Histopathological Characteristics of Experimental Candida tropicalis Induced Acute Systemic Candidiasis in BALB/c Mice

Systemic candidiasis caused by Candida tropicalis is potentially fatal in human but studies relating the histological characteristics with C. tropicalis induced acute systemic candidiasis are few in number. Hence, this study was undertaken to establish and to characterize the distinctive histopathological features of acute systemic candidiasis by varying the inoculum size of C. tropicalis injected in mice. Thirty BALB/c mice were divided into three groups and were injected with either 1x105 or 1x107 C. tropicalis cells. On observation, the histopathological findings and the fungal burden load following intravenous injection were similar to the previously reported mouse model for Candida albicans. Viable yeast cells in the kidneys reached approximately 22.5 log10 cfu g-1 at day 7 post-infection. Compared with the control group, the infected mice group developed acute pyelonephritis characterized by infiltration of large masses of neutrophils within the infected nephrons. Similarly, foci of acute renal inflammation within the kidney were more pronounced when the C. tropicalis inoculum was increased. Interestingly, we also observed infection of mice with a higher inoculum of C. tropicalis resulted in more severe invasiveness. In conclusion, these results suggest that the BALB/c mouse is highly susceptible to C. tropicalis dissemination and represents a significant model system of acute systemic candidiasis.