Antifungal Activity and Potential Action Mechanism of Allicin against Trichosporon asahii.

Trichosporon asahii is an emerging opportunistic pathogen that causes potentially fatal disseminated trichosporonosis. The global prevalence of coronavirus disease 2019 (COVID-19) poses an increasing fungal infection burden caused by T. asahii. Allicin is the main biologically active component with broad-spectrum antimicrobial activity in garlic. In this study, we performed an in-depth analysis of the antifungal characteristics of allicin against T. asahii based on physiological, cytological, and transcriptomic assessments. In vitro, allicin inhibited the growth of T. asahii planktonic cells and biofilm cells significantly. In vivo, allicin improved the mean survival time of mice with systemic trichosporonosis and reduced tissue fungal burden. Electron microscopy observations clearly demonstrated damage to T. asahii cell morphology and ultrastructure caused by allicin. Furthermore, allicin increased intracellular reactive oxygen species (ROS) accumulation, leading to oxidative stress damage in T. asahii cells. Transcriptome analysis showed that allicin treatment disturbed the biosynthesis of cell membrane and cell wall, glucose catabolism, and oxidative stress. The overexpression of multiple antioxidant enzymes and transporters may also place an additional burden on cells, causing them to collapse. Our findings shed new light on the potential of allicin as an alternative treatment strategy for trichosporonosis. IMPORTANCE Systemic infection caused by T. asahii has recently been recognized as an important cause of mortality in hospitalized COVID-19 patients. Invasive trichosporonosis remains a significant challenge for clinicians, due to the limited therapeutic options. The present work suggests that allicin holds great potential as a therapeutic candidate for T. asahii infection. Allicin demonstrated potent in vitro antifungal activity and potential in vivo protective effects. In addition, transcriptome sequencing provided valuable insights into the antifungal effects of allicin.

Assessment of Risk Factors and Clinical Outcomes in Hospitalized COVID-19 Patients with Candida spp. Co-infections: Species Distribution and Antifungal Susceptibility Patterns of Isolates.

INTRODUCTION: Fungal co-infections are considered an important complication in hospitalized patients with SARS-CoV-2 that can be attributed to disease aggravation, increased mortality, and poor outcomes. This study was conducted to determine the species distribution and antifungal susceptibility patterns of Candida isolates from hospitalized COVID-19 patients in Shiraz, Iran, in addition to associated risk factors and outcomes of co-infections with Candida species. MATERIALS AND METHODS: In this single-center study, a total of 106 hospitalized COVID-19 patients were evaluated for clinical characteristics and outcomes. Species identification was performed by ITS1-5.8S-ITS2 gene sequencing. Antifungal susceptibility testing to fluconazole, itraconazole, voriconazole, posaconazole, caspofungin, amphotericin B, and nystatin was determined according to the M27-A3/S4 CLSI protocol. RESULTS: Candida species were recovered from 48% (51/106) of hospitalized COVID-19 patients. Statistical analysis showed that patients who had heart failure, bacterial co-infection, and were receiving empirical antifungal therapy had a higher risk of developing Candida co-infection. In total, 71 Candida isolates were recovered, of which C. albicans (69%) was the most prevalent isolate. The majority of the Candida isolates were susceptible to all classes of tested antifungal drugs. DISCUSSION: Our results elucidate a high rate of Candida co-infections among hospitalized COVID-19 patients. Comorbidities such as heart failure, HTN, COPD, bacterial infections as well as therapeutic interventions including catheterization, mechanical ventilation, and ICU admission increased the risk of Candida spp. isolation from the bloodstream, respiratory tract and urine samples, which led to a higher in-hospital mortality rate. Additionally, obtained data clarified that empirical antifungal therapy was not as successful as anticipated.

Liposomal amphotericin B-the future.

