Preoperative oral antibiotics reduce septic complications of colon operations: results of prospective, randomized, double-blind clinical study

The Impact of Surgical Bowel Preparation on the Microbiome in Colon and Rectal Surgery

Preoperative bowel preparation, through iterations over time, has evolved with the goal of optimizing surgical outcomes after colon and rectal surgery. Although bowel preparation is commonplace in current practice, its precise mechanism of action, particularly its effect on the human gut microbiome, has yet to be fully elucidated. Absent intervention, the gut microbiota is largely stable, yet reacts to dietary influences, tissue injury, and microbiota-specific byproducts of metabolism. The routine use of oral antibiotics and mechanical bowel preparation prior to intestinal surgical procedures may have detrimental effects previously thought to be negligible. Recent evidence highlights the sensitivity of gut microbiota to antibiotics, bowel preparation, and surgery; however, there is a lack of knowledge regarding specific causal pathways that could lead to therapeutic interventions. As our understanding of the complex interactions between the human host and gut microbiota grows, we can explore the role of bowel preparation in specific microbiome alterations to refine perioperative care and improve outcomes. In this review, we outline the current fund of information regarding the impact of surgical bowel preparation and its components on the adult gut microbiome. We also emphasize key questions pertinent to future microbiome research and their implications for patients undergoing colorectal surgery.

Colorectal Disease and the Gut Microbiome: What a Surgeon Needs to Know

The gut microbiome is defined as the microorganisms that reside within the gastrointestinal tract and produce a variety of metabolites that impact human health. These microbes play an intricate role in human health, and an imbalance in the gut microbiome, termed gut dysbiosis, has been implicated in the development of varying diseases. The purpose of this review is to highlight what is known about the microbiome and its impact on colorectal cancer, inflammatory bowel disease, constipation, Clostridioides difficile infection, the impact of bowel prep, and anastomotic leaks.

Successful Clinical Avoidance of Colorectal Anastomotic Leakage through Local Decontamination

AIM

An anastomotic leak is an unpredictable postoperative complication during recovery from colorectal surgery that may require a re-operation. Potentially pathogenic bacteria like Pseudomonas (and Enterococcus) contribute to the pathogenesis of an anastomotic leak through their capacity to degrade collagen and to activate tissue matrix metalloprotease-9 in host intestinal tissues. The microbiome, therefore, is the key to preventing an anastomotic leak after colorectal surgery. The aim of this trial was to investigate whether perioperative selective decontamination with a new mixture of locally acting antibiotics specially designed against Pseudomonas aeruginosa and Enterococcus faecalis can reduce or even stop early symptomatic leakage.

METHOD

All hospitalized patients in our University Clinic undergoing colorectal surgery with a left-sided anastomosis were included as two groups; patients in the intervention group received polymyxin B, gentamicin and vancomycin every six hours for five postoperative days and those in the control group did not receive such an intervention. An anastomotic leak was defined as a clinically obvious defect of the intestinal wall integrity at the colorectal anastomosis site (including suture) that leads to a communication between the intra- and extraluminal compartments, requiring a re-do surgery within seven postoperative days.

RESULTS

Between February 2017 and May 2023, a total of 301 patients (median age of 63 years) were analyzed. An anastomotic leak was observed in 11 patients in the control group (n = 152), but in no patients in the intervention group (n = 149); this difference was highly significant.

CONCLUSION

The antibiotic mixture (with polymyxin B, gentamicin and vancomycin) used for local decontamination in our study stopped the occurrence of anastomotic leaks completely. According to the definition of anastomotic leak, no further surgery was required after local perioperative decontamination.

Mechanical bowel preparations not supported in elective colo-rectal surgeries with anastomosis: A retrospective study

OBJECTIVE

To analyze the risk and benefit of bowel preparations in elective colo-rectal surgery.

BACKGROUND

Mechanical bowel preparations (MBPs) have been popularized in colo-rectal surgery since studies in the 1970s, but recent data has called their use into question and examined complication rates between patients with and without bowel preparations.

METHODS

A retrospective case-review was performed consisting of 1237 elective colo-rectal surgeries performed by two surgeons between 2008 and 2021. Patients received either a MBP, a mechanical bowel preparation with oral antibiotics (OAMBP), oral antibiotics alone (OA), or no bowel preparation; some patients across all categories received an enema.

RESULTS

Bowel preparations combined (MBP and OAMBP) totaled 436 patients and showed no statistically significant difference (P > .05) in primary outcomes of wound infection and anastomotic leak when compared to the 636 patients without a bowel preparation and 165 patients with OA. The analysis controlled for comorbidities and presence of enema. Of secondary outcomes, urinary tract infections (UTIs) were significantly more common in patients who received a bowel preparation (P = .047). All other outcomes showed no significant difference between groups, including complications on day of surgery; complications, readmission with and without surgery, and ileus formation within 30 days of surgery; sepsis; pneumonia; and length of stay (LOS). The presence of enemas did not have a statistically significant effect on outcomes.

CONCLUSIONS

This study's data does not support the routine use of MBPs in elective colo-rectal surgery and draws into further question whether MBPs should remain standard of care.

Region-specific protection effect of preoperative oral antibiotics combined with mechanical bowel preparation before laparoscopic colorectal resection: a prospective randomized controlled trial

BACKGROUND

Oral antibiotics (OA) combined with mechanical bowel preparation (MBP) significantly decrease the rate of surgical site infections (SSIs). However, the prophylactic effects in region-specific colorectal surgery have not been assessed.

MATERIALS AND METHODS

A single-centre, single-blind, randomized controlled trial was conducted from 2019 to 2022. Patients were eligible if they were diagnosed with nonmetastatic colorectal malignancy, and laparoscopic colorectal surgery was indicated. Participants were randomly assigned (1:1) to the experimental (OA+MBP preparation) or control group (MBP preparation). The randomization was further stratified by resected region. The primary outcome was the incidence of SSIs. Patients were followed up for 1 month postoperatively, and all complications were recorded.

RESULT

Between 2019 and 2022, 157 and 152 patients were assigned to the experimental and control groups, respectively, after 51 patients were excluded. The incidence of SSIs in the control group (27/152) was significantly higher than that in the experimental group (13/157; P =0.013), as was the incidence of superficial SSIs (5/157 vs. 14/152, P =0.027) and deep SSIs (7/157 vs. 16/152, P =0.042). After redistribution according to the resected region, the incidence of SSIs was significantly higher in the control group with left-sided colorectal resection (descending, sigmoid colon, and rectum) (9/115 vs. 20/111, P =0.022) but was similar between the groups with right-sided colon resection (ascending colon) (3/37 vs. 7/36, P =0.286). No differences were noted between the groups in terms of other perioperative complications.

CONCLUSION

OA+MBP before colorectal surgery significantly reduced the incidence of SSIs. Such a prophylactic effect was particularly significant for left-sided resection. This preparation mode should be routinely adopted before elective left-region colorectal surgeries.

