Polymerase chain reaction for Enterococcus faecalis in drain fluid: the first screening test for symptomatic colorectal anastomotic leakage. The Appeal-study: analysis of parameters predictive for evident anastomotic leakage

Impact of gut microbiota on colorectal anastomotic healing (Review)

Intestinal anastomosis is a critical procedure in both emergency and elective surgeries to maintain intestinal continuity. However, the incidence of anastomotic leakage (AL) has recently increased, reaching up to 20%, imposing major clinical and economic burdens. Substantial perioperative alterations in the intestinal microbiota composition may contribute to AL, particularly due to disruptions in key microbial populations essential for intestinal health and healing. The intricate interplay between the intestinal microbiota and the host immune system, along with microbial changes before and during surgery, significantly influences anastomotic integrity. Notably, specific pathogens such as Enterococcus and Pseudomonas aeruginosa have been implicated in AL pathogenesis. Preventive strategies including dietary regulation, personalized intestinal preparation, microbiota restoration and enhanced recovery after surgery protocols, may mitigate AL risks. Future research should focus on elucidating the precise mechanisms linking intestinal microbiota alterations to anastomotic healing and developing targeted interventions to improve surgical outcomes.

Gut microbiota and gastrointestinal tumors: insights from a bibliometric analysis

Introduction

Despite the growing number of studies on the role of gut microbiota in treating gastrointestinal tumors, the overall research trends in this field remain inadequately characterized.

Methods

A bibliometric analysis was conducted using publications retrieved from the Web of Science Core Collection (up to September 30, 2024). Analytical tools including VOSviewer, CiteSpace, and an online bibliometric platform were employed to evaluate trends and hotspots.

Results

Analysis of 1,421 publications revealed significant geographical disparities in research output, with China and the United States leading contributions. Institutionally, the University of Adelaide, Zhejiang University, and Shanghai Jiao Tong University were prominent contributors. Authorship analysis identified Hannah R. Wardill as the most prolific author, while the International Journal of Molecular Sciences emerged as a leading journal. Rapidly growing frontiers include "proliferation," "inhibition," "immunotherapy," "drug delivery," and "tumorigenesis."

Discussion

This study provides a comprehensive overview of research trends and highlights emerging directions, aiming to advance scientific and clinical applications of gut microbiota in gastrointestinal tumor therapy.

Out-of-Hospital Cardiac Arrest 30-Day-Outcomes: The Importance of the First Electrocardiogram After Successful Resuscitation

BACKGROUND

While there is substantial evidence on the impact of prehospital resuscitation efforts on survival after out-of-hospital cardiac arrest (OHCA), the importance of the first electrocardiogram after return of spontaneous circulation has been much less studied.

OBJECTIVES

The aim of this study was to identify prognostically relevant electrocardiographic findings in patients after OHCA due to myocardial infarction (MI).

METHODS

A total of 119 patients admitted to hospital after suffering an OHCA due to MI were retrospectively analyzed. Patient characteristics and the first 12-lead electrocardiogram after return of spontaneous circulation were collected. The primary outcome was 30-day mortality.

RESULTS

A number of electrocardiographic findings were significantly associated with 30-day mortality: atrial fibrillation/flutter (HR 2.29 [95% CI 1.17-4.49, p = 0.015]), right bundle branch block (HR 2.23 [95% CI 1.14-4.56, p = 0.020]), bifascicular block (HR 2.51 [95% CI 1.04-6.059, p = 0.040]), T inversion (HR 2.01 [95% CI 1.02-3.99, p = 0.043]), QTc duration ≥500 ms (HR 2.21 [95% CI 1.10-4.42, p = 0.025]) and QT dispersion ≥ 100 ms (HR 2.11 [95% CI 1.02-4.37, p = 0.045]).

CONCLUSION

Several different electrocardiographic findings are associated with increased mortality in patients with OHCA due to MI.

