The Oxford Pleural Infection Endotyping Study

Samples collected for the PILOT clinical trial (DOI: 10.1183/13993003.00130-2020) used for the TORPIDS-2 study. Patients were included if they had a clinical presentation consistent with pleural infection and any of the following criteria: 1. pleural fluid that was macroscopically purulent; or 2. pleural fluid that was positive on culture for bacterial infection; or 3. pleural fluid that demonstrated bacteria on Gram staining; or 4. pleural fluid with a pH ≤7.2 (measured by blood gas analyser) or low glucose level (≤3 mmol·L-1 or ≤55 mg·dL-1) in a patient with clinical evidence of infection; or 5. contrast-enhanced computed tomography (CT) evidence of pleural infection (consolidation of underlying lung with enhancing pleural collection) in a patient with clinical evidence of infection, alongside exclusion of other sources of infection. Evidence of infection was assessed by the recruiting physician on the basis of fever, an elevated peripheral blood white-cell count, or elevated serum inflammatory markers such as C-reactive protein (CRP). Study exclusion criteria were as follows: 1. age \<18 years; 2. no pleural fluid available for analysis; 3. previous pneumonectomy on the side of pleural infection; and 4. expected survival of \<3 months due to co-morbid disease, as judged by the recruiting physician.