The effect of mechanical bowel preparation on postoperative complications in laparoscopic right colectomy: a retrospective propensity score matching analysis

PURPOSE

To assess whether full bowel preparation affects 30-day surgical outcomes in laparoscopic right colectomy for colon cancer.

METHODS

A retrospective chart review of all elective laparoscopic right colectomies performed for colonic adenocarcinoma between Jan 2011 and Dec 2021. The cohort was divided into two groups-no bowel preparation (NP) group and patients who received full bowel preparation (FP), including oral and mechanical cathartic bowel preparation. All anastomoses were extracorporeal stapled side-to-side. The two groups were compared at baseline and then were matched using propensity score based on demographic and clinical parameters. The primary outcome was 30-day postoperative complication rate, mainly anastomotic leak (AL) and surgical site infection (SSI) rate.

RESULTS

The original cohort included 238 patients with a median age of 68 (SD 13) and equal M:F ratio. Following propensity score matching, 93 matched patients were included in each group. Analysis of the matched cohort showed a significantly higher overall complication rate in the FP group (28 vs 11.8%, p = 0.005) which was mostly due to minor type II complications. There were no differences in major complication rates, SSI, ileus, or AL rate. Although operative time was significantly longer in the FP group (119 vs 100 min, p ≤ 0.001), length of stay was significantly shorter in the FP group (5 vs 6 days, p = 0.001).

CONCLUSIONS

Aside from a shorter hospital stay, full mechanical bowel preparation for laparoscopic right colectomy does not seem to have any benefit and may be associated with a higher overall complication rate.

The role of preoperative mechanical bowel preparation and oral antibiotics in prevention of anastomotic leakage following restorative resection for primary rectal cancer - a systematic review and meta-analysis

PURPOSE

Anastomotic leakage after colorectal cancer resection is a feared postoperative complication seen among up till 10-20% of patients, with a higher risk following rectal resection than colon resection. Recent studies suggest that the combined use of preoperative mechanical bowel preparation and oral antibiotics may have a preventive effect on anastomotic leakage. This systematic review aims to explore the association between preoperative mechanical bowel preparation combined with oral antibiotics and the risk of anastomotic leakage following restorative resection for primary rectal cancer.

METHODS

Three databases were systematically searched in February 2022. Studies reporting anastomotic leakage rate in patients, who received mechanical bowel preparation and oral antibiotics before elective restorative resection for primary rectal cancer, were included. A meta-analysis was conducted based on the risk ratios of anastomotic leakage.

RESULTS

Among 839 studies, 5 studies met the eligibility criteria. The median number of patients were 6111 (80-29,739). The combination of preoperative mechanical bowel preparation and oral antibiotics was associated with a decreased risk of anastomotic leakage (risk ratio = 0.52 (95% confidence interval 0.39-0.69), p-value < 0.001). Limitations included a low number of studies, small sample sizes and the studies being rather heterogenous.

CONCLUSION

This systematic review and meta-analysis found that the use of mechanical bowel preparation and oral antibiotics is associated with a decreased risk of anastomotic leakage among patients undergoing restorative resection for primary rectal cancer. The limitations of the review should be taken into consideration when interpreting the results.

Mechanical bowel preparation and antibiotics in elective colorectal surgery: network meta-analysis

BACKGROUND

The use of intravenous antibiotics at anaesthetic induction in colorectal surgery is the standard of care. However, the role of mechanical bowel preparation, enemas, and oral antibiotics in surgical site infection, anastomotic leak, and other perioperative outcomes remains controversial. The aim of this study was to determine the optimal preoperative bowel preparation strategy in elective colorectal surgery.

METHODS

A systematic review and network meta-analysis of RCTs was performed with searches from PubMed/MEDLINE, Scopus, Embase, and the Cochrane Central Register of Controlled Trials from inception to December 2022. Primary outcomes included surgical site infection and anastomotic leak. Secondary outcomes included 30-day mortality rate, ileus, length of stay, return to theatre, other infections, and side effects of antibiotic therapy or bowel preparation.

RESULTS

Sixty RCTs involving 16 314 patients were included in the final analysis: 3465 (21.2 per cent) had intravenous antibiotics alone, 5268 (32.3 per cent) had intravenous antibiotics + mechanical bowel preparation, 1710 (10.5 per cent) had intravenous antibiotics + oral antibiotics, 4183 (25.6 per cent) had intravenous antibiotics + oral antibiotics + mechanical bowel preparation, 262 (1.6 per cent) had intravenous antibiotics + enemas, and 1426 (8.7 per cent) had oral antibiotics + mechanical bowel preparation. With intravenous antibiotics as a baseline comparator, network meta-analysis demonstrated a significant reduction in total surgical site infection risk with intravenous antibiotics + oral antibiotics (OR 0.47 (95 per cent c.i. 0.32 to 0.68)) and intravenous antibiotics + oral antibiotics + mechanical bowel preparation (OR 0.55 (95 per cent c.i. 0.40 to 0.76)), whereas oral antibiotics + mechanical bowel preparation resulted in a higher surgical site infection rate compared with intravenous antibiotics alone (OR 1.84 (95 per cent c.i. 1.20 to 2.81)). Anastomotic leak rates were lower with intravenous antibiotics + oral antibiotics (OR 0.63 (95 per cent c.i. 0.44 to 0.90)) and intravenous antibiotics + oral antibiotics + mechanical bowel preparation (OR 0.62 (95 per cent c.i. 0.41 to 0.94)) compared with intravenous antibiotics alone. There was no significant difference in outcomes with mechanical bowel preparation in the absence of intravenous antibiotics and oral antibiotics in the main analysis.

CONCLUSION

A bowel preparation strategy with intravenous antibiotics + oral antibiotics, with or without mechanical bowel preparation, should represent the standard of care for patients undergoing elective colorectal surgery.

Clostridium difficile Infections in an Emergency Surgical Unit from North-East Romania

Background and Objectives: Colitis with Clostridium difficile is an important health problem that occurs with an intensity that varies between mild and severe. Surgical interventions are required only in fulminant forms. There is little evidence regarding the best surgical intervention in these cases. Materials and Methods: Patients with C. difficile infection were identified from the two surgery clinics from the 'Saint Spiridon' Emergency Hospital Iași, Romania. Data regarding the presentation, indication for surgery, antibiotic therapy, type of toxins, and post-operative outcomes were collected over a 3-year period. Results: From a total of 12,432 patients admitted for emergency or elective surgery, 140 (1.12%) were diagnosed with C. difficile infection. The mortality rate was 14% (20 cases). Non-survivors had higher rates of lower-limb amputations, bowel resections, hepatectomy, and splenectomy. Additional surgery was necessary in 2.8% of cases because of the complications of C. difficile colitis. In three cases, terminal colostomy was performed and as well as one case with subtotal colectomy with ileostomy. All patients who required the second surgery died within the 30-day mortality period. Conclusions: In our prospective study, the incidence was increased both in cases of patients with interventions on the colon and in those requiring limb amputations. Surgical interventions are rarely required in patients with C. difficile colitis.

