Role of sputum cultures in diagnosis and surgical outcome prediction of bacterial empyema

Background: Thoracic empyema is a serious infectious disease worldwide. Video-assisted thoracoscopic surgery is strongly recommended as a treatment, and pleural fluid and tissue cultures can be obtained intraoperatively. The combination of a pleural peels tissue culture and a pleural fluid culture improves the positive culture rate. We aimed to investigate the role of sputum cultures to determine the optimal management for improving surgical outcome. Methods: This retrospective study identified 1197 patients with phase II or III thoracic empyema from our institution. Patients who underwent decortication of the pleura from April 2011 to May 2022 with a positive pleural culture were included. Results: There were 225 empyema patients with either a positive pleural fluid culture or a positive pleural peel tissue culture. Of these, 76 patients had positive sputum culture findings during hospitalization. The most common species of pathogens were Pseudomonas aeruginosa (44%) and Klebsiella pneumoniae (16%) in the sputum cultures and Streptococcus spp. (20%) and Staphylococcus aureus(11%) in the pleural cultures. There were 30 patients who had a common pathogen in a sputum culture and in the pleural fluid/tissue culture. Poor outcome measures were found in these patients, including the longer use of antibiotics preoperatively (19.03±37.66 days versus 9.59±27.09 days, p=0.006) and a higher mortality rate during hospitalization (40.0% versus 17.4%, p=0.002). Conclusions: The sputum culture plays an essential role in diagnosis of bacterial empyema and in prediction of surgical outcome. Obtaining the sputum specimen promptly through proper methods helps to improve the survival of empyema patients.