Risk of re- infection

Patient: Question is that i am due to have a full knee replacement on the 23 of August 2011, my immuneity is extremly low due to some other cronic deases, i have just currently finished a coarse of Antibotics, we had planed a quick day trip before surgery 2morrow but have a concern as a family member has come home 2nite with a cold,as we would all be in the car together would it be best that we advoided being that close together knowing surg in a couple of days risk of getting another cold??????????