Compared to other metals gold has a comparably good biocompatibility, whereas other metals like platinum may have, depending on their surface properties more or less antimicrobial activities. The problem with gold is that it is not completely inert so there may be a salt formation which might again have surface-antimicrobial activity. For this reason the gold electrodes are often coated with an intrinsically conductive polymer, like Polyaniline (Emeraldine salt).
In my personal opinion, using carbon electrodes is far superior than any metal based electrodes because these are inexpensive and can form a biofilm