This is a descriptive clinical research aiming:

• To describe the clinical spectrum and clinical characteristics of community acquired pneumonia (CAP) in patients admitted to hospital
• To identify the etiology of CAP and the antibiotic sensitivity of the isolated organisms
• To identify the risk factors that influence the severity of CAP

In Vietnam, the range and relative contribution of organisms causing CAP remain unclear, largely because diagnostic tools are limited and clinical research uncommon. An improved understanding of the risk factors, etiology and clinical outcomes of CAP in Vietnam would contribute to improved approaches to patient diagnosis and clinical management. This will be achieved by following the clinical and laboratory progress and treatment outcomes of in-patients diagnosed with CAP from admission to discharge. Comparative analyses will be between subgroups including survivor and non-survivor, severe CAP and non-severe CAP, known etiology and unknown etiology, SIRS, sepsis, severe sepsis and shock septic.

Inclusion Criteria:

• Patients > or = 18 years of age
• Patient meets the criteria of pneumonia (below), established within 36h of hospitalization
• Patient is not hospitalized or residing in a long-term-care facility within 14 days before the onset of symptoms
• Patient has not been at a referral hospital for >2 days before admission to the study hospital
• Informed consent to participate in the study is provided

Exclusion Criteria:

• Severe immunosuppression as judged by the enrolling physician (e.g. HIV, leukemia, lymphoma, chemotherapy for solid tumors, long-term corticosteroid use or other immunosuppressive drugs)
• Known active tuberculosis or current treatment for tuberculosis

300 patients with community acquired pneumonia who meet the below inclusion/ exclusion criteria will be recruited at two hospitals in Vietnam.