Summary Recent discoveries of novel systemic fungal pathogens with thermally dimorphic yeast-like phases have challenged the current taxonomy of the Ajellomycetaceae, a family currently comprising the genera Blastomyces, Emmonsia, Emmonsiellopsis, Helicocarpus, Histoplasma, Lacazia and Paracoccidioides. Our morphological, phylogenetic and phylogenomic analyses demonstrated species relationships and their specific phenotypes, clarified generic boundaries and provided the first annotated genome assemblies to support the description of two new species. A new genus, Emergomyces, accommodates Emmonsia pasteuriana as type species, and the new species Emergomyces africanus, the etiological agent of case series of disseminated infections in South Africa. Both species produce small yeast cells that bud at a narrow base at 37 °C and lack adiaspores classically associated with the genus Emmonsia. Another novel dimorphic pathogen, producing broad-based budding cells at 37 °C and occurring outside North America, proved to belong to the genus Blastomyces, and is described as Blastomyces percursus.

Introduction Candida auris is a multidrug-resistant fungal pathogen endemic in South African hospitals. Materials and methods We tested bloodstream C. auris isolates that were submitted to a reference laboratory for national laboratory-based surveillance for candidaemia, 2016-2017. We confirmed species identification by phenotypic/molecular methods. We tested susceptibility to amphotericin B, anidulafungin, caspofungin, micafungin, itraconazole, posaconazole, voriconazole, fluconazole and flucytosine using broth microdilution (BMD) and Etest. We interpreted minimum inhibitory concentrations (MICs) using tentative breakpoints. We sequenced the genomes of a subset of isolates and compared to the C. auris B8441 reference strain. Results Of 400 C. auris isolates, 361 (90%) were resistant to at least one antifungal agent, 339 (85%) to fluconazole alone (MIC of ≥32 mg/L), 19 (5%) to fluconazole and amphotericin B (MIC ≥2 mg/L) and one (0.3%) to amphotericin B alone. Two (0.5%) isolates from a single patient were pan-resistant (fluconazole, amphotericin B, echinocandins). Of 93 isolates selected for whole genome sequencing, 78 clustered in clade III including the pan-resistant isolates, 13 in clade I and two in clade IV. Eighty-four of these (91%) were resistant to at least one antifungal agent; both resistant and susceptible isolates had mutations. The common substitutions identified across the different clades were VF125AL, Y132F, K177R, N335S, E343D in ERG11 ; N647T in MRR1; A651P, A657V, S195G in TAC1b; S639P in FKS1; and S58T in ERG3 genes. Conclusions Most South African C. auris isolates were resistant to azoles, though resistance to polyenes and echinocandins was less common. We observed mutations in resistance genes even in phenotypically-susceptible isolates.

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Disseminated emmonsiosis is an important AIDS-related mycosis in SouthAfrica that is caused by Emergomyces africanus, a newly described and renamed dimorphic fungal pathogen. In vitro antifungal susceptibility data can guide management. Identification of invasive clinical isolates was confirmed phenotypically and by sequencing of the internal transcribed spacer region. Yeast and mold phase MICs of fluconazole, voriconazole, itraconazole, posaconazole, caspofungin, anidulafungin, micafungin, and flucytosine were determined with custom-made frozen broth microdilution (BMD) panels in accordance with Clinical and Laboratory Standards Institute recommendations. MICs of amphotericin B, itraconazole, posaconazole, and voriconazole were determined by Etest. Fifty unique E. africanus isolates were tested. The yeast and mold phase geometric mean (GM) BMD and Etest MICs of itraconazole were 0.01 mg/liter. The voriconazole and posaconazole GM BMD MICs were 0.01 mg/liter for both phases, while the GM Etest MICs were 0.001 and 0.002 mg/liter, respectively. The fluconazole GM BMD MICs were 0.18 mg/liter for both phases. The GM Etest MICs of amphotericin B, for the yeast and mold phases were 0.03 and 0.01 mg/liter. The echinocandins and flucytosine had very limited in vitro activity. Treatment and outcome data were available for 37 patients; in a multivariable model including MIC data, only isolation from blood (odds ratio [OR], 8.6; 95% confidence interval [CI], 1.3 to 54.4; P ϭ 0.02) or bone marrow (OR, 12.1; 95% CI, 1.2 to 120.2; P ϭ 0.03) (versus skin biopsy) was associated with death. In vitro susceptibility data support the management of disseminated emmonsiosis with amphotericin B, followed by itraconazole, voriconazole, or posaconazole. Fluconazole was a relatively less potent agent.