Advances in medicine have led to a growing number of people with compromised or suppressed immune systems who are susceptible to invasive fungal infections. In particular, severe fungal infections are becoming increasingly common in ICUs, affecting people within and outside of traditional risk groups alike. This is exemplified by the emergence of severe viral pneumonia as a significant risk factor for invasive pulmonary aspergillosis, and the recognition of influenza-associated pulmonary aspergillosis and, more recently, COVID-19-associated pulmonary aspergillosis. The treatment landscape for haematological malignancies has changed considerably in recent years, and some recently introduced targeted agents, such as ibrutinib, are increasing the risk of invasive fungal infections. Consideration must also be given to the risk of drug-drug interactions between mould-active azoles and small-molecule kinase inhibitors. At the same time, infections caused by rare moulds and yeasts are increasing, and diagnosis continues to be challenging. There is growing concern about azole resistance among both moulds and yeasts, mandating continuous surveillance and personalized treatment strategies. It is anticipated that the epidemiology of fungal infections will continue to change and that new populations will be at risk. Early diagnosis and appropriate treatment remain the most important predictors of survival, and broad-spectrum antifungal agents will become increasingly important. Liposomal amphotericin B will remain an essential therapeutic agent in the armamentarium needed to manage future challenges, given its broad antifungal spectrum, low level of acquired resistance and limited potential for drug-drug interactions.

Targeting Sterylglucosidase A to Treat Aspergillus fumigatus Infections.

Invasive fungal infections are a leading cause of death in immunocompromised patients. Current therapies have several limitations, and innovative antifungal agents are critically needed. Previously, we identified the fungus-specific enzyme sterylglucosidase as essential for pathogenesis and virulence of Cryptococcus neoformans and Aspergillus fumigatus (Af) in murine models of mycoses. Here, we developed Af sterylglucosidase A (SglA) as a therapeutic target. We identified two selective inhibitors of SglA with distinct chemical scaffolds that bind in the active site of SglA. Both inhibitors induce sterylglucoside accumulation and delay filamentation in Af and increase survival in a murine model of pulmonary aspergillosis. Structure-activity relationship (SAR) studies identified a more potent derivative that enhances both in vitro phenotypes and in vivo survival. These findings support sterylglucosidase inhibition as a promising antifungal approach with broad-spectrum potential. IMPORTANCE Invasive fungal infections are a leading cause of death in immunocompromised patients. Aspergillus fumigatus is a fungus ubiquitously found in the environment that, upon inhalation, causes both acute and chronic illnesses in at-risk individuals. A. fumigatus is recognized as one of the critical fungal pathogens for which a substantive treatment breakthrough is urgently needed. Here, we studied a fungus-specific enzyme, sterylglucosidase A (SglA), as a therapeutic target. We identified selective inhibitors of SglA that induce accumulation of sterylglucosides and delay filamentation in A. fumigatus and increase survival in a murine model of pulmonary aspergillosis. We determined the structure of SglA, predicted the binding poses of these inhibitors through docking analysis, and identified a more efficacious derivative with a limited SAR study. These results open several exciting avenues for the research and development of a new class of antifungal agents targeting sterylglucosidases.

Hospital Clonal Outbreak of Fluconazole-Resistant Candida parapsilosis Harboring the Y132F ERG11p Substitution in a French Intensive Care Unit.

We report the first identification of a fluconazole-resistant Candida parapsilosis (FR-Cp) strain in our hospital, which subsequently caused an outbreak involving 17 patients (12 deaths) within a 26-bed French intensive care unit. Microsatellite genotyping confirmed that all FR-Cp isolates belonged to the same clone. Given recent reports of rapid dissemination of these emerging clones, routine testing of azole susceptibility for all Candida parapsilosis isolates should be encouraged, at least in ICU patients.

Utility of itraconazole and terbinafine in mucormycosis: a proof-of-concept analysis.