The Influence of the Microbiome on Anastomotic Leak

Anastomotic leak, defined by the International Study Group of Rectal Cancer as "a communication between the intra- and extraluminal compartments owing to a defect of the integrity of the intestinal wall at the anastomosis," is one of the most devastating complications in colorectal surgery. Much work has been done to identify causes of leak; however, despite advances in surgical technique, the prevalence of anastomotic leak has remained at around 11%. The potential causative role of bacteria in the etiopathology of anastomotic leak was established in the 1950s. More recently, alterations in the colonic microbiome have been shown to affect rates of anastomotic leak. Multiple perioperative factors that alter the homeostasis of the gut microbiota community structure and function have been linked to anastomotic leak after colorectal surgery. Here, we discuss the role of diet, radiation, bowel preparation, medications including nonsteroidal anti-inflammatory drugs, morphine, and antibiotics, and specific microbial pathways that have been implicated in anastomotic leak via their effects on the microbiome.

The Role of the Gut Microbiome on the Development of Surgical Site Infections

Despite advances in antisepsis techniques, surgical site infection remains the most common and most costly reason for hospital readmission after surgery. Wound infections are conventionally thought to be directly caused by wound contamination. However, despite strict adherence to surgical site infection prevention techniques and bundles, these infections continue to occur at high rates. The contaminant theory of surgical site infection fails to predict and explain most postoperative infections and still remains unproven. In this article we provide evidence that the process of surgical site infection development is far more complex than what can be explained by simple bacterial contamination and hosts' ability to clear the contaminating pathogen. We show a link between the intestinal microbiome and distant surgical site infections, even in the absence of intestinal barrier breach. We discuss the Trojan-horse mechanisms by which surgical wounds may become seeded by pathogens from within one's own body and the contingencies that need to be met for an infection to develop.

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.

Mechanical bowel preparation combined with oral antibiotics reduces infectious complications and anastomotic leak in elective colorectal surgery: a pooled-analysis with trial sequential analysis

OBJECTIVE

A pooled analysis combined with trial sequential analysis (TSA) was conducted in order to explore the effect of mechanical bowel preparation (MBP) combined with oral antibiotic bowel decontamination (OAB) versus MBP alone on patients who have undergone colorectal resection.

METHODS

Comprehensive and systematic searches of PubMed, Embase, Cochrane Library, Web of Knowledge, and Clinical Trials.gov databases were conducted. The quality of literature was evaluated using Cochrane risk bias assessment tool as well as Newcastle-Ottawa Scale (NOS) score. A pooled analysis of randomized controlled trials (RCTs) and prospective studies was performed comparing patients who underwent colorectal resection and received MBP plus OAB or MBP alone. The outcome endpoints were the incidence of anastomotic leak (AL) and surgical site infection (SSI). TSA is a tool used to assess the reliability of currently available evidence to determine further clinical trial validation.

RESULTS

The analysis included a total of 22 studies involving 8852 patients, including 3016 patients in the MBP + OAB group and 4415 patients exposed to MBP alone. The pooled analysis showed that the incidence of postoperative anastomotic leak was significantly lower in the group treated with MBP plus OAB compared with MBP alone (OR = 0.43, 95% CI: 0.23-0.81, P = 0.009, I2 = 73%). The incidence of postoperative surgical site infections was significantly lower in the group exposed to the combination of MBP and OAB compared with MBP alone (OR = 0.38, 95% CI: 0.32-0.46, P < 0.0001, I2 = 24%). The TSA demonstrated significant benefits of MBP plus OAB intervention in terms of AL and SSI.

CONCLUSION

MBP combined with OAB significantly reduces the incidence of AL and SSI in patients after colorectal resection compared with MBP alone.

Bundles reduce anastomosis leak in patients undergoing elective colorectal surgery. A propensity score-matched study

Background

anastomosis leak still being a handicap in colorectal surgery. Bowel mechanical preparation and oral antibiotics are not a practice recommended in many clinical practice guides. The aim is to analyse the decrease in frequency and severity of postoperative complications, mainly related to anastomotic leak, after the establishment of a bundle.

Methods

Single-center, before-after study. A bundle was implemented to reduce anastomotic leaks and their consequences. The Bundle group were matched to Pre-bundle group by propensity score matching. Mechanical bowel preparation, oral and intravenous antibiotics, inflammatory markers measure and early diagnosis algorithm were included at the bundle.

Results

The bundle group shown fewer complications, especially in Clavien Dindós Grade IV complications (2.3% vs. 6.2% p < 0.01), as well as a lower rate of anastomotic leakage (15.5% vs. 2.2% p < 0.01). A significant decrease in reinterventions, less intensive unit care admissions, a shorter hospital stay and fewer readmissions were also observed. In multivariate analysis, the application of a bundle was an anastomotic leakage protective factor (OR 0.121, p > 0.05).

Conclusions

The implementation of our bundle in colorectal surgery which include oral antibiotics, mechanical bowel preparation and inflammatory markers, significantly reduces morbidity adjusted to severity of complications, the anastomotic leakage rate, hospital stay and readmissions.

Register study

The study has been registered at clinicaltrials.gov Code: nct04632446.

Has network meta-analysis resolved the controversies related to bowel preparation in elective colorectal surgery?

AIM

There are discrepancies in the guidelines on preparation for colorectal surgery. While intravenous antibiotics (IV) are usually administered, the use of mechanical bowel preparation (MBP) and/or oral antibiotics (OA) is controversial. A recent network meta-analysis (NMA) demonstrated that the addition of OA reduced incisional surgical site infections (iSSIs) by more than 50%. We aimed to perform a NMA including only the highest quality randomized clinical trials (RCTs) in order to determine the ranking of different treatment strategies and assess these RCTs for methodological problems that may affect the conclusions of the NMAs.

METHOD

A NMA was performed according to PRISMA guidelines. RCTs of adult patients undergoing elective colorectal surgery with appropriate antibiotic cover and with at least 250 participants recruited, clear definition of endpoints and duration of follow-up extending beyond discharge from hospital were included. The search included Medline, Embase, Cochrane and SCOPUS databases. Primary outcomes were iSSI and anastomotic leak (AL). Statistical analysis was performed in Stata v.15.1 using frequentist routines.

RESULTS

Ten RCTs including 5107 patients were identified. Treatments compared IV (2218 patients), IV + OA (460 patients), MBP + IV (1405 patients), MBP + IV + OA (538 patients) and OA (486 patients). The likelihood of iSSI was significantly lower for IV + OA (rank 1) and MBP + IVA + OA (rank 2), reducing iSSIs by more than 50%. There were no differences between treatments for AL. Methodological issues included differences in definition, assessment and frequency of primary endpoint infections and the limited number of participants included in some treatment options.

CONCLUSION

While this NMA supports the addition of OA to IV to reduce iSSI it also highlights unanswered questions and the need for well-designed pragmatic RCTs.

