Analysis of pathogens and drug-resistance characteristics of intra-abdominal infection in patients undergoing acute appendicitis surgery based on clinical data from 2023 to 2026 and comparative analysis with published literature

Objective To analyze the distribution of pathogenic bacteria and antimicrobial resistance characteristics in intraoperative intra-abdominal infection specimens from patients undergoing acute appendicitis surgery, to compare our local antibiogram with published studies, and to analyze temporal trends in major resistance indicators, thereby providing evidence for empirical antimicrobial therapy and local antimicrobial stewardship. Methods This was a single-center retrospective descriptive cross-sectional study. Patients who underwent appendectomy between January 2023 and July 2026, with intraoperative appendiceal lumen pus swabs sent for bacterial culture and antimicrobial susceptibility testing, were included. Pathogen distribution, extended-spectrum β -lactamase (ESBL) prevalence, multidrug-resistant (MDR) prevalence, and susceptibility rates to various antibiotics were collected. PubMed, Embase, CNKI, and Wanfang databases were searched through July 2026. Chi-square tests were used to compare Escherichia coli susceptibility rates with the study meeting all comparator criteria; Cochran–Armitage trend tests analyzed annual resistance trends from 2024 to 2026, with Bonferroni correction for multiple comparisons. Results A total of 301 patients were included, yielding 399 isolates. Gram-negative bacteria predominated (89.7%). E. coli was the leading pathogen (252 isolates, 63.2%), followed by Pseudomonas aeruginosa (41, 10.3%) and Klebsiella pneumoniae (28, 7.0%). ESBL prevalence among E. coli was 28.2% (71/252), MDR prevalence 29.8% (75/252), and carbapenem-resistant Enterobacterales (CRE) 1 isolate (0.4%). E. coli showed high susceptibility to amikacin (99.5%), carbapenems (99.1%), cefoperazone–sulbactam (98.6%), piperacillin–tazobactam (96.8%), and cefoxitin (91.0%), but low susceptibility to trimethoprim–sulfamethoxazole (41.2%) and levofloxacin (22.9%). Trend analysis from 2024 to 2026 showed no significant changes in ESBL+ rate (30.0% → 30.4% → 21.9%, P = 0.445) or MDR rate (26.2% → 37.0% → 25.0%, P = 0.182). Compared with Lu et al. (117 E. coli isolates from Guangzhou), our ESBL+ rate was significantly lower (28.2% vs. 40.2%, P = 0.022), while susceptibility to ceftazidime (82.5% vs. 58.1%, P < 0.001), cefepime (82.1% vs. 58.1%, P < 0.001), and ceftriaxone (67.6% vs. 55.6%, P = 0.029) was significantly higher; however, levofloxacin susceptibility was significantly lower (22.9% vs. 65.0%, P < 0.001). No obligate anaerobes were recovered, as anaerobic culture was not performed. Conclusion E. coli predominates in intra-abdominal infections of acute appendicitis in our region. Third-generation cephalosporin susceptibility is higher than reported in other Chinese centers, but fluoroquinolone susceptibility is markedly low. Empirical therapy should be guided by local resistance patterns; fluoroquinolones should be avoided. For low-risk patients, cefoxitin monotherapy is preferred; for high-risk patients, piperacillin–tazobactam or cefoperazone–sulbactam may be considered.