An epidemic of mucormycosis followed the second wave of COVID 19 in the state of Uttar Pradesh, India in May 2021. This epidemic, however, had additional challenges to offer in the form of acute shortage of all forms of amphotericin B, posaconazole and isavuconazole. It was, therefore, planned to assess the trends in minimum inhibitory concentration (MIC) of antifungal agents, viz itraconazole and terbinafine, and provide a template for personalized therapy to see whether the results could be translated clinically. This is an observational, single-center study. Samples comprising nasal swab, nasal and paranasal sinus tissue, brain tissue, brain abscess and orbital content, derived from 322 patients from northern India with mucormycosis, of whom 215 were male and 107 were female, were used for analysis. Cultures were identified both by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and conventional methods of identification. Antifungal susceptibility was done for amphotericin B, posaconazole, isavuconazole, itraconazole and terbinafine as per Clinical Laboratory Standard Institute M38-A2. The outcome was identification of the species of mucormycosis and susceptibility to itraconazole and terbinafine besides other primary antifungal agents. Patients or the public were not involved in the design, or conduct, or reporting or in the dissemination plans of our research. Of 322 patients, 203 were culture-positive, of whom 173 were positive by both MALDI-TOF and conventional methods of identification. Final antifungal susceptibility testing was available for 150 patients. The most common Mucorales found to cause this epidemic was Rhizopus oryzae, followed by R. microsporus Amphotericin B, posaconazole and isavuconazole had low MIC values in 98.8% of all Mucorales identified. The MIC of itraconazole was species-dependent. 97.7% of Roryzae had MIC ≤2 µg/mL. However, only 36.5% of Rmicrosporus had MIC ≤2 µg/mL. For terbinafine, 85.2% of R. microsporus had MIC ≤2 µg/mL. We conclude that identification at the species level is required as antifungal susceptibilities seem to be species-dependent. Assessment of the efficacy of itraconazole and terbinafine warrants further studies with clinical assessment and therapeutic drug monitoring as they seem to be potential candidates especially when the primary agents are not available.

Cryptococcus neoformans, a global threat to human health.

BACKGROUND: Emerging fungal pathogens pose important threats to global public health. The World Health Organization has responded to the rising threat of traditionally neglected fungal infections by developing a Fungal Priority Pathogens List (FPPL). Taking the highest-ranked fungal pathogen in the FPPL, Cryptococcus neoformans, as a paradigm, we review progress made over the past two decades on its global burden, its clinical manifestation and management of cryptococcal infection, and its antifungal resistance. The purpose of this review is to drive research efforts to improve future diagnoses, therapies, and interventions associated with fungal infections. METHODS: We first reviewed trends in the global burden of HIV-associated cryptococcal infection, mainly based on a series of systematic studies. We next conducted scoping reviews in accordance with the guidelines described in the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension for Scoping Reviews using PubMed and ScienceDirect with the keyword Cryptococcus neoformans to identify case reports of cryptococcal infections published since 2000. We then reviewed recent updates on the diagnosis and antifungal treatment of cryptococcal infections. Finally, we summarized knowledge regarding the resistance and tolerance of C. neoformans to approved antifungal drugs. RESULTS: There has been a general reduction in the estimated global burden of HIV-associated cryptococcal meningitis since 2009, probably due to improvements in highly active antiretroviral therapies. However, cryptococcal meningitis still accounts for 19% of AIDS-related deaths annually. The incidences of CM in Europe and North America and the Latin America region have increased by approximately two-fold since 2009, while other regions showed either reduced or stable numbers of cases. Unfortunately, diagnostic and treatment options for cryptococcal infections are limited, and emerging antifungal resistance exacerbates the public health burden. CONCLUSION: The rising threat of C. neoformans is compounded by accumulating evidence for its ability to infect immunocompetent individuals and the emergence of antifungal-resistant variants. Emphasis should be placed on further understanding the mechanisms of pathogenicity and of antifungal resistance and tolerance. The development of novel management strategies through the identification of new drug targets and the discovery and optimization of new and existing diagnostics and therapeutics are key to reducing the health burden.

