Antibiotic prophylaxis in colorectal surgery: are oral, intravenous or both best and is mechanical bowel preparation necessary?

The Impact of Mechanical Bowel Preparation and Oral Antibiotics in Colorectal Cancer Surgery (MECCA Study): A Prospective Randomized Clinical Trial

Background: Colorectal cancer surgery has been associated with surgical site infections (SSIs), leading to an increase in postoperative morbidity, length of stay and total cost. The aim of the present randomized study was to investigate the relationship between the preoperative administration of oral antibiotic therapy and SSI rate, as well as other postoperative outcomes in patients undergoing colorectal cancer surgery. Material and Methods: Patients who underwent colorectal cancer surgery in a university surgical department were included in the present study. Patients were randomized into two groups using the "block randomization" method. The intervention group received three doses of 400 mg rifaximin and one dose of 500 mg metronidazole per os, as well as mechanical bowel preparation the day before surgery. The control group underwent only mechanical bowel preparation the day before surgery. The study has been registered in ClinicalTrials.gov (NCT03563586). Results: Two hundred and five patients were finally included in the present study, 97 of whom received preoperative antibiotic therapy per os (intervention group). Patients of this group demonstrated a significantly lower SSI rate compared with patients who did not receive preoperative antibiotic therapy (7% vs. 16%, p = 0.049). However, preoperative antibiotic administration was not correlated with any other postoperative outcome (anastomotic leak, overall complications, readmissions, length of stay). Conclusions: Preoperative antibiotic therapy in combination with mechanical bowel preparation seemed to be correlated with a lower SSI rate after colorectal cancer surgery.

Mechanical bowel preparation in elective colorectal surgery: a propensity score-matched analysis of the Italian colorectal anastomotic leakage (iCral) study group prospective cohorts

Retrospective evaluation of the effects of mechanical bowel preparation (MBP) on data derived from two prospective open-label observational multicenter studies in Italy regarding elective colorectal surgery. MBP for elective colorectal surgery remains a controversial issue with contrasting recommendations in current guidelines. The Italian ColoRectal Anastomotic Leakage (iCral) study group, therefore, decided to estimate the effects of no MBP (treatment variable) versus MBP for elective colorectal surgery. A total of 8359 patients who underwent colorectal resection with anastomosis were enrolled in two consecutive prospective studies in 78 surgical centers in Italy from January 2019 to September 2021. A retrospective PSMA was performed on 5455 (65.3%) cases after the application of explicit exclusion criteria to eliminate confounders. The primary endpoints were anastomotic leakage (AL) and surgical site infections (SSI) rates; the secondary endpoints included SSI subgroups, overall and major morbidity, reoperation, and mortality rates. Overall length of postoperative hospital stay (LOS) was also considered. Two well-balanced groups of 1125 patients each were generated: group A (No MBP, true population of interest), and group B (MBP, control population), performing a PSMA considering 21 covariates. Group A vs. group B resulted significantly associated with a lower risk of AL [42 (3.5%) vs. 73 (6.0%) events; OR 0.57; 95% CI 0.38-0.84; p = 0.005]. No difference was recorded between the two groups for SSI [73 (6.0%) vs. 85 (7.0%) events; OR 0.88; 95% CI 0.63-1.22; p = 0.441]. Regarding the secondary endpoints, no MBP resulted significantly associated with a lower risk of reoperation and LOS > 6 days. This study confirms that no MBP before elective colorectal surgery is significantly associated with a lower risk of AL, reoperation rate, and LOS < 6 days when compared with MBP.

Meta-analysis of efficacy of perioperative oral antibiotics in intestinal surgery with surgical site infection

OBJECTIVES

Surgical site infection (SSI) is a serious complication of intestinal surgery. In this meta-analysis, we aimed to explore the efficacy and safety of different preoperative oral antibiotic preparation (OABP) compared with intravenous antibiotic preparation (IVAP) and/or mechanical bowel preparation (MBP).

METHODS

A meta-analysis consisting of adult patients adopting oral antibiotics versus other regimens during the preoperative preparation of elective intestinal surgery was performed. The outcome included overall SSI, organ space SSI, superficial SSI, deep SSI, and mortality rate.