Selective decontamination of the digestive tract in colorectal surgery reduces anastomotic leakage and costs: a propensity score analysis

Purpose

Anastomotic leakage (AL) and surgical site infection (SSI) account for most postoperative complications in colorectal surgery. The aim of this retrospective trial was to investigate whether perioperative selective decontamination of the digestive tract (SDD) reduces these complications and to provide a cost-effectiveness model for elective colorectal surgery.

Methods

All patients operated between November 2016 and March 2020 were included in our analysis. Patients in the primary cohort (PC) received SDD and those in the historical control cohort (CC) did not receive SDD. In the case of rectal/sigmoid resection, SDD was also applied via a transanally placed Foley catheter (TAFC) for 48 h postoperatively. A propensity score-matched analysis was performed to identify risk factors for AL and SSI. Costs were calculated based on German diagnosis-related group (DRG) fees per case.

Results

A total of 308 patients (154 per cohort) with a median age of 62.6 years (IQR 52.5–70.8) were analyzed. AL was observed in ten patients (6.5%) in the PC and 23 patients (14.9%) in the CC (OR 0.380, 95% CI 0.174–0.833; P = 0.016). SSI occurred in 14 patients (9.1%) in the PC and 30 patients in the CC (19.5%), representing a significant reduction in our SSI rate (P = 0.009). The cost-effectiveness analysis showed that SDD is highly effective in saving costs with a number needed to treat of 12 for AL and 10 for SSI.

Conclusion

SDD significantly reduces the incidence of AL and SSI and saves costs for the general healthcare system.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00423-022-02540-6.

Risk adjustment performance between NNIS index and NHSN model for postoperative colorectal surgical site infection: A retrospective cohort study

Background

Risk stratifications to predict development of surgical site infections (SSI) are crucial methods before surgery. Hence, we aimed to compare the performance of risk adjustment between the former NNIS risk index and the new NHSN procedure-specific risk model for postoperative colorectal SSI.

Materials and methods

A retrospective cohort study was conducted. Data of post-colorectal SSI, indicating the use of the NNIS risk index for SSI adjustment, were retrieved from the medical records. Data were taken from patients who underwent colorectal surgery procedures between January 2005 and December 2016. Additional information regarding emergency colorectal surgery was retrieved to fulfill the requirements for calculation of the risks for SSI; via the new model. The predictive performance between the two models was compared using the means of the area under the receiver operating characteristic curve.

Results

In total 1989 patients were included. Fifteen patients were excluded; thus, the remaining number of procedures was 1974. Surgical site infections occurred in 85 (4.3%) procedures. In colectomy surgery, the means of area under the curve (AUC) yielded 0.6196 and 0.5976 for the NNIS risk index model and the new NHSN risk model, respectively; differences in the AUC were not statistically significant (p = 0.39). In rectal surgery, the means of the AUC yielded 0.516 and 0.49 for the NNIS risk index model and the new NHSN procedure-specific risk model, respectively; differences in the AUC were not statistically significant (p = 0.56).

Conclusion

The new NHSN procedure-specific risk model was not superior to the former NNIS risk index.

•

The NHSN risk model was not superior to the NNIS risk index.

•

The recommendation is for the application of the NNIS risk index be applied.

•

This is the first reporting on the novel performance of CDC risk adjustment for colorectal SSI.

•

This paper builds upon concerns for infectious, nosocomial surveillances; especially for low resources countries.

Bowel Preparation for Elective Hartmann Operation: Analysis of the National Surgical Quality Improvement Program Database

Background: Use of pre-operative bowel preparation in colorectal resection has not been examined solely in patients who have had colorectal resection with primary colostomy (Hartmann procedure). We aimed to evaluate the association of bowel preparations with short-term outcomes after non-emergent Hartmann procedure. Patients and Methods: The National Surgical Quality Improvement Program Participant Use File colectomy database was queried for patients who had elective open or laparoscopic Hartmann operation. Patients were grouped by pre-operative bowel preparation: no bowel preparation, oral antibiotic agents, mechanical preparation, or both mechanical and oral antibiotic agent preparation (combined). Propensity analysis was performed, and outcomes were compared by type of pre-operative bowel preparation. The primary outcome was rate of any surgical site infection (SSI). Secondary outcomes included overall complication, re-operation, re-admission, Clostridioides difficile colitis, and length of stay. Results: Of the 4,331 records analyzed, 2,040 (47.1%) patients received no preparation, 251 (4.4%) received oral antibiotic preparation, 1,035 (23.9%) received mechanical bowel preparation, and 1,005 (23.2%) received combined oral antibiotic and mechanical bowel preparation. After propensity adjustment, rates of any SSI, overall complication, and length of hospital stay varied significantly between pre-operative bowel regimens (p < 0.005). The use of combined bowel preparation was associated with decreased rate of SSI, overall complication, and length of stay. No difference in rate of re-operation or post-operative Clostridioides difficile infection was observed based on bowel preparation. Conclusions: Compared with no pre-operative bowel preparation, any bowel preparation was associated with reduced rate of SSI, but not rate of re-operation or post-operative Clostridioides difficile infection.

Factors Associated with Receipt of Oral Antibiotic Agents and Mechanical Bowel Preparation before Elective Colectomy

Background: Pre-operative administration of combined oral antibiotic agents and mechanical bowel preparation has been demonstrated to improve post-operative outcomes after elective colectomy, however, many patients do not receive combined preparation. Patient and procedural determinants of combined preparation receipt remain understudied. Patients and Methods: All patients undergoing elective colectomy within the 2018 American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) Participant Use File and Targeted Colectomy datasets were included. Univariable and multivariable logistic regression analyses were performed to identify factors associated with receipt of combined preparation. Results: A total of 21,889 patients were included, of whom 13,848 (63.2%) received combined preparation pre-operatively. Patients who received combined preparation tended to be younger, male, of white race, and of non-Hispanic ethnicity (all p < 0.05). After multivariable adjustment, male gender, body mass index (BMI) 30-39 kg/m², independent functional status, and laparoscopic and robotic surgical approaches were associated with receipt of combined preparation (all p < 0.05), whereas Asian race, hypertension, disseminated cancer, and inflammatory bowel disease were associated with omission of combined preparation (all p < 0.05). Conclusions: Patients with risk factors for infectious complications-including a poor functional status, comorbid conditions, and undergoing an open procedure-are less likely to receive combined preparation before elective colectomy. Similarly, female and Asian patients are less likely to receive combined preparation, emphasizing the need for equitable administration of combined preparation.

Strategies for Antibiotic Administration for Bowel Preparation Among Patients Undergoing Elective Colorectal Surgery: A Network Meta-analysis

Importance

There are discrepancies in guidelines on preparation for colorectal surgery. While intravenous (IV) antibiotics are usually administered, the use of mechanical bowel preparation (MBP), enemas, and/or oral antibiotics (OA) is controversial.