Antimicrobial Performance of Innovative Functionalized Surfaces Based on Enamel Coatings: The Effect of Silver-Based Additives on the Antibacterial and Antifungal Activity.

Frequently touched surfaces (FTS) that are contaminated with pathogens are one of the main sources of nosocomial infections, which commonly include hospital-acquired and healthcare-associated infections (HAIs). HAIs are considered the most common adverse event that has a significant burden on the public's health worldwide currently. The persistence of pathogens on contaminated surfaces and the transmission of multi-drug resistant (MDR) pathogens by way of healthcare surfaces, which are frequently touched by healthcare workers, visitors, and patients increase the risk of acquiring infectious agents in hospital environments. Moreover, not only in hospitals but also in high-traffic public places, FTS play a major role in the spreading of pathogens. Consequently, attention has been devoted to developing novel and alternative methods to tackle this problem. This study planned to produce and characterize innovative functionalized enameled coated surfaces supplemented with 1% AgNO3 and 2% AgNO3. Thus, the antimicrobial properties of the enamels against relevant nosocomial pathogens including the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli and the yeast Candida albicans were assessed using the ISO:22196:2011 norm.

Visible-Light-Activated Molecular Machines Kill Fungi by Necrosis Following Mitochondrial Dysfunction and Calcium Overload.

Invasive fungal infections are a growing public health threat. As fungi become increasingly resistant to existing drugs, new antifungals are urgently needed. Here, it is reported that 405-nm-visible-light-activated synthetic molecular machines (MMs) eliminate planktonic and biofilm fungal populations more effectively than conventional antifungals without resistance development. Mechanism-of-action studies show that MMs bind to fungal mitochondrial phospholipids. Upon visible light activation, rapid unidirectional drilling of MMs at ≈3 million cycles per second (MHz) results in mitochondrial dysfunction, calcium overload, and ultimately necrosis. Besides their direct antifungal effect, MMs synergize with conventional antifungals by impairing the activity of energy-dependent efflux pumps. Finally, MMs potentiate standard antifungals both in vivo and in an ex vivo porcine model of onychomycosis, reducing the fungal burden associated with infection.

Nano-combination for Reviving the Activity of Fluconazole against Rhizopus delemar.

BACKGROUND: Rhizopus delemar, the main causative pathogen for the lethal mucormycosis and a severe threat during the COVID-19 pandemic, is resistant to most antifungals, including fluconazole, a known selective antifungal drug. On the other hand, antifungals are known to enhance fungal melanin synthesis. Rhizopus melanin plays an important role in fungal pathogenesis and in escaping the human defense mechanism, thus complicating the use of current antifungal drugs and fungal eradication. Because of drug resistance and the slow discovery of effective antifungals, sensitizing the activity of older ones seems a more promising strategy. METHODS: In this study, a strategy was employed to revive the use and enhance the effectiveness of fluconazole against R. delemar. UOSC-13, a compound synthesized in-house to target the Rhizopus melanin, was combined with fluconazole either as is or after encapsulation in poly (lactic-coglycolic acid) nanoparticles (PLG-NPs). Both combinations were tested for the growth of R. delemar, and the MIC50 values were calculated and compared. RESULTS: The activity of fluconazole was found to be enhanced several folds following the use of both combined treatment and nanoencapsulation. The combination of fluconazole with UOSC-13 caused a 5-fold reduction in the MIC50 value of fluconazole. Furthermore, encapsulating UOSC-13 in PLG-NPs enhanced the activity of fluconazole by an additional 10 folds while providing a wide safety profile. CONCLUSION: Consistent with previous reports, the encapsulation of fluconazole without sensitization showed no significant difference in activity. Collectively, sensitization of fluconazole represents a promising strategy to revive the use of outdated antifungal drugs back in the market.

Brevicillin, a novel lanthipeptide from the genus Brevibacillus with antimicrobial, antifungal, and antiviral activity.