RESULTS

A total of 35 randomized controlled trials (RCTs) consisting of 8445 adult patients were included in our present analysis. OABP regimens were combined with IVAP in 29 RCTs. In general, the incidence of overall SSI in the OABP group was less compared with the IVAP alone or IVAP+MBP group (RR 0.56, 95% CI 0.46-0.69, P < .00001, I2 = 47%). Metronidazoles plus quinolones or aminoglycosides showed the best effect on reducing the overall SSI. OABP in combination with preoperative and postoperative IVAP was both significantly associated with reduced SSI. IVAP before and within 24 h after surgery showed the best advantage. No difference was found between the OABP without IVAP group and the control group in reducing SSI. OABP regimens also demonstrated a lower incidence rate of organ space SSI, superficial SSI, deep SSI, and mortality.

CONCLUSION

OABP in combination with preoperative IVAP and within 24 h post-operation significantly reduced the incidence of SSI in intestinal surgery. Metronidazoles accompanied with quinolones or aminoglycosides might be the appropriate combinations for OABP regimens.

Is There a Role for Mechanical and Oral Antibiotic Bowel Preparation for Patients Undergoing Minimally Invasive Colorectal Surgery? A Systematic Review and Meta-analysis

INTRODUCTION

To date, all meta-analyses on oral antibiotic prophylaxis (OA) and mechanical bowel preparation (MBP) in colorectal surgery have included results of both open and minimally invasive approaches. Mixing both procedures may lead to false conclusions. The aim of the study was to assess the available evidence of mechanical and oral antibiotic bowel preparation in reducing the incidence of surgical site infection (SSI) and other complications following minimally invasive elective colorectal surgery.

METHODS

We searched PubMed, Science Direct, Google Scholar and Cochrane Library from 2000 to May 1, 2022. Comparative randomized and non-randomized studies were included. We reviewed the use of oral OA, MBP and combinations of these treatments. The methodological quality of the included studies was assessed using the Rob v2 and Robins-I tools.

RESULTS

We included 18 studies (7 randomized controlled trials and 11 cohort studies). Meta-analysis of the included studies showed that the combination of MBP + OA was associated with a significant reduction in SSI, AL and overall morbidity compared with the other options no preparation, MBP only and OA only.  CONCLUSION: Adding OA with MBP has a positive impact in reducing the incidence of SSI, AL and overall morbidity after minimally invasive colorectal surgery. Therefore, the combination of OA and MBP should be encouraged in this selected group of patients undergoing minimally invasive surgery.

Preoperative combined mechanical and oral antibiotic bowel preparation for preventing complications in elective colorectal surgery

BACKGROUND

The success of elective colorectal surgery is mainly influenced by the surgical procedure and postoperative complications. The most serious complications include anastomotic leakages and surgical site infections (SSI)s, which can lead to prolonged recovery with impaired long-term health.  Compared with other abdominal procedures, colorectal resections have an increased risk of adverse events due to the physiological bacterial colonisation of the large bowel. Preoperative bowel preparation is used to remove faeces from the bowel lumen and reduce bacterial colonisation. This bowel preparation can be performed mechanically and/or with oral antibiotics. While mechanical bowel preparation alone is not beneficial, the benefits and harms of combined mechanical and oral antibiotic bowel preparation is still unclear.

OBJECTIVES

To assess the evidence for the use of combined mechanical and oral antibiotic bowel preparation for preventing complications in elective colorectal surgery.

SEARCH METHODS

We searched MEDLINE, Embase, CENTRAL and trial registries on 15 December 2021. In addition, we searched reference lists and contacted colorectal surgery organisations.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of adult participants undergoing elective colorectal surgery comparing combined mechanical and oral antibiotic bowel preparation (MBP+oAB) with either MBP alone, oAB alone, or no bowel preparation (nBP). We excluded studies in which no perioperative intravenous antibiotic prophylaxis was given.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as recommended by Cochrane. Pooled results were reported as mean difference (MD) or risk ratio (RR) and 95 % confidence intervals (CIs) using the Mantel-Haenszel method. The certainty of the evidence was assessed with GRADE.