C-Reactive Protein in Peritoneal Fluid for Predicting Anastomotic Leakage After Colorectal Cancer Surgery: A Systematic Review and Meta-Analysis

Background: Anastomotic leakage (AL) is a serious and potentially fatal complication that can occur after colorectal cancer (CRC) surgery, and it significantly affects patient recovery and increases morbidity. While serum C-reactive protein (CRP) is a recognized systemic inflammatory marker, the level of CRP in peritoneal fluid may serve as a more specific and localized biomarker for early AL detection. This meta-analysis explores the diagnostic potential of peritoneal fluid CRP, aiming to enhance postoperative care for CRC patients. Methods: A comprehensive literature search was conducted following the PRISMA guidelines. Eligible studies were included based on strict inclusion and exclusion criteria. Diagnostic accuracy was pooled using a random-effects model. The risk of bias was assessed using the QUADAS-2 tool. Results: The pooled sensitivity and specificity were 0.74 and 0.83, respectively, with an area under the curve (AUC) of 0.84, indicating good diagnostic accuracy. The overall diagnostic performance was consistent for sensitivity with no significant heterogeneity, but high heterogeneity was observed for specificity, suggesting variability between studies. Subgroup analysis revealed improved diagnostic performance between postoperative days 5-7 and higher CRP cut-off values (70-150 mg/L). The analysis confirmed the stability of the results through a sensitivity analysis and found no significant publication bias. Conclusions: Peritoneal fluid CRP is a reliable biomarker for detecting AL after CRC surgery, especially in the later postoperative period. However, heterogeneity in study methodologies and patient populations limits the generalizability of the findings. Future research should focus on standardizing protocols and exploring additional biomarkers to improve diagnostic accuracy.

Prediction of anastomotic insufficiency based on the mucosal microbiome prior to colorectal surgery: a proof-of-principle study

Anastomotic leakage (AL) is a potentially life-threatening complication following colorectal cancer (CRC) resection. In this study, we aimed to unravel longitudinal changes in microbial structure before, during, and after surgery and to determine if microbial alterations may be predictive for risk assessment between sufficient anastomotic healing (AS) and AL prior surgery. We analysed the microbiota of 134 colon mucosal biopsies with 16S rRNA V1-V2 gene sequencing. Samples were collected from three location sites before, during, and after surgery, and patients received antibiotics after the initial collection and during surgery. The microbial structure showed dynamic surgery-related changes at different time points. Overall bacterial diversity and the abundance of some genera such as Faecalibacterium or Alistipes decreased over time, while the genera Enterococcus and Escherichia_Shigella increased. The distribution of taxa between AS and AL revealed significant differences in the abundance of genera such as Prevotella, Faecalibacterium and Phocaeicola. In addition to Phocaeicola, Ruminococcus2 and Blautia showed significant differences in abundance between preoperative sample types. ROC analysis of the predictive value of these genera for AL revealed an AUC of 0.802 (p = 0.0013). In summary, microbial composition was associated with postoperative outcomes, and the abundance of certain genera may be predictive of postoperative complications.

Collagenase-producing bacteria are common in anastomotic leakage after colorectal surgery: a systematic review

PURPOSE

Some gut bacteria can produce enzymes (collagenases) that can break down collagen in the intestinal wall. This could be a part of the pathophysiology of anastomotic leakage (AL). This systematic review aimed to investigate if such bacteria were present more frequently in AL patients versus non-AL patients following colorectal surgery.

METHODS

This systematic review was reported according to the PRISMA and AMSTAR guidelines. Before the literature search, a study protocol was registered at PROSPERO (CRD42022363454). We searched PubMed, EMBASE, Google Scholar, and Cochrane CENTRAL on April 9th, 2023, for randomized and observational human studies of AL following colorectal surgery with information on gastrointestinal bacteria. The primary outcome was bacteria with the potential to produce collagenase. The risk of bias was assessed with the Newcastle-Ottawa Scale, as all studies were observational.

RESULTS

We included 15 studies, with a total of 52,945 patients, of which 1,747 had AL, and bacteriological information from feces, mucosa, the resected specimen, or drain fluid was presented. In 10 of the 15 studies, one or more collagenase-producing bacteria were identified in the patients with AL. Neither the bacteria nor the collagenase production were quantified in any of the studies. The studies varied greatly in terms of sample material, analytical method, and time of collection. Studies using DNA sequencing methods did not report findings of collagenase-producing bacteria.