AIM: This study was aimed to determine antimicrobial and antiviral activity of a novel lanthipeptide from a Brevibacillus sp. for disinfectant application. METHODS AND RESULTS: The antimicrobial peptide (AMP) was produced by a bacterial strain AF8 identified as a member of the genus Brevibacillus representing a novel species. Whole genome sequence analysis using BAGEL identified a putative complete biosynthetic gene cluster involved in lanthipeptide synthesis. The deduced amino acid sequence of lanthipeptide named as brevicillin, showed >30% similarity with epidermin. Mass determined by MALDI-MS and Q-TOF suggested posttranslational modifications like dehydration of all Ser and Thr amino acids to yield Dha and Dhb, respectively. Amino acid composition determined upon acid hydrolysis is in agreement with core peptide sequence deduced from the putative biosynthetic gene bvrAF8. Biochemical evidence along with stability features ascertained posttranslational modifications during formation of the core peptide. The peptide showed strong activity with 99% killing of pathogens at 12 µg ml-1 within 1 minute. Interestingly, it also showed potent anti-SARS-CoV-2 activity by inhibiting ∼99% virus growth at 10 µg ml-1 in cell culture-based assay. Brevicillin did not show dermal allergic reactions in BALB/c mice. CONCLUSION: This study provides detailed description of a novel lanthipeptide and demonstrates its effective antibacterial, antifungal and anti-SARS-CoV-2 activity.

The first case of clade I Candida auris candidemia in a patient with COVID-19 in Japan.

Candida auris is a health hazard because of its antifungal resistance and the potential to cause healthcare-associated outbreaks. To our knowledge, no previous cases of candidemia caused by C. auris have been reported in Japan. Herein, we report the first known case of clade I C. auris candidemia in a Japanese man with coronavirus disease 2019 (COVID-19) infection who was medically evacuated from the Philippines. A 71-year-old Japanese man traveled to Cebu Island in the Philippines 5 months before admission to our hospital. He contracted severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the Philippines and was admitted to the intensive care unit (ICU) in a local hospital. During his medical evacuation, we implemented precautions given his history of COVID-19 and pneumonia caused by multi-drug-resistant Acinetobacter baumannii complex. His blood culture revealed that C. auris infection was treated with antifungal agents but he did not survive. No evidence of nosocomial transmission was found among other patients in the ICU. This case study determines that accurate detection of C. auris, appropriate antifungal agent selection, precautions, and patient isolation are crucial to prevent nosocomial outbreaks, especially in patients with a history of multidrug-resistant organism (MDRO) colonization or international hospitalization. Medical professionals should recognize the risk of MDROs in international medical evacuation settings, considering the recent resumption of cross-border travel after the COVID-19 pandemic.

Opportunistic Candida Infections in Critical COVID-19 Patients.

