A novel, broadly applicable approach to isolation of fungi in diverse growth media

Creatinine (CRN) is a vertebrate metabolic waste product normally found in blood and urine. Previous work demonstrated that the hydrochloride salt of creatinine (CRN-HCl) acted as a potent inhibitor of bacterial replication. Creatinine hydrochloride does not inhibit the growth of yeasts or molds (i.e. fungi), making it a potentially useful addition to growth media to facilitate isolation of environmental or clinically relevant fungal species. Sabouraud dextrose agar is the current medium of choice for detection and isolation of fungi although it does not offer optimal nutritional requirements for some fungi and can permit growth of bacteria which may subsequently inhibit fungal growth and/or obscure fungal isolation. We show that CRN-HCl effectively suppresses bacterial growth in either liquid or solid agar media while allowing outgrowth of slower growing fungi using either experimentally prepared samples or environmental samples.