Study of the influence of fecal material on the prognosis of intra-abdominal candidiasis using a murine model of technetium-99 m (99 mTc)-Candida albicans

Abstract

Intra-abdominal candidiasis (IAC) occurs due to the direct inoculation of Candida into the sterile peritoneal cavity or leakage of the gastrointestinal tract. An important difference between the two forms of the disease is the presence of fecal material, which is exclusive to the latter condition. However, the influence of fecal material on the prognosis of IAC is still poorly understood. Furthermore, methodologies that use the quantification of fungal load by culture methods have low sensitivity, as they do not adequately show the precocity of the infectious process. Here, we developed a new method to evaluate the aspects of the pathophysiology of IAC, mainly the influence of fecal material on the prognosis of infection, by using C. albicans radiolabeled with technetium-99 m (99 mTc). C. albicans was successfully radiolabeled with 99 mTc (18.5 MBq) using dihydrate stannous chloride (100 µM) as a reducing agent. This binding was stable for 72 h. Viability, yeast-to-hyphae transition, morphology, and antifungal susceptibility were not altered by radiolabeling C. albicans with 99 mTc. The biomass and the fungal load of 99 mTc-C. albicans biofilms were reduced compared to the C. albicans non-radiolabeled after 72 h and 48 h of incubation, respectively. In the IAC model, the fungal load in the biodistribution of 99 mTc-C. albicans and culture assays was higher in animals receiving fungal inoculum without fecal material, suggesting that the presence of this component reduces the invasiveness of the pathogen.