CONCLUSION

Collagenase-producing bacteria are more common in patients with AL following colorectal surgery than in patients without AL, but the significance is unclear. From the current studies, it is not possible to determine the pathogenicity of the individual gut bacteria.

Ileocolonic Healing after Small Ileocecal Resection in Mice: NOD2 Deficiency Impairs Anastomotic Healing by Local Mechanisms

Ileocecal resection (ICR) is frequently performed in Crohn's disease (CD). NOD2 mutations are risk factors for CD. Nod2 knockout (ko) mice show impaired anastomotic healing after extended ICR. We further investigated the role of NOD2 after limited ICR. C57B16/J (wt) and Nod2 ko littermates underwent limited ICR including 1-2 cm terminal ileum and were randomly assigned to vehicle or MDP treatment. Bursting pressure was measured on POD 5, and the anastomosis was analyzed for matrix turn-over and granulation tissue. Wound fibroblasts from subcutaneously implanted sponges were used for comparison. The M1/M2 macrophage plasma cytokines were analyzed. Mortality was not different between groups. Bursting pressure was significantly decreased in ko mice. This was associated with less granulation tissue but was not affected by MDP. However, anastomotic leak (AL) rate tended to be lower in MDP-treated ko mice (29% vs. 11%, p = 0.07). mRNA expression of collagen-1α (col1 α), collagen-3α (col3 α), matrix metalloproteinase (mmp)2 and mmp9 was increased in ko mice, indicating increased matrix turn-over, specifically in the anastomosis. Systemic TNF-α expression was significantly lower in ko mice. Ileocolonic healing is impaired in Nod2 ko mice after limited ICR by local mechanisms maybe including local dysbiosis.

Serum and peritoneal biomarkers for the early prediction of symptomatic anastomotic leakage in patients following laparoscopic low anterior resection: A single-center prospective cohort study

BACKGROUND

Anastomotic leakage (AL) is one of the common complications after rectal cancer surgery. This study aimed to evaluate the combination of biomarkers for the early prediction of symptomatic AL after surgery.

METHODS

A prospective cohort study evaluated the serum and peritoneal biomarkers of patients who underwent laparoscopic low anterior resection (Lap LAR) from November 1, 2021, to May 1, 2022. Multivariate-penalized logistic regression was performed to explore the independent biomarker with a P-value <.1, and receiver operating characteristic (ROC) curve was used to analyze the area under the curve (AUC), sensitivity, and specificity of the independent biomarkers. A predictive model for symptomatic AL was built based on the independent biomarkers and was visualized with a nomogram. The calibration curve with the concordance index (c-index) was further applied to evaluate the efficacy of the predictive model.

RESULTS

A total of 157 patients were included in this study, and 7 (4.5%) were diagnosed with symptomatic AL. C-reactive protein/album ratio (CAR) on postoperative day 1 and systemic immune-inflammation index (SII) and peritoneal interleukin-6 (IL-6) on postoperative day 3 were proven to be independent predictors for the early prediction of symptomatic AL. The optimal cutoff values of CAR, SII, and peritoneal IL-6 were 1.04, 916.99, and 26430.09 pg/ml, respectively. Finally, the nomogram, including these predictors, was established, and the c-index of this nomogram was 0.812, indicating that the nomogram could be used for potential clinical reference.

CONCLUSION

The combination of CAR, SII, and peritoneal IL-6 might contribute to the early prediction of symptomatic AL in patients following Lap LAR. Given the limitations of this study and the emergence of other novel biomarkers, multicenter prospective studies are worthy of further exploration.

New understanding of gut microbiota and colorectal anastomosis leak: A collaborative review of the current concepts

Anastomotic leak (AL) is a life-threatening postoperative complication following colorectal surgery, which has not decreased over time. Until now, no specific risk factors or surgical technique could be targeted to improve anastomotic healing. In the past decade, gut microbiota dysbiosis has been recognized to contribute to AL, but the exact effects are still vague. In this context, interpretation of the mechanisms underlying how the gut microbiota contributes to AL is significant for improving patients' outcomes. This review concentrates on novel findings to explain how the gut microbiota of patients with AL are altered, how the AL-specific pathogen colonizes and is enriched on the anastomosis site, and how these pathogens conduct their tissue breakdown effects. We build up a framework between the gut microbiota and AL on three levels. Firstly, factors that shape the gut microbiota profiles in patients who developed AL after colorectal surgery include preoperative intervention and surgical factors. Secondly, AL-specific pathogenic or collagenase bacteria adhere to the intestinal mucosa and defend against host clearance, including the interaction between bacterial adhesion and host extracellular matrix (ECM), the biofilm formation, and the weakened host commercial bacterial resistance. Thirdly, we interpret the potential mechanisms of pathogen-induced poor anastomotic healing.

