Candida auris MIC testing by EUCAST and CLSI broth microdilution, and gradient diffusion strips; to be or not to be amphotericin B resistant?

OBJECTIVES: Reported amphotericin B resistance rates for Candida auris vary considerably. This may reflect clinically relevant differences in susceptibility, technical issues with testing or adoption of a clinical breakpoint (BP) that bisects the wild-type population. We compared reference methods and two gradient diffusion strips using a shared C. auris strain collection. METHODS: Forty C. auris strains from nine US states and ≥3 clades were included. Fourteen MIC data sets were generated using EUCAST E.Def 7.4, CLSI M27Ed4, Etest and MTS (Liofilchem) strip MICs. MICs ≤1 mg/L were classified as susceptible. RESULTS: EUCAST and CLSI amphotericin B MIC testing were robust across included method variables. The modal MIC was 1 mg/L, distributions unimodal and narrow with similar GM-MICs (0.745-1.072); however, susceptibility classification varied (0-28% resistance). Gradient diffusion strip testing resulted in wider and bimodal distributions for 8/9 data sets. If adopting, per manufacturer's protocol, double inoculation for the Etest method, the modal MIC increased to 2-4 mg/L and resistance rates to 45-63% versus 25-30% with the single inoculation. The EUCAST, CLSI, Etest and MTS strip MICs correlated to the OD of drug-free control EUCAST wells suggesting that some isolates grew better than others and that this was associated with MIC. CONCLUSIONS: The EUCAST and CLSI MIC results were in close agreement, whereas the strip test showed wider and bimodal distributions with reader to reader and centre to centre variation. Our study adds to the concern for commercial MIC testing of amphotericin B against C. auris and suggest the current breakpoint leads to random susceptibility classification.

Intra-abdominal nocardiosis and scedosporiosis in a dog: case report and literature review.

A 2-y-old, intact female, mixed-breed dog was presented to the veterinary hospital with abdominal distension, anemia, and lethargy following a chronic history of nonspecific gastrointestinal signs. CBC and serum biochemistry revealed moderate nonregenerative anemia with neutrophilia, hypoalbuminemia, hyperglobulinemia, hypoglycemia, decreased urea and creatinine, and hypercholesterolemia. Abdominal radiographs and ultrasound revealed a large heterogeneous mesenteric mass and ascites. Abdominocentesis confirmed septic peritonitis with filamentous bacteria. Fine-needle aspiration of the mass yielded pyogranulomatous inflammation and hyphae. An exploratory laparotomy revealed a large cranial abdominal mass with granulomas present throughout the abdominal cavity. Due to the poor prognosis and disseminated disease, the owner elected euthanasia. Postmortem and histologic examinations detected intralesional mycetomas and bacterial colonies within the mesenteric masses. 16S ribosomal RNA gene PCR and sequencing using formalin-fixed, paraffin-embedded sections identified Nocardia yamanashiensis, Nocardioides cavernae, and Nocardioides zeicaulis. Fungal culture, PCR, and sequencing confirmed Scedosporium apiospermum. Our report highlights the importance of molecular methods in conjunction with culture and histologic findings for diagnosing coinfections caused by infrequent etiologic agents. Additionally, we provide a comprehensive literature review of Scedosporium apiospermum infections in dogs.

Case report: Localized coloproctitis caused by novel Basidiobolus arizonensis in a dog.

A 6-year-old male neutered boxer mix canine was presented for a one-month history of dyschezia, hematochezia, and constipation. Colonoscopy and endoscopic biopsies revealed non-specific lymphoplasmacytic, eosinophilic colitis. Despite pursuing various therapies over a 3.5-month clinical course (including hypoallergenic diet, antibiotics, prokinetics, laxatives, and anti-inflammatory glucocorticoids), the patient's condition did not improve. Two and a half months after initial presentation, the patient developed circumferential proctitis with multiple draining tracts and obstipation. Humane euthanasia and postmortem examination were elected. Gross and histological findings revealed locally extensive pyogranulomatous coloproctitis with many intralesional PAS-positive, GMS-negative 30-40 µm in diameter, hyaline, pauciseptate, irregularly branching fungal hyphae, hyphal bodies or chlamydospores and 25-45 µm in diameter thick-walled zygospores. Fungal culture of fluid from the draining tracts was performed, and DNA sequence analysis of the ITS and partial LSU of the nuclear ribosomal RNA genes were used to identify and confirm a novel species, Basidiobolus arizonensis. Basidiobolus spp. are saprobes in the order Basidiobolales and most commonly cause granulomatous infections of the skin, respiratory tract, and gastrointestinal tract in veterinary species and humans. To the authors' knowledge, this is the first report of novel Basidiobolus arizonensis causing localized coloproctitis in a dog.

