Developed coffee agar for identification of Cryptococcus neoformans

Abstract

Cryptococcus neoformans, a causative agent of Cryptococcosis, is commonly isolated from soil or avian droppings. C. neoformons causes an opportunistic infection in immunocompromised hosts. C. neoformans contains the enzyme phenoloxidase, which is able to catalyse phenol compound substrates such as caffeic acid and 3.4-dihydrosyphenylalanine (DOPA) to produce a melanin pigment. resulting in brown colonies. Various types of media, such as caffeic acid agar, niger seed agar bird seed agar, have been used in the identification of C. neoformans. However, commercial agars are expensive and have to be imported. The objective of this study was to develop an alternative phenol compound substrate that can be used to test melanin pigment production for C. neoformums identification and that is available worldwide and easily accessible to all laboratories. Our study has found that instant coffee powder can be used as a substantial source caffeic acid. Two of five brands of instant coffee powder were shown to be effective for melanin pigment production on a C. neoformans reference strain, compared to a negative control of Candida albicans. Melanin pigment production on coffee agar with a Sabouraud dextrose agar base or a caffeic acid agar base was not significantly different. Our developed coffee agar is low-cost and can be used as an alternative method in laboratories where no caffeic acid or L-DOPA is locally available.