Don't ever think that working in a supposedly clean place like an office will ever exempt you from germ contact, because germs are everywhere. They do not exempt anyone.
Hygiene in the office is still of utmost importance. General cleanliness in facilities and everything that you will do will not only be good for your health, but also for the others who work in the same office as you do.
Make sure that your office space is always clean and free of unnecessary dirt. I am not sure about the negotiations between offices and the janitorial staff, but it would be common courtesy to not entirely rely on your janitors if it is, for example, just some dust that needs to be wiped off.
Be also careful with the way you interact with your officemates. Handshakes are fairly common in this kind of workspace, so you also have to make sure that your hands are always clean. You don't want to pass off the germs on your skin to your workmates, do you? Simple activities like using a hand sanitizer after using the bathroom (door knobs are the dirtiest of them all!) is already enough for your part.
The office is you and your workmates' second home. This post does not ask you to become the office's resident janitor. There are people assigned to do that kind of work. However, we all have the obligation to make the office clean, even if those are just small cleanliness tasks that you have to do. Do your part and tell others as well.