Problem:

A group of smokers suffering from the outcome of severe Staphylococcus aureus infections, MRSA, are suing the cigarette companies for extent of their injuries. They claim that the disease was aggravated by cigarette smoking. The group is citing studies indicating that phagocytes are inhibited in their action by compounds in cigarette smoke. A statement prepared by their lawyers states that the S. aureus would not have caused such a severe disease if the phagocytes and immune system overall were functioning properly. During the proceedings, a microbiologist was called in as a professional witness for the court. Required:

Question: What were her conclusions about the validity of the claim?

Could someone explain this to me?