There are relatively few pieces of malware that target the Mac and most of those that do target OS X’s Java environment, which is no longer installed by default with OS X. There are frequent security updates to OS X, with all publicly known malware that targets systems blocked by the latest updates.
However, patch management remains the Mac’s security Achilles' heel, with system updates handled through the App Store in the Apple menu.
Administrator rights are needed to install the updates, so an admin needs to manually update every Mac. However, you can do this more efficiently by activating the “Remote Login” function in the “Sharing” system preference pane. Restrict access to it by clicking on the + sign and adding the administrator account to the list of users allowed to use the function.