Pathogenicity of Candida viswanathii for normal and cortisone-treated mice.

The pathogenicity of Candida viswanathii, PCI 501/1 (CBS 4024), originally isolated from CSF of a fatal case of meningitis in India, is reported. Also, included is a global overview of the occurrence of C. viswanathii in clinical and environmental sources. The investigation was done in normal and cortisone-treated albino mice challenged intravenously with variable doses of 1×10(6), 4×10(6) and 16×10(6) actively growing yeast cells of the fungus. The animals were kept under observation up to 3 weeks when they were sacrificed for a mycological and histopathologic study. As apparent from the data on morbidity and mortality, the species exhibited low virulence for normal mice, whereas it caused significantly higher mortality (P<0.0008) and morbidity (macroscopic lesions) (P<0.0004) in cortisone group. Likewise, there was overall higher recovery of C. viswanathii in culture from the cortisone-treated than in the normal group of mice. These observations are indicative of C. viswanathii being an opportunistic pathogen. It is recognized that a definitive identification of C. viswanathii requires mycological expertise for comprehensive phenotypic characterization or the application of expensive techniques such as Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) and molecular techniques, facilities for which are generally lacking in a vast majority of laboratory diagnostic centers especially in developing countries. Consequently, the prevalence of C. viswanathii in clinical and environmental samples is currently likely to be underestimated.