The frequency of opportunistic fungal infections in critically ill patients whose intensive care unit stays are prolonged due to coronavirus disease 2019 (COVID-19) is higher than in the period before COVID-19. We planned this study to improve the management of Candida infections by defining the Candida species, the etiology of infections caused by Candida species, and the antifungal susceptibility of the species. This retrospective study included patients older than 18 hospitalized in the intensive care unit (ICU) with a definitive diagnosis of COVID-19 for seven months (from March 2021 to September 2021). All study data that we recorded in a standard study form were analyzed with TURCOSA (Turcosa Analytics Ltd. Co., Turkey, www.turcosa.com.tr) statistical software. The patients were evaluated in four groups as group 1 (candidemia patients, n = 78), group 2 (candiduria patients, n = 189), group 3 (control patients, n = 57), and group 4 (patients with candidemia in urine cultures taken before Candida was detected in blood culture, n = 42). Candida species were identified using both conventional and VITEK® 2 (BioMérieux, France) methods. The antifungal susceptibility of fungi was determined using the E test method. Of the 5,583 COVID-19 patients followed during the study period, 78 developed candidemia, and 189 developed candiduria. The incidence of candidemia (per 1,000 admissions) was determined to be 1.6. As a result of statistical analysis, we found that Candida albicans was the dominant strain in candidemia and candiduria, and there was no antifungal resistance except for naturally resistant strains. Candida strains grown in blood and urine were the same in 40 of 42 patients. Mortality was 69.2% for group 1, 60.4% for group 2, and 57.8% for group 3. Antifungals were used in 34 (43.5%) patients from group 1, and 95 (50.2%) from group 2. In the candidemia group without antifungal use, mortality was quite high (77.2%). Antifungal use reduced mortality in the group 2 (p < 0.05). Length of ICU stays, comorbidity, broad-spectrum antibiotics, and corticosteroids are independent risk factors for candidemia in critically ill COVID-19 patients. Our study contributes to the knowledge of risk factors for developing COVID-19-related candida infections. The effect of candiduria on the development of candidemia in critically ill COVID-19 patients should be supported by new studies.

No evidence of resistance to itraconazole in a prospective real-world trial of dermatomycosis in India.

BACKGROUND: The prevalence of superficial fungal infections in India is believed to have increased substantially in the past decade. We evaluated the treatment outcomes and risk factors associated with clinical response to a treatment course of itraconazole for the management of dermatomycosis in India. METHODS: In this real-world, prospective pilot study (August 2019 to March 2020), adult participants (18-60 years), diagnosed with T. cruris or T. corporis, received itraconazole 200 mg/day (any formulation) orally for 7 days, and were followed for an additional 7 days. RESULTS: The study was terminated early due to the COVID-19 pandemic. Of 40 enrolled participants (mean [SD] age, 35.5 [12.73] years; {62.5%}] male; 37 received itraconazole and 20 (50%) completed the study. The median (range) Clinical Evaluation Tool Signs and Symptoms total score at baseline was 5.5 (2-10). Clinical response of "healed" or "markedly improved" based on the Investigator Global Evaluation Tool at day 7 (primary objective) was 42.9% (12/28; 95% CI: 24.53%, 61.19%). Itraconazole minimum inhibitory concentration for identified microorganisms, T. mentagrophytes species complex (91.7%) and T. rubrum (8.3%), was within the susceptibility range (0.015-0.25 mcg/mL). At day 14, 8/13 (61.5%) participants achieved a mycological response, 2/13 participants (15.4%) had a mycological failure and 90% showed a clinical response. CONCLUSION: COVID-19 pandemic affected patient recruitment and follow-up, so the findings call for a careful interpretation. Nevertheless, this real-world study reconfirmed the clinical efficacy and microbial susceptibility to itraconazole for the fungi causing dermatophytosis in India. TRIAL REGISTRATION: Trial registration number: Clinicaltrials.gov NCT03923010.

Risk Factors for Candidemia in Intensive Care Unit: A Matched Case Control Study from North-Western India.

Candidemia is one of the significant causes of mortality amongst critically ill patients in Intensive Care Units (ICUs). This study aimed to assess the incidence, risk factors and antifungal susceptibility pattern in candidemia cases admitted in ICU in a tertiary care hospital in Jaipur, Rajasthan from June 2021 to November 2021. Candida species isolated from blood culture of clinically suspected patients of sepsis were defined as candidemia cases. Blood culture and antifungal susceptibility testing were performed as per standard laboratory protocol. Analyses of risk factors was done between candidemia cases and matched controls in a ratio of 1 : 3. Forty-six candidemic cases and 150 matched controls were included in the study. C. tropicalis was the most prevalent species (22/46; 48%) followed by C. auris (8/46; 17%) and C. albicans (7/46; 15%). Candida species showed good sensitivity to echinocandins (97%) followed by amphotericin B (87%) and voriconazole (80%). In multivariate analysis, longer stay in ICU, presence of an indwelling device, use of immunosuppressive drugs and positive SARS-CoV-2 infection were associated with increased risk of candidemia. The constant evaluation of risk factors is required as prediction of risks associated with candidemia may help to guide targeted preventive measures with reduced morbidity and mortality.

