Genomic description of human clinical Aspergillus fumigatus isolates, California, 2020.

Aspergillus fumigatus, an environmental mold, causes life-threatening infections. Studies on the phylogenetic structure of human clinical A. fumigatus isolates are limited. Here, we performed whole genome sequencing of 24 A. fumigatus isolates collected from 18 patients in U.S. healthcare facilities in California. Single-nucleotide polymorphism (SNP) differences between patient isolates ranged from 187 to 70 829 SNPs. For five patients with multiple isolates, we calculated the within-host diversities. Three patients had a within-host diversity that ranged from 4 to 10 SNPs and two patients ranged from 2 to 16 977 SNPs. Findings revealed highly diverse A. fumigatus strains among patients and two patterns of diversity for isolates that come from the same patient, low and extremely high diversity.

Aspergillus fumigatus is an environmental mold. It can cause a severe infection called aspergillosis in patients with weakened immune systems. We analyzed A. fumigatus DNA from patients at California hospitals. We described genetic diversity between samples from the same patients and among different patients. Our findings provide insight on using genomic sequencing to investigate aspergillosis in hospitals.

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.

Molecular Epidemiology of Blastomyces gilchristii Clusters, Minnesota, USA.

We characterized 2 clusters of blastomycosis cases in Minnesota, USA, using whole-genome sequencing and single-nucleotide polymorphism analyses. Blastomyces gilchristii was confirmed as the cause of infection. Genomic analyses corresponded with epidemiologic findings for cases of B. gilchristii infections, demonstrating the utility of genomic methods for future blastomycosis outbreak investigations.

Candida parapsilosis Mdr1B and Cdr1B Are Drivers of Mrr1-Mediated Clinical Fluconazole Resistance.

Candida parapsilosis is a common cause of invasive candidiasis worldwide and is the most commonly is7olated Candida species among pediatric and neonatal populations. Previous work has demonstrated that nonsynonymous mutations in the gene encoding the putative transcription factor CpMrr1 can influence fluconazole susceptibility. However, the direct contribution of these mutations and how they influence fluconazole resistance in clinical isolates are poorly understood. We identified 7 nonsynonymous CpMRR1 mutations in 12 isolates from within a collection of 35 fluconazole-resistant clinical isolates. The mutations leading to the A854V, R479K, and I283R substitutions were further examined and found to be activating mutations leading to increased fluconazole resistance. In addition to CpMDR1, we identified two other genes, one encoding a major facilitator superfamily (MFS) transporter (CpMDR1B, CPAR2_603010) and one encoding an ATP-binding cassette (ABC) transporter (CpCDR1B, CPAR2_304370), as being upregulated in isolates carrying CpMRR1-activating mutations. Overexpression of CpMDR1 in a susceptible strain and disruption in resistant clinical isolates that overexpress CpMDR1 had little to no effect on fluconazole susceptibility. Conversely, overexpression of either CpMDR1B or CpCDR1B increased resistance, and disruption in clinical isolates overexpressing these genes decreased fluconazole resistance. Our findings suggest that activating mutations in CpMRR1 represent important genetic determinants of fluconazole resistance in clinical isolates of C. parapsilosis, and unlike what is observed in Candida albicans, this is primarily driven by upregulation of both MFS (CpMdr1B) and ABC (CpCdr1B) transporters.

Rapid Assessment and Containment of Candida auris Transmission in Postacute Care Settings-Orange County, California, 2019.

BACKGROUND: Candida auris, a multidrug-resistant yeast, can spread rapidly in ventilator-capable skilled-nursing facilities (vSNFs) and long-term acute care hospitals (LTACHs). In 2018, a laboratory serving LTACHs in southern California began identifying species of Candida that were detected in urine specimens to enhance surveillance of C auris, and C auris was identified in February 2019 in a patient in an Orange County (OC), California, LTACH. Further investigation identified C auris at 3 associated facilities. OBJECTIVE: To assess the prevalence of C auris and infection prevention and control (IPC) practices in LTACHs and vSNFs in OC. DESIGN: Point prevalence surveys (PPSs), postdischarge testing for C auris detection, and assessments of IPC were done from March to October 2019. SETTING: All LTACHs (n = 3) and vSNFs (n = 14) serving adult patients in OC. PARTICIPANTS: Current or recent patients in LTACHs and vSNFs in OC. INTERVENTION: In facilities where C auris was detected, PPSs were repeated every 2 weeks. Ongoing IPC support was provided. MEASUREMENTS: Antifungal susceptibility testing and whole-genome sequencing to assess isolate relatedness. RESULTS: Initial PPSs at 17 facilities identified 44 additional patients with C auris in 3 (100%) LTACHs and 6 (43%) vSNFs, with the first bloodstream infection reported in May 2019. By October 2019, a total of 182 patients with C auris were identified by serial PPSs and discharge testing. Of 81 isolates that were sequenced, all were clade III and highly related. Assessments of IPC identified gaps in hand hygiene, transmission-based precautions, and environmental cleaning. The outbreak was contained to 2 facilities by October 2019. LIMITATION: Acute care hospitals were not assessed, and IPC improvements over time could not be rigorously evaluated. CONCLUSION: Enhanced laboratory surveillance and prompt investigation with IPC support enabled swift identification and containment of C auris. PRIMARY FUNDING SOURCE: Centers for Disease Control and Prevention.

