Microbiological Profiles of Suspected Postoperative Pneumonia After Esophagectomy: A Focus on Gram-negative Pathogens

BACKGROUND/AIM: Postoperative pneumonia is an important complication after esophagectomy for esophageal cancer. Although sputum cultures are often obtained when pneumonia is suspected, the microbiological profiles detected in this setting remain insufficiently characterized. This study aimed to describe sputum culture findings at suspected postoperative pneumonia onset, focusing on Gram-negative organisms and targetable pathogens relevant to antimicrobial selection. PATIENTS AND METHODS: We retrospectively reviewed 150 consecutive patients who underwent esophagectomy for esophageal cancer between January 2014 and April 2026. Patients were classified into early video-assisted thoracoscopic (VATS) esophagectomy, robot-assisted minimally invasive esophagectomy (RAMIE), and late VATS esophagectomy groups. Clinically relevant postoperative pneumonia was defined as Clavien-Dindo grade II or higher pneumonia within 30 days after surgery. Sputum cultures obtained at suspected pneumonia onset were reviewed. Sputum cultures were positive in all 44 pneumonia cases, and 60 organisms were detected. Gram-negative organisms accounted for 41 isolates (68.3%), and at least one Gram-negative organism was detected in 36 patients (81.8%). Targetable pathogens were detected in 33 patients (75.0%). No clear surgical-era-specific microbiological profile was identified among pneumonia cases. CONCLUSION: Sputum cultures, after esophagectomy, obtained at suspected postoperative pneumonia onset frequently revealed Gram-negative organisms and targetable pathogens. These findings provide a clinical basis for empirical antimicrobial selection and subsequent de-escalation strategies, but detected organisms should be interpreted as organism distribution rather than definitive causative pathogens.