Evaluation of nikkomycin Z with frequent oral administration in an experimental model of central nervous system coccidioidomycosis.

We evaluated the in vivo activity of nikkomycin Z against central nervous system coccidioidomycosis. Mice were inoculated intracranially with arthroconidia of Coccidoides immitis, and treatment with nikkomycin Z (50, 100, or 300 mg/kg orally TID) or fluconazole (25 mg/kg orally BID) began 2 days later. Each dose of nikkomycin Z and fluconazole significantly improved survival and reduced brain fungal burden compared with vehicle control. Further studies of nikkomycin Z against coccidioidomycosis are warranted. IMPORTANCE: Coccidioides species are endemic fungi that are capable of causing disease in patients with various comorbidities, as well as in otherwise healthy individuals. Treatment options for coccidioidomycosis are suboptimal, as azole antifungals may be limited by drug interactions and adverse effects due to interactions with enzymes found in humans and other mammals. Nikkomycin Z is an investigational agent that works against a target specific to the fungal cell wall (chitin), which is not present in the cells of humans or other mammals. In this study, we show that frequent oral administration of nikkomycin Z is effective in an experimental model of central nervous system coccidioidomycosis. Further studies of nikkomycin Z against coccidioidomycosis may be warranted.

A Mini-Review of In Vitro Data for Candida Species, Including C. auris, Isolated during Clinical Trials of Three New Antifungals: Fosmanogepix, Ibrexafungerp, and Rezafungin.

This mini-review summarizes the clinical outcomes and antifungal susceptibility results, where available, for three new antifungals, including fosmanogepix, ibrexafungerp, and rezafungin, against Candida isolates cultured from patients in clinical trials. When reported, most of the data were generated by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method or by both the CLSI and European Committee on Antimicrobial Susceptibility Testing (EUCAST) methodologies. For fosmanogepix, we summarize the in vitro data for C. auris isolates from 9 patients and for Candida spp. cultured from 20 patients in two clinical trials. Ibrexafungerp has also been evaluated in several clinical trials. From conference proceedings, a total of 176 Candida isolates were evaluated in the FURI and CARES studies, including 18 C. auris isolates (CARES study). However, MIC data are not available for all clinical isolates. Results from the ReSTORE rezafungin phase 3 clinical study also included in vitro results against Candida spp., but no patients with C. auris infections were included. In conclusion, this mini-review summarizes insights regarding clinical outcomes and the in vitro activity of three new antifungals against Candida spp. cultured from patients in clinical trials.

Choanephora infundibulifera Rhinosinusitis in Man with Acute Lymphoblastic Leukemia, Tennessee, USA.

Choanephora infundibulifera is a member of the Mucorales order of fungi. The species is associated with plants as a saprophyte or parasite and may be responsible for spoilage or disease but is an uncommon cause of human infection. We describe C. infundibulifera rhinosinusitis in a young man with leukemia in Tennessee, USA.

Cutaneous Lagenidium deciduum infection in a patient with relapsed acute myeloid leukemia.

BACKGROUND: Lagenidium deciduum is an oomycete that can cause infections in mammals that present similarly to pythiosis and mucormycosis. Most of the existing case reports have occurred in canines and have been fatal. In animals, medical therapy has not been successful, so surgical excision is the mainstay of treatment. Lagenidium sp. infections in humans are rare. There is only one case of a human Lagenidium sp. infection in the literature, and it presented as an ocular infection. The human ocular infection was resistant to medical therapy and required a penetrating keratoplasty for cure. Additional reports of effective therapy are needed to guide management of this emerging pathogen. We present the first case of a cutaneous Lagenidium deciduum infection in a human patient, which is also the first documented case of a Lagenidium deciduum infection in an immunocompromised host of any species. CASE PRESENTATION: An 18-year-old female with relapsed acute myeloid leukemia, awaiting a haploidentical stem cell transplant, presented with erythematous cutaneous lesions on her left hip and bilateral buttocks that enlarged and blackened over several days. About 1 week later, boil-like lesions appeared on her bilateral buttocks. The skin lesions were initially presumed to be bacterial in origin, so the patient was treated with clindamycin and cefepime with little improvement. Upon further investigation, fungal cultures and skin biopsies revealed aseptate hyphae, so the patient was switched to isavuconazole and amphotericin B due to concern for mucormycosis. Phenotypic characterization and DNA sequencing were performed by the Fungus Testing Laboratory, University of Texas Health Science Center at San Antonio, which identified the causal fungal organism as Lagenidium deciduum. All of her cutaneous lesions were surgically excised, and the patient was treated with micafungin, terbinafine, doxycycline, and azithromycin. Micafungin and terbinafine were continued until she achieved engraftment post-transplant. CONCLUSIONS: We report the first successful treatment of a human Lagenidium infection in an immunocompromised host through a combination of aggressive surgical excision and prolonged antifungal therapy during the prolonged neutropenia associated with allogeneic stem cell transplant. Prompt diagnosis and management may prevent disseminated oomycosis.

