Characteristics and risk factors of postoperative pneumonia after emergency surgery in tertiary general hospitals (2015–2024): a 10-year comparative analysis with elective surgery

Objective To analyze the characteristics and risk factors of postoperative pneumonia (POP) in emergency surgery at tertiary general hospitals, aiming to provide scientific evidence for early screening of high-risk populations and optimization of POP prevention strategies. Methods A retrospective analysis was performed on POP data from emergency and elective surgery patients between 2015 and 2024. Infection characteristics were compared between the two groups. Results Among 399,347 surgical patients, 2,478 (0.62%) developed POP. The incidence of POP was significantly higher in emergency surgery (2.28%) than in elective surgery (0.53%, p < 0.001). Emergency surgery departments with the highest POP incidence were neurosurgery (18.30%), cardiovascular surgery (12.24%), and thoracic surgery (9.04%). Predominant pathogens were Gram-negative bacteria, followed by fungi and Gram-positive bacteria. The detection rate of multidrug-resistant organisms (MDROs) was significantly higher in emergency surgery than in elective surgery (42.19% vs. 32.90%, p < 0.001), with the most common MDROs being pandrug-resistant Acinetobacter baumannii (PDR-AB), carbapenem-resistant Enterobacteriaceae (CRE), and pandrug-resistant Pseudomonas aeruginosa (PDR-PA). Multivariate analysis showed that preoperative hospitalization duration of 6–48 h was a protective factor for POP in emergency surgery; male sex, age ≥60 years, admission to ICU, ASA score ≥3, general anesthesia, surgical duration ≥3 h, and intraoperative blood loss >1,000 mL were independent risk factors ( p < 0.05). Conclusion Emergency surgery carries a significantly higher risk of POP than elective surgery. Special attention should be paid to patients undergoing neurosurgery, cardiovascular surgery, and thoracic surgery. For patients with identified risk factors, enhanced perioperative management and individualized preventive strategies are essential to reduce POP incidence and improve emergency surgery outcomes.