OUP accepted manuscript

Background

Anastomotic leakage (AL) is a severe complication after colorectal surgery. This study aimed to investigate a method for the early diagnosis of AL after surgical resection by analysing inflammatory factors (IFs) in peritoneal drainage fluid.

Methods

Abdominal drainage fluid of patients with colorectal cancer who underwent resection between April 2017 and April 2018, were prospectively collected in the postoperative interval. Six IFs, including interleukin (IL)-1β, IL-6, IL-10, tumour necrosis factor (TNF)-α, matrix metalloproteinase (MMP)2, and MMP9, in drainage were determined by multiplex immunoassay to investigate AL (in patients undergoing resection and anastomosis) and pelvic collection (in patients undergoing abdominoperineal resection). Sparreboom and colleagues’ prediction model was first evaluated for AL/pelvic collection, followed by a new IF-based score system (AScore) that was developed by a least absolute shrinkage and selection operator (LASSO) regression, for the same outcomes. The model performance was tested for the area under the curve (AUC), sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV).

Results

Out of 123 patients eligible, 119 patients were selected, including 12 patients with AL/pelvic collection. Sparreboom and colleagues’ prediction model was documented with the best diagnostic efficacy on postoperative day 3 (POD3), with an AUC of 0.77. After optimization, AScore on POD3 increased the AUC to 0.83 and on POD1 showed the best diagnostic efficiency, with an AUC of 0.88. Based on the Youden index, the cut-off value of AScore on POD1 was set as −2.46 to stratify patients into low-risk and high-risk groups for AL/pelvic collection. The model showed 90.0 per cent sensitivity, 69.7 per cent specificity, 98.4 per cent NPV, and 25.0 per cent PPV.

Conclusions

The early determination of IFs in abdominal drainage fluid of patients undergoing colorectal surgery could be useful to predict AL or pelvic collection.

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.

Bacteriological concentration of peritoneal drainage fluid could make an early diagnosis of anastomotic leakage following rectal resection

To investigate that the bacteriological concentration and pH value in peritoneal drainage fluid might serve as indicators of early diagnosis of anastomotic leakage following rectal resection. We prospectively analyzed consecutive patients who were treated for rectal diseases with anastomosis at the department of general surgery, the affiliated hospital of Nanjing University Medical School between August 2018 and December 2020. The bacteriological concentration and the pH value in peritoneal drainage fluid were tested on the first, fourth, seventh days postoperatively. A total of 300 consecutive patients underwent rectal resection were tested. 21 patients present with AL and the overall AL rate was 7%. The bacteriological concentration in peritoneal drainage fluid of AL group was significantly higher than that in non-AL group. The AUC value was 0.98 (95% confidence intervals 0.969-1.000) according to the ROC curve. The best cut-off value was 1143/uL. The sensitivity and specificity were 100% and 93.19% respectively. There was no difference of pH value between the AL and non-AL groups. According the results of present study, a high bacteriological concentration in peritoneal drainage fluid is a good marker for predicting and diagnosing AL following rectal resection. However, owing to the limitation of the sample, there was no validation attempt in the study. A large sample study is needed to validate the conclusion.

An umbrella systematic review of drain fluid analysis in colorectal surgery for the detection of anastomotic leak: Not yet ready to translate research studies into clinical practice

AIM

Anastomotic leak (AL) is the most important complication of intestinal surgery with an anastomosis. Whilst a number of studies have defined risk factors for AL, frustratingly, low-risk patients still develop AL. Studies have looked at drain fluid analysis for detection of AL, but these findings have failed to translate into routine clinical practice. This umbrella systematic review aims to provide an overview of the promising candidate biomarkers (BMs) that show potential to translate into clinical practice.

