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Published on: February 14, 2018
[Evaluation of a new medium, eggplant (Solanum melongena) agar as a screening medium for Cryptococcus neoformans in
Mustafa Sengul1, Cağrı Ergin, Tuğba Kartal
1Pamukkale University Faculty of Medicine, Department of Medical Microbiology, Denizli, Turkey. msengul@pau.edu.tr.
Abstract:
Cryptococcus neofomans is an encapsulated yeast-like fungus that causes life-threatening infections, especially in immunosuppresive patients. C.neoformans infection is believed to be acquired via inhalation of aerosolized particles from the environment. Avian guano, decaying tree hollows and soil are the related known environmental niches. Brown pigmented yeast growth from the precursors in growth media is an important step for the identification and isolation of C.neoformans. Seeds of plants in nature are preferred owing to easy accessibility and low costs for the preparation of such media. Guizotia abysinicca (Niger seed) as Staib agar, Helianthus annus (Sunflower) as Pal's medium, Brassica nigra (Mustard) agar, tobacco agar, Mucuna pruriens (Velvet bean) seed agar, Perilla frutescens (Beefsteak plant) seed agar, Rubus fruticosus (Blackberry) agar and ground red hot pepper agar are pigment-based selective media for the differentiation of C.neoformans. The aim of this study was to observe the pigment production of C.neoformans in a new medium based on eggplant (Solanum melongena) and also to compare its performance with the simplified Staib, Pal's and tobacco agar for isolation from the environment. Three different eggplant-based medium (S.melongena Melanzaza viserba, S.melongena Pinstripe F1 and S.ovigerum Ivory F1) were included in the study. Pigment-forming eggplant medium, simplified Staib agar, Pal's agar and tobacco agar were used for the cultivation of the environmental swabbed samples from 19 Eucalyptus camaldulensis trunk hollows in continuous colonization region. While pigment formation were observed with S.melongena Melanzaza viserba and S.melongena Pinstripe F1 containing media, S.ovigerum Ivory F1 medium was found to be non-reactive. In colonization area (Gökova-Akyaka, Turkey), 11 (57.9%) out of 19 E.camaldulensis samples were positive with simplified Staib agar, Pal's agar and eggplant agar while 10 (52.6%) of them are positive with tobacco agar. C.neoformans colony forming unit (cfu) per plate were found as 51, 57 and 48 (median values) on simplified Staib agar, Pal's agar and eggplant agar, respectively, while tobacco agar has lower performance with 33 cfu/petri. No statistically significant difference were found between simplified Staib agar, Pal's agar and eggplant agar's performances for C.neoformans isolations from the nature (p=0.71). In conclusion, easily prepared eggplant agar is as functional as widely used media such as simplified Staib agar and Pal's agar for the isolation of C.neoformans from the natural environment.
Insights
Eggplant-based agar effectively isolates Cryptococcus neoformans, a fungus causing serious infections, from natural environments. This new medium performs comparably to established methods like Staib and Pal
Area of Science:
- Medical Mycology
- Environmental Microbiology
- Fungal Pathogenesis
Background:
- Cryptococcus neoformans is an encapsulated yeast causing life-threatening infections, particularly in immunocompromised individuals.
- Infection is acquired through inhalation of C. neoformans from environmental sources like soil and avian guano.
- Accurate isolation and identification of C. neoformans from environmental samples are crucial for understanding transmission.
Purpose of the Study:
- To evaluate a novel eggplant-based medium for C. neoformans pigment production and isolation.
- To compare the efficacy of eggplant agar with established selective media (Staib, Pal's, tobacco agar).
- To assess C. neoformans isolation rates and colony-forming units from environmental samples.
Main Methods:
- Three eggplant-based media (Solanum melongena Melanzaza viserba, S. melongena Pinstripe F1, S. ovigerum Ivory F1) were formulated.
- Environmental samples were collected from Eucalyptus camaldulensis trunk hollows.
- Samples were cultured on eggplant media, simplified Staib agar, Pal's agar, and tobacco agar for pigment formation and isolation.
Main Results:
- S. melongena Melanzaza viserba and S. melongena Pinstripe F1 media showed pigment formation, indicating C. neoformans presence.
- Eggplant agar, Staib agar, and Pal's agar demonstrated similar isolation rates (57.9%) from environmental samples.
- Median colony-forming units were comparable: 51 (Staib), 57 (Pal's), and 48 (eggplant agar), with no statistically significant difference (p=0.71).
Conclusions:
- Easily prepared eggplant agar is a viable and effective medium for isolating C. neoformans from natural environments.
- Eggplant agar performs comparably to widely used selective media like simplified Staib and Pal's agar.
- This finding offers a cost-effective and accessible alternative for C. neoformans environmental surveillance.
