A 72-year-old patient with a history of asthma has a positive tuberculin test result and is admitted to the hospital and placed in respiratory isolation. During her stay, she also contracts methicillin-resistant Staphylococcus aureus (MRSA) and is placed in Contact Isolation. Visitors are found not wearing gowns, gloves, and masks, insisting they were not going to "dress up and treat the patient like a germ!" Why must these visitors follow isolation and barrier precautions? What actions should the nurse implement? .