Objective To explore the clinical characteristics and prognostic factors of patients with complicated intra‑abdominal infections based on intra‑abdominal infection zones.

Methods The retrospective case‑control study was conducted. The clinical data of 372 patients with complica-ted intra‑abdominal infections who were admitted to The First Affiliated Hospital of Xi′an Jiaotong University from January 2021 to December 2024 were collected. There were 204 males and 168 females, aged (57±10)years. Among the 372 patients, 72 patients had single‑zone infection without zone D, 165 patients had multi‑zone infections without zone D (≥3 zones), and 135 patients had multi‑zone infections with zone D (≥3 zones). Observation indicators: (1) comparison of clinical characteristics among patients with different complicated intra‑abdominal infection zones; (2) treatment and prognosis for patients with different complicated intra‑abdominal infection zones; (3) analysis of prognostic factors in patients with complicated intra‑abdominal infections. Comparison of measure-ment data with normal distribution among multiple groups was conducted using the one‑way analysis of variance and pairwise comparison between groups was conducted using the post-hoc LSD test. Comparison of measurement data with skewed distribution among multiple groups was conducted using the Kruskal‑Wallis H test and pairwise comparison between groups was conducted using the Bonferroni method. Comparison of count data was conducted using the chi‑square test or Fisher exact probability and pairwise comparison between groups was conducted using the Bonferroni method. The Logistic regression model was used for univariate and multivariate analyses.

Results (1) Comparison of clinical characteristics among patients with different complicated intra-abdominal infection zones. For patients had single‑zone infection without zone D, multi-zone infec-tions without zone D, and multi‑zone infections with zone D, the acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) scores were 12±4, 17±6,20±5, respectively, the procalcitonin levels were (9.9±2.8)ng/mL, (17.3±5.1)ng/mL, (13.4±4.9)ng/mL, cases from community were 41, 8, and 0, cases from other medical institutions were 19, 86, and 99, and cases from this hospital related to surgery were 12, 71, and 36. Cases with infection of organ abscess were 28, 9, 0, cases with cholangitis were 17, 6, 0, cases with intestinal ischemia and necrosis were 13, 7, 8, cases with pancreatic necrosis infection were 0, 32, 94, cases with anastomotic fistula were 5, 88, 18, cases with pathogenic micro-organism as fungus were 4, 19, 24, cases with pathogenic microorganism as carbapenem-resistant Gram‑negative bacilli were 4, 41, 40. There were significant differences in the above indicators among the three groups of patients (P<0.05). Results of further pairwise comparison showed that compared to patients with single-zone or multi-zone infections without zone D, patients with multi-zone infections with zone D had higher proportion of cases from other medical institutions, lower proportions of cases with infection of organ abscess and cholangitis, and higher proportion of cases with pancreatic necrosis infection (P<0.05). (2) Treatment and prognosis among patients with different complicated intra‑abdominal infection zones. For patients had single‑zone infection without zone D, multi‑zone infections without zone D, and multi‑zone infections with zone D, cases receiving conser-vative treatment were 23, 0, 0, cases receiving percutaneous drainage were 44, 14, 123, cases receiving surgical treatment were 5, 38, 56, cases receiving surgical treatment≥2 times were 0, 13, 37, cases with complications as septic shock were 4, 63, 58, cases with intra‑abdominal hemorrhage were 3, 15, 27, cases with digestive tract fistula were 0, 22, 31, duration of intensive care unit stay (ICU) were (9.7±2.5)days, (16.3±6.5)days, (23.8±9.7)days, the number of patients who died within 28 days of hospitalization were 1, 15, 24. There were significant differences in the above indicators among the three groups of patients (P<0.05). Results of further pairwise comparison showed that compared to patients with single-zone or multi-zone infections without zone D, patients with multi-zone infections with zone D had higher proportions of percutaneous drainage, surgical treatment, surgical treatment ≥2 times, intra-abdominal hemorrhage, and digestive tract fistula, a longer duration of ICU (P<0.05). (3) Analysis of prognostic factors for patients with complicated intra‑abdominal infections. Results of multivariate analysis showed that APACHE Ⅱ score ≥15, pathogenic micro-organism as the carba-penem-resistant Gram‑negative bacilli, surgical treatment ≥2 times and septic shock were independent risk factors for death of complicated intra‑abdominal infection patients within 28 days of hospitalization (odds ratio=2.15, 2.68, 2.32, 3.08, 95% confidence interval as 1.03-4.50, 1.28-5.64, 1.09-4.96, 1.39-6.82, P<0.05).

Conclusions Compared to patients with single-zone or multi-zone infections without zone D, patients with multi‑zone infections with zone D have higher proportions of pancreatic necrosis infection, percutaneous drainage, surgical treatment, surgical treatment ≥2 times, intra‑abdominal hemorrhage, and digestive tract fistula, a longer duration of ICU. APACHE Ⅱ score ≥15, pathogenic microorganism as the carbapenem‑resistant Gram‑negative bacilli, surgical treatment ≥2 times and septic shock are independent risk factors for death of com-plicated intra‑abdominal infection patients within 28 days of hospitalization.