Long-term antimicrobial prophylaxis in lung cancer surgery: correlation between microbiological findings and empyema...

This study was planned in order to determine the value of antimicrobial prophylaxis in preventing post-operative empyema in patients undergoing lung cancer surgery. Two-hundred consecutive subjects operated upon for lung cancer received teicoplanin and aztreonam, starting at the induction of anesthesia and lasting until removal of the pleural drains. Cultures for aerobic and anaerobic bacteria were taken from: (1) the bronchus at the time of surgical division; (2) the pleural space before closure of the chest; (3) the pleural fluid during the post-operative period; and (4) the tips of chest drains at the time of their removal. In the 200 patients receiving antibiotic prophylaxis, the number of post-operative empyemas (1%) was lower than that (7.5%) found in 53 comparable patients who were previously treated with placebo. In the 'placebo group', empyema was due to gram-positive bacteria, while in the 'prophylaxis group', it was caused by Gram-negative bacteria (Pseudomonas aeruginosa). A significant (P < 0.05) correlation between infected bronchial secretions, pleural space contamination at surgery, contamination of chest fluid and drains during the post-operative period, and empyema development was demonstrated. In conclusion, antibiotic prophylaxis, while being effective in preventing post-operative empyema, may induce the colonization of the respiratory tract with highly resistant gram-negative bacteria.