My roommate has tested positive for TB and I have 4 kids including a new baby what should I do?

Get Tested. First, it depends on what you mean by your roommate being positive for tb. Does that mean they have been actually diagnosed, or that their PPD skin test is positive? A positive skin test does not necessarily mean one has tb. However, TB is very contagious, so if you even suspect your roommate has tb, you need to isolate yourself and your children from said roommate and get everyone tested.