Objective

To summarize all data from randomized clinical trials (RCTs) that met selection criteria using network meta-analysis (NMA) to determine the ranking of different bowel preparation treatment strategies for their associations with postoperative outcomes.

Data Sources

Data sources included MEDLINE, Embase, Cochrane, and Scopus databases with no language constraints, including abstracts and articles published prior to 2021.

Study Selection

Randomized studies of adults undergoing elective colorectal surgery with appropriate aerobic and anaerobic antibiotic cover that reported on incisional surgical site infection (SSI) or anastomotic leak were selected for inclusion in the analysis. These were selected by multiple reviewers and adjudicated by a separate lead investigator. A total of 167 of 6833 screened studies met initial selection criteria.

Data Extraction and Synthesis

NMA was performed according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines. Data were extracted by multiple independent observers and pooled in a random-effects model.

Main Outcomes and Measures

Primary outcomes were incisional SSI and anastomotic leak. Secondary outcomes included other infections, mortality, ileus, and adverse effects of preparation.

Results

A total of 35 RCTs that included 8377 patients were identified. Treatments compared IV antibiotics (2762 patients [33%]), IV antibiotics with enema (222 patients [3%]), IV antibiotics with OA with or without enema (628 patients [7%]), MBP with IV antibiotics (2712 patients [32%]), MBP with IV antibiotics with OA (with good IV antibiotic cover in 925 patients [11%] and with good overall antibiotic cover in 375 patients [4%]), MBP with OA (267 patients [3%]), and OA (486 patients [6%]). The likelihood of incisional SSI was significantly lower for those receiving IV antibiotics with OA with or without enema (rank 1) and MBP with adequate IV antibiotics with OA (rank 2) compared with all other treatment options. The addition of OA to IV antibiotics, both with and without MBP, was associated with a reduction in incisional SSI by greater than 50%. There were minimal differences between treatments in anastomotic leak and in any of the secondary outcomes.

Conclusions and Relevance

This NMA demonstrated that the addition of OA to IV antibiotics were associated with a reduction in incisional SSI by greater than 50%. The results support the addition of OA to IV antibiotics to reduce incisional SSI among patients undergoing elective colorectal surgery.

Influence of the Microbiome on Anastomotic Leak

Despite advances in surgical technique and the expanded use of antibiotics, anastomotic leak remains a dreaded complication leading to increased hospital length of stay, morbidity, mortality, and cost. Data continues to grow addressing the importance of a functional and diverse colonic microbiome to ensure adequate healing. Individual pathogens, such as Enterococcus faecalis and Pseudomonas aeruginosa , have been implicated in the pathogenesis of anastomotic leak. Yet how these pathogens proliferate remains unclear. It is possible that decreased microbial diversity promotes a shift to a pathologic phenotype among the remaining microbiota which may lead to anastomotic breakdown. As the microbiome is highly influenced by diet, antibiotic use, the stress of surgery, and opioid use, these factors may be modifiable at various phases of the surgical process. A large amount of data remains unknown about the composition and behavior of the "normal" gut microbiome as compared with an altered community. Therefore, targeting the gut microbiome as a modifiable factor in anastomotic healing may represent a novel strategy for the prevention of anastomotic leak.

Mechanical bowel preparation combined with oral antibiotics in colorectal cancer surgery: a nationwide population-based study

BACKGROUND

The guidelines for reducing surgical site infection in colorectal surgery recommend mechanical bowel preparation with oral antibiotics; however, this recommendation remains controversial. This study aimed to reveal the effect of oral antibiotics combined with mechanical bowel preparation in colorectal surgery.

METHODS

This study was a nationwide population-based retrospective study. Data between January 1, 2016, and December 31, 2018, from the Korean National Health Insurance Service database were analyzed. Patients who underwent elective colorectal cancer surgery were included.

RESULTS

A total of 20,740 patients were finally included, comprising 14,554 (70.2%) who underwent mechanical bowel preparation alone and 6186 (29.8%) who underwent mechanical bowel preparation with oral antibiotics. The mechanical bowel preparation alone group was older than the mechanical bowel preparation with oral antibiotics group (65.7 ± 11.9 vs. 64.7 ± 11.8 years, p < 0.001). Rectal cancer patients and patients who underwent open surgery were more likely to receive mechanical bowel preparation with oral antibiotics. Patients who underwent mechanical bowel preparation with oral antibiotics demonstrated lower surgical-site infection rate (2.9% vs. 9.4%, p < 0.001), shorter hospital stay (11.7 ± 5.5 vs. 13.5 ± 7.3 days, p < 0.001), and lower medical cost (US$7414 ± 2762 vs. US$7791 ± 3235, p < 0.001) than those who underwent mechanical bowel preparation alone. The 30-day readmission rates and mortality were not significantly different.

CONCLUSIONS

The use of mechanical bowel preparation with oral antibiotics reduces surgical site infection, hospital stay, and medical cost in colorectal cancer surgery.

Mechanical bowel preparation and oral antibiotics versus mechanical bowel preparation only prior rectal surgery (MOBILE2): a multicentre, double-blinded, randomised controlled trial-study protocol

INTRODUCTION

Mechanical bowel preparation (MBP) prior to rectal surgery is widely used. Based on retrospective data many guidelines recommend mechanical and oral antibiotic bowel preparation (MOABP) to reduce postoperative complications and specifically surgical site infections (SSIs). The primary aim of this study is to examine whether MOABP reduces complications of rectal surgery.

METHODS AND ANALYSIS

The MOBILE2 (Mechanical Bowel Preparation and Oral Antibiotics vs Mechanical Bowel Preparation Only Prior Rectal Surgery) trial is a multicentre, double-blinded, parallel group, superiority, randomised controlled trial comparing MOABP to MBP among patients scheduled for rectal surgery with colorectal or coloanal anastomosis. The patients randomised to the MOABP group receive 1 g neomycin and 1 g metronidazole two times on a day prior to surgery and patients randomised to the MBP group receive identical placebo. Based on power calculations, 604 patients will be enrolled in the study. The primary outcome is Comprehensive Complication Index within 30 days after surgery. Secondary outcomes are SSIs within 30 days after surgery, the number and classification of anastomosis dehiscences, the length of hospital stay, mortality within 90 days after surgery and the number of patients who received adjuvant treatment if needed. Tertiary outcomes are overall survival, disease-specific survival, recurrence-free survival and difference in quality-of-life before and 1 year after surgery. In addition, the microbiota differences in colon mucosa are analysed.

ETHICS AND DISSEMINATION

The Ethics Committee of Helsinki University Hospital approved the study. The findings will be disseminated in peer-reviewed academic journals.

TRIAL REGISTRATION NUMBER

NCT04281667.

