Sporotrichosis in Children: an Update

A Lateral Flow Assay for the Immunodiagnosis of Human Cat-Transmitted Sporotrichosis

BACKGROUND

Cat-transmitted sporotrichosis (CTS) caused by Sporothrix brasiliensis has emerged as an important zoonosis in Brazil and neighboring countries.

OBJECTIVES

Evaluate the performance of a lateral flow assay (LFA) for the detection of anti-Sporothrix antibodies in human sera.

METHODS

A LFA for the detection of anti-Sporothrix antibodies (Anti-Sporo LFA) in human sera, developed by IMMY, was evaluated using 300 human sera collected prospectively at the Hospital de Clínicas, Federal University of Paraná (HC-UFPR), in Curitiba, Brazil. These specimens included 100 sera from patients with CTS. CTS cases were classified as: 59 lymphocutaneous, 27 fixed cutaneous,13 ocular, and one mixed form. One-hundred specimens from patients with other mycoses, including cryptococcosis (n=32), candidemia (n=27), paracoccidioidomycosis (n=14), aspergillosis (n=10), histoplasmosis (n=9), fusariosis (n=4), lobomycosis (n=1), chromoblastomycosis (n=1), mucormycosis (n=1), and trichosporonosis (n=1). And 100 specimens from apparently healthy volunteers (AHV).

RESULTS

The Anti-Sporo LFA showed a global sensitivity of 83% (95% confidence interval [CI] = 74%-90%), a global specificity of 82% (95% CI = 76%-87%), and accuracy of 82% (95% CI = 77%-86%). By clinical form sensitivity was as follows: Mixed form 100%, ocular 92%, lymphocutaneous 83%, and fixed cutaneous 78%. False-positive results were observed in 11 specimens from people with other mycoses and 26 specimens from AHV.

CONCLUSION-DISCUSSION

This study presents the results of the evaluation of the first lateral flow assay for the detection of anti-Sporothrix antibodies in human sera. The findings here show evidence that IMMY´s Anti-Sporo LFA is a promising tool for the rapid diagnosis of CTS.

Sporotrichosis: From KOH to Molecular Biology

Sporotrichosis is a cosmopolitan, chronic granulomatous mycosis, acquired by traumatic inoculation and caused by Sporothrix schenckii complex. Several methods of diagnostic are available, from KOH to molecular biology. In this review, we describe from the simplest (clinical diagnosis) to the most advanced diagnostic techniques (molecular biology).

Multicenter, International Study of MIC/MEC Distributions for Definition of Epidemiological Cutoff Values for Sporothrix Species Identified by Molecular Methods

Clinical and Laboratory Standards Institute (CLSI) conditions for testing the susceptibilities of pathogenic Sporothrix species to antifungal agents are based on a collaborative study that evaluated five clinically relevant isolates of Sporothrixschenckii sensu lato and some antifungal agents. With the advent of molecular identification, there are two basic needs: to confirm the suitability of these testing conditions for all agents and Sporothrix species and to establish species-specific epidemiologic cutoff values (ECVs) or breakpoints (BPs) for the species. We collected available CLSI MICs/minimal effective concentrations (MECs) of amphotericin B, five triazoles, terbinafine, flucytosine, and caspofungin for 301 Sporothrix schenckii sensu stricto, 486 S. brasiliensis, 75 S. globosa, and 13 S. mexicana molecularly identified isolates. Data were obtained in 17 independent laboratories (Australia, Europe, India, South Africa, and South and North America) using conidial inoculum suspensions and 48 to 72 h of incubation at 35°C. Sufficient and suitable data (modal MICs within 2-fold concentrations) allowed the proposal of the following ECVs for S. schenckii and S. brasiliensis, respectively: amphotericin B, 4 and 4 μg/ml; itraconazole, 2 and 2 μg/ml; posaconazole, 2 and 2 μg/ml; and voriconazole, 64 and 32 μg/ml. Ketoconazole and terbinafine ECVs for S. brasiliensis were 2 and 0.12 μg/ml, respectively. Insufficient or unsuitable data precluded the calculation of ketoconazole and terbinafine (or any other antifungal agent) ECVs for S. schenckii, as well as ECVs for S. globosa and S. mexicana These ECVs could aid the clinician in identifying potentially resistant isolates (non-wild type) less likely to respond to therapy.

Cutaneous Disseminated and Extracutaneous Sporotrichosis: Current Status of a Complex Disease

Sporotrichosis is an implantation or inoculation mycosis caused by species of Sporothrix schenckii complex; its main manifestations are limited to skin; however, cutaneous-disseminated, disseminated (visceral) and extracutaneous variants of sporotrichosis can be associated with immunosuppression, including HIV-AIDS, chronic alcoholism or more virulent strains. The most common extracutaneous form of sporotrichosis includes pulmonary, osteoarticular and meningeal. The laboratory diagnosis requires observing yeast forms and isolating the fungus; the two main causative agents are Sporothrix schenckii (ss) and Sporothrix brasiliensis. Antibody levels and species recognition by Polimerase Chain Reaction using biological samples or cultures are also useful. The treatment of choice for most cases is amphotericin B and subsequent itraconazole for maintenance therapy.