A nurse will leave the toilet - she's attracted to light so turn off your flashlight. Kill her with fast attacks (LMB/A) or one strong stab (RMB/X). You can use powerful strike - simply by holding RMB/X. If you just wait in the darkness she should stop moving after a while - that's a good moment to knock her out.
Xbox 360: You will receive Alchemilla's Finest achievement (10 p.).
Now go to the Men's Restroom. To get there, squeeze through a crack in the wall, near the place the nurse came from.
Take the First Aid Kit from the wall to the left of the door. Leave the restroom and enter the corridor. Unfortunately, all doors are locked except the exit to the south. There is a note in this room which describes survival methods: simply don't use your flashlight when monsters are near and try to move quietly.
Currently you're on the second floor, so go upstairs to the next floor. Turn off a flashlight and enter the Day Room through the window.