Systemic inflammatory response syndrome (SIRS) is characterized by changes in body temperature, heart rate, respiratory rate, or peripheral blood white cell count, and is often a heralding manifestation of blood infection (ie., sepsis or bloodstream infection). SIRS however can occur as a result of a stroke without sepsis. When SIRS occurs after stroke, patients are subjected to blood cultures and tests to exclude sepsis, and are often empirically treated with antibiotics potentially leading to a serious gastrointestinal infection called C. difficile enterocolitis, and bacterial antibiotic resistance. Development of a blood test that could provide sufficient sensitivity to exclude blood infection in stroke would therefore prevent numerous tests, cultures, antibiotics, and costs. In recent years, there has been increasing evidence that procalcitonin (PCT) may serve as diagnostic marker to distinguish between infectious and non-infectious SIRS. The investigators hypothesize that PCT can differentiate SIRS after stroke into patients with infection and those without infection. Such screening tests would provide crucial information to clinicians that could improve patient care by reducing the number of tests and antibiotics used, as well as antibiotic-related infections, bacterial resistance and hospital costs.