Antibiotic Prescribing Patterns and Risk Factors for Multidrug-Resistant Organisms in Critically Ill Surgical Patients with Intra-Abdominal Infections

Background: Guidelines for the treatment of intra-abdominal infections (IAIs) recommend a variety of potential antimicrobial regimens; however, there is a lack of real-world data documenting prescribing practices and incidence of multidrug-resistant organisms (MDROs). Methods: A single-center, retrospective study from June 1, 2021 to April 30, 2023, was conducted to evaluate patients with an IAI admitted to the surgical intensive care unit. Patients were categorized into four groups based on the primary gram-negative antibiotic initially prescribed for IAI treatment: piperacillin-tazobactam, cefepime, levofloxacin, and meropenem. The primary outcome was antibiotic prescribing practices for IAI. Regression analyses were conducted to evaluate risk factors for MDRO, duration of antibiotics, and mortality. Results: A total of 334 patients were included. Most patients received piperacillin-tazobactam (n = 227, 68%), followed by cefepime (n = 122, 36.5%), meropenem (n = 73, 21.9%), and levofloxacin (n = 61, 18.3%). There were 301 patients prescribed vancomycin for a median of 4 days (interquartile range [IQR]: 3-7). The median antibiotic duration was 8 days (IQR: 5-12). Variables associated with prolonged antibiotics were infectious disease consult (p < 0.001), multiple intra-abdominal procedures (p = 0.006), and exposure to more than one gram-negative antibiotic (p = 0.004). Predictors of MDRO were longer durations of antibiotics (odds ratio [OR]: 1.04, 95% confidence interval [CI]: 1.01-1.07) and meropenem exposure (OR: 2.11, 95% CI: 1.12-3.98). Older age (OR: 1.05, 95% CI: 1-1.08, p = 0.007) and septic shock (OR: 2.8, 95% CI: 1.3-6.1, p = 0.003) were risk factors for mortality. Conclusions: Piperacillin-tazobactam was the most frequently prescribed antibiotic for treatment of IAI in critically ill surgical patients. Prolonged durations of broad-spectrum antibiotics should be avoided due to the risk of developing an MDRO infection.