Tinea capitis due to Microsporum ferrugineum: A case of unusual laboratory finding on direct microscopic examination of infected hairs and skin lesions

Tinea capitis is a chronic fungal infection of the scalp occurring commonly in children of school age, especially in developing countries. It is caused primarily by the dermatophyte members of genera Microsporum and Trichophyton. Here we report presence of free-living mycelial stage of dermatophytes, a stage of fungal growth which form in culture medias, around affected hairs and skin scrapings of scalp lesions in a 3-year-old boy presenting with alopecia and multiple scaly, non-erythematous plaques. On direct microscopy examination using 10 % potassium hydroxide, the fungal hyphae and arthrospores were detected in ectothrix form. In addition, we also observed numerous multicellular, thick-walled spindle-shaped macroconidia around hairs and skin scrapings. To our knowledge this is the first study reporting dermatophyte's macroconidia directly seen on clinical samples. Species level identification of the dermatophyte isolate growing on Mycosel™ agar was confirmed by PCR-sequencing of internal transcribed spacer of ribosomal RNA as Microsporum ferrugineum. The patient was successfully treated with systemic itraconazole combined with topical ketoconazole shampoo.

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.

P081 Azole-resistant Aspergillus fumigatus among NIH hospitalized patients with underlying primary immunodeficiencies

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM

 

Objectives

Aspergillus fumigatus causes a variety of diseases in humans. The drugs recommended for treatment of Aspergillus diseases are the mold-active azole antifungals. However, a wide range of mutations in A. fumigatus confers azole resistance, which commonly involves modifications in the cyp51Agene, the target for azole antifungal drugs.

Methods

We investigated 255 clinical A. fumigatus isolates obtained from patients hospitalized at National Institutes of Health Clinical Center, Bethesda, Maryland, USA. The species-level identification of each isolate was evaluated by colony morphology, microscopic characteristics, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF), and PCR-sequencing of the β-tubulin gene. We also studied sequence-based analysis of the Cyp51A gene for the azole-resistant isolates.

The azole antifungal susceptibility profile of each isolate was initially evaluated using 4-well triazole screen plates (Microbiology Associates LLC, Rockville, MD, USA) containing itraconazole (4 μg/ml), voriconazole (2 μg/ml), posaconazole (0.5 μg/ml), and growth control. The full array of antifungal susceptibility was confirmed using microbroth dilution method according to Clinical and Laboratory Standards Institute CLSI M38-A3 guidelines.

Results

Of 255 A. fumigatus isolates, 12 grew on the wells containing azoles, indicating an azole-resistant phenotype. The results were read and recorded after 24 and 48 h of incubation at 35-37°C. Majority of our isolates had visible growth at 24 h. Sequence analysis of the CYP51A gene indicated the presence of M220K mutation in all 12 isolates and no mutations in the other isolates.

The fact that the azole resistance was found in A. fumigatus isolated from patients with previous azole exposure, underscores the possibility that prevalence of azole-resistance might be underestimated in various patient populations because in-vitro susceptibility testing of A. fumigatus is not routinely performed.

Conclusion

In conclusion, prevalence of azole resistance in clinical A. fumigatus isolates obtained from NIH patients underlying primary immunodeficiencies was 4.7%; all the resistant isolates exhibited azole-resistance mutation in Cyp51A gene.

Our finding adds to the growing list of regions where acquired resistance in A. fumigatus of is documented. Our results also indicate that 4-well triazole screen plates are a reliable tool for azole-resistance screening and the selection of isolates that require a full panel of antifungal susceptibility testing.

S10.5d Disseminated pulmonary infection due to Mortierella wolfii in a 6-year-old patient with X-linked CGD receiving MUD-HSCT

 

S10.5 Fungal respiratory infections in Cystic Fibrosis, September 24, 2022, 10:30 AM - 12:00 PM

Objectives

Invasive fungal infections represent one of the major limiting factors for the successful outcome of patients receiving hematopoietic stem cell transplantation (HSCT). The identification and successful treatment of pretransplant fungal colonization/infections may allow for risk modifications before or at the time of HSCT. Here, we report a case of disseminated pulmonary infection due to a hyaline non-septate mold, Mortierella wolfii in an X-linked chronic granulomatous disease (X-linked CGD) patient that was successfully treated with a combination of terbinafine and posaconazole antifungal therapy.

Methods

A 6-year-old male with X-linked CGD from Sri Lanka was admitted to NIH Clinical Center, Bethesda, MD, USA to receive a matched unrelated donor (MUD) hematopoietic stem cell transplantation (HSCT). During pre-transplant immunosuppressive conditioning, the patient developed complicated pulmonary signs resulting in diffuse lymphadenitis and meningitis. Upon further radiologic evaluation, a lung biopsy was performed. The lung biopsy sample was submitted to Microbiology Service of Department of Microbiology at NIH Clinical Center for Fungal culture. Antifungal susceptibility testing was conducted in accordance with the Clinical and Laboratory Standards Institute CLSI M38-A3 guidelines.

Results

A pure heavy growth of white mold grew within 2 days on Sabouraud's Dextrose Agar. Microscopic examination showed hyaline (non-pigmented), non-septate branched hyphae. Sporangiophore-like structures were also present. The species-level identification of the isolate was confirmed as M. wolfii by PCR-sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA.

Minimum inhibitory/effective concentrations (μg/ml) were as follows in increasing order: terbinafine = 0.25, amphotericin B = 1, isavuconazole = 4, micafungin >8, itraconazole >16, voriconazole >16, and posaconazole >16. To evaluate the interactions between antifungal drugs, the activity of the posaconazole in combination with terbinafine were also evaluated M. wolfii using agar diffusion test. A combination of posaconazole and terbinafine, significantly inhibited the mycelial growth, which indicates synergism. The patient’s treatment was started on terbinafine in combination with posaconazole. On several follow-up examinations following treatment on day 30, 90 and 120, the infection had not recurred.

Conclusion

The species of M. wolfii a is an environmental mold belongs to the order Mortierellales within the subphylum Mortierellomycotina of Kingdom Fungi. This fungus has been mostly associated with fungal infections leading to abortion in dairy cows feeding moldy hays and ensilage.

Although posaconazole exhibited high MICs against M. wolfii, our in vitro combination study demonstrated that posaconazole and terbinafine combined are significantly more potent than either drug alone. As a suggestion, combination therapy could provide an option for the treatment of severe cases of M. wolfii in patients with underlying primary immunodeficiencies.

As molecular identification and sequencing techniques continue to develop and become more available, we will likely see more diverse pathogens emerge in patients with underlying primary immunodeficiencies. In this current case. Additional study is warranted to explore insight into human immunity and the efficacy of combination therapy against rare fungal species in CGD patients.