We’ve had good results using either pet enzyme or FAE, then following up with Final Step Deodorizer. In situations like this, we treat with the enzyme as usual then use up to about 6 ounces of Final Step deodorizer per room, all over the carpet, then we groom the carpet to work it in a little.
Another thing we have done in apartments with foul odors is to leave a mesh bag filled with charcoal in the middle of the room for a couple of days. We’ve had good results using this in combination with the Final Step deodorizer.