When databases run on a unix server as different unix accounts, can an agent running as user oracle

       I've been given an existing server with four databases to support.  I was going to install an agent and set it up for monitoring.  However, I just found out that each database was created, and owned and runs as a different unix account.  The group isn't even dba.  Will this even work with an agent?  Only the oracle software is owned by the user oracle.
       I have the accounts and passwords, but there are 4 of them, or 5 if you count oracle.  I hate to install and not be able to monitor anyway.  Has anyone done this?