METHODS

A systematic literature search was conducted in MEDLINE, EMBASE, and the Cochrane, KSR Evidence and the Epistemonikos databases on the 14 April 2021. Only systematic reviews of cohort or controlled studies measuring drain fluid biomarkers in humans were included. The methodological quality of the reviews was assessed using the AMSTAR 2 instrument. Clinical trial registries were searched for trials actively investigating drain fluid BMs. Candidate BMs were classified, and threshold values investigated.

RESULTS

Nine systematic reviews, published between 2007 and 2020, met the inclusion criteria, and contained a total of 36 cohort studies. A total of 38 different BMs were studied. The most promising category of drain fluid BM was the extravasated intra-luminal substances (EILS) and five registered trials of these BMs were found. Two of nine reviews were of moderate quality.

CONCLUSIONS

The majority of BMs show inconsistent threshold values and are in the experimental stage. A number are not readily available for adoption into routine clinical practice. Most do not state a cut-off value to be considered as diagnostic.

Early Diagnosis of Anastomotic Leakage After Gastric Cancer Surgery Via Analysis of Inflammatory Factors in Abdominal Drainage

BACKGROUND

Anastomotic leakage (AL) is the most serious postoperative complication for patients with gastric cancer. We aim to develop clinically tools to detect AL in the early phase by analysis of the inflammatory factors (IFs) in abdominal drainage.

METHODS

We prospectively included 326 patients to establish two independent cohorts, and the concentration of IFs within abdominal drainage was detected. In the primary cohort, an IF-based AL prediction model was constructed using the least absolute shrinkage and selection operator (LASSO) regression. The predictive value of the model was later validated via the validation cohort.

RESULTS

Analyzing the IFs with LASSO regression, we developed an Anastomotic Score system on postoperative Day 3 (AScore-POD3), which yielded high diagnostic efficacy in the primary cohort (the area under the curve (AUC) = 0.87). The predictive value of AScore-POD3 was validated in the validation cohort, and its AUC was 0.83. We further built an AScore-POD3 based nomogram by combining the AScore-POD3 system with other clinical risk factors of AL. The C-index of the nomogram was 0.93 in the primary cohort and 0.82 in the validation cohort.

CONCLUSIONS

Our study suggests that AL can be early diagnosed after gastric cancer surgery by measuring drainage IFs.

Omitting nasogastric tube placement after gastrectomy does not enhance postoperative recovery: a propensity score matched analysis

PURPOSE

Enhanced recovery after surgery (ERAS) program has become the main trend in gastrointestinal surgery. This study aims to investigate factors influencing the decision-making of nasogastric tube (NGT) placement and its safety and efficacy after gastrectomy.

METHODS

We analyzed our prospectively maintained database including 287 patients who underwent elective gastrectomy in our department from January 1 to December 31, 2017. All cases were divided into two groups, namely, the no-NGT group and the NGT group. Logistic regression was used to analyze factors that affected the decision of NGT placement, and propensity score matching (PSM) was later applied to balance those factors for the analysis of safety outcomes between groups.

RESULTS

Multivariate analysis showed resection range (p = 0.004, proximal gastrectomy: OR = 4.555, 95%CI = 1.392-14.905, p = 0.016; total gastrectomy: OR = 1.990, 95%CI = 1.205-3.287, p = 0.009) was the only independent risk factor of NGT placement. NGT was omitted in the majority (58.8%) of distal gastrectomy but only in 42.5% and 25% in total and proximal gastrectomy. After PSM, we found no significant differences between patients with or without NGT in postoperative hospital stay, time to first flatus and defecation, time to fluid and semi-fluid diet, rate of reinsertion, or hospitalization expenditure (p > 0.05, respectively). The incidence of postoperative complications in the two groups were 21.7% and 23.5%, respectively (p = 0.753), and the incidence of major complications was 7.0% and 9.6% (p = 0.472).

CONCLUSION

The decision-making of NGT placement is mainly influenced by the resection range. Omitting NGT is a safe approach in all types of gastrectomy but was not able to enhance the recovery in our practice.

