DOES USE OF MECHANICAL BOWEL PREPARATION AND ORAL ANTIBIOTICS BEFORE ELECTIVE COLORECTAL RESECTION REDUCE TOTAL POSTOPERATIVE INFECTION RATES IN NEW ZEALAND? A RETROSPECTIVE COHORT STUDY. claudia.paterson@auckland.ac.nz

411-08

DOES USE OF MECHANICAL BOWEL PREPARATION AND ORAL ANTIBIOTICS BEFORE ELECTIVE COLORECTAL RESECTION REDUCE TOTAL POSTOPERATIVE INFECTION RATES IN NEW ZEALAND? A RETROSPECTIVE COHORT STUDY.

6

New Zealand

Oral or Poster

Recent evidence suggests that use of mechanical bowel preparation (MBP) combined with oral antibiotics (OABs) prior to elective colorectal resection (CR) reduces postoperative infection rates. Our institution has recently impleted routine use of MBP + OABs (ciprofloxacin and metronidazole). This study aimed to compare postoperative infection rates before and after implementation.

We conducted a single-site retrospective cohort study of adult patients undergoing elective CR with an anastomosis in 2018 (pre-implementation) and 2023 (post-implementation). Patients in 2018 who received MBP + OABs were excluded, and those in 2023 who did not were excluded. Demographics, perioperative data, and postoperative outcome data were extracted from electronic clinical records. The primary outcome was total postoperative infection rates within 30 days. Continuous variables were analysed using t-tests or Mann-Whitney U tests, and categorical variables using Fisher’s exact test. Analyses were performed using R.

Of 274 patients screened, 199 were included (2018: n=119; 2023: n=80). Total postoperative infection rates were 22.7% in 2018 and 16.3% in 2023 (p=0.29). Urinary tract infection (UTIs) decreased from 10.9% to 2.5% (p=0.03). No significant differences were observed in superficial or deep incisional surgical site infections, intra-abdominal abscesses, anastomotic leaks, lower respiratory tract infections, line infections, sepsis, or Clostridium difficile colitis.

Use of MBP + OABs was associated with a significant reduction in UTIs but not in total postoperative infection rates. Findings are limited by sample size and potential for type II error. Larger prospective studies are warranted to confirm efficacy and investigate optimal antibiotic combinations and resistance patterns.