loss after candidemia in KTRs. METHODS: This is a retrospective multicentre study enrolling all KTRs ≥15 years old with candidemia diagnosed at hospitals in Brazil, Spain and Italy from 2010 to 2020. Primary endpoints were mortality rates at 14 and 30 days. Secondary endpoints were prognostic factors of 14-day mortality and overall graft loss. RESULTS: We enrolled 93 KTRs of which 75 were from Brazil. The mean time interval from transplantation to the onset of candidemia was 45.2 ± 61.5 months. 42% of all patients were on haemodialysis, 31.3% had an episode of sepsis and 39% underwent surgery within 30 days before fungemia. European patients were more likely to receive echinocandin (32 vs. 72%, p < .001). 22.7% of Brazilian patients did not receive any antifungal before death. All-cause mortality at 14 days was higher in Brazil (41.3 vs. 11.1%, p = .016). Candida colonisation (OR 6.91 [95% CI: 1.08-44.3], p = .042) and hypotension (OR 4.87 [95% CI: 1.62-14.66], p = .005) were associated with 14-day mortality. Echinocandin treatment had a protective effect (OR 0.19 [95% CI: 0.05-0.73], p = .015). Graft loss at 90 days occurred in 48% of patients (70.7 in Brazil vs. 22.2% in Europe, p < .01). CONCLUSIONS: Candidemia in KTR is usually documented late after engraftment in patients requiring HD, surgical procedures and dysbiosis secondary to antibiotic use. Mortality was higher in Brazil. Echinocandin therapy was associated with improved survival.

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.

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.

Echinocandin Resistance in Candida auris Occurs in the Murine Gastrointestinal Tract Due to FKS1 Mutations.

Candida auris is resistant to multiple antifungal agents. This study investigated its antifungal susceptibility and explored FKS1 mutations across the isolates from mice enterically colonized with wild-type C. auris and treated with echinocandin. Resistant C. auris with FKS1 mutations, including S639F, S639Y, D642Y, R1354H, or R1354Y, were isolated and found to be micafungin- and caspofungin-resistant in vivo; however, the MICs of isolates with mutation in R1354 remained below the micafungin breakpoint in vitro.

Novel Non-Hot Spot Modification in Fks1 of Candida auris Confers Echinocandin Resistance.

We determined the echinocandin susceptibility and FKS1 genotypes of 13 clinical isolates of Candida auris that were recovered from 4 patients at a tertiary care center in Salvador, Brazil. Three isolates were categorized as echinocandin-resistant, and they harbored a novel FKS1 mutation that led to an amino acid change W691L located downstream from hot spot 1. When introduced to echinocandin-susceptible C. auris strains by CRISPR/Cas9, Fks1 W691L induced elevated MIC values to all echinocandins (anidulafungin, 16 to 32×; caspofungin, >64×; micafungin, >64×).

Crosstalk between the calcineurin and cell wall integrity pathways prevents chitin overexpression in Candida albicans.

Echinocandins such as caspofungin are frontline antifungal drugs that compromise ß-1,3 glucan synthesis in the cell wall. Recent reports have shown that fungal cells can resist killing by caspofungin by upregulation of chitin synthesis, thereby sustaining cell wall integrity (CWI). When echinocandins are removed, the chitin content of cells quickly returns to basal levels, suggesting that there is a fitness cost associated with having elevated levels of chitin in the cell wall. We show here that simultaneous activation of the calcineurin and CWI pathways generates a subpopulation of Candida albicans yeast cells that have supra-normal chitin levels interspersed throughout the inner and outer cell wall, and that these cells are non-viable, perhaps due to loss of wall elasticity required for cell expansion and growth. Mutations in the Ca2+-calcineurin pathway prevented the formation of these non-viable supra-high chitin cells by negatively regulating chitin synthesis driven by the CWI pathway. The Ca2+-calcineurin pathway may therefore act as an attenuator that prevents the overproduction of chitin by coordinating both chitin upregulation and negative regulation of the CWI signaling pathway. This article has an associated First Person interview with the first author of the paper.

Development and Validation of TaqMan Chemistry Probe-Based Rapid Assay for the Detection of Echinocandin-Resistance in Candida auris.