Antifungal Susceptibility Testing: Current Approaches.

Although not as ubiquitous as antibacterial susceptibility testing, antifungal susceptibility testing (AFST) is a tool of increasing importance in clinical microbiology laboratories. The goal of AFST is to reliably produce MIC values that may be used to guide patient therapy, inform epidemiological studies, and track rates of antifungal drug resistance. There are three methods that have been standardized by standards development organizations: broth dilution, disk diffusion, and azole agar screening for Aspergillus Other commonly used methods include gradient diffusion and the use of rapid automated instruments. Novel methodologies for susceptibility testing are in development. It is important for laboratories to consider not only the method of testing but also the interpretation (or lack thereof) of in vitro data.

Categorizing Susceptibility of Clinical Isolates of Candida auris to Amphotericin B, Caspofungin, and Fluconazole by Use of the CLSI M44-A2 Disk Diffusion Method.

We evaluated the CLSI M44ed3E disk diffusion method compared with the CLSI M27ed4 broth microdilution method for caspofungin and fluconazole and the Etest method for amphotericin B to categorize susceptibility of 347 clinical isolates of Candida auris Utilizing the zone diameter cutoffs established here, we observed overall categorical agreement between the two methods. For caspofungin, concordant results were observed for 98% of isolates, with <1% very major and 1% major errors. For fluconazole, concordant results were observed for 91% of isolates, with 1% very major and 8% major errors. For amphotericin B, concordant results were observed for 74% of isolates, with <1% very major errors and 25% major errors. The disk diffusion approach provides an accurate method for determining the susceptibility of C. auris for caspofungin and fluconazole and for identification of at least 75% of amphotericin B-susceptible isolates.

Antifungal activity of nikkomycin Z against Candida auris.

BACKGROUND: Nikkomycin Z is a competitive inhibitor of chitin synthase-an enzyme needed for synthesis of the fungal cell wall. Nikkomycin Z shows promise as a treatment for coccidioidomycoses and mixed activity has been described against other fungi and yeast. To our knowledge, it has not previously been tested against the emerging fungal pathogen Candida auris. OBJECTIVES: To determine the in vitro activity of nikkomycin Z against C. auris. METHODS: Nikkomycin Z was tested by broth microdilution against a panel of 100 isolates of genetically diverse C. auris from around the world. RESULTS: Nikkomycin Z showed mixed activity against the tested isolates, with an MIC range of 0.125 to >64 mg/L. The MIC50 and MIC90 were 2 and 32 mg/L, respectively. CONCLUSIONS: These findings suggest nikkomycin Z has in vitro activity against some, but not all isolates of C. auris.

Candida auris Isolates Resistant to Three Classes of Antifungal Medications - New York, 2019.

Candida auris is a globally emerging yeast that causes outbreaks in health care settings and is often resistant to one or more classes of antifungal medications (1). Cases of C. auris with resistance to all three classes of commonly prescribed antifungal drugs (pan-resistance) have been reported in multiple countries (1). C. auris has been identified in the United States since 2016; the largest number (427 of 911 [47%]) of confirmed clinical cases reported as of October 31, 2019, have been reported in New York, where C. auris was first detected in July 2016 (1,2). As of June 28, 2019, a total of 801 patients with C. auris were identified in New York, based on clinical cultures or swabs of skin or nares obtained to detect asymptomatic colonization (3). Among these patients, three were found to have pan-resistant C. auris that developed after receipt of antifungal medications, including echinocandins, a class of drugs that targets the fungal cell wall. All three patients had multiple comorbidities and no known recent domestic or foreign travel. Although extensive investigations failed to document transmission of pan-resistant isolates from the three patients to other patients or the environment, the emergence of pan-resistance is concerning. The occurrence of these cases underscores the public health importance of surveillance for C. auris, the need for prudent antifungal prescribing, and the importance of conducting susceptibility testing on all clinical isolates, including serial isolates from individual patients, especially those treated with echinocandin medications. This report summarizes investigations related to the three New York patients with pan-resistant infections and the subsequent actions conducted by the New York State Department of Health and hospital and long-term care facility partners.

