Scedosporium apiospermum Otitis Complicated by a Temporomandibular Arthritis: A Case Report and Mini-Review

Scedosporiosis and lomentosporiosis: modern perspectives on these difficult-to-treat rare mold infections

SUMMARYAlthough Scedosporium species and Lomentospora prolificans are uncommon causes of invasive fungal diseases (IFDs), these infections are associated with high mortality and are costly to treat with a limited armamentarium of antifungal drugs. In light of recent advances, including in the area of new antifungals, the present review provides a timely and updated overview of these IFDs, with a focus on the taxonomy, clinical epidemiology, pathogenesis and host immune response, disease manifestations, diagnosis, antifungal susceptibility, and treatment. An expansion of hosts at risk for these difficult-to-treat infections has emerged over the last two decades given the increased use of, and broader population treated with, immunomodulatory and targeted molecular agents as well as wider adoption of antifungal prophylaxis. Clinical presentations differ not only between genera but also across the different Scedosporium species. L. prolificans is intrinsically resistant to most currently available antifungal agents, and the prognosis of immunocompromised patients with lomentosporiosis is poor. Development of, and improved access to, diagnostic modalities for early detection of these rare mold infections is paramount for timely targeted antifungal therapy and surgery if indicated. New antifungal agents (e.g., olorofim, fosmanogepix) with novel mechanisms of action and less cross-resistance to existing classes, availability of formulations for oral administration, and fewer drug-drug interactions are now in late-stage clinical trials, and soon, could extend options to treat scedosporiosis/lomentosporiosis. Much work remains to increase our understanding of these infections, especially in the pediatric setting. Knowledge gaps for future research are highlighted in the review.

A rare cause of malignant otitis externa and skull base osteomyelitis

An elderly male with type 2 diabetes presented with a 2-month history of otalgia and severe headaches. He was diagnosed with malignant otitis externa (MOE) and was commenced on empirical treatment with oral ciprofloxacin. Pseudomonas is the most common cause of MOE. A baseline CT scan was undertaken that demonstrated skull base osteomyelitis (SBO) due to findings of bone erosion at the mastoid tip and an infiltrating soft tissue mass eroding the clivus. Eight weeks later, he returned with worsening and bilateral symptoms of otitis externa, hearing loss, temporomandibular pain and dysfunction. Worsening and now bilateral malignant otitis externa were confirmed with an MRI scan that also demonstrated a small fluid collection in his left temporal region. The collection was aspirated and grew scedosporium apiospermum. He was diagnosed with fungal SBO and was commenced on treatment with the antifungal voriconazole, with significant improvement in symptoms and radiological findings. Fungal osteomyelitis is more likely in immunosuppressed patients, particularly those with type 2 diabetes. Fungal aetiology should be suspected in patients with progressive symptoms, despite treatment. A microbiology diagnosis of fungal SBO or MOE can be challenging to obtain and can lead to diagnostic delay. A sampling of the external auditory canal can aid in diagnosing MOE; however, scedosporium may also be isolated as a commensal organism. Aspirations from accessible fluid collections, infratemporal fossa needle sample and bone biopsy can provide material for diagnosis. Scedosporium is a rare cause of disease in humans, however, fungal infections are increasing in humans, due to an increase in susceptible populations. Scedosporium apiospermum is a rare cause of SBO and should be considered in patients not responding to standard treatment.

Multi-organ involvement caused by Scedosporium apiospermum infection after near drowning: a case report and literature review

BACKGROUND

Scedosporium apiospermum (S. apiospermum) is a rare fungal pathogen that causes disseminated infections. It rarely affects immunocompetent individuals and has a poor prognosis.

CASE PRESENTATION

A 37-year-old woman presented with multiple lesions in the lungs, brain, and eyes, shortly after near drowning in a car accident. The primary symptoms were chest tightness, limb weakness, headache, and poor vision in the left eye. S. apiospermum infection was confirmed by metagenomic next-generation sequencing (mNGS) of intracranial abscess drainage fluid, although intracranial metastases were initially considered. After systemic treatment with voriconazole, her symptoms improved significantly; however, she lost vision in her left eye due to delayed diagnosis.

CONCLUSION

While S. apiospermum infection is rare, it should be considered even in immunocompetent patients. Prompt diagnosis and treatment are essential. Voriconazole may be an effective treatment option.