A Review of Bowel Preparation Before Colorectal Surgery

Infectious complications are the biggest problem during bowel surgery, and one of the approaches to minimize them is the bowel cleaning method. It was expected that bowel cleaning could facilitate bowel manipulation as well as prevent infectious complications and further reduce anastomotic leakage. In the past, with the development of antibiotics, bowel cleaning and oral antibiotics (OA) were used together. However, with the success of emergency surgery and Enhanced Recovery After Surgery, bowel cleaning was not routinely performed. Consequently, bowel cleaning using OA was gradually no longer used. Recently, there have been reports that only bowel cleaning is not helpful in reducing infectious complications such as surgical site infection (SSI) compared to OA and bowel cleaning. Accordingly, in order to reduce SSI, guidelines are changing the trend of only intestinal cleaning. However, a consistent regimen has not yet been established, and there is still controversy depending on the location of the lesion and the surgical method. Moreover, complications such as Clostridium difficile infection have not been clearly analyzed. In the present review, we considered the overall bowel preparation trends and identified the areas that require further research.

The gut microbiota and colorectal surgery outcomes: facts or hype? A narrative review

BACKGROUND

The gut microbiota (GM) has been proposed as one of the main determinants of colorectal surgery complications and theorized as the "missing factor" that could explain still poorly understood complications. Herein, we investigate this theory and report the current evidence on the role of the GM in colorectal surgery.

METHODS

We first present the findings associating the role of the GM with the physiological response to surgery. Second, the change in GM composition during and after surgery and its association with colorectal surgery complications (ileus, adhesions, surgical-site infections, anastomotic leak, and diversion colitis) are reviewed. Finally, we present the findings linking GM science to the application of the enhanced recovery after surgery (ERAS) protocol, for the use of oral antibiotics with mechanical bowel preparation and for the administration of probiotics/synbiotics.

RESULTS

According to preclinical and translational evidence, the GM is capable of influencing colorectal surgery outcomes. Clinical evidence supports the application of an ERAS protocol and the preoperative administration of multistrain probiotics/synbiotics. GM manipulation with oral antibiotics with mechanical bowel preparation still has uncertain benefits in right-sided colic resection but is very promising for left-sided colic resection.

CONCLUSIONS

The GM may be a determinant of colorectal surgery outcomes. There is an emerging need to implement translational research on the topic. Future clinical studies should clarify the composition of preoperative and postoperative GM and the impact of the GM on different colorectal surgery complications and should assess the validity of GM-targeted measures in effectively reducing complications for all colorectal surgery locations.

Intestinal Microbiota in Colorectal Cancer Surgery

The intestinal microbiota consists of numerous microbial species that collectively interact with the host, playing a crucial role in health and disease. Colorectal cancer is well-known to be related to dysbiotic alterations in intestinal microbiota. It is evident that the microbiota is significantly affected by colorectal surgery in combination with the various perioperative interventions, mainly mechanical bowel preparation and antibiotic prophylaxis. The altered postoperative composition of intestinal microbiota could lead to an enhanced virulence, proliferation of pathogens, and diminishment of beneficial microorganisms resulting in severe complications including anastomotic leakage and surgical site infections. Moreover, the intestinal microbiota could be utilized as a possible biomarker in predicting long-term outcomes after surgical CRC treatment. Understanding the underlying mechanisms of these interactions will further support the establishment of genomic mapping of intestinal microbiota in the management of patients undergoing CRC surgery.

Prospective randomised controlled trial using the REthinking Clinical Trials (REaCT) platform and National Surgical Quality Improvement Program (NSQIP) to compare no preparation versus preoperative oral antibiotics alone for surgical site infection rates in elective colon surgery: a protocol

INTRODUCTION

Despite 40 randomised controlled trials (RCTs) investigating preoperative oral antibiotics (OA) and mechanical bowel preparation (MBP) to reduce surgical site infection (SSI) rate following colon surgery, there has never been an RCT published comparing OA alone versus no preparation. Of the four possible regimens (OA alone, MBP alone, OA plus MBP and no preparation), randomised evidence is conflicting for studied groups. Furthermore, guidelines vary, with recommendations for OA alone, OA plus MBP or no preparation. The National Surgical Quality Improvement Program (NSQIP) has automated data collection for surgical patients. Similarly, the 'REthinking Clinical Trials' (REaCT) platform increases RCT enrolment by simplifying pragmatic trial design. In this novel RCT protocol, we combine REaCT and NSQIP to compare OA alone versus no preparation for SSI rate reduction in elective colon surgery. To our knowledge, this is the first published RCT protocol that leverages NSQIP for data collection. In our feasibility study, 67 of 74 eligible patients (90%) were enrolled and 63 of 67 (94%) were adherent to protocol. The 'REaCT-NSQIP' trial design has great potential to efficiently generate level I evidence for other perioperative interventions.

METHODS AND ANALYSIS

SSI rates following elective colorectal surgery after preoperative OA or no preparation will be compared. We predict 45% relative rate reduction of SSI, improvement in length of stay, reduced costs and increased quality of life, with similar antibiotic-related complications. Consent, using the 'integrated consent model', and randomisation on a mobile device are completed by the surgeon in a single clinical encounter. Data collection for the primary end point is automatic through NSQIP. Analysis of cost per weighted case, cost utility and quality-adjusted life years will be done.

ETHICS AND DISSEMINATION

This study is approved by The Ontario Cancer Research Ethics Board. Results will be disseminated in surgical conferences and peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03663504; Pre-results, recruitment phase.

[Role of Mechanical Bowel Preparation for Elective Colorectal Surgery]

The presence of bowel contents during colorectal surgery has been related to surgical site infections (SSI), anastomotic leakage (AL) and postoperative complications theologically. Mechanical bowel preparation (MBP) for elective colorectal surgery aims to reduce fecal materials and bacterial count with the objective to decrease SSI rate, including AL. Based on many observational data, meta-analysis and multicenter randomized control trials (RTC), non-MBP did not increase AL rates or SSI and other complications in colon and even rectal surgery. In 2011 Cochrane review, there is no significant benefit MBP compared with non-MBP in colon surgery and also no better benefit MBP compared with rectal enemas in rectal surgery. However, in surgeon's perspectives, MBP is still in widespread surgical practice, despite the discomfort caused in patients, and general targeting of the colon microflora with antibiotics continues to gain popularity despite the lack of understanding of the role of the microbiome in anastomotic healing. Recently, there are many evidence suggesting that MBP+oral antibiotics (OA) should be the growing gold standard for colorectal surgery. However, there are rare RCT studies and still no solid evidences in OA preparation, so further studies need results in both MBP and OA and only OA for colorectal surgery. Also, MBP studies in patients with having minimally invasive surgery (MIS; laparoscopic or robotics) colorectal surgery are still warranted. Further RCT on patients having elective left side colon and rectal surgery with primary anastomosis in whom sphincter saving surgery without MBP in these MIS and microbiome era.

Preoperative mechanical bowel preparation with oral antibiotics reduces surgical site infection after elective colorectal surgery for malignancies: results of a propensity matching analysis

BACKGROUND

Surgical site infections (SSIs) are a major postoperative complication after colorectal surgery. Current study aims to evaluate prophylactic function of oral antibiotic (OA) intake in combination with mechanical bowel preparation (MBP) relative to MBP alone with respect to postoperative SSI incidence.

