A conceptual framework for nomenclatural stability and validity of medically important fungi: a proposed global consensus guideline for fungal name changes supported by ABP, ASM, CLSI, ECMM, ESCMID-EFISG, EUCAST-AFST, FDLC, IDSA, ISHAM, MMSA, and MSGERC

The rapid pace of name changes of medically important fungi is creating challenges for clinical laboratories and clinicians involved in patient care. We describe two sources of name change which have different drivers, at the species versus the genus level. Some suggestions are made here to reduce the number of name changes. We urge taxonomists to provide diagnostic markers of taxonomic novelties. Given the instability of phylogenetic trees due to variable taxon sampling, we advocate to maintain genera at the largest possible size. Reporting of identified species in complexes or series should where possible comprise both the name of the overarching species and that of the molecular sibling, often cryptic species. Because the use of different names for the same species will be unavoidable for many years to come, an open access online database of the names of all medically important fungi, with proper nomenclatural designation and synonymy, is essential. We further recommend that while taxonomic discovery continues, the adaptation of new name changes by clinical laboratories and clinicians be reviewed routinely by a standing committee for validation and stability over time, with reference to an open access database, wherein reasons for changes are listed in a transparent way.

1282. Manogepix, the Active Moiety of the Investigational Agent Fosmanogepix, Demonstrates In vitro Activity Against Members of the Fusarium oxysporum and Fusarium solani Species Complexes

Background

Invasive fusariosis is associated with marked morbidity and mortality in immunocompromised hosts, and treatment options are limited. Common etiologic agents include members of the F. oxysporum and F. solani species complexes (FOSC and FSSC, respectively). Manogepix (MGX), the active moiety of fosmanogepix, is a novel GWT1 inhibitor with broad antifungal activity. Fosmanogepix has previously shown in vivo efficacy in an immunocompromised murine model of invasive fusariosis. Our objective was to evaluate the in vitro activity of MGX against FOSC and FSSC isolates.

Methods

Clinical isolates of FOSC (n=49) and FSSC (19) were identified by combined phenotypic characteristics and DNA sequence analysis of the translation elongation factor 1-alpha (TEF1α) and RNA polymerase II second largest subunit (RPB2). Antifungal susceptibility testing was performed by CLSI M38 broth microdilution. Minimum effective concentrations (MEC) and minimum inhibitory concentrations (MIC) were read after 48 hours of incubation at 50% and 100% inhibition of growth for MGX, and MIC values were read for amphotericin B, posaconazole, isavuconazole, and voriconazole at 100% inhibition of growth.

Results

MGX demonstrated potent in vitro activity against both FOSC and FSSC isolates. Against the 49 FOSC isolates, the MGX MECs ranged from <0.015-0.03 mg/mL, and MICs at the 50% inhibition of growth endpoint ranged from <0.015-0.12 mg/mL (Table). MIC values were higher when read at 100% inhibition of growth. Similar results were observed against FSSC isolates (MEC and MIC ranges <0.015 and <0.015-0.25 mg/mL, respectively). MGX MEC and MIC 50% inhibition values were in close agreement for both FOSC and FSSC isolates. Of the other antifungals tested, amphotericin B demonstrated in vitro good activity (MIC ranges 1-4 and 0.25-4 mg/mL against FOSC and FSSC, respectively). In contrast, the azoles demonstrated reduced susceptibility (MIC range 1- >16 mg/mL).

MIC/MEC values (mcg/mL) for manogepix and other antifungals against FOSC and FSSC isolates

Conclusion

MGX demonstrated in vitro activity against FOSC and FSSC clinical isolates. Both changes in fungal morphology (MEC) and reductions in growth (MIC 50% inhibition) were observed. Clinical studies are ongoing to determine the efficacy of fosmanogepix in patients with invasive fungal infections.

