Phaeohyphomycosis caused by Phaeoacremonium species in a patient taking infliximab

Immune responses to human fungal pathogens and therapeutic prospects

Pathogenic fungi have emerged as significant causes of infectious morbidity and death in patients with acquired immunodeficiency conditions such as HIV/AIDS and following receipt of chemotherapy, immunosuppressive agents or targeted biologics for neoplastic or autoimmune diseases, or transplants for end organ failure. Furthermore, in recent years, the spread of multidrug-resistant Candida auris has caused life-threatening outbreaks in health-care facilities worldwide and raised serious concerns for global public health. Rapid progress in the discovery and functional characterization of inborn errors of immunity that predispose to fungal disease and the development of clinically relevant animal models have enhanced our understanding of fungal recognition and effector pathways and adaptive immune responses. In this Review, we synthesize our current understanding of the cellular and molecular determinants of mammalian antifungal immunity, focusing on observations that show promise for informing risk stratification, prognosis, prophylaxis and therapies to combat life-threatening fungal infections in vulnerable patient populations.

Human Dectin-1 deficiency impairs macrophage-mediated defense against phaeohyphomycosis

Subcutaneous phaeohyphomycosis typically affects immunocompetent individuals following traumatic inoculation. Severe or disseminated infection can occur in CARD9 deficiency or after transplantation, but the mechanisms protecting against phaeohyphomycosis remain unclear. We evaluated a patient with progressive, refractory Corynespora cassiicola phaeohyphomycosis and found that he carried biallelic deleterious mutations in CLEC7A encoding the CARD9-coupled, β-glucan-binding receptor, Dectin-1. The patient's PBMCs failed to produce TNF-α and IL-1β in response to β-glucan and/or C. cassiicola. To confirm the cellular and molecular requirements for immunity against C. cassiicola, we developed a mouse model of this infection. Mouse macrophages required Dectin-1 and CARD9 for IL-1β and TNF-α production, which enhanced fungal killing in an interdependent manner. Deficiency of either Dectin-1 or CARD9 was associated with more severe fungal disease, recapitulating the human observation. Because these data implicated impaired Dectin-1 responses in susceptibility to phaeohyphomycosis, we evaluated 17 additional unrelated patients with severe forms of the infection. We found that 12 out of 17 carried deleterious CLEC7A mutations associated with an altered Dectin-1 extracellular C-terminal domain and impaired Dectin-1-dependent cytokine production. Thus, we show that Dectin-1 and CARD9 promote protective TNF-α- and IL-1β-mediated macrophage defense against C. cassiicola. More broadly, we demonstrate that human Dectin-1 deficiency may contribute to susceptibility to severe phaeohyphomycosis by certain dematiaceous fungi.

The type isolate of a rare Phaeoacremonium species as a cause of human eumycetoma

An isolate of unknown identity that had been identified as causing eumycetoma was retained in an international culture collection, and eventually became the nomenclatural type isolate of the rarely encountered Phaeoacremonium sphinctrophorum. The case featured an indurated, painless, swollen lesion on the dorsum of the foot that had developed in a Canadian resident who had previously been a farmer in Laos. Resection alone was curative.

Cutaneous infection by Phaeoacremonium parasiticum

BACKGROUND

Phaeoacremonium parasiticum is considered a rare infectious agent that is part of a heterogeneous group of fungi causing phaeohyphomycosis. This organism is capable of producing subcutaneous infections, eumycetomas, osteomyelitis, arthritis, myositis and also disseminated diseases, such as fungemia and endocarditis.

CASE REPORT

We describe a case of cutaneous infection by P. parasiticum in a kidney transplant patient. The identification of this microorganism was performed by microbiological and histopathological studies and confirmed with the sequence of the gene encoding β-tubulin and a real time panfungal PCR targeting 18S ribosomal RNA gene. The microorganism was correctly identified by phenotypic and molecular methods. The patient was treated with oral antifungal therapy and a debulking surgery and evolved without any complication.

CONCLUSIONS

The diagnosis of this infection is difficult and usually affects kidney transplant patients, but the reasons of this association are still unknown.

Dematiaceous Molds

Dematiaceous fungi are the cause of phaeohyphomycosis, a term that encompasses many clinical syndromes, from local infections due to trauma to widely disseminated infection in immunocompromised patients. These fungi are unique owing to the presence of melanin in their cell walls, which imparts the characteristic dark color to their spores and hyphae. Melanin may also be a virulence factor. Local infection may be cured with excision alone, whereas systemic disease is often refractory to therapy. Azoles have the most consistent in vitro activity. Further studies are needed to better understand the pathogenesis and treatment of these uncommon infections.

