Run ahead of the Little Sister once you are in the South Wing and hack the Security Camera over the test subject. The Little Sister will spend roughly two minutes at the end of the hall draining Adam from the corpse on display and it’s up to you to protect her. Splicers come at this location from both directions of this U-shaped wing and, although the Security Camera and Security Bots are a big help, you’re going to have to cover her. Fire several Trap Bolts into the walls on either hallway to slow down the Splicers as they attack. Use Antipersonnel Auto Rounds as well as the Shotgun should they get close, and try to take the bullets for her.
She’ll eventually get up and continue on her way towards the Central Atrium. The second test subject is not far after the first, so reload your weapon and be ready for another battle. Fortunately, there are more nearby Security Cameras and Turrets that you can hack to gain the upper hand.