Differences in virulence between isolates of feline Sporotrichosis

Abstract

Sporotrichosis is a chronic subcutaneous mycosis caused by Sporothrix schenckii. This work aimed to evaluate the virulence of two different isolates of S. schenckii from cutaneous (CUT) and systemic (SYS) forms of feline sporotrichosis. A standard inoculum with 2 x 10(3) yeast cells/ml was prepared from each of the isolates. The experimental infection was carried out with 0.1 ml of the inoculum from both isolates and then injected in the paw pads of Swiss albino mice of groups CUT and SYS. The clinical evolution of the disease and the diameter of the lesion at the inoculated sites were evaluated during nine weeks. Four necropsies were done to collect material from the lesions (p < 0.01). Group CUT demonstrated a more evident clinical evolution of the disease from week two to week five; large lesions in the paw pad on week four (p < 0.01); and a higher incidence of lesions in other parts of the body (p < 0.01) than group SYS (p < 0.01). S. schenckii was isolated from the inoculated site in groups SYS and CUT until days 30 and 45, respectively. Granulomas with yeast cells usually localized in the central area were observed in histopathology sections on days 15 and 30 post-inoculations. Those yeast cells decreased on day 45 being absent on day 62 when tissue repair initiated. The results showed that distinct clinical isolates of S. schenckii cause significant differences in the clinical evolution of sporotrichosis.

Sporothrix schenckii and Sporotrichosis

“…The virulence of S. schenckii is one of the factors thought to play a role in the development of sporotrichosis (32), but there are discordant results concerning disease evolution in experimental sporotrichosis with S. schenckii clinical isolates from cutaneous and disseminated infection (29,176), indicating that host immune responses also substantially participate in the progress of sporotrichosis (32).…”

Immunity and Treatment of Sporotrichosis

“…These organisms are an interesting model to study the biochemical, genetic, molecular, and physiological basis of cell differentiation and morphogenesis. Differences in terms of the disease evolution have been reported in experimental models of sporotrichosis and in different Sporothrix clinical isolates [ 35 , 36 ]. Moreover, some studies have indicated that the immune response of the host determines the degree of invasion [ 37 ].…”

Sporotrichosis in cats

“…2 In cats, however, differences in virulence have been found between isolates from individuals showing cutaneous forms versus disseminated forms. 3…”