MAIN RESULTS

We included 21 RCTs analysing 5264 participants who underwent elective colorectal surgery. None of the included studies had a high risk of bias, but two-thirds of the included studies raised some concerns. This was mainly due to the lack of a predefined analysis plan or missing information about the randomisation process. Most included studies investigated both colon and rectal resections due to malignant and benign surgical indications. For MBP as well as oAB, the included studies used different regimens in terms of agent(s), dosage and timing.  Data for all predefined outcomes could be extracted from the included studies. However, only four studies reported on side effects of bowel preparation, and none recorded the occurrence of adverse effects such as dehydration, electrolyte imbalances or the need to discontinue the intervention due to side effects. Seventeen trials compared MBP+oAB with sole MBP. The incidence of SSI could be reduced through MBP+oAB by 44% (RR 0.56, 95% CI 0.42 to 0.74; 3917 participants from 16 studies; moderate-certainty evidence) and the risk of anastomotic leakage could be reduced by 40% (RR 0.60, 95% CI 0.36 to 0.99; 2356 participants from 10 studies; moderate-certainty evidence). No difference between the two comparison groups was found with regard to mortality (RR 0.87, 95% CI 0.27 to 2.82; 639 participants from 3 studies; moderate-certainty evidence), the incidence of postoperative ileus (RR 0.89, 95% CI 0.59 to 1.32; 2013 participants from 6 studies, low-certainty of evidence) and length of hospital stay (MD -0.19, 95% CI -1.81 to 1.44; 621 participants from 3 studies; moderate-certainty evidence). Three trials compared MBP+oAB with sole oAB. No difference was demonstrated between the two treatment alternatives in terms of SSI (RR 0.87, 95% CI 0.34 to 2.21; 960 participants from 3 studies; very low-certainty evidence), anastomotic leakage (RR 0.84, 95% CI 0.21 to 3.45; 960 participants from 3 studies; low-certainty evidence), mortality (RR 1.02, 95% CI 0.30 to 3.50; 709 participants from 2 studies; low-certainty evidence), incidence of postoperative ileus (RR 1.25, 95% CI 0.68 to 2.33; 709 participants from 2 studies; low-certainty evidence) or length of hospital stay (MD 0.1 respectively 0.2, 95% CI -0.68 to 1.08; data from 2 studies; moderate-certainty evidence). One trial (396 participants) compared MBP+oAB versus nBP. The evidence is uncertain about the effect of MBP+oAB on the incidence of SSI as well as mortality (RR 0.63, 95% CI 0.33 to 1.23 respectively RR 0.20, 95% CI 0.01 to 4.22; low-certainty evidence), while no effect on the risk of anastomotic leakages (RR 0.89, 95% CI 0.33 to 2.42; low-certainty evidence), the incidence of postoperative ileus (RR 1.18, 95% CI 0.77 to 1.81; low-certainty evidence) or the length of hospital stay (MD 0.1, 95% CI -0.8 to 1; low-certainty evidence) could be demonstrated.

AUTHORS' CONCLUSIONS

Based on moderate-certainty evidence, our results suggest that MBP+oAB is probably more effective than MBP alone in preventing postoperative complications. In particular, with respect to our primary outcomes, SSI and anastomotic leakage, a lower incidence was demonstrated using MBP+oAB. Whether oAB alone is actually equivalent to MBP+oAB, or leads to a reduction or increase in the risk of postoperative complications, cannot be clarified in light of the low- to very low-certainty evidence. Similarly, it remains unclear whether omitting preoperative bowel preparation leads to an increase in the risk of postoperative complications due to limited evidence. Additional RCTs, particularly on the comparisons of MBP+oAB versus oAB alone or nBP, are needed to assess the impact of oAB alone or nBP compared with MBP+oAB on postoperative complications and to improve confidence in the estimated effect. In addition, RCTs focusing on subgroups (e.g. in relation to type and location of colon resections) or reporting side effects of the intervention are needed to determine the most effective approach of preoperative bowel preparation.

The Use of Mechanical Bowel Preparation and Oral Antibiotic Prophylaxis in Elective Colorectal Surgery: A Call for Change in Practice

Elective colorectal surgery is associated with one of the highest rates of surgical site infections (SSIs), which result in prolonged length of stay, morbidity, and mortality for these patients and have a significant financial burden to healthcare systems. In an effort to reduce the frequency of SSI rates associated with colorectal surgery, the 2018 World Health Organisation (WHO) guidelines recommend the routine use of mechanical bowel preparation (MBP) and oral antibiotic prophylaxis (OAP) in adult patients undergoing elective colorectal surgery. However, this recommendation remains a topic of debate internationally. The National Institute of Clinical Excellence (NICE) guidelines, last revised in 2019, recommend against the routine use of MBP and do not address the issue of OAP. In this communication, we reviewed the current guidelines and examined the most recent evidence from randomised-control trials (RCTs) and meta-analyses on the effect of MBP and OAP on SSI rates since the 2019 NICE guideline review. This recent evidence clearly demonstrated an SSI-risk-reduction benefit with the additional use of OAP and the combination of MBP and OAP in this group of patients, and we therefore highlight the need for change of the current NICE guidelines.