METHODS

A retrospective analysis of eligible patients was conducted using the databases of the Gastrointestinal Surgery Centre, Third Affiliated Hospital of Sun Yat-sen University from 2011 to 2017. Data pertaining to postoperative hospital stay length, expenses, SSI incidence, anastomotic fistula incidence, and rates of other complications were extracted and compared. A propensity analysis was conducted to minimize bias associated with demographic characteristics. Subgroup analyses were performed to further explore protective effects of OA in different surgical sites.

RESULTS

The combination of OAs and MBP was related to a significant decrease in the incidence of overall SSIs, superficial SSI, and hospitalization expenses. The MBP + OA modality was particularly beneficial for patients undergoing left-side colon or rectum resections, with clear prophylactic efficacy. The combination of MPB + OA did not exhibit significant prophylactic efficacy in patients undergoing right hemi-colon resection. Age, surgical duration, and application of OA were all independent factors associated with the occurrence of SSIs.

CONCLUSION

These results suggest that the combination of OA + MBP should be recommended for patients undergoing elective colorectal surgery, particularly for operations on the left side of the colon or rectum.

TRIAL REGISTRATION

NCT04258098. Retrospectively registered.

Re-examining causes of surgical site infections following elective surgery in the era of asepsis

The currently accepted assumption that most surgical site infections (SSIs) occurring after elective surgery under standard methods of antisepsis are due to an intraoperative contamination event, remains unproven. We examined the available evidence in which microbial cultures of surgical wounds were taken at the conclusion of an operation and determined that such studies provide more evidence to refute that an SSI is due to intraoperative contamination than support it. We propose that alternative mechanisms of SSI development should be considered, such as when a sterile postoperative wound becomes infected by a pathogen originating from a site remote from the operative wound-eg, from the gums or intestinal tract (ie, the Trojan Horse mechanism). We offer a path forward to reduce SSI rates after elective surgery that includes undertaking genomic-based microbial tracking from the built environment (ie, the operating room and hospital bed), to the patient's own microbiome, and then to the surgical site. Finally, we posit that only by generating this dynamic microbial map can the true pathogenesis of SSIs be understood enough to inform novel preventive strategies against infection following elective surgery in the current era of asepsis.

Prevention of Anastomotic Leak Via Local Application of Tranexamic Acid to Target Bacterial-mediated Plasminogen Activation: A Practical Solution to a Complex Problem

OBJECTIVE

To investigate the role of bacterial- mediated plasminogen (PLG) activation in the pathogenesis of anastomotic leak (AL) and its mitigation by tranexamic acid (TXA).

BACKGROUND

AL is the most feared complication of colorectal resections. The pathobiology of AL in the setting of a technically optimal procedure involves excessive submucosal collagen degradation by resident microbes. We hypothesized that activation of the host PLG system by pathogens is a central and targetable pathway in AL.

METHODS

We employed kinetic analysis of binding and activation of human PLG by microbes known to cause AL, and collagen degradation assays to test the impact of PLG on bacterial collagenolysis. Further, we measured the ability of the antifibrinolytic drug TXA to inhibit this process. Finally, using mouse models of pathogen-induced AL, we locally applied TXA via enema and measured its ability to prevent a clinically relevant AL.

RESULTS

PLG is deposited rapidly and specifically at the site of colorectal anastomoses. TXA inhibited PLG activation and downstream collagenolysis by pathogens known to have a causal role in AL. TXA enema reduced collagenolytic bacteria counts and PLG deposition at anastomotic sites. Postoperative PLG inhibition with TXA enema prevented clinically and pathologically apparent pathogen-mediated AL in mice.

CONCLUSIONS

Bacterial activation of host PLG is central to collagenolysis and pathogen-mediated AL. TXA inhibits this process both in vitro and in vivo. TXA enema represents a promising method to prevent AL in high-risk sites such as the colorectal anastomoses.

Oral Polyphosphate Suppresses Bacterial Collagenase Production and Prevents Anastomotic Leak Due to Serratia marcescens and Pseudomonas aeruginosa

OBJECTIVE

The objective of this study was to determine the effect of polyphosphate on intestinal bacterial collagenase production and anastomotic leak in mice undergoing colon surgery.

BACKGROUND

We have previously shown that anastomotic leak can be caused by intestinal pathogens that produce collagenase. Because bacteria harbor sensory systems to detect the extracellular concentration of phosphate which controls their virulence, we tested whether local phosphate administration in the form of polyphosphate could attenuate pathogen virulence and prevent leak without affecting bacterial growth.

METHODS

Groups of mice underwent a colorectal anastomosis which was then exposed to collagenolytic strains of either Serratia marcescens or Pseudomonas aeruginosa via enema. Mice were then randomly assigned to drink water or water supplemented with a 6-mer of polyphosphate (PPi-6). All mice were sacrificed on postoperative day 10 and anastomoses assessed for leakage, the presence of collagenolytic bacteria, and anastomotic PPi-6 concentration.

RESULTS

PPi-6 markedly attenuated collagenase and biofilm production, and also swimming and swarming motility in both S. marcescens and P. aeruginosa while supporting their normal growth. Mice drinking PPi-6 demonstrated increased levels of PPi-6 and decreased colonization of S. marcescens and P. aeruginosa, and collagenase activity at anastomotic tissues. PPi-6 prevented anastomotic abscess formation and leak in mice after anastomotic exposure to S. marcescens and P. aeruginosa.

CONCLUSIONS

Polyphosphate administration may be an alternative approach to prevent anastomotic leak induced by collagenolytic bacteria with the advantage of preserving the intestinal microbiome and its colonization resistance.

The Role of Oral Antibiotic Preparation in Elective Colorectal Surgery: A Meta-analysis

OBJECTIVES

To compare the impact of the use of oral antibiotics (OAB) with or without mechanical bowel preparation (MBP) on outcome in elective colorectal surgery.

SUMMARY BACKGROUND DATA

Meta-analyses have demonstrated that MBP does not impact upon postoperative morbidity or mortality, and as such it should not be prescribed routinely. However, recent evidence from large retrospective cohort and database studies has suggested that there may be a role for combined OAB and MBP, or OAB alone in the prevention of surgical site infection (SSI).

METHODS

A meta-analysis of randomized controlled trials and cohort studies including adult patients undergoing elective colorectal surgery, receiving OAB with or without MBP was performed. The outcome measures examined were SSI, anastomotic leak, 30-day mortality, overall morbidity, development of ileus, reoperation and Clostridium difficile infection.