Candida auris is a multidrug-resistant yeast pathogen causing outbreaks in health care facilities worldwide, and the emergence of echinocandin-resistant C. auris is a concern. Currently used Clinical and Laboratory Standards Institute (CLSI) and commercial antifungal susceptibility tests (AFST) are phenotype-based, slow, and not scalable, limiting their effectiveness in the surveillance of echinocandin-resistant C. auris. The urgent need for accurate and rapid methods of assessment of echinocandin resistance cannot be overstated, as this class of antifungal drugs is preferred for patient management. We report the development and validation of a TaqMan chemistry probe-based fluorescence melt curve analysis (FMCA) following asymmetric polymerase chain reaction (PCR) to assess mutations within the hot spot one (HS1) region of FKS1, the gene responsible for encoding 1,3-ß-d-glucan synthase that is a target for echinocandins. The assay correctly identified F635C, F635Y, F635del, F635S, S639F or S639Y, S639P, and D642H/R645T mutations. Of these mutations, F635S and D642H/R645T were not involved in echinocandin resistance, while the rest were, as confirmed by AFST. Of 31 clinical cases, the predominant mutation conferring echinocandin resistance was S639F/Y (20 cases) followed by S639P (4 cases), F635del (4 cases), F635Y (2 cases), and F635C (1 case). The FMCA assay was highly specific and did not cross-react with closely and distantly related Candida and other yeast and mold species. Structural modeling of the Fks1 protein, its mutants, and docked conformations of three echinocandin drugs suggest a plausible Fks1 binding orientation for echinocandins. These findings lay the groundwork for future evaluations of additional FKS1 mutations and their impact on the development of drug resistance. The TaqMan chemistry probe-based FMCA would allow rapid, high throughput, and accurate detection of FKS1 mutations conferring echinocandin resistance in C. auris.

Whole-genome sequencing of Candida haemulonii species complex from Brazil and the United States: Genetic diversity and antifungal susceptibility.

Candida haemulonii complex species can be multidrug-resistant and cause infections such as candidemia. This study determined the genetic relationship between isolates from Brazil and the United States through whole-genome sequencing and performed antifungal susceptibility testing to investigate drug resistance. Contrary to what is widely described, most isolates were susceptible to azoles. However, an atypical susceptibility profile was found in 50% of Candida pseudohaemulonii strains, including resistance to the three echinocandins. Isolates from both countries formed distinct clusters with wide genetic diversity. Isolates from three hospitals in Brazil were clonal and involved in candidemia cases, pointing to the importance of improving hospital infection control measures and molecular identification.

Candida haemulonii complex species is worldwide distributed, and this study aimed to evaluate the resistance to antifungal drugs in cases from Brazil and the United States, and also compare their genetic relationships. A total of 50 strains were studied; most of them from Brazil were from cases of bloodstream infections, while the strains from the United States came from cases of wounds and may be associated with diabetic patients. The vast majority of strains were resistant to amphotericin B, one of the most effective drugs, and susceptible to fluconazole. In addition, 50% of C. pseudohaemulonii strains were resistant to echinocandins. The strains from Brazil and the United States had no genetic relationship and formed two distinct groups. In three Brazilian hospitals, strains were clonal, indicating an intra-hospital transmission. Our findings contribute to guiding therapy in bloodstream fungal infections caused by C. haemulonii species and alerting for nosocomial transmission of this yeast complex species.

Critical appraisal beyond clinical guidelines for intraabdominal candidiasis.

BACKGROUND: Regardless of the available antifungals, intraabdominal candidiasis (IAC) mortality continues to be high and represents a challenge for clinicians. MAIN BODY: This opinion paper discusses alternative antifungal options for treating IAC. This clinical entity should be addressed separately from candidemia due to the peculiarity of the required penetration of antifungals into the peritoneal cavity. Intraabdominal concentrations may be further restricted in critically ill patients where pathophysiological facts alter normal drug distribution. Echinocandins are recommended as first-line treatment in guidelines for invasive candidiasis. However, considering published data, our pharmacodynamic analysis suggests the required increase of doses, postulated by some authors, to attain adequate pharmacokinetic (PK) levels in peritoneal fluid. Given the limited evidence in the literature on PK/PD-based treatments of IAC, an algorithm is proposed to guide antifungal treatment. Liposomal amphotericin B is advocated as first-line therapy in patients with sepsis/septic shock presenting candidemia or endophthalmitis, or with prior exposure to echinocandins and/or fluconazole, or with infections by Candida glabrata. Other situations and alternatives, such as new compounds or combination therapy, are also analysed. CONCLUSION: There is a critical need for more robust clinical trials, studies examining patient heterogeneity and surveillance of antifungal resistance to enhance patient care and optimise treatment outcomes. Such evidence will help refine the existing guidelines and contribute to a more personalised and effective approach to treating this serious medical condition. Meanwhile, it is suggested to broaden the consideration of other options, such as liposomal amphotericin B, as first-line treatment until the results of the fungogram are available and antifungal stewardship could be implemented to prevent the development of resistance.

