Species-level identification of Candidaand their antifungal sensitivity testing should be performed to achieve better clinical results.

Objectives Candida auris is an emerging, often MDR, yeast pathogen. Efficient animal models are needed to study its pathogenicity and treatment. Therefore, we developed a C. auris fruit fly infection model. Methods TollI-RXA/Tollr632 female flies were infected with 10 different C. auris strains from the CDC Antimicrobial Resistance bank panel. We used three clinical Candida albicans strains as controls. For drug protection assays, fly survival was assessed along with measurement of fungal burden (cfu/g tissue) and histopathology in C. auris-infected flies fed with fluconazole- or posaconazole-containing food. Results Despite slower in vitro growth, all 10 C. auris isolates caused significantly greater mortality than C. albicans in infected flies, with >80% of C. auris-infected flies dying by day 7 post-infection (versus 67% with C. albicans, P < 0.001–0.005). Comparison of C. auris isolates from different geographical clades revealed more rapid in vitro growth of South American isolates and greater virulence in infected flies, whereas the aggregative capacity of C. auris strains had minimal impact on their growth and pathogenicity. Survival protection and decreased fungal burden of fluconazole- or posaconazole-fed flies infected with two C. auris strains were in line with the isolates’ disparate in vitro azole susceptibility. High reproducibility of survival curves for both non-treated and antifungal-treated infected flies was seen, with coefficients of variation of 0.00–0.31 for 7 day mortality. Conclusions Toll-deficient flies could provide a fast, reliable and inexpensive model to study pathogenesis and drug activity in C. auris candidiasis.

Chronic exposure to airborne carbon black ultrafine (nCB) particles generated from incomplete combustion of organic matter drives IL-17A–dependent emphysema. However, whether and how they alter the immune responses to lung cancer remains unknown. Here, we show that exposure to nCB particles increased PD-L1 + PD-L2 + CD206 + antigen-presenting cells (APCs), exhausted T cells, and T reg cells. Lung macrophages that harbored nCB particles showed selective mitochondrial structure damage and decreased oxidative respiration. Lung macrophages sustained the HIF1α axis that increased glycolysis and lactate production, culminating in an immunosuppressive microenvironment in multiple mouse models of non–small cell lung cancers. Adoptive transfer of lung APCs from nCB-exposed wild type to susceptible mice increased tumor incidence and caused early metastasis. Our findings show that nCB exposure metabolically rewires lung macrophages to promote immunosuppression and accelerates the development of lung cancer.

Background Candida auris is an emerging multi-drug-resistant human pathogen. Experimental data on the pathogenicity of C. auris is scarce, especially regarding its virulence compared with C. albicans. Additionally, studies of drug efficacy against C. auris rely on conventional animal models that are laborious and low throughput; alternative, less cumbersome models are desirable. To that end, we developed a C. auris fly infection model.MethodsWe injected 2-week-old TollI-RXA/Tollr632 female flies with a needle dipped in Candida solutions (108 yeast cells/mL) in the dorsal side of the thorax. Flies were infected with 10 different C. auris strains (source: CDC/FDA) and a C. albicansclinical strain. For drug protection studies, C. auris isolate AR-BANK#0386 [MICs: fluconazole (FLC) > 64, posaconazole (POSA) 0.125–0.25, isavuconazole (ISA) 0.25–1, voriconazole (VRC) 0.5–2 µg/mL)] was used. We assessed survival differences associated with different inocula (107 to 1010 yeast cells/mL) and yeast strains. Moreover, protection conferred by addition of FLC, VRC, ISA, POSA, or FLC combined with 5-FC (flucytosine) and/or nikkomycin Z (NikZ) to fly food was studied. Three independent runs were performed for each experiment.ResultsA) All C. auris strains and C. albicans exhibited comparable in vitro growth rates. B) All strains of C. auris were similarly more virulent than C. albicans (P < 0.0001), with all flies dying by day 7 post-infection. C) FLC, VRC, ISA, FLC+5-FC, FLC+NikZ, or FLC+NikZ+5-FC-fed flies infected with C. auris #0386 had comparably poor survival outcomes compared with untreated C. auris #0386-infected flies. Interestingly, survival rates were improved in POSA-fed infected flies compared with FLC-treated or untreated infected flies (P < 0.0001). As POSA is a cell-associated drug, we are conducting C. auris phagocytosis assays with Drosophila hemocytes that are co-incubated or not with POSA.Conclusion Drosophila is a promising, fast, and inexpensive in-vivo model to study pathogenesis and drug activity in C. auris candidiasis.Disclosures N. Beyda, Astellas: Scientific Advisor, Grant recipient. D. P. Kontoyiannis, Merck: Consultant, Research support and Speaker honorarium. Pfizer: Consultant, Research support. Astellas: Consultant, Research support and Speaker honorarium. Gilead: Speaker’s Bureau, Speaker honorarium. F2G Inc.: Speaker’s Bureau, Speaker honorarium. Cidara Inc.: Speaker’s Bureau, Speaker honorarium. Jazz Pharmaceuticals: Speaker’s Bureau, Speaker honorarium.