Photo Organization Application

I am fairly new to the Mac world and need some advice.

Here is my question.... what is the appropriate software to use for cataloging photos given the following:

We conduct investigations of construction defects. 30 to 40 projects at any one time. Each project may include 2,500 total photos. 4-5 photographers, each using a different digital camera.

The photos must be able to be filtered (searched) by any of several criteria, such as project, date, building, elevation, unit #, component etc.

We have tried using Adobe Bridge for key-wording but find it does not work well when networked. IPhoto and Portfolio were not satisfactory. I am looking at Lightroom now but wonder if there is not a more appropriate application considering we only want key-wording and search functions, not any type of image enhancement.

Seems like there should be some database type of application for this? Thanks for any advise you can offer.