Universal digital high-resolution melting for the detection of pulmonary mold infections.

Invasive mold infections (IMIs) are associated with high morbidity, particularly in immunocompromised patients, with mortality rates between 40% and 80%. Early initiation of appropriate antifungal therapy can substantially improve outcomes, yet early diagnosis remains difficult to establish and often requires multidisciplinary teams evaluating clinical and radiological findings plus supportive mycological findings. Universal digital high-resolution melting (U-dHRM) analysis may enable rapid and robust diagnoses of IMI. A universal fungal assay was developed for U-dHRM and used to generate a database of melt curve signatures for 19 clinically relevant fungal pathogens. A machine learning algorithm (ML) was trained to automatically classify these pathogen curves and detect novel melt curves. Performance was assessed on 73 clinical bronchoalveolar lavage samples from patients suspected of IMI. Novel curves were identified by micropipetting U-dHRM reactions and Sanger sequencing amplicons. U-dHRM achieved 97% overall fungal organism identification accuracy and a turnaround time of ~4 hrs. U-dHRM detected pathogenic molds (Aspergillus, Mucorales, Lomentospora, and Fusarium) in 73% of 30 samples classified as IMI, including mixed infections. Specificity was optimized by requiring the number of pathogenic mold curves detected in a sample to be >8 and a sample volume to be 1 mL, which resulted in 100% specificity in 21 at-risk patients without IMI. U-dHRM showed promise as a separate or combination diagnostic approach to standard mycological tests. U-dHRM's speed, ability to simultaneously identify and quantify clinically relevant mold pathogens in polymicrobial samples, and detect emerging opportunistic pathogens may aid treatment decisions, improving patient outcomes. IMPORTANCE: Improvements in diagnostics for invasive mold infections are urgently needed. This work presents a new molecular detection approach that addresses technical and workflow challenges to provide fast pathogen detection, identification, and quantification that could inform treatment to improve patient outcomes.

Ibrexafungerp is efficacious in a neutropenic murine model of pulmonary mucormycosis as monotherapy and combined with liposomal amphotericin B.

Ibrexafungerp (formerly SCY-078) is the first member of the triterpenoid class that prevents the synthesis of the fungal cell wall polymer ß-(1,3)-D-glucan by inhibiting the enzyme glucan synthase. We evaluated the in vivo efficacy of ibrexafungerp against pulmonary mucormycosis using an established murine model. Neutropenic mice were intratracheally infected with either Rhizopus delemar or Mucor circinelloides. Treatment with placebo (diluent control), ibrexafungerp (30 mg/kg, PO BID), liposomal amphotericin B (LAMB 10 mg/kg IV QD), posaconazole (PSC 30 mg/kg PO QD), or a combination of ibrexafungerp plus LAMB or ibrexafungerp plus PSC began 16 h post-infection and continued for 7 days for ibrexafungerp or PSC and through day 4 for LAMB. Ibrexafungerp was as effective as LAMB or PSC in prolonging median survival (range: 15 days to >21 days) and enhancing overall survival (30%-65%) vs placebo (9 days and 0%; P < 0.001) in mice infected with R. delemar. Furthermore, median survival and overall percent survival resulting from the combination of ibrexafungerp plus LAMB were significantly greater compared to all monotherapies (P ≤ 0.03). Similar survival results were observed in mice infected with M. circinelloides. Monotherapies also reduce the lung and brain fungal burden by ~0.5-1.0log10 conidial equivalents (CE)/g of tissue vs placebo in mice infected with R. delemar (P < 0.05), while a combination of ibrexafungerp plus LAMB lowered the fungal burden by ~0.5-1.5log10 CE/g compared to placebo or any of the monotherapy groups (P < 0.03). These results are promising and warrant continued investigation of ibrexafungerp as a novel treatment option against mucormycosis.