Molecular Epidemiology of Candida auris in Colombia Reveals a Highly Related, Countrywide Colonization With Regional Patterns in Amphotericin B Resistance.

Background: Candida auris is a multidrug-resistant yeast associated with hospital outbreaks worldwide. During 2015-2016, multiple outbreaks were reported in Colombia. We aimed to understand the extent of contamination in healthcare settings and to characterize the molecular epidemiology of C. auris in Colombia. Methods: We sampled patients, patient contacts, healthcare workers, and the environment in 4 hospitals with recent C. auris outbreaks. Using standardized protocols, people were swabbed at different body sites. Patient and procedure rooms were sectioned into 4 zones and surfaces were swabbed. We performed whole-genome sequencing (WGS) and antifungal susceptibility testing (AFST) on all isolates. Results: Seven of the 17 (41%) people swabbed were found to be colonized. Candida auris was isolated from 37 of 322 (11%) environmental samples. These were collected from a variety of items in all 4 zones. WGS and AFST revealed that although isolates were similar throughout the country, isolates from the northern region were genetically distinct and more resistant to amphotericin B (AmB) than the isolates from central Colombia. Four novel nonsynonymous mutations were found to be significantly associated with AmB resistance. Conclusions: Our results show that extensive C. auris contamination can occur and highlight the importance of adherence to appropriate infection control practices and disinfection strategies. Observed genetic diversity supports healthcare transmission and a recent expansion of C. auris within Colombia with divergent AmB susceptibility.

In Vitro Activity of Ibrexafungerp, a Novel Glucan Synthase Inhibitor against Candida glabrata Isolates with FKS Mutations.

Ibrexafungerp is a first-in-class glucan synthase inhibitor. In vitro activity was determined for 89 Candida glabrata isolates with molecularly identified FKS1 or FKS2 mutations conferring resistance to the echinocandins. All isolates were resistant to at least one echinocandin (i.e., anidulafungin, caspofungin, or micafungin) by broth microdilution. Results for ibrexafungerp were compared with those for each echinocandin. Ibrexafungerp had good activity against all echinocandin-resistant C. glabrata isolates.

The Fungal Cyp51-Specific Inhibitor VT-1598 Demonstrates In Vitro and In Vivo Activity against Candida auris.

Candida auris is an emerging pathogen associated with significant mortality and often multidrug resistance. VT-1598, a tetrazole-based fungal CYP51-specific inhibitor, was evaluated in vitro and in vivo against C. auris Susceptibility testing was performed against 100 clinical isolates of C. auris by broth microdilution. Neutropenic mice were infected intravenously with C. auris, and treatment began 24 h postinoculation with a vehicle control, oral VT-1598 (5, 15, and 50 mg/kg of body weight once daily), oral fluconazole (20 mg/kg once daily), or intraperitoneal caspofungin (10 mg/kg once daily), which continued for 7 days. Fungal burden was assessed in the kidneys and brains on day 8 in the fungal burden arm and on the days the mice succumbed to infection or on day 21 in the survival arm. VT-1598 plasma trough concentrations were also assessed on day 8. VT-1598 demonstrated in vitro activity against C. auris, with a mode MIC of 0.25 µg/ml and MICs ranging from 0.03 to 8 µg/ml. Treatment with VT-1598 resulted in significant and dose-dependent improvements in survival (median survival, 15 and >21 days for VT-1598 at 15 and 50 mg/kg, respectively) and reductions in kidney and brain fungal burden (reductions of 1.88 to 3.61 log10 CFU/g) compared to the control (5 days). The reductions in fungal burden correlated with plasma trough concentrations. Treatment with caspofungin, but not fluconazole, also resulted in significant improvements in survival and reductions in fungal burden compared to those with the control. These results suggest that VT-1598 may be a future option for the treatment of invasive infections caused by C. auris.

Identification of Candida auris by Use of the Updated Vitek 2 Yeast Identification System, Version 8.01: a Multilaboratory Evaluation Study.

