Less is More: Reducing Antibiotic Burden in Elective Colorectal Surgery Preparation

Year Submitted: 2025
Published Date: 14 January 2026

Tags: Applied/Translational Research, Quantitative Research, Inpatient Care, Outpatient Care, Care Continuum

About this Content

Aims

To evaluate the clinical effectiveness of a reduced-dose oral antibiotic regime (1g Neomycin and 1g Metronidazole) with MBP in elective colorectal surgery evaluating on the incidence of SSI rates within 30days, hospital length of stay and cost implications

Background

Colorectal surgery carries a significant risk of surgical site infections (SSIs), with rates ranging from 5 to 23%. SSIs typically occur within the first 30 days after surgery, involving either superficial tissue or deeper structures near the surgical area. They are characterised by redness, pain, heat, and swelling at the incision wound, or discharge of pus. This may prolong the patient's hospitalization and increase healthcare costs, adding both clinical and financial burden. Additionally, while ERAS guidelines advise that mechanical bowel preparation (MBP) is not recommended for all patients, in rectal surgery, if MBP is used, it should be combined with oral antibiotics to reduce SSIs. However, what the guidelines do not tell us is how much or what dosing regimen is bestleaving wide variation in practice.

Diving into literatures, whilst the conventional regimen includes 2L polyethylene glycol with 2g each of neomycin and metronidazole, evidence shows that halving the antibiotic doses (1g) also reduces overall SSIs. This variability highlights an important knowledge gap: whether reduced-dose oral antibiotics are equally effective, potentially minimizing antibiotic burden and cost.

Methods

A single-center retrospective review analyzed 102 patients undergoing elective colorectal surgery (open resection, rectal resection with ileostomy, or laparoscopic surgery for tumors) between July 2024 and May 2025. Patients received either reduced-dose (1g) (n=54) or standard-dose (2g) (n=48) oral Neomycin and Metronidazole combinations, followed by standard post-operative care and wound review at 2-3 weeks. Participants with no bowel prep and antibiotics were excluded from the study.
Data collection included baseline demographics, SSI outcomes within 30 days, length of stay, and cost outcomes, with early review available for suspected infections through direct contact with general surgery nurses by the patients.
Statistical analysis employed Mann-Whitney U test for Length of Stay, Chi-square test with Fisher's Exact for SSI rates, and Independent t-test for age.

Results

The study found that patients receiving 1g oral antibiotics had significantly better outcomes than those receiving 2g, despite the 2g group being older with higher ASA scores and more open surgeries.
Both groups were comparable at baseline with no significant differences: Mean age: 1g - 64.81-year-old vs 2g - 67.42-year-old, p=0.200; Mean BMI: 1g - 24.81 kg/m vs 2g - 25.84 kg/m, p=0.320; Male sex: 1g - 61% vs 2g - 62.5%, p=0.885; Open surgery: 1g - 24.1% vs 2g - 37.5%, p=0.141; ASA III-IV: 1g 33.33% vs 2g - 50%, p=0.088.

The 2g group showed significantly higher 30-day SSI rates (2g 18.8% vs 1g 5.6%, p=0.039 unadjusted). While the adjusted p-value of 0.082 doesn't quite reach statistical significance, the large effect size suggests genuine clinical importance as the 1g protocol showed an 80% reduction in infection odds.
The hospital length of stay was significantly shorter in the 1g group - a median of 4 days compared to 6.5 days in the 2g group [2g - 6 (IQR 8) vs 1g - 4 (IQR 3) days, p=0.002], representing a highly significant 2.5-day reduction.

Reduced-dose oral antibiotics (1g Neomycin and 1g Metronidazole) in elective colorectal surgery has halved the pill burden and shortened hospitalization stay by 2.5 median days, saving approximately $2507.32 per patient. Additionally, when we applied to our study cohort, this represents potential savings exceeding $135,000.

Conclusion

In conclusion, the 1g oral antibiotic protocol demonstrates superior clinical outcomes and substantial economic advantages compared to 2g dosing. These findings suggest that lower, appropriately dosed antibiotic regimens may optimize patient outcomes while reducing healthcare costs. However, the retrospective design and limited risk-factor data warrant future prospective studies.

Lessons Learnt

One of the lessons learnt from this study is that less can be more in antibiotic prophylaxis for colorectal surgery. Contrary to the assumption that higher antibiotic doses provide better protection, this research demonstrates that reduced-dose oral antibiotics (1g vs 2g) resulted in superior clinical outcomes.

Additional Information

Sliver - Singapore Nursing Award for Singapore Health and Biomedial Congress (SHBC) 2025

Keywords

Surgical site infection, SSI, Colorectal Surgery, Oral Antibiotic, ERAS

Innovators' Details

Connect with this contributor!

Rachel Soh - soh.rachel.ej@nhghealth.com.sg

Project Attachment

SHBC Poster_Less is more.pdf