Postoperative infection (PI) is among the most common complications following surgery (1). PI can occur in patients of any age, with its incidence significantly influenced by patient-related risk factors and the type of surgical procedure (2). Complete surgical resection remains the cornerstone of treatment for patients with localized esophageal thoracic squamous carcinoma (ETS) (3). In addition, neoadjuvant and adjuvant chemotherapy or chemoradiotherapy can improve postoperative prognosis in patients with advanced localized ETS (4). Due to immunosuppression, prolonged operative duration, and extensive surgical trauma, patients undergoing esophageal surgery are particularly susceptible to infections, especially respiratory tract infections, as esophageal procedures carry inherent contamination risks (5). Considerable attention has been directed toward PI as a critical postoperative complication in surgical patients.

Recent studies have highlighted the significance of PI of patients on cancer prognosis (6, 7). Many patients present with comorbidities such as hypertension and hyperglycemia, which reduce tolerance to surgical trauma. A proportion of PIs can be prevented through the implementation of evidence-based preventive strategies, among which the identification of sensitive risk factors serves as a cost-effective measure (8).

Guangyuan et al. (9) identified multiple risk factors contributing to postoperative pulmonary infection in patients undergoing minimally invasive esophagectomy. Clinical staff should recognize these factors promptly and implement early prevention and intervention to reduce the incidence of pulmonary infection and improve patient outcomes. Dindo D et al. further reported that smoking index, pleural adhesions, and prolonged operation duration are associated with an increased risk of pulmonary infection following esophagectomy (10). However, limited evidence exists regarding infectious complications and their associated risk factors in patients aged 60 years and older undergoing ETS. The present study aimed to identify key risk factors associated with postoperative infectious complications in this population and to investigate trends in bacterial resistance.

The present study aimed to identify risk factors associated with nosocomial PI and to characterize the bacterial spectrum in patients aged ≥60 years undergoing ETS. The overall incidence of PI in this cohort was 29.6%. Gram-negative bacteria accounted for most identified pathogens, and the predominant pattern of polymicrobial infections involved a combination of Gram-negative bacteria and fungi. Klebsiella pneumoniae was the most frequently isolated pathogen, followed by Pseudomonas aeruginosa, Enterobacter cloacae, and Candida albicans, each representing more than 10% of the documented isolates. These findings align with previous studies, which reported that Haemophilus influenzae, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Enterobacter cloacae were detected in approximately 70% of postoperative pulmonary infections. In addition, Staphylococcus aureus has also been frequently implicated in such cases (11, 12).

Our previous study demonstrated that a prolonged preoperative hospital stay increased the risk of postoperative infection in esophageal tumor patients (p < 0.05) (13). A likely explanation is that extended hospitalization facilitates colonization by multisite pathogens and elevates the risk of cross-infection. In the current study, smoking, surgical duration, and postoperative blood glucose levels ( Figure 1 ) were identified as significant risk factors for PI following ETS. Notably, surgical duration and postoperative blood glucose are potentially modifiable, offering actionable targets for clinical intervention. Meanwhile, Tobacco smoking is also a risk factor for several adverse post-operative outcomes (14). Smoking impairs pulmonary function through mechanisms such as ciliary damage, impaired mucociliary clearance, and increased mucus production (15), thereby promoting pathogen colonization and elevating the risk of postoperative pneumonia (16). These findings are consistent with previous literature, which has emphasized smoking as a significant contributor to postoperative respiratory complications. Akutsu et al. (17) highlighted the benefits of perioperative management strategies, including smoking cessation and preoperative respiratory rehabilitation, in reducing postoperative pneumonia following esophagectomy. Such interventions enable smokers to quit before surgery, facilitate the practice of coughing and deep-breathing exercises, and promote adherence to nutritional and physical rehabilitation programs (18, 19).

The present study confirms that prolonged surgical duration serves as an independent predictor of postoperative pulmonary complications. Previous guidelines from the American College of Physicians have similarly highlighted that procedures lasting between 3 to 4 hours are significantly associated with an increased risk of perioperative pulmonary events (20, 21). In our study population, patients undergoing esophageal tumor surgery with an operative time exceeding 4 hours showed a markedly elevated risk of PI (OR value 1.43). The resistance patterns are concerning. Among various risk factors, surgical duration directly influences the length of exposure of the surgical wound to environmental pathogens (22). Prolonged operative time increases the risk of surgical site infection due to extended wound exposure to ambient air (23). When prolonged surgical duration is anticipated, adjustments to preoperative prophylactic antibiotic protocols should be considered, and intraoperative manipulation should be performed with care to minimize trauma to surrounding structures (24). Although the duration of surgery is inherently influenced by the procedure type and patient complexity, optimized preoperative planning and enhanced intraoperative efficiency may prevent unnecessary prolongation, ultimately reducing the risk of PI.

Naoko Ito et al. reported that hyperglycemia on postoperative day 3 was a significant predictor of postoperative infections following highly invasive esophageal cancer surgery (25). Dronge et al. demonstrated that adequate preoperative glycemic control (HbA1c levels <7.0%) was associated with a reduced incidence of postoperative infectious complications across a range of major noncardiac surgical procedures (26).

The incidence of postoperative infection was notably higher among patients with diabetes, and several pathophysiological mechanisms may contribute to this increased risk. In individuals with diabetes, persistent hyperglycemia leads to elevated plasma osmotic pressure, which impairs leukocyte chemotaxis, phagocytosis, and adhesion. These impairments weaken the host immune defense against pathogens, increasing susceptibility to infection (27). Diabetic patients often exhibit significantly higher HbA1c levels compared to non-diabetic individuals. Elevated HbA1c shifts the oxyhemoglobin dissociation curve to the left, enhancing oxygen-binding affinity but impairing oxygen release to tissues. This impairs gas exchange and reduces oxygen delivery to pulmonary capillary beds, exacerbating the risk of pulmonary infections (28). Surgical trauma induces a stress response contributing to peripheral insulin resistance and inhibiting pancreatic β-cell insulin secretion. Reduced insulin activity results in perioperative hyperglycemia, suppressed protein synthesis, enhanced protein catabolism, and an increased risk of infection (29). Vitamin A metabolism is impaired in diabetic patients due to reduced hepatic conversion, leading to diminished respiratory mucosal protection. This impairment predisposes lung tissue to infection (30). These findings highlight the critical importance of perioperative glycemic control in diabetic patients. To reduce the risk of postoperative infection, blood glucose should be carefully managed and maintained within the target range of 7.8–11.1 mmol/L during both intraoperative and early postoperative periods (31).

The findings of this study should be considered when formulating targeted intervention strategies to reduce the risk of postoperative infection. Further research is warranted, particularly studies exploring the utility of preoperative sputum or fecal screening, the effectiveness of perioperative antimicrobial prophylaxis, and optimal management strategies for PI in esophagectomy patients.

In conclusion, this retrospective study suggests that PI remains a common complication following esophagectomy, despite recent improvements in perioperative care. Gram-negative bacteria were identified as the predominant pathogens in patients aged ≥60 years. Smoking, prolonged operative duration, and postoperative hyperglycemia were significantly associated with an increased risk of infection, potentially contributing to a higher incidence of postoperative complications. However, due to the inherent limitations of the retrospective study design, causal relationships cannot be definitively established.