I have spent some time creating a keyword system for 15000 photos of wildlife including many sub-keywords (eg birds - eagles - bateleur). This makes tagging the keywords fairly easy. Is there any way of using the same system for searching quickly; the only way Bridge seems to provide is a long alphabetical list using filter which is actually not at all useful. And the 'right-click, find...' option is much slower and not as useful for me as the filter option.
There are a lot of differences between Search (Find) and Filter. Filter only works on the current folder. Search starts on the folder pointed to and works it way down the folders to the end.
With search you can add multiple search lines and add include all or only or to give you some logic to the search.
I have spent some time creating a keyword system for 15000 photos
Like Curt says, but after all this work make sure you have a proper back up of your keyword list. Use the tiny little menu icon top right in metadata panel and choose export to create a copy of your list so you can always revert to it using import in case something bad happens.
And with those keywords written to the files in the IPTC many other applications (or clients) can read and search those keywords