Specific Aim 2: Biomarker development for early differentiation of poor outcome in CAP Complications of CAP, including respiratory failure, other organ system failure and severe sepsis, are major determinants of morbidity and mortality. At time of presentation with CAP, accurate identification of patients who will have a complicated course or poor outcome is critical for effective management and positive outcome. In parallel with Specific Aim 1, we propose to identify biomarkers for early diagnosis/prognosis of poor outcome in patients with CAP ("severe CAP"). The biomarkers will be several, host response, plasma proteins that differentiate mild and severe CAP. Early diagnosis of severe CAP will enable patient selection for hospitalization, thereby reducing mortality and increasing effectiveness of resource allocation.