Adobe Reader can search multiple bookmarks.
With the advanced search, you can
search all PDF files in a directory
and its sub-directories in a single
go. By default, if you open Adobe
Reader and press CTRL +
F, you’ll get the normal
search box. It is located at the top
right in the menu bar.
To use the advanced PDF search option,
you can choose Open Full Reader
Search in the drop down menu of the
search box or press SHIFT +
CTRL + F.
Go ahead and enter the phrase you are
searching for in the search box. Next
choose the All PDF Documents In
option under Where would you like to
search heading.

Browse to the folder where all of your
PDF documents are stored and then
choose the option Include
Bookmarks (searches the text of any
bookmarks, as viewed in the Bookmarks
panel).