Candida auris is an emerging multidrug-resistant yeast that has been systematically incorrectly identified by phenotypic methods in clinical microbiology laboratories. The Vitek 2 automated identification system (bioMérieux) recently included C. auris in its database (version 8.01). We evaluated the performance of the Vitek 2 YST ID card to identify C. auris and related species. A panel of 44 isolates of Candida species (C. auris, n = 35; Candida haemulonii, n = 5; Candida duobushaemulonii, n = 4) were tested by three different hospital-based microbiology laboratories. Among 35 isolates of C. auris, Vitek 2 yielded correct identification in an average of 52% of tested samples. Low-discrimination (LD) results with an inability to distinguish between C. auris, C. duobushaemulonii, and Candida famata were obtained in an average of 27% of samples. Incorrect identification results were obtained in an average of 21% of samples, the majority (91%) of which were reported as C. duobushaemulonii and the remaining 9% of which were reported as Candida lusitaniae/C. duobushaemulonii. The proportion of correct identification was not statistically different across different centers (P = 0.78). Stratification by genetic clades demonstrated that 100% (n = 8) of the strains of the South American clade were correctly identified compared to 7% (n = 10) and 0% (n = 4) from the African and East Asian clades, respectively. None of the non-auris Candida strains (n = 9) were incorrectly identified as C. auris Our results show that the Vitek 2 (version 8.01) yeast identification system has a limited ability to correctly identify C. auris These data suggest that an identification result for C. duobushaemulonii should warrant further testing to rule out C. auris The overall performance of the Vitek 2 seems to differ according to C. auris genetic clade, with the South American isolates yielding the most accurate results.

Candida auris: The recent emergence of a multidrug-resistant fungal pathogen.

Candida auris is an emerging multidrug-resistant yeast that causes serious invasive infections with high mortality. It was first discovered in 2009, and since then, individual cases or outbreaks have been reported from over 20 countries on five continents. Controlling C. auris is challenging for several reasons: (1) it is resistant to multiple classes of antifungals, (2) it can be misidentified as other yeasts by commonly available identification methods, and (3) because of its ability to colonize patients perhaps indefinitely and persist in the healthcare environment, it can spread between patients in healthcare settings. The transmissibility and high levels of antifungal resistance that are characteristic of C. auris set it apart from most other Candida species. A robust response that involves the laboratory, clinicians, and public health agencies is needed to identify and treat infections and prevent transmission. We review the global emergence, biology, challenges with laboratory identification, drug resistance, clinical manifestations, treatment, risk factors for infection, transmission, and control of C. auris.

Detection of TR34/L98H CYP51A Mutation through Passive Surveillance for Azole-Resistant Aspergillus fumigatus in the United States from 2015 to 2017.

The emergence of azole-resistant Aspergillus fumigatus has become a clinical problem in many parts of the world. Several amino acid mutations in the azole target protein Cyp51Ap contribute to this resistance, with the most concerning being the environmentally derived TR34/L98H and TR46/Y121F/T289A mutations. Here, we performed passive surveillance to assess a sample of the A. fumigatus population in the United States for the presence of these mutations. We found 1.4% of those isolates to exhibit elevated MIC via broth microdilution, and five of those isolates harbored the TR34/L98H mutation.

Emerging Multidrug-Resistant Candida duobushaemulonii Infections in Panama Hospitals: Importance of Laboratory Surveillance and Accurate Identification.

Candida duobushaemulonii, a yeast closely related to Candida auris, is thought to cause infections in rare cases and is often misidentified. In October 2016, the Panamanian Ministry of Health implemented laboratory surveillance for C. auris Suspected C. auris isolates were forwarded to the national reference laboratory for identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry and antifungal susceptibility testing. Between November 2016 and May 2017, 17 of 36 (47%) isolates suspected to be C. auris were identified as C. duobushaemulonii. These 17 isolates were obtained from 14 patients at six hospitals. Ten patients, including three children, had bloodstream infections, and MICs for fluconazole, voriconazole, and amphotericin B were elevated. No resistance to echinocandins was observed. C. duobushaemulonii causes more invasive infections than previously appreciated and poses a substantial problem, given its resistance to multiple antifungals. Expanded laboratory surveillance is an important step in the detection and control of such emerging pathogens.

Activity of novel antifungal compound APX001A against a large collection of Candida auris.