RESULTS

A total of 40 studies with 69,517 patients (28 randomized controlled trials, n = 6437 and 12 cohort studies, n = 63,080) were included. The combination of MBP+OAB versus MBP alone was associated with a significant reduction in SSI [risk ratio (RR) 0.51, 95% confidence interval (CI) 0.46-0.56, P < 0.00001, I = 13%], anastomotic leak (RR 0.62, 95% CI 0.55-0.70, P < 0.00001, I = 0%), 30-day mortality (RR 0.58, 95% CI 0.44-0.76, P < 0.0001, I = 0%), overall morbidity (RR 0.67, 95% CI 0.63-0.71, P < 0.00001, I = 0%), and development of ileus (RR 0.72, 95% CI 0.52-0.98, P = 0.04, I = 36%), with no difference in Clostridium difficile infection rates. When a combination of MBP+OAB was compared with OAB alone, no significant difference was seen in SSI or anastomotic leak rates, but there was a significant reduction in 30-day mortality, and incidence of postoperative ileus with the combination. There is minimal literature available on the comparison between combined MBP+OAB versus no preparation, OAB alone versus no preparation, and OAB versus MBP.

CONCLUSIONS

Current evidence suggests a potentially significant role for OAB preparation, either in combination with MBP or alone, in the prevention of postoperative complications in elective colorectal surgery. Further high-quality evidence is required to differentiate between the benefits of combined MBP+OAB or OAB alone.

Comparative Effectiveness and Risks of Bowel Preparation Before Elective Colorectal Surgery

OBJECTIVE

The objective of this study was to determine the relationship between bowel preparation and surgical site infections (SSIs), and also other postoperative complications, after elective colorectal surgery.

BACKGROUND

SSI is a major source of postoperative morbidity/costs after colorectal surgery. The value of preoperative bowel preparation to prevent SSI remains controversial.

METHODS

We analyzed 32,359 patients who underwent elective colorectal resections in the American College of Surgeons National Surgery Quality Improvement Program database from 2012 to 2014. Univariable and multivariable analyses were performed; propensity adjustment using patient/procedure characteristics was used to account for nonrandom receipt of bowel preparation.

RESULTS

26.7%, 36.6%, 3.8%, and 32.9% of patients received no bowel preparation, mechanical bowel preparation (MBP), oral antibiotics (OA), and MBP + OA, respectively. After propensity adjustment, MBP was not associated with decreased risk of SSI compared with no bowel preparation. In contrast, both OA and OA + MBP were associated with decreased risk of any SSI (adjusted odds ratio 0.49, 95% confidence interval 0.38-0.64; and adjusted odds ratio 0.45, 95% confidence interval 0.40-0.50, respectively) compared with no bowel preparation. OA and MBP + OA were associated with decreased risks of anastomotic leak, postoperative ileus, readmission, and also shorter length of stay (all P < 0.05). Bowel preparation was not associated with increased risk of cardiac/renal complications compared with no preparation.

CONCLUSIONS

The use of MBP alone before elective colorectal resection to prevent SSI is ineffective and should be abandoned. In contrast, OA and MBP + OA are associated with decreased risks of SSI and are not associated with increased risks of other adverse outcomes compared with no preparation. Prospective studies to determine the efficacy of OA are warranted; in the interim, MBP + OA should be used routinely before elective colorectal resection to prevent SSI.

Mechanical bowel preparation and oral antibiotic prophylaxis in colorectal surgery: Analysis of evidence and narrative review

The role of oral antibiotic prophylaxis and mechanical bowel preparation in colorectal surgery remains controversial. The lack of efficacy of mechanical preparation to improve infection rates, its adverse effects, and multimodal rehabilitation programs have led to a decline in its use. This review aims to evaluate current evidence on antegrade colonic cleansing combined with oral antibiotics for the prevention of surgical site infections. In experimental studies, oral antibiotics decrease the bacterial inoculum, both in the bowel lumen and surgical field. Clinical studies have shown a reduction in infection rates when oral antibiotic prophylaxis is combined with mechanical preparation. Oral antibiotics alone seem to be effective in reducing infection in observational studies, but their effect is inferior to the combined preparation. In conclusion, the combination of oral antibiotics and mechanical preparation should be considered the gold standard for the prophylaxis of postoperative infections in colorectal surgery.

Importance of Adding Neomycin to Metronidazole for Bowel Preparation1

A prospective randomized trial has investigated whether it is necessary to add oral neomycin to oral metronidazole as a means of preventing sepsis in elective colonic resection. Seventy-three patients completed the study; 41 received metronidazole and placebo neomycin and 32 received metronidazole and active neomycin. There was a significant reduction in the incidence of wound infection in patients receiving neomycin and metronidazole (22%) compared with metronidazole alone (51%, P < 0.02). There was also a significant reduction in anaerobic infections in the group receiving metronidazole and neomycin compared with metronidazole alone (P < 0.05). These results indicate that oral metronidazole alone is of no benefit for patients requiring elective colonic operations and that if oral metronidazole is advised it should always be given in combination with oral neomycin.

Collagenase Inhibition in the Healing Colon

A randomized controlled trial was performed to assess the effect of intravenous aprotinin (Trasylol) on the healing of experimental colonic anastomoses in the rabbit following a standard left colonic resection anastomosis. Assessment of tensile strength was by means of both bursting pressure and breaking strength. Those animals subjected to bursting pressure assessment received intravenous aprotinin 80 000 KIU (kallikrein inhibitory units) at the time of anaesthesia, and postoperatively 160000 KIU per day given in divided doses for three days. Control animals received saline placebo. A further group of animals received a lower loading and maintenance aprotinin dose (40 000 KIU and 60000 KIU per day respectively) with control animals receiving saline. Breaking strength was employed as the means of assessment.

The mean bursting pressures were 47.7 ∓ 2.9 mmHg and 37.5 ∓ 3.4 mmHg for aprotinin and controls respectively (P≤0.05). The mean difference in collagen content of the anastomosis compared to the resected specimen was +1.25 ∓0.50 μg/mg and −1.02 ∓ 0.47 ug/mg for aprotinin and placebo groups (P ≤ 0.005).

The mean breaking strength in the aprotinin group was 169.6 ∓74.5 g and 110.0 ∓65.9 g for the saline group (P≤0.02). The mean difference in collagen content of the anastomosis compared to the resected specimen was +0.95 ∓0.69 ug/mg and −1.5 ∓0.78 ug/mg for the aprotinin and saline groups respectively (P≤0.05).

The significant elevation of both bursting pressure and breaking strength assessments, with a significant improvement in the collagen content of the anastomoses, may be the result of collagenase inhibition following the use of intravenous aprotinin in the experimental model.

Role of oral antibiotics for prophylaxis against surgical site infections after elective colorectal surgery

Over the past few decades, surgeons have made many attempts to reduce the incidence of surgical site infections (SSI) after elective colorectal surgery. Routine faecal diversion is no longer practiced in elective colonic surgery and mechanical bowel preparation is on the verge of being eliminated altogether. Intravenous antibiotics have become the standard of care as prophylaxis against SSI for elective colorectal operations. However, the role of oral antibiotics is still being debated. We review the available data evaluating the role of oral antibiotics as prophylaxis for SSI in colorectal surgery.