To investigate the microbiological epidemiology and clinical use of antibiotics in patients complicated intra-abdominal infection (cIAI), therefore to optimize antibiotic use and to promote antimicrobial stewardship.

A total of 451 patients with cIAI from a Chinese tertiary hospital between January 2015 and December 2016 were retrospectively reviewed. The infection severity, timing of microbiological specimen sampling, culture results, initial antibiotic selection and later anti-infective regimen adjustment were analyzed.

Three hundred and sixteen (70.1%, 316/451) patients undergone microbiological investigation at infection sites within 3 days and 133 (42.1%) patients had a positive culture, of which 64.5% were Enterobacteriaceae. Three hundred seventy-four patients (82.9%) initially received broad-spectrum antibiotics against gram-negative bacilli. Sixty-five patients (14.4%) initially received combined antibiotic therapy, of which 30.8% were deemed as overuse. Among 308 patients who initially received broad-spectrum antibiotic therapy, 268 patients (87.0%) clinically improved in five days, while de-escalation was only conducted in 72 cases (26.9%). On average, patients were treated with (2.29±1.30) antibiotics for a duration of (10.6±6.5) days, and 42.4% received combined antibiotic therapy during hospitalization.

The major microbiological pathogens in cIAI patients in our hospital were Enterobacteriaceae. However, there are phenomena such as excessive usage with broad-spectrum antibiotics, insufficient awareness of de-escalation, and long course of anti-infective therapy, which needs to be further improved.

Complicated; Intra-abdominal infection; Antibiotics; De-escalation; Antimicrobial stewardship