Background: APX001A is an antifungal agent that targets a novel pathway-glycosylphosphatidylinositol glycolipid biosynthesis. It has been shown to be effective against a variety of fungal species, including Candida spp., Aspergillus spp. and other filamentous fungi. Objectives: To determine the activity of APX001A against the emerging fungal pathogen Candida auris. Methods: APX001A was tested by broth microdilution against 100 geographically distinct isolates of C. auris. Results: APX001A showed activity against all isolates, including some that were resistant to one or more antifungals, with MIC50 and MIC90 of 0.002 and 0.008 mg/L, respectively. Conclusions: These findings suggest that APX001A shows encouraging activity against the emerging fungal pathogen C. auris.

Changes in the epidemiological landscape of invasive candidiasis.

The epidemiology of invasive candidiasis has evolved in recent years, warranting a review of the changes and the implications for current and future diagnosis and treatment. The overall burden of invasive candidiasis remains high, particularly in the expanding populations of patients at risk of opportunistic infection, such as the elderly or immunosuppressed. Progressive shifts from Candida albicans to non-albicans Candida spp. have been observed globally. The recent emergence of novel, multiresistant species, such as Candida auris, amplifies the call for vigilance in detection and advances in treatment. Among the current treatment options, fluconazole is still widely used throughout the world. Increased resistance to fluconazole, both acquired and naturally emerging, has been observed. Resistance to echinocandins is presently low but this may change with increased use. Improvement of diagnostic techniques and strategies, development of international surveillance networks and implementation of antifungal stewardship programmes represent major challenges for a better epidemiological control of invasive candidiasis.

Ceragenins are active against drug-resistant Candida auris clinical isolates in planktonic and biofilm forms.

Background: Candida auris has emerged as a serious threat to human health. Of particular concern are the resistance profiles of many clinical isolates, with some being resistant to multiple classes of antifungals. Objectives: Measure susceptibilities of C. auris isolates, in planktonic and biofilm forms, to ceragenins (CSAs). Determine the effectiveness of selected ceragenins in gel and cream formulations in eradicating fungal infections in tissue explants. Materials and methods: A collection of 100 C. auris isolates available at CDC was screened for susceptibility to a lead ceragenin. A smaller collection was used to characterize antifungal activities of other ceragenins against organisms in planktonic and biofilm forms. Effects of ceragenins on fungal cells and biofilms were observed via microscopy. An ex vivo model of mucosal fungal infection was used to evaluate formulated forms of lead ceragenins. Results: Lead ceragenins displayed activities comparable to those of known antifungal agents against C. auris isolates with MICs of 0.5-8 mg/L and minimum fungicidal concentrations (MFCs) of 2-64 mg/L. No cross-resistance with other antifungals was observed. Fungal cell morphology was altered in response to ceragenin treatment. Ceragenins exhibited activity against sessile organisms in biofilms. Gel and cream formulations including 2% CSA-44 or CSA-131 resulted in reductions of over 4 logs against established fungal infections in ex vivo mucosal tissues. Conclusions: Ceragenins demonstrated activity against C. auris, suggesting that these compounds warrant further study to determine whether they can be used for topical applications to skin and mucosal tissues for treatment of infections with C. auris and other fungi.

Multidrug-Resistant Aspergillus fumigatus Carrying Mutations Linked to Environmental Fungicide Exposure - Three States, 2010-2017.

The environmental mold Aspergillus fumigatus is the primary cause of invasive aspergillosis. In patients with high-risk conditions, including stem cell and organ transplant recipients, mortality exceeds 50%. Triazole antifungals have greatly improved survival (1); however, triazole-resistant A. fumigatus infections are increasingly reported worldwide and are associated with increased treatment failure and mortality (2). Of particular concern are resistant A. fumigatus isolates carrying either TR34/L98H or TR46/Y121F/T289A genetic resistance markers, which have been associated with environmental triazole fungicide use rather than previous patient exposure to antifungals (3,4). Reports of these triazole-resistant A. fumigatus strains have become common in Europe (2,3), but U.S. reports are limited (5). Because of the risk posed to immunocompromised patients, understanding the prevalence of such isolates in patients is important to guide clinical and public health decision-making. In 2011, CDC initiated passive laboratory monitoring for U.S. triazole-resistant A. fumigatus isolates through outreach to clinical laboratories. This system identified five TR34/L98H isolates collected from 2016 to 2017 (6), in addition to two other U.S. isolates collected in 2010 and 2014 and reported in 2015 (5). Four of these seven isolates were reported from Pennsylvania, two from Virginia, and one from California. Three isolates were collected from patients with invasive pulmonary aspergillosis, and four patients had no known previous triazole exposure. A. fumigatus resistant to all triazole medications is emerging in the United States, and clinicians and public health personnel need to be aware that resistant infections are possible even in patients not previously exposed to these medications.