Tobacco Agar as a Novel Medium for Chlamydospore Induction in Candida Species: A Cross-sectional Study

Introduction: Candida species, especially Candida albicans and Candida dubliniensis, are major opportunistic pathogens in humans, distinguished by their ability to form chlamydospores. Traditional diagnostic methods rely on phenotypic traits, with chlamydospore production serving as a key differentiator. Tobacco agar has emerged as a potential low-cost, effective medium to induce chlamydospore formation, particularly useful in resource-limited settings. Aim: To evaluate the efficacy of tobacco agar in inducing chlamydospore formation for the presumptive identification of Candida species. Materials and Methods: This cross-sectional study was conducted in the Department of Microbiology at Shri MP Shah Government Medical College, Jamnagar, Gujarat, India over the period of six months from October 2019 to March 2020. A total of 100 non duplicate sputum samples from patients suspected of fungal respiratory infections were included based on Bartlett’s criteria. Samples were cultured on Sabouraud Dextrose Agar, and isolates showing creamy white colonies were presumptively identified as Candida spp. These were further subcultured on inhouse prepared tobacco agar using the Dalmau plate technique to induce chlamydospore formation and aid species-level identification. Microscopic evaluation began 48 hours postinoculation, and isolates were classified based on germ tube and chlamydospore presence. Fisher's exact test assessed the association between incubation parameters and chlamydospore development, with a significance threshold of p-value < 0.05. Results: Candida species were isolated from 30 (30.0%) of 100 sputum samples. Among these, 19 (63.3%) showed germ tube formation and chlamydospore production consistent with C. albicans/C. dubliniensis, while 11 (36.7%) were identified as non albicans Candida. Chlamydospore induction occurred in 19 (63.3%) isolates on both tobacco agar and Cornmeal Agar (CMA). Optimal induction was noted at 28°C after 48-72 hours, with no formation at 37°C or 24 hours. Conclusion: Tobacco agar demonstrates reproducible morphological responses in Candida isolates under controlled conditions, which may support presumptive differentiation Its use may encourage broader adoption of low-cost, observationbased tools in diagnostic mycology.