Species distribution and antifungal susceptibility of clinical Aspergillus isolates: A multicentre study in Taiwan, 2016-2020.

BACKGROUND: Epidemiological knowledge is important to guide antifungal therapy. OBJECTIVE: This multicentre study aimed to investigate the species distribution and antifungal susceptibility of Aspergillus isolates in Taiwan. METHOD: Four hundred and ninety-two clinical Aspergillus isolates, collected during 2016-2020, were identified by calmodulin sequencing and tested for antifungal susceptibility using CLSI M38-A3. The Cyp51A sequences of azole-resistant Aspergillus fumigatus and Aspergillus flavus isolates were analysed. RESULTS: This collection comprised 30 species from eight Aspergillus sections-Flavi (33.5%), Nigri (26.0%), Fumigati (24.2%), Terrei (10.0%), Nidulantes (5.1%), Circumdati (0.8%), Restricti (0.2%) and Aspergillus (0.2%). Sections Fumigati, Flavi and Terrei were primarily represented by A. fumigatus (99.2%), A. flavus (95.8%) and A. terreus (100%), respectively. Section Nigri comprised nine species, mostly A. welwitschiae (60.2%), A. niger (12.5%), A. brunneoviolaceus (10.9%) and A. tubingensis (10.2%). A. fumigatus (39.6%) and A. flavus (26.4%) predominated among 53 isolates from lower respiratory samples, whereas section Nigri species (46.2%) and A. terreus (29.2%) predominated among 65 isolates from ear samples. Reduced susceptibility to amphotericin B (minimal inhibitory concentration (MIC) > 1 µg/mL) was noted in A. flavus (7.0%), A. terreus (6.1%), A. nidulans and section Circumdati (A. flocculosus, A. subramanianii and A. westerdijkiae) isolates. Acquired azole resistance was observed in seven A. fumigatus (5.9%), all of which carried TR34 /L98H or TR34 /L98H/S297T/F495I mutation, and three A. flavus (1.9%), one of which carried G441S mutation. Reduced susceptibility to itraconazole (MIC >1 µg/mL) was noted in 55.5% of section Nigri isolates, mainly in A. welwitschiae, A. niger and A. tubingensis, whereas A. brunneoviolaceus, A. aculeatinus and A. japonicus were hypersusceptible to azoles. Anidulafungin was active against all isolates except for one isolate. CONCLUSIONS: This study depicted the molecular epidemiology and species-specific characteristics of Aspergillus in Taiwan, which aids in appropriate antifungal therapy and underlines the need of speciation and susceptibility testing of disease-causing Aspergillus.

Analysis of the Localization of Schizosaccharomyces pombe Glucan Synthases in the Presence of the Antifungal Agent Caspofungin.

In recent years, invasive fungal infections have emerged as a common source of infections in immunosuppressed patients. All fungal cells are surrounded by a cell wall that is essential for cell integrity and survival. It prevents cell death and lysis resulting from high internal turgor pressure. Since the cell wall is not present in animal cells, it is an ideal target for selective invasive fungal infection treatments. The antifungal family known as echinocandins, which specifically inhibit the synthesis of the cell wall ß(13)glucan, has been established as an alternative treatment for mycoses. To explore the mechanism of action of these antifungals, we analyzed the cell morphology and glucan synthases localization in Schizosaccharomyces pombe cells during the initial times of growth in the presence of the echinocandin drug caspofungin. S. pombe are rod-shaped cells that grow at the poles and divide by a central division septum. The cell wall and septum are formed by different glucans, which are synthesized by four essential glucan synthases: Bgs1, Bgs3, Bgs4, and Ags1. Thus, S. pombe is not only a perfect model for studying the synthesis of the fungal ß(1-3)glucan, but also it is ideal for examining the mechanisms of action and resistance of cell wall antifungals. Herein, we examined the cells in a drug susceptibility test in the presence of either lethal or sublethal concentrations of caspofungin, finding that exposure to the drug for long periods at high concentrations (>10 µg/mL) induced cell growth arrest and the formation of rounded, swollen, and dead cells, whereas low concentrations (<10 µg/mL) permitted cell growth with a mild effect on cell morphology. Interestingly, short-term treatments with either high or low concentrations of the drug induced effects contrary to those observed in the susceptibility tests. Thus, low drug concentrations induced a cell death phenotype that was not observed at high drug concentrations, which caused transient fungistatic cell growth arrest. After 3 h, high concentrations of the drug caused the following: (i) a decrease in the GFP-Bgs1 fluorescence level; (ii) altered locations of Bgs3, Bgs4, and Ags1; and (iii) a simultaneous accumulation of cells with calcofluor-stained incomplete septa, which at longer times resulted in septation uncoupling from plasma membrane ingression. The incomplete septa revealed with calcofluor were found to be complete when observed via the membrane-associated GFP-Bgs or Ags1-GFP. Finally, we found that the accumulation of incomplete septa depended on Pmk1, the last kinase of the cell wall integrity pathway.

