The inclusion criteria included 1) pleural fluid with any of the following: (a) exudative and loculated effusion in a patient with pneumonia, (b) gram stain/culture positive, (c) macroscopically purulent 2) chest tube placement during current hospitalization 3) concurrent administration of intrapleural tPA and DNase (4mg and 10mg per instillation respectively). Here, PLAT is linked to susceptibility to pneumonia measurement.