Disclosures

Ashraf S. Ibrahim, PhD, Astellas Pharma (Research Grant or Support) Karen J. Shaw, PhD, Amplyx (Consultant)Forge Therapeutics (Consultant) Nathan P. Wiederhold, PharmD, Astellas (Grant/Research Support)BioMerieux (Grant/Research Support)Cepheid (Grant/Research Support)Covance (Grant/Research Support)F2G (Grant/Research Support)Gilead (Speaker’s Bureau)Mayne Pharma (Advisor or Review Panel member)Sfunga (Grant/Research Support)

Development of High-Level Echinocandin Resistance in a Patient With Recurrent Candida auris Candidemia Secondary to Chronic Candiduria

Objective

Candida auris is a globally emerging pathogen associated with significant mortality. This pathogen frequently is misidentified by traditional biochemical methods and is resistant to commonly used antifungals. The echinocandins currently are recommended as the first-line treatment for C. auris infections. The objective of this work is to demonstrate the challenges associated with C. auris in the real-world setting.

Methods

A 54-year-old male presented to our institution for concerns of sepsis on multiple occasions over a 5-month period. Eleven urine cultures were positive over this timeframe for yeast (9 unidentified Candida isolates and 2 C. lusitaniae isolates). On day 27, the patient developed echinocandin-susceptible candidemia, which was initially identified as C. haemulonii but later accurately identified as C. auris at an outside mycology reference laboratory. Approximately 10 weeks later, the patient had a recurrence of candidemia, this time caused by an echinocandin-resistant C. auris strain.

Results

Genomic DNA sequencing performed at the outside mycology reference laboratory identified a single serine to proline base pair change at position 639 (S639P) in the hotspot 1 region of the FKS1 gene of the echinocandin-resistant strain.

Conclusions

Our experiences highlight 4 major concerns associated with C. auris: misidentification, persistent colonization, infection recurrence despite the receipt of appropriate initial therapy, and development of resistance.

Gastrointestinal pythiosis with concurrent presumptive gastrointestinal basidiobolomycosis in a Boxer dog

A 2-year-old female spayed Boxer dog was presented for a 1-month history of progressive hemorrhagic diarrhea with tenesmus and weight loss despite trial courses of antibiotics and diet change. Abdominal ultrasound revealed severe, focal thickening, and loss of normal architecture of the colonic wall with abdominal lymphadenomegaly. Dry-mount fecal cytology, performed on several consecutive days, consistently revealed numerous, round, 16-20 μm structures with basophilic, granular content, and a thin cell wall. Transmission electron microscopy identified these structures as fungi. Culture, polymerase chain reaction (PCR), and sequencing of the internal transcribed spacer, D1/D2 regions, and DNA-directed RNA polymerase II core subunit (RPB2) confirmed the presence of Basidiobolus microsporus in the feces. Biopsies collected via ileocolonoscopy revealed marked, multifocal, chronic, neutrophilic, and eosinophilic ileitis and colitis with ulceration, granulation tissue, and intralesional hyphae (identified with Gomori methenamine silver stain). A Pythium enzyme-linked immunosorbent assay and Pythium-specific PCR performed on the formalin-fixed paraffin-embedded biopsy specimens were positive while Basidiobolus-specific PCR was negative, thus confirming a diagnosis of pythiosis. This report describes a fatal case of colonic and intestinal pythiosis with the presence of fecal Basidiobolus sp. spores, suggestive of concurrent gastrointestinal basidiobolomycosis.

Novel Paranannizziopsis species in a Wagler's viper (Tropidolaemus wagleri), tentacled snakes (Erpeton tentaculatum), and a rhinoceros snake (Rhynchophis boulengeri) in a zoological collection