Novel antifungals and treatment approaches to tackle resistance and improve outcomes of invasive fungal disease.

SUMMARYFungal infections are on the rise, driven by a growing population at risk and climate change. Currently available antifungals include only five classes, and their utility and efficacy in antifungal treatment are limited by one or more of innate or acquired resistance in some fungi, poor penetration into "sequestered" sites, and agent-specific side effect which require frequent patient reassessment and monitoring. Agents with novel mechanisms, favorable pharmacokinetic (PK) profiles including good oral bioavailability, and fungicidal mechanism(s) are urgently needed. Here, we provide a comprehensive review of novel antifungal agents, with both improved known mechanisms of actions and new antifungal classes, currently in clinical development for treating invasive yeast, mold (filamentous fungi), Pneumocystis jirovecii infections, and dimorphic fungi (endemic mycoses). We further focus on inhaled antifungals and the role of immunotherapy in tackling fungal infections, and the specific PK/pharmacodynamic profiles, tissue distributions as well as drug-drug interactions of novel antifungals. Finally, we review antifungal resistance mechanisms, the role of use of antifungal pesticides in agriculture as drivers of drug resistance, and detail detection methods for antifungal resistance.

Disseminated Aspergillus citrinoterreus and concurrent localized dermal phaeohyphomycosis in an immunosuppressed dog.

Key Clinical message: We report on a dog with immune-mediated hemolytic anemia (IMHA) treated with immunomodulatory therapy that developed phaeohyphomycosis and Aspergillus citrinoterreus infections. This is the first reported case of A. citrinoterreus in dogs. It details cytological and microbiological findings leading to diagnosis and highlights the importance of investigating new lesions in immunocompromised patients. Abstract: A 5-year-old Staffordshire terrier mix treated with immunosuppressive therapy for IMHA was diagnosed with concurrent disseminated A. citrinoterreus and localized Curvularia lunata infections. This case highlights the potential development of multiple concurrent opportunistic fungal infections and is the first reported case of A. citrinoterreus infection in a dog.

A Recombinant Multivalent Vaccine (rCpa1) Induces Protection for C57BL/6 and HLA Transgenic Mice against Pulmonary Infection with Both Species of Coccidioides.

Coccidioidomycosis is caused by Coccidioides posadasii (Cp) and Coccidioides immitis (Ci), which have a 4-5% difference in their genomic sequences. There is an urgent need to develop a human vaccine against both species. A previously created recombinant antigen (rCpa1) that contains multiple peptides derived from Cp isolate C735 is protective against the autologous isolate. The focus of this study is to evaluate cross-protective efficacy and immune correlates by the rCpa1-based vaccine against both species of Coccidioides. DNA sequence analyses of the homologous genes for the rCpa1 antigen were conducted for 39 and 17 clinical isolates of Cp and Ci, respectively. Protective efficacy and vaccine-induced immunity were evaluated for both C57BL/6 and human HLA-DR4 transgenic mice against five highly virulent isolates of Cp and Ci. There are total of seven amino acid substitutions in the rCpa1 antigen between Cp and Ci. Both C57BL/6 and HLA-DR4 mice that were vaccinated with an rCpa1 vaccine had a significant reduction of fungal burden and increased numbers of IFN-γ- and IL-17-producing CD4+ T cells in the first 2 weeks post challenge. These data suggest that rCpa1 has cross-protection activity against Cp and Ci pulmonary infection through activation of early Th1 and Th17 responses.

Tuning sterol extraction kinetics yields a renal-sparing polyene antifungal.

Decades of previous efforts to develop renal-sparing polyene antifungals were misguided by the classic membrane permeabilization model1. Recently, the clinically vital but also highly renal-toxic small-molecule natural product amphotericin B was instead found to kill fungi primarily by forming extramembraneous sponge-like aggregates that extract ergosterol from lipid bilayers2-6. Here we show that rapid and selective extraction of fungal ergosterol can yield potent and renal-sparing polyene antifungals. Cholesterol extraction was found to drive the toxicity of amphotericin B to human renal cells. Our examination of high-resolution structures of amphotericin B sponges in sterol-free and sterol-bound states guided us to a promising structural derivative that does not bind cholesterol and is thus renal sparing. This derivative was also less potent because it extracts ergosterol more slowly. Selective acceleration of ergosterol extraction with a second structural modification yielded a new polyene, AM-2-19, that is renal sparing in mice and primary human renal cells, potent against hundreds of pathogenic fungal strains, resistance evasive following serial passage in vitro and highly efficacious in animal models of invasive fungal infections. Thus, rational tuning of the dynamics of interactions between small molecules may lead to better treatments for fungal infections that still kill millions of people annually7,8 and potentially other resistance-evasive antimicrobials, including those that have recently been shown to operate through supramolecular structures that target specific lipids9.