A Repertoire of Clinical Non-Dermatophytes Moulds

Humans are constantly exposed to micromycetes, especially filamentous fungi that are ubiquitous in the environment. In the presence of risk factors, mostly related to an alteration of immunity, the non-dermatophyte fungi can then become opportunistic pathogens, causing superficial, deep or disseminated infections. With new molecular tools applied to medical mycology and revisions in taxonomy, the number of fungi described in humans is rising. Some rare species are emerging, and others more frequent are increasing. The aim of this review is to (i) inventory the filamentous fungi found in humans and (ii) provide details on the anatomical sites where they have been identified and the semiology of infections. Among the 239,890 fungi taxa and corresponding synonyms, if any, retrieved from the Mycobank and NCBI Taxonomy databases, we were able to identify 565 moulds in humans. These filamentous fungi were identified in one or more anatomical sites. From a clinical point of view, this review allows us to realize that some uncommon fungi isolated in non-sterile sites may be involved in invasive infections. It may present a first step in the understanding of the pathogenicity of filamentous fungi and the interpretation of the results obtained with the new molecular diagnostic tools.

Pseudallescheria/Scedosporium complex species: From saprobic to pathogenic fungus

Scedosporiosis is an emerging fungal infection caused by Pseudallescheria/Scedosporium complex species (PSC). This pathogen has been drawn significant interest in recent years due to its worldwide prevalence, the seriousness of its infection, associated with high mortality in both immunocompromised and immunocompetent hosts and its cryptic ecology, distribution and epidemiology across the globe. These species complexes can be found in environments impacted by human. The purpose of this review is to describe the characteristics, mode of transmission, ecology, prevalence, global epidemiology of this fungal group in order to increase the awareness of among clinicians and microbiologists, especially in regions with high endemic, as well as to promote further research on all of its aspects.

Scedosporium apiospermum infectious scleritis following posterior subtenon triamcinolone acetonide injection: a case report and literature review

Background

Ubiquitous fungi of the Scedosporium apiospermum species complex (SASC) cause various opportunistic infections. Posterior subtenon triamcinolone acetonide (STTA) injection is a standard therapy for intraocular inflammation and macular edema. We report a case of Scedosporium apiospermum infectious scleritis after a posterior STTA injection.

Case presentation

A 75-year-old man received a posterior STTA injection to treat macular edema in his left eye. After 3 months, he complained of ocular pain and hyperemia in his left eye. Examination showed a subtenon abscess in the site corresponding with the STTA injection. After incising the abscess, the smear revealed numerous conidia-like structures. Although we suspected fungal infection and started topical voriconazole (VRCZ) and levofloxacin, the inflammation of the eye worsened. Fungal culture revealed filamentous fungus growth. Subsequently, we added systemic VRCZ and performed surgical debridement of the infected sclera and Tenon’s capsule. Pathology of the sclera showed fungal hyphae. The antifungal susceptibility test revealed low minimum inhibitory concentrations for micafungin, VRCZ and miconazole (0.06, 0.25 and 0.5 μg/mL, respectively). After 2 months, the ciliary injection subsided and VRCZ therapy was stopped. However, subtenon abscess recurred 1 month after discontinuation of topical VRCZ. Surgical debridement and topical VRCZ were resumed, with the eye finally improving after 5 months of management. The fungal species was identified as Scedosporium apiospermum sensu stricto morphologically and by DNA sequencing.

Conclusions

This case was successfully treated by topical and systemic VRCZ and repeated surgical debridement. Infectious scleritis caused by SASC rarely develops after posterior STTA. SASC can produce conidia in the enclosed subtenon space. Late-onset infectious scleritis after a posterior STTA injection suggests the presence of a fungal infection, including SASC, thereby requiring extensive and prolonged medical and surgical treatment.

Scedosporium apiospermum: a rare cause of malignant otitis externa

A 79-year-old man, with a history of well-controlled diabetes mellitus, presented with left-sided otalgia. With an initial diagnosis of simple otitis externa, he was discharged on topical drops. He represented 2 months later with worsening otalgia and discharge. A diagnosis of malignant otitis externa was made based on clinical and radiological findings. Intravenous Tazocin and Gentamicin were given based on previous bacterial culture from ear swabs. The patient failed to improve and developed left-sided facial nerve palsy. His condition stabilised following a change in antimicrobial therapy and his management continued in the community on intravenous Meropenem with twice weekly aural toilet. Repeated nuclear medicine imaging failed to demonstrate resolution. A bony sequestration was removed from the external auditory canal in the outpatient clinic, which following extended culture grew Scedosporium apiospermum; his management was subsequently changed to oral Voriconazole. This led to rapid clinical improvement and disease resolution over a 6 -week period.