Universal codes are fairly well studied, and many asymptotically optimal universal codes exist for binary data (see https://en.wikipedia.org/wiki/Universal_code_(data_compression) especially https://en.wikipedia.org/wiki/Elias_delta_coding and https://en.wikipedia.org/wiki/Elias_omega_coding).
I know that no optimal universal code can be created (as per Variable Length Encoding of Integers).
My question is if there are any known asymptotically optimal universal codes in other bases. For example I feel as though one could construct a universal code in any base using similar methods to the elias delta and omega codes, I just don't know if that would constitute an asymptotically optimal code, nor how best to describe such a code.
Does anybody know or have any references to universal codes in non-binary bases?