Enterococcus faecalis Is Associated with Anastomotic Leak in Patients Undergoing Colorectal Surgery

Background: Anastomotic leak is among the most dreaded complications in patients undergoing colorectal surgery. We have discovered that in rodents, collagenase-producing bacteria, particularly Enterococcus faecalis, promotes anastomotic leak by degrading healing anastomotic tissue. Yet, it is unclear if these organisms play a role in humans. Patients and Methods: Patients undergoing colorectal resection at the University of Chicago from July 2014 through June 2019 who developed a post-operative infection were stratified into infections that resulted from an anastomotic leak, a Hartmann pouch stump leak, or a deep infection without an associated staple line leak. Results: Forty-two patients had available culture data. Of these patients, 19 were found to have an anastomotic leak, 7 had a stump leak, and 16 had a deep infection that was not associated with a staple line. Enterococcus faecalis was identified in 24% of all infections and was associated with the development of anastomotic leak (p = 0.029). When the organisms were classified into their known ability to produce collagenase, 74% of patients with an anastomotic leak were colonized with collagenase-producing organisms, compared with only 28% of patients with a deep infection or stump leak (p = 0.022). Antibiotic-resistant organisms were more common in patients with anastomotic leak (p = 0.01). Conclusions: Collagenase-producing and antibiotic-resistant organisms are more prevalent in anastomotic leak infections compared with other deep or organ/space infections. This lends evidence to a bacterial driven pathogenesis of leak and suggests that targeting these organisms may be a novel strategy to reduce this complication.

Predictive and Diagnostic Biomarkers of Anastomotic Leakage: A Precision Medicine Approach for Colorectal Cancer Patients

Development of an anastomotic leak (AL) following intestinal surgery for the treatment of colorectal cancers is a life-threatening complication. Failure of the anastomosis to heal correctly can lead to contamination of the abdomen with intestinal contents and the development of peritonitis. The additional care that these patients require is associated with longer hospitalisation stays and increased economic costs. Patients also have higher morbidity and mortality rates and poorer oncological prognosis. Unfortunately, current practices for AL diagnosis are non-specific, which may delay diagnosis and have a negative impact on patient outcome. To overcome these issues, research is continuing to identify AL diagnostic or predictive biomarkers. In this review, we highlight promising candidate biomarkers including ischaemic metabolites, inflammatory markers and bacteria. Although research has focused on the use of blood or peritoneal fluid samples, we describe the use of implantable medical devices that have been designed to measure biomarkers in peri-anastomotic tissue. Biomarkers that can be used in conjunction with clinical status, routine haematological and biochemical analysis and imaging have the potential to help to deliver a precision medicine package that could significantly enhance a patient's post-operative care and improve outcomes. Although no AL biomarker has yet been validated in large-scale clinical trials, there is confidence that personalised medicine, through biomarker analysis, could be realised for colorectal cancer intestinal resection and anastomosis patients in the years to come.

Gut Microbiota as Potential Biomarker and/or Therapeutic Target to Improve the Management of Cancer: Focus on Colibactin-Producing Escherichia coli in Colorectal Cancer

The gut microbiota is crucial for physiological development and immunological homeostasis. Alterations of this microbial community called dysbiosis, have been associated with cancers such colorectal cancers (CRC). The pro-carcinogenic potential of this dysbiotic microbiota has been demonstrated in the colon. Recently the role of the microbiota in the efficacy of anti-tumor therapeutic strategies has been described in digestive cancers and in other cancers (e.g., melanoma and sarcoma). Different bacterial species seem to be implicated in these mechanisms: F. nucleatum, B. fragilis, and colibactin-associated E. coli (CoPEC). CoPEC bacteria are prevalent in the colonic mucosa of patients with CRC and they promote colorectal carcinogenesis in susceptible mouse models of CRC. In this review, we report preclinical and clinical data that suggest that CoPEC could be a new factor predictive of poor outcomes that could be used to improve cancer management. Moreover, we describe the possibility of using these bacteria as new therapeutic targets.

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.