In Vitro Susceptibility Profiles of Eight Antifungal Drugs against Clinical and Environmental Strains of Phaeoacremonium

In vitro susceptibilities of a worldwide collection of molecularly identified Phaeoacremonium strains (n = 43) belonging to seven species and originating from human and environmental sources were determined for eight antifungal drugs. Voriconazole had the lowest geometric mean MIC (0.35 μg/ml), followed by posaconazole (0.37 μg/ml), amphotericin B (0.4 μg/ml), and isavuconazole (1.16 μg/ml). Caspofungin, anidulafungin, fluconazole, and itraconazole had no activity.

Dual Invasive Infection with Phaeoacremonium parasiticum and Paraconiothyrium cyclothyrioides in a Renal Transplant Recipient: Case Report and Comprehensive Review of the Literature of Phaeoacremonium Phaeohyphomycosis

Despite increasing reports of human infection, data about the optimal care of Phaeoacremonium infections are missing. We report a case of an infection due to Phaeoacremonium parasiticum and Paraconiothyrium cyclothyrioides, initially localized to skin and soft tissue, in a kidney transplant patient. Despite surgical drainage and excision of the lesion and combination antifungal therapy with voriconazole and liposomal amphotericin B, a disseminated infection involving the lungs and brain developed and led to death. We performed a systematic literature review to assess the general features and outcome of human infections due to Phaeoacremonium species. Thirty-six articles were selected, and 42 patients, including ours, were reviewed. Thirty-one patients (74%) were immunocompromised because of organ or bone marrow transplantation (n = 17), diabetes or glucose intolerance (n = 10), rheumatoid arthritis or Still's disease (n = 4), chronic hematological diseases (n = 3), or chronic granulomatous disease (n = 3). Ten patients (24%) reported initial cutaneous trauma. Skin and soft tissue infections represented 57% of infections (n = 24), and disseminated infections, all occurring in immunocompromised patients, represented 14% of infections (n = 6). The main antifungal drugs used were azoles (n = 41) and amphotericin B (n = 16). Surgical excision or drainage was performed in 64% of cases (n = 27). The cure rate was 67% (n = 28). There were 10% cases of treatment failure or partial response (n = 4), 19% relapses (n = 8), and 7% losses to follow-up (n = 3). The death rate was 19% (n = 8). Management of Phaeoacremonium infections is complex because of slow laboratory identification and limited clinical data, and treatment relies on a combination of surgery and systemic antifungal therapy.

Pulmonary phaeohyphomycosis caused by phaeoacremonium in a kidney transplant recipient: successful treatment with posaconazole

We report a rare case of pulmonary phaeohyphomycosis in a 49-year-old woman 6 years after kidney transplantation. She presented with dyspnea, cough, and fatigue. Her chest CT scan revealed nodular opacities in the right upper lung. A fine needle aspirate biopsy culture yielded Phaeoacremonium and surgical pathology of the biopsy showed chronic inflammation. We successfully treated her with posaconazole and managed drug interactions between posaconazole and tacrolimus. This is the second reported case of biopsy-proven pulmonary infection by Phaeoacremonium in a kidney transplant recipient and successfully treated with posaconazole.

Phaeoacremonium parasiticum phaeohyphomycosis in a patient with systemic lupus erythematosus treated successfully with surgical debridement and voriconazole: A case report and review of the literature

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Purulent drainage, woody induration and sinus tract formation suggest mycetoma.

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Phaeohyphomycosis management may require debridement and prolonged antifungal therapy.

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Microbiological identification is needed for optimal medical management.

A 26-year old woman presented for evaluation of extensive edema, erythema, sinus tract formation and purulent drainage from the left lower extremity after trauma from a wooden object approximately three months prior. Skin biopsies and blood cultures revealed Phaeoacremonium parasiticum consistent with a diagnosis of phaeohyphomycosis. Despite hospitalization and initial treatment with several antifungals, including voriconazole, her infection progressed. Surgical debridement with split thickness skin grafting was performed. Subsequent clinical improvement allowed a transition from intravenous to oral voriconazole and discharge home. Seven months post presentation she remained on oral voriconazole with significant improvement and no clinical evidence of recurrence. This case illustrates an approach to management where aggressive debridement with split-thickness skin grafting and a prolonged course of intravenous and oral antifungals resulted in a good long-term outcome for the patient.