Characterization of Aspergillus spp. isolated from patients with coronavirus disease 2019.

INTRODUCTION: Invasive pulmonary aspergillosis (IPA) is an important complication of coronavirus disease 2019 (COVID-19), and while there are case reports and epidemiological studies, few studies have isolated Aspergillus strains from patients. Therefore, we analyzed the strains, sensitivities, and genetic homology of Aspergillus spp. Isolated from patients with COVID-19. METHODS: We investigated the Aspergillus strains detected from patients with COVID-19 hospitalized in Osaka Metropolitan University Hospital from December 2020 to June 2021. A molecular epidemiological analysis of Aspergillus spp. was performed using drug susceptibility tests and TRESPERG typing, and data on patient characteristics were collected from electronic medical records. RESULTS: Twelve strains of Aspergillus were detected in 11 of the 122 patients (9%) with COVID-19. A. fumigatus was the most common species detected, followed by one strain each of Aspergillus aureolus, Aspergillus nidulans, Aspergillus niger, and Aspergillus terreus. A. aureolus was resistant to voriconazole, and no resistance was found in other strains. All A. fumigatus strains were genetically distinct strains. Six of the 11 patients that harbored Aspergillus received antifungal drug treatment and tested positive for ß-D-glucan and/or Aspergillus galactomannan antigen. The results indicated that Aspergillus infections were acquired from outside the hospital and not from nosocomial infections. CONCLUSION: Strict surveillance of Aspergillus spp. is beneficial in patients at high-risk for IPA. When Aspergillus is detected, it is important to monitor the onset of IPA carefully and identify the strain, perform drug sensitivity tests, and facilitate early administration of therapeutic agents to patients with IPA.

Serine/Threonine Phosphatase Calcineurin Orchestrates the Intrinsic Resistance to Micafungin in the Human-Pathogenic Fungus Mucor circinelloides.

Procedures such as solid-organ transplants and cancer treatments can leave many patients in an immunocompromised state. This leads to their increased susceptibility to opportunistic diseases such as fungal infections. Mucormycosis infections are continually emerging and pose a serious threat to immunocompromised patients. Recently there has been a sharp increase in mucormycosis cases as a secondary infection in patients battling severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Mucorales fungi are notorious for presenting resistance to most antifungal drugs. The absence of effective means to treat these infections results in mortality rates approaching 100% in cases of disseminated infection. One of the most effective antifungal drug classes currently available is the echinocandins. Echinocandins seem to be efficacious in the treatment of many other fungal infections. Unfortunately, susceptibility testing has found that echinocandins have little to no effect on Mucorales fungi. In this study, we found that the model Mucorales Mucor circinelloides genome carries three copies of the genes encoding the echinocandin target protein ß-(1,3)-d-glucan synthase (fksA, fksB, and fksC). Interestingly, we found that exposing M. circinelloides to micafungin significantly increased the expression of the fksA and fksB genes, resulting in an increased accumulation of ß-(1,3)-d-glucan on the cell walls. However, this overexpression of the fks genes is not directly connected to the intrinsic resistance. Subsequent investigation discovered that the serine/threonine phosphatase calcineurin regulates the expression of fksA and fksB, and the deletion of calcineurin results in a decrease in expression of all three fks genes. Deletion of calcineurin also results in a lower minimum effective concentration (MEC) of micafungin. In addition, we found that duplication of the fks gene is also responsible for the intrinsic resistance, in which lack of either fksA or fksB led a lower MEC of micafungin. Together, these findings demonstrate that calcineurin and fks gene duplication contribute to the intrinsic resistance to micafungin we observe in M. circinelloides.