Infection sous-cutanée disséminée par Scytalidium (Neoscytalidium) dimidiatum

Developing diagnostic criteria to differentiate fungal foot infections caused by Neoscytalidium dimidiatum and dermatophytes

Background

The predisposing factors and clinical presentations of fungal foot infections caused by non-dermatophytes and dermatophytes are challenging to differentiate. Definite diagnoses of non-dermatophyte infections at first visits facilitate their treatment.

Objectives

This study aimed to develop diagnostic criteria to differentiate fungal foot infections caused by Neoscytalidium dimidiatum and dermatophytes.

Methods

Diagnostic prediction research based on a retrospective, observational, cross-sectional study. The reviewed patients were aged ≥18 and underwent a mycological examination for fungal foot infections. A fungal culture at the initial visit was the gold standard for determining causative organisms.

Results

Analyses were carried out on the data from 371 patients. N. dimidiatum accounted for 184 (49.6%) infections, and dermatophytes caused the remaining 187 (50.4%) cases. Five significant predefined predictors were used to develop the diagnostic criteria and score. They were immunocompetence status, no family history of fungal infections, the absence of pruritus, the absence of other concurrent fungal skin infections, and agricultural work. The lower score cutoff was <8 (sensitivity 97.8% and specificity 25.7%). The higher cutoff was >11 (sensitivity 83.7% and specificity 57.8%). The score showed an area under the receiver operating characteristic curve of 0.755 and was well calibrated.

Conclusions

The criteria and score show promise for clinical use, with acceptable discriminative performance and good calibration. They will help physicians differentiate the causative organisms in patients with fungal foot infections at the first visit, enabling the determination of appropriate antifungal treatment.

Deep Cutaneous Neoscytalidium dimidiatum Infection: Successful Outcome with Amphotericin B Therapy

Phaeohyphomycosis is a term used to describe a heterogenous group of cutaneous and systemic mycotic infections caused by melanized fungi. Many fungi have been reported as pathogens of this disease. The disease spectrum ranges from superficial cutaneous infections, deep cutaneous infections, to systemic infections with internal organ involvement. We report two cases of deep cutaneous phaeohyphomycosis on the foot clinically presenting as cellulitis with abscess formation. The pathogens were isolated from the lesion and both were identified as Neoscytalidium dimidiatum by their colony morphology, microscopic features, and sequences of internal transcribed spacers of ribosomal DNA. Both patients did not respond to the therapy with voriconazole and itraconazole, but improved after intravenous amphotericin B.

Invasive cutaneous Neoscytalidium infections in renal transplant recipients: a series of five cases

Background

Neoscytalidium species (formerly Scytalidium species) are black fungi that usually cause cutaneous infections mimicking dermatophytes lesions. Very few publications have reported invasive or disseminated infections.

Case presentation

In this paper, we report the clinical presentations, treatments and outcomes of five cases of invasive Neoscytalidium infections with cutaneous involvement, including two cases with disseminated infection, in five renal transplant recipients. To our knowledge, this is the first report of a series—albeit small—of renal transplant patients in whom this infection was identified. All cases occurred in a single hospital in Paris, France, between 2001 and 2011. Patients all originate from tropical area.

Conclusion

Treatments of Neoscytalidium infection varied greatly, underlining the lack of a recommendation for a standardized treatment. All patients were cured after long-term antifungal therapy and/or surgical excision. Interestingly, one patient with disseminated infection involving the left elbow, the right leg, the lungs and the nasal septum was cured by medical therapy only without surgery. This may suggest that in contrast to others mycoses (such as mucormycosis), an adequate medical treatment could be sufficient for treating Neoscytalidium. We also point out the difficulties we had in diagnosing two patients with Kaposi’s sarcoma because of the similarity of the lesions. Furthermore, our report underlines the need to check for this rare infection in immunocompromised kidney transplant recipients originating from tropical areas.