What type of agar is used to selectively isolate fungi?

The choice of Sabouraud dextrose agar as the appropriate medium for selectively isolating fungi is based on its specific formulation that supports fungal growth while inhibiting bacterial proliferation. This medium is enriched with a high concentration of dextrose, which provides a readily available energy source for fungi. The lower pH of around 5.6 also creates an environment that is more favorable for fungal organisms compared to most bacteria, which prefer neutral to slightly basic conditions.

In contrast, nutrient agar serves as a general-purpose medium that supports the growth of a wide variety of organisms without selectivity, making it less effective for isolating fungi specifically. Blood agar is designed to support the growth of fastidious bacteria and allows for the detection of hemolytic activity, but it is not selective for fungi. MacConkey agar is selective for Gram-negative bacteria and contains bile salts and crystal violet, which inhibit Gram-positive organisms. This characteristic further emphasizes why Sabouraud dextrose agar is favored for fungal isolation, due to its formulation tailored toward fungal growth rather than bacteria.