A Network Meta-Analysis and GRADE Assessment of the Effect of Preoperative Oral Antibiotics with and Without Mechanical Bowel Preparation on Surgical Site Infection Rate in Colorectal Surgery

Objective

To compare the effect of different methods of bowel preparation on the incidence of surgical site infections (SSI), anastomotic leakage (AL), and mortality in patients undergoing elective colorectal surgery.

Background

Recent guidelines advise mechanical bowel preparation with oral antibiotics (MBP-OA) for the prevention of SSI in colorectal surgery. Recent trials suggest oral antibiotics (OA) alone may be sufficient.

Methods

PubMed, MEDLINE, and Embase were searched from inception until 10-08-2021. We included randomized controlled trials (RCTs) comparing multiple methods of bowel preparation (mechanical bowel preparation [MBP], OA, MBP-OA, or no preparation) with regards to clinical outcomes such as incidence of SSI, AL, and mortality rates. A frequentist random-effects network meta-analysis was conducted to estimate the network effects of the different treatment options.

Results

We included 48 studies with 13,611 patients. Compared to no preparation, combined direct and indirect network estimates showed a relative risk (RR) for SSI of 0.57 (95% confidence interval [CI], 0.45-0.72) for MBP-OA, 0.68 (95% CI, 0.49-0.95) for OA, and 1.05 (95% CI, 0.87-1.26) for MBP. The RR for MBP-OA compared to OA was 0.84 (95% CI, 0.60-1.19); in sensitivity analysis of mainly laparoscopic procedures this effect of MBP-OA was more profound (RR, 0.56; 95% CI, 0.31-0.99).

Conclusions

This network meta-analysis of RCTs finds that both mechanical bowel preparation with oral antibiotics and oral antibiotics alone are comparably effective in the prevention of SSI. The evidence is uncertain about the relative benefit of MBP-OA compared to OA alone. Therefore, it seems justified to use either of the 2 for the prevention of SSI in colorectal surgery.

Bowel decontamination before colonic and rectal surgery

Several strategies are available to reduce adverse events after colonic and rectal surgery. Oral and intravenous antibiotics have proven efficacy in reducing surgical-site infections, and might be beneficial against anastomotic leaks. The role of mechanical bowel preparation needs further elucidation.

Oral Antibiotic Prophylaxis Reduces Surgical Site Infection and Anastomotic Leakage in Patients Undergoing Colorectal Cancer Surgery

BACKGROUND

Surgical-site infection (SSI) and anastomotic leakage (AL) are major complications following surgical resection of colorectal carcinoma (CRC). The beneficial effect of prophylactic oral antibiotics (OABs) on AL in particular is inconsistent. We investigated the impact of OABs on AL rates and on SSI.

METHODS

A systematic review and meta-analysis of recent RCTs and cohort studies was performed including patients undergoing elective CRC surgery, receiving OABs with or without mechanical bowel preparation (MBP). Primary outcomes were rates of SSI and AL. Secondarily, rates of SSI and AL were compared in broad-spectrum OABs and selective OABs (selective decontamination of the digestive tract (SDD)) subgroups.

RESULTS

Eight studies (seven RCTs and one cohort study) with a total of 2497 patients were included. Oral antibiotics combined with MBP was associated with a significant reduction in SSI (RR = 0.46, 95% confidence interval (CI) 0.31-0.69), I² = 1.03%) and AL rates (RR = 0.58, 95% CI 0.37-0.91, I² = 0.00%), compared to MBP alone. A subgroup analysis demonstrated that SDD resulted in a significant reduction in AL rates compared to broad-spectrum OABs (RR = 0.52, 95% CI 0.30 to 0.91), I² = 0.00%).

CONCLUSION

OABs in addition to MBP reduces SSI and AL rates in patients undergoing elective CRC surgery and, more specifically, SDD appears to be more effective compared to broad-spectrum OABs in reducing AL.

Bowel preparation in colorectal surgery: the day of reckoning is here

Before the use of mechanical bowel preparation is either eliminated or subjected to a clinical trial, its scientific premise should be reconsidered, and consensus of its redesign discussed by a panel of experts including surgeons, infectious disease specialists, microbiome scientists, and clinical trialists.