Universal Digital High Resolution Melt for the detection of pulmonary mold infections.

Background: Invasive mold infections (IMIs) such as aspergillosis, mucormycosis, fusariosis, and lomentosporiosis are associated with high morbidity and mortality, particularly in immunocompromised patients, with mortality rates as high as 40% to 80%. Outcomes could be substantially improved with early initiation of appropriate antifungal therapy, yet early diagnosis remains difficult to establish and often requires multidisciplinary teams evaluating clinical and radiological findings plus supportive mycological findings. Universal digital high resolution melting analysis (U-dHRM) may enable rapid and robust diagnosis of IMI. This technology aims to accomplish timely pathogen detection at the single genome level by conducting broad-based amplification of microbial barcoding genes in a digital polymerase chain reaction (dPCR) format, followed by high-resolution melting of the DNA amplicons in each digital reaction to generate organism-specific melt curve signatures that are identified by machine learning. Methods: A universal fungal assay was developed for U-dHRM and used to generate a database of melt curve signatures for 19 clinically relevant fungal pathogens. A machine learning algorithm (ML) was trained to automatically classify these 19 fungal melt curves and detect novel melt curves. Performance was assessed on 73 clinical bronchoalveolar lavage (BAL) samples from patients suspected of IMI. Novel curves were identified by micropipetting U-dHRM reactions and Sanger sequencing amplicons. Results: U-dHRM achieved an average of 97% fungal organism identification accuracy and a turn-around-time of 4hrs. Pathogenic molds (Aspergillus, Mucorales, Lomentospora and Fusarium) were detected by U-dHRM in 73% of BALF samples suspected of IMI. Mixtures of pathogenic molds were detected in 19%. U-dHRM demonstrated good sensitivity for IMI, as defined by current diagnostic criteria, when clinical findings were also considered. Conclusions: U-dHRM showed promising performance as a separate or combination diagnostic approach to standard mycological tests. The speed of U-dHRM and its ability to simultaneously identify and quantify clinically relevant mold pathogens in polymicrobial samples as well as detect emerging opportunistic pathogens may provide information that could aid in treatment decisions and improve patient outcomes.

Coccidioides species antifungal susceptibility testing: Experience from a large healthcare system in the endemic region.

The clinical utility of Coccidioides species antifungal susceptibility testing (AST) remains unclear. This study describes the clinical course of eight patients with severe or chronic coccidioidomycosis and subsequent Coccidioides AST. We present the clinical manifestations, antifungal treatment regimens, and clinical outcomes for these patients.

The role of antifungal susceptibility in the management of coccidioidomycosis remains unknown. This report presents cases of complex coccidioidomycosis where clinicians elected to conduct antifungal susceptibility testing as part of the treatment approach.

High-Throughput Screening of the Repurposing Hub Library to Identify Drugs with Novel Inhibitory Activity against Candida albicans and Candida auris Biofilms.

Candidiasis is one of the most frequent nosocomial infections affecting an increasing number of at-risk patients. Candida albicans remains the most frequent causative agent of candidiasis, but, in the last decade, C. auris has emerged as a formidable multi-drug-resistant pathogen. Both species are fully capable of forming biofilms, which contribute to resistance, increasing the urgency for new effective antifungal therapies. Repurposing existing drugs could significantly accelerate the development of novel therapies against candidiasis. Here, we have screened the Repurposing Hub library from the Broad Institute, containing over 6000 compounds, in search for inhibitors of C. albicans and C. auris biofilm formation. The primary screen identified 57 initial hits against C. albicans and 33 against C. auris. Confirmatory concentration-dependent assays were used to validate the activity of the initial hits and, at the same time, establish their anti-biofilm potency. Based on these results, ebselen, temsirolimus, and compound BAY 11-7082 emerged as the leading repositionable compounds. Subsequent experiments established their spectrum of antifungal activity against yeasts and filamentous fungi. In addition, their in vivo activity was examined in the murine models of hematogenously disseminated C. albicans and C. auris infections. Although promising, further in vitro and in vivo studies are needed to confirm their potential use for the therapy of candidiasis and possibly other fungal infections.