We report several cases of fungal infections in snakes associated with a new species within the genus Paranannizziopsis. Three juvenile Wagler's vipers (Tropidolaemus wagleri) presented with skin abnormalities or ulcerative dermatitis, and two snakes died. Histologic examination of skin from the living viper revealed hyperplastic, hyperkeratotic, and crusting epidermitis with intralesional fungal elements. The terrestrial Wagler's vipers were housed in a room with fully aquatic tentacled snakes (Erpeton tentaculatum), among which there had been a history of intermittent skin lesions. Approximately 2 months after the biopsy of the viper, a skin sample was collected from one tentacled snake (TS1) with skin abnormalities and revealed a fungal infection with a similar histologic appearance. Fungal isolates were obtained via culture from the Wagler's viper and TS1 and revealed a novel species, Paranannizziopsis tardicrescens, based on phenotypic characterization and molecular analysis. P. tardicrescens was cultured and identified by DNA sequence analysis 8 months later from a dead tentacled snake in an exhibit in an adjacent hallway and 13 months later from a living rhinoceros snake (Rhynchophis boulengeri) with two focal skin lesions. Antifungal susceptibility testing on three of four cultured isolates demonstrated potent in vitro activity for terbinafine and voriconazole.

Peritonitis due to Curvularia inaequalis in an elderly patient undergoing peritoneal dialysis and a review of six cases of peritonitis associated with other Curvularia spp

Fungal peritonitis due to Curvularia species in patients undergoing peritoneal dialysis is a very rare problem. We report a case of peritonitis caused by Curvularia inaequalis. This is the first report in the English literature of this species causing human infection. We also review the six previously reported cases of continuous ambulatory peritoneal dialysis peritonitis caused by other Curvularia species.

Knowledge-based design of a soluble bacteriorhodopsin

Much knowledge has been accrued from high resolution protein structures. This knowledge provides rules and guidelines for the rational design of soluble proteins. We have extracted these rules and applied them to redesigning the structure of bacteriorhodopsin and to creating blueprints for a monomeric, soluble seven-helix bundle protein. Such a protein is likely to have desirable properties, such as ready crystallization, which membrane proteins lack and an internal structure similar to that of the native protein. While preserving residues shown to be necessary for protein function, we made modifications to the rest of the sequence, distributing polar and charged residues over the surface of the protein to achieve an amino acid composition as akin to that of soluble helical proteins as possible. A secondary goal was to increase apolar contacts in the helix intercalation regions of the protein. The scheme used to design the model sequences requires knowledge of the number and orientation of helices and some information about interior contacts, but detailed structural knowledge is not required to use a scheme of this type.

Light saturation curves show competence of the water splitting complex in inactive Photosystem II reaction centers

Photosystem II complexes of higher plants are structurally and functionally heterogeneous. While the only clearly defined structural difference is that Photosystem II reaction centers are served by two distinct antenna sizes, several types of functional heterogeneity have been demonstrated. Among these is the observation that in dark-adapted leaves of spinach and pea, over 30% of the Photosystem II reaction centers are unable to reduce plastoquinone to plastoquinol at physiologically meaningful rates. Several lines of evidence show that the impaired reaction centers are effectively inactive, because the rate of oxidation of the primary quinone acceptor, QA, is 1000 times slower than in normally active reaction centers. However, there are conflicting opinions and data over whether inactive Photosystem II complexes are capable of oxidizing water in the presence of certain artificial electron acceptors. In the present study we investigated whether inactive Photosystem II complexes have a functional water oxidizing system in spinach thylakoid membranes by measuring the flash yield of water oxidation products as a function of flash intensity. At low flash energies (less that 10% saturation), selected to minimize double turnovers of reaction centers, we found that in the presence of the artificial quinone acceptor, dichlorobenzoquinone (DCBQ), the yield of proton release was enhanced 20±2% over that observed in the presence of dimethylbenzoquinone (DMBQ). We argue that the extra proton release is from the normally inactive Photosystem II reaction centers that have been activated in the presence of DCBQ, demonstrating their capacity to oxidize water in repetitive flashes, as concluded by Graan and Ort (Biochim Biophys Acta (1986) 852: 320-330). The light saturation curves indicate that the effective antenna size of inactive reaction centers is 55±12% the size of active Photosystem II centers. Comparison of the light saturation dependence of steady state oxygen evolution in the presence of DCBQ or DMBQ support the conclusion that inactive Photosystem II complexes have a functional water oxidation system.