P4 Peptide in Community Acquired Pneumonia

Inclusion Criteria for ITU patients: * Adults (\>18y) with community acquired pneumonia. * Diagnosis of CAP upon hospital admission requires: Radiographic shadowing unexplained by other causes plus Symptoms/signs consistent with acute lower respiratory tract infection. Exclusion Criteria for ITU patients: * Previous hospital admission within 14 days (implies hospital acquired). * Immunocompromising comorbidity or therapy (e.g. HIV infection, chemotherapy). * Pregnancy. * Deemed inappropriate by responsible Intensivist. Already recruited in to an interventional study (where the study therapy may influence the results of this study). * Failure to obtain consent. Bronchoscopy Exclusion criteria (ITU patients): * The patient does not require a bronchoscopy for clinical reasons * The patient is not invasively ventilated therefore not requiring a bronchoscopy * The patient condition deteriorates prior to bronchoscopy such that they might no longer tolerate the procedure (e.g. those progressing to require high frequency oscillation, prone-positioning, PEEP\>15cmH2O or FiO2\>0.8 for ventilation). * Patient does not tolerate bronchoscopy, i.e. if there is oxygen desaturation to \<90% for \>60 seconds or haemodynamic disturbance during the procedure. * The intensive care clinician responsible for the patient develops any new concerns about the safety of bronchoscopy or bronchoalveolar lavage. Inclusion/ Exclusion Criteria for healthy volunteers: * Adults (\>18y). * Able to give …