Clinical predictive efficacy of C-reactive protein for diagnosing infectious complications after gastric surgery

BACKGROUND

With the popularization of Enhanced Recovery After Surgery (ERAS), identifying patients with complications before discharging becomes important. This study aimed to explore the efficacy of C-reactive protein (CRP) in predicting infectious complications after gastrectomy.

METHODS

Patients with gastric cancer who underwent gastrectomy at Beijing Cancer Hospital from March 2017 to April 2018 were enrolled in the training set. Complications were prospectively registered. Receiver operating characteristic analysis was performed to assess the diagnostic accuracy of CRP via evaluating the area under the curve (AUC). Patients who had CRP tested on postoperative day (POD) 5 and accepted gastrectomy from April to December 2018 were included in the validation set to validate the cut-off value of CRP obtained from the training set.

RESULTS

A total of 350 patients were included (263 patients in the training set and 87 patients in the validation set). Out of these, 24 patients were diagnosed with infectious complications and 17 patients had anastomotic leakage in the training set. The CRP level on POD5 had superior diagnostic accuracy for infectious complications with an AUC of 0.81. The cut-off value of CRP on POD5 at 166.65 mg/L yielded 93% specificity and 97.2% negative predict value (NPV); For anastomotic leakage, the AUC of CRP on POD5 was 0.81. Using the cut-off value of CRP at 166.65 mg/L on POD5 achieved 92% specificity and 98.6% NPV. The optimal cut-off value (CRP 166.65 mg/L on POD5) was validated in the validation set. It achieved 97.5% specificity and 94.0% NPV for infectious complications, and 97.6% specificity and 96.4% NPV for anastomotic leakage.

CONCLUSION

CRP is a reliable predictive marker for the diagnosis of inflammatory complications following gastric surgery. However, this study was based on preliminary data. The validity of this data needs confirmation by a larger number of cases.

A multicentre cohort study of serum and peritoneal biomarkers to predict anastomotic leakage after rectal cancer resection

AIM

Anastomotic leakage (AL) is one of the most feared complications after rectal resection. This study aimed to assess a combination of biomarkers for early detection of AL after rectal cancer resection.

METHOD

This study was an international multicentre prospective cohort study. All patients received a pelvic drain after rectal cancer resection. On the first three postoperative days drain fluid was collected daily and C-reactive protein (CRP) was measured. Matrix metalloproteinase-2 (MMP2), MMP9, glucose, lactate, interleukin 1-beta (IL1β), IL6, IL10, tumour necrosis factor alpha (TNFα), Escherichia coli, Enterococcus faecalis, lipopolysaccharide-binding protein and amylase were measured in the drain fluid. Prediction models for AL were built for each postoperative day using multivariate penalized logistic regression. Model performance was estimated by the c-index for discrimination. The model with the best performance was visualized with a nomogram and calibration was plotted.

RESULTS

A total of 292 patients were analysed; 38 (13.0%) patients suffered from AL, with a median interval to diagnosis of 6.0 (interquartile ratio 4.0-14.8) days. AL occurred less often after partial than after total mesorectal excision (4.9% vs 15.2%, P = 0.035). Of all patients with AL, 26 (68.4%) required reoperation. AL was more often treated by reoperation in patients without a diverting ileostomy (18/20 vs 8/18, P = 0.03). The prediction model for postoperative day 1 included MMP9, TNFα, diverting ileostomy and surgical technique (c-index = 0.71). The prediction model for postoperative day 2 only included CRP (c-index = 0.69). The prediction model for postoperative day 3 included CRP and MMP9 and obtained the best model performance (c-index = 0.78).

CONCLUSION

The combination of serum CRP and peritoneal MMP9 may be useful for earlier prediction of AL after rectal cancer resection. In clinical practice, this combination of biomarkers should be interpreted in the clinical context as with any other diagnostic tool.

Enterococcus faecalis exploits the human fibrinolytic system to drive excess collagenolysis: implications in gut healing and identification of druggable targets

Perforations, anastomotic leak, and subsequent intra-abdominal sepsis are among the most common and feared complications of invasive interventions in the colon and remaining intestinal tract. During physiological healing, tissue protease activity is finely orchestrated to maintain the strength and integrity of the submucosa collagen layer in the wound. We (Shogan, BD et al. Sci Trans Med 7: 286ra68