Update on Outbreak of Fungal Meningitis among U.S. Residents who Received Epidural Anesthesia at Two Clinics in Matamoros, Mexico.

BACKGROUND: Public health officials are responding to an outbreak of fungal meningitis among patients who received procedures under epidural anesthesia at two clinics (River Side Surgical Center and Clinica K-3) in Matamoros, Mexico, during January 1-May 13, 2023. This report describes outbreak epidemiology and outlines interim diagnostic and treatment recommendations. METHODS: Interim recommendations for diagnosis and management were developed by the Mycoses Study Group Research Education and Consortium (MSGERC) based on the clinical experience of clinicians caring for patients during the current outbreak or during previous outbreaks of healthcare-associated fungal meningitis in Durango, Mexico, and the United States. RESULTS: As of July 7, 2023, the situation has evolved into a multistate and multinational fungal meningitis outbreak. A total of 185 residents in 22 U.S. states and jurisdictions have been identified who might be at risk of fungal meningitis because they received epidural anesthesia at the clinics of interest in 2023. Among these patients, 11 suspected, 10 probable, and 10 confirmed U.S. cases have been diagnosed, with severe vascular complications and eight deaths occurring. Fusarium solani species complex has been identified as the causative agent, with antifungal susceptibility testing of a single isolate demonstrating poor in vitro activity for most available antifungals. Currently, triple therapy with intravenous voriconazole, liposomal amphotericin B, and fosmanogepix is recommended. CONCLUSIONS: Efforts to understand the source of this outbreak and optimal treatment approaches are ongoing, but infectious diseases physicians should be aware of available treatment recommendations. New information will be available on CDC's website.

Kneiffiella palmae: A non-Aspergillus fungal infection isolated from a pulmonary nodule in a child with chronic granulomatous disease.

We report the first known human case of Kneiffiella palmae in the medical literature. K. palmae was isolated from a pulmonary nodule in a 7-year-old male with chronic granulomatous disease. The mold was identified as K. palmae at a national reference laboratory, where 17 other human respiratory samples tested positive for K. palmae from 2013 to 2021. Optimal antimicrobial treatment is unknown, but azoles and amphotericin B demonstrated in vitro activity against each tested isolate.

Low Rates of Antifungal Therapeutic Drug Monitoring Among Inpatients Who Received Itraconazole, Posaconazole, or Voriconazole, United States, 2019-2021.

Antifungal therapeutic drug monitoring (TDM) is recommended for hospitalized patients receiving itraconazole, posaconazole, or voriconazole for treatment or prophylaxis. In this analysis of hospital-based data, TDM was uncommonly performed (15.8%) in a large cohort of eligible patients, suggesting missed opportunities to avoid subtherapeutic drug levels and minimize toxicity.

Terbinafine-Resistant Dermatophytes and the Presence of Trichophyton indotineae in North America.

Dermatophytes are common causes of skin, hair, and nail infections in humans. The most common species causing infections in humans are Trichophyton rubrum, Trichophyton mentagrophytes, and Trichophyton interdigitale. Outbreaks of recalcitrant dermatophytosis have been reported in parts of South Asia, including those caused by a hypervirulent and resistant species, Trichophyton indotineae. We evaluated the antifungal susceptibility profiles of dermatophytes received by our laboratory from institutions across North America between 2021 and 2022 and performed species identification for isolates deemed to demonstrate in vitro resistance. Susceptibility testing was performed by CLSI broth microdilution methods, and species identification was performed by DNA sequence analysis. During this 2-year period, 271 dermatophyte isolates were included, the majority of which demonstrated low MIC values for terbinafine (geometric mean [GM] and modal MIC, 0.031 µg/mL and 0.008 µg/mL, respectively) and the azoles itraconazole, posaconazole, and voriconazole (0.035 to 0.049 µg/mL and ≤0.03 µg/mL). However, 18.6% of the isolates tested were resistant to terbinafine (MIC ≥ 0.5 µg/mL), including 21 T. rubrum and 21 T. indotineae isolates. These isolates were received from several different states in the United States and two provinces in Canada. In contrast, resistance to itraconazole was relatively rare. We also searched our laboratory database for earlier isolates that were resistant to terbinafine and identified 3 additional T. indotineae isolates, the earliest of which was from 2017. These results demonstrate that terbinafine resistance in dermatophytes was relatively common over this 2-year period and that T. indotineae is present in multiple areas in North America. Continued surveillance is warranted.