Mechanism of antifungal action of potassium iodide on sporotrichosis

Sporothrix brasiliensis and Feline Sporotrichosis in the Metropolitan Region of Rio de Janeiro, Brazil (1998–2018)

Feline sporotrichosis is enzootic in different regions of Brazil, especially in Rio de Janeiro. This study compared the genotype profiles of Sporothrix sp. isolated from cats in Rio de Janeiro between 1998 and 2018 and evaluated their association with clinical and epidemiological characteristics. One hundred nineteen Sporothrix sp. isolates from a cohort of cats with sporotrichosis seen at INI/Fiocruz were included. Clinical and epidemiological data were obtained from the medical records of the animals. T3B PCR fingerprinting was used for molecular identification of the Sporothrix species. All isolates were characterized as Sporothrix brasiliensis, with the observation of low intraspecific variation in 31 isolates (31.3%). The interval between lesion onset and first medical visit at INI/Fiocruz, as well as treatment duration until clinical cure, was longer in cats from the first decade of the epizootic. In addition, the frequency of the variables “good general status” and “presence of lymphadenomegaly” was higher among cats whose strains did not exhibit intraspecific variation. So far, S. brasiliensis has been the only species identified in feline cases of sporotrichosis since the beginning of the epizootic in Rio de Janeiro at INI/Fiocruz.

Treatment of cutaneous sporotrichosis with one daily dose of potassium iodide

BACKGROUND

Recommended treatment for cutaneous sporotrichosis consists of a saturated solution of potassium iodide (SSKI) administered in three daily doses (tid). Because compliance with this regimen has been a problem in our previous experience, we evaluated the use of one daily (qd) full dose of SSKI.

METHODS

Patients with culture-confirmed cutaneous sporotrichosis were entered in a randomized, nonblinded study to compare the safety and efficacy of qd vs. tid dosage of SSKI.

RESULTS

Fifty-seven patients were enrolled to receive either qd (29) or tid (28) SSKI. Three (1 in the qd and 2 in the tid group) were not compliant with the assigned regimen. Side effects were common but mild in both treatment groups (61% in the qd and 42% in the tid group, P = 0.17); treatment had to be discontinued because of side effects in 3 cases (2 in the qd and 1 in the tid group). Overall 26 (89.6%) and 25 (89.2%) of the individuals initially assigned to the qd and tid dosing schedule, respectively, were cured by the treatment. No relapse was detected after 45 days of follow-up.

CONCLUSION

These findings suggest that a single daily full dose of SSKI appears to be appropriate therapy for cutaneous sporotrichosis; further studies with larger numbers of patients are required.

Ultrastructure of Sporothrix schenckii treated with iodine-potassium iodide solution

The ultrastructural changes produced by iodine-potassium iodide solution on yeast cells of Sporothrix schenckii were investigated by transmission electron microscopy in order to clarify the mechanism of oral potassium iodide therapy for sporotrichosis. Yeast cells were dipped with solutions containing various concentrations of iodine. The rate of germination decreased markedly between the range of iodine concentrations from 0.63 microgram/ml to 5.0 micrograms/ml. No significant ultrastructural changes were seen at the concentration of the iodine of 1.25 microgram/ml (80% germination) or less. In the concentration of 2.5 micrograms/ml (50% germination), normal cells and degenerated cells coexisted. When the cells were treated with 5.0 micrograms of iodine per ml (0% germination) or more, their interior structures were completely destroyed. It is assumed that iodine treatment of the organism causes rapid destruction in the whole cell.

Sporotrichosis in India: first authentic case report from the north-western region and a critical literature review

The first case of sporotrichosis from north-western region is reported along with a critical review of the work done on this disease in India. The patient, a 55-year-old housewife with multiple lymphocutaneous lesions on her left arm, had never travelled to north-eastern India where sporotrichosis occurs endemically. She was a resident of Ranikhet, District Nainital, Uttar Pradesh (U.P.), situated about 235 km north-east of Delhi. The diagnosis was established by demonstration of Sporothrix schenckii through direct microscopy and culture of pus collected from multiple suppurative lesions, verification of the dimorphic character of the fungus in vitro and its pathogenicity to white mice. She was treated successfully with oral administration of potassium iodide for 6 weeks.

Phialophora richardsiae isolated from infected human bone: morphological, physiological and antifungal susceptibility studies

A dematiaceous fungus, Phialophora richardsiae (Nannf.) Conant, was isolated from human bone. In culture the fungus produced no yeast forms and was less pigmented than two other P. richardsiae isolates. While growth rates were similar, colonial forms differed. Phialides were of two kinds. While both had broad bases and tapered at the tips, only one terminated with a cupulate or rarely a saucer-shaped collarette. Most phialides were hyaline with a few lightly pigmented ones in older cultures. Broth dilution susceptibility testing of the isolates against amphotericin B, miconazole, ketoconazole, clotrimazole, and 5-fluorocytosine showed the fungus was susceptible to miconazole, ketoconazole and amphotericin B at achievable serum levels and resistant to 5-fluorocytosine and clotrimazole. The other isolates were reported to differ in their resistance to miconazole and amphotericin B. Enzyme and salinity studies showed minor difference among the isolates.

Disseminate sporotrichosis of skin and bone cured with 5-fluorocytosine: Photosensitivity as a complication

Disseminate cutaneous and osseous sporotrichosis is reported in a patient who failed to respond to 6 months of iodide therapy. Although the patient showed improvement on a 2-month course of amphotericin B, he experienced a fulminant relapse 12 days after the amphotericin B was stopped. Cure was achieved after 6 months of 5-fluorocytosine (8 gm/day) in conjunction with amphotericin B (total, 4.8 gm). The fluorocytosine was continued for an entire year. Two years after all treatment was discontinued the patient remained in good health. The only complication was a marked photosensitivity associated with the 5-fluorocytosine therapy. This is the second case of such photosensitivity in the literature.

Sporothrix schenckii and related species of Ceratocystis

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