Impact of FKS1 Genotype on Echinocandin In Vitro Susceptibility in Candida auris and In Vivo Response in a Murine Model of Infection.

Echinocandins are frontline antifungal agents in the management of invasive infections due to multidrug resistant Candida auris. The study aimed to evaluate echinocandin resistance in C. auris isolates of multicentric origin, identify the resistance mechanism, and analyze the pharmacodynamic response to caspofungin in a neutropenic mouse model of infection. A total of 199 C. auris isolates originating from 30 centers across India were tested for susceptibility to echinocandins. Isolates with reduced susceptibility were evaluated for FKS1 mutations and in vivo response to caspofungin in a murine model of disseminated candidiasis. In addition, the response to echinocandins was assessed in light of in vitro growth kinetics, chitin content; and transcript levels of chitin synthase and FKS1 genes. We report 10 resistant C. auris isolates with four FKS1 mutations: F635Y (n = 2), F635L (n = 4), S639F (n = 3), and R1354S (n = 1). Of these, F635Y and R1354S exhibited the most profound resistance in mouse model of disseminated infection. S639F and F635L mutations conferred a moderate in vivo resistance, whereas wild-type isolates exhibiting borderline MIC were susceptible in vivo. FKS1 genotype was more accurate predictor of in vivo response than the MIC of the isolates. Isolates with high basal or inducible chitin content exhibited higher in vitro MIC in FKS1 mutant compared to wild type. FKS1 mutations play a major role in clinically relevant echinocandin resistance in C. auris with differential in vivo outcomes. This study could have implications for clinical practice and, therefore, warrants further studies.

Echinocandins and Their Activity against Aspergillus terreus Species Complex: a Novel Agar Screening Method.

We evaluated the newly proposed agar screening method for echinocandin susceptibility testing of 144 Aspergillus section Terrei isolates compared with the Etest method. Both methods defined the isolates to be wild-type strains for anidulafungin and micafungin, with Etest minimal effective concentrations (MECs) of ≤0.004 mg/L. For caspofungin, the novel agar screening method identified 37 isolates to be caspofungin non-wild type based on their fluffy colony appearance on caspofungin agar. Etest MECs for caspofungin for these isolates were scattered widely from 0.002 to 0.750 mg/L, showing only partial accordance between the two methods.

Highly Conserved gsc1 Gene of Pneumocystis jirovecii in Patients with or without Prior Exposure to Echinocandins.

Echinocandins are noncompetitive inhibitors of the GSC1 subunit of the enzymatic complex involved in synthesis of 1,3-beta-d-glucan, a cell wall component of most fungi, including Pneumocystis spp. Echinocandins are widely used for treating systemic candidiasis and rarely used for treating Pneumocystis pneumonia. Consequently, data on P. jirovecii gsc1 gene diversity are still scarce compared to that for the homologous fks1 gene of Candida spp. In this study, we analyzed P. jirovecii gsc1 gene diversity and the putative selection pressure of echinocandins on P. jirovecii. gsc1 gene sequences of P. jirovecii specimens from two patient groups were compared. One group of 27 patients had prior exposure to echinocandins, whereas the second group of 24 patients did not, at the time of P. jirovecii infection diagnoses. Two portions of the P. jirovecii gsc1 gene, HS1 and HS2, homologous to hot spots described in Candida spp., were sequenced. Three single-nucleotide polymorphisms (SNPs) at positions 2204, 2243, and 2303 close to the HS1 region and another SNP at position 4540 more distant from the HS2 region were identified. These SNPs represent synonymous mutations. Three gsc1 HS1 alleles, A, B, and C, and two gsc1 HS2 alleles, a and b, and four haplotypes, Ca, Cb, Aa, and Ba, were defined, without significant difference in haplotype distribution in both patient groups (P = 0.57). Considering the identical diversity of P. jirovecii gsc1 gene and the detection of synonymous mutations in both patient groups, no selection pressure of echinocandins among P. jirovecii microorganisms can be pointed out so far.

Candida auris Pan-Drug-Resistant to Four Classes of Antifungal Agents.

Candida auris is an urgent antimicrobial resistance threat due to its global emergence, high mortality, and persistent transmissions. Nearly half of C. auris clinical and surveillance cases in the United States are from the New York and New Jersey Metropolitan area. We performed genome, and drug-resistance analysis of C. auris isolates from a patient who underwent multi-visceral transplantation. Whole-genome comparisons of 19 isolates, collected over 72 days, revealed closed similarity (Average Nucleotide Identity > 0.9996; Aligned Percentage > 0.9764) and a distinct subcluster of NY C. auris South Asia Clade I. All isolates had azole-linked resistance in ERG11(K143R) and CDR1(V704L). Echinocandin resistance first appeared with FKS1(S639Y) mutation and then a unique FKS1(F635C) mutation. Flucytosine-resistant isolates had mutations in FCY1, FUR1, and ADE17. Two pan-drug-resistant C. auris isolates had uracil phosphoribosyltransferase deletion (FUR1[1Δ33]) and the elimination of FUR1 expression, confirmed by a qPCR test developed in this study. Besides ERG11 mutations, four amphotericin B-resistant isolates showed no distinct nonsynonymous variants suggesting unknown genetic elements driving the resistance. Pan-drug-resistant C. auris isolates were not susceptible to two-drug antifungal combinations tested by checkerboard, Etest, and time-kill methods. The fungal population pattern, discerned from SNP phylogenetic analysis, was consistent with in-hospital or inpatient evolution of C. auris isolates circulating locally and not indicative of a recent introduction from elsewhere. The emergence of pan-drug-resistance to four major classes of antifungals in C. auris is alarming. Patients at high risk for drug-resistant C. auris might require novel therapeutic strategies and targeted pre-and/or posttransplant surveillance.

The effect of antifungal resistance development on the virulence of Candida species.

In recent years, the relevance of diseases associated with fungal pathogens increased worldwide. Members of the Candida genus are responsible for the greatest number of fungal bloodstream infections every year. Epidemiological data consistently indicate a modest shift toward non-albicans species, albeit Candidaalbicans is still the most recognizable species within the genus. As a result, the number of clinically relevant pathogens has increased, and, despite their distinct pathogenicity features, the applicable antifungal agents remained the same. For bloodstream infections, only three classes of drugs are routinely used, namely polyenes, azoles and echinocandins. Antifungal resistance toward all three antifungal drug classes frequently occurs in clinical settings. Compared with the broad range of literature on virulence and antifungal resistance of Candida species separately, only a small portion of studies examined the effect of resistance on virulence. These studies found that resistance to polyenes and echinocandins concluded in significant decrease in the virulence in different Candida species. Meanwhile, in some cases, resistance to azole type antifungals resulted in increased virulence depending on the species and isolates. These findings underline the importance of studies aiming to dissect the connections of virulence and resistance in Candida species.

Impact of COVID-19 on the antifungal susceptibility profiles of isolates collected in a global surveillance program that monitors invasive fungal infections.

Studies demonstrated the impact of the COVID-19 pandemic in the prevalence and susceptibility profiles of bacterial and fungal organisms. We analyzed 4821 invasive fungal isolates collected during 2018, 2019, and 2020 in 48 hospitals worldwide to evaluate the impact of this event in the occurrence and susceptibility rates of common fungal species. Isolates were tested using the CLSI broth microdilution method. While the percentage of total isolates that were C. glabrata (n = 710 isolates) or C. krusei (n = 112) slightly increased in 2020, the percentage for C. parapsilosis (n = 542), A. fumigatus (n = 416), and C. lusitaniae (n = 84) significantly decreased (P < .05). Fluconazole resistance in C. glabrata decreased from 5.8% in 2018-2019 to 2.0% in 2020, mainly due to fewer hospitals in the US having these isolates (5 vs. 1 hospital). Conversely, higher fluconazole-resistance rates were noted for C. parapsilosis (13.9 vs. 9.8%) and C. tropicalis (3.5 vs. 0.7%; P < .05) during 2020. Voriconazole resistance also increased for these species. Echinocandin resistance was unchanged among Candida spp. Voriconazole susceptibility rates in A. fumigatus were similar in these two periods (91.7% in 2018 and 2019 vs. 93.0% in 2020). Changes were also noticed in the organisms with smaller numbers of collected isolates. We observed variations in the occurrence of organisms submitted to a global surveillance and the susceptibility patterns for some organism-antifungal combinations. As the COVID-19 pandemic is still ongoing, the impact of this event must continue to be monitored to guide treatment of patients affected by bacterial and fungal infections. LAY SUMMARY: Secondary infections were documented in COVID-19 patients. We compared the prevalence of invasive fungal isolates consecutively collected in 48 worldwide hospitals and their susceptibility patterns between 2020, the year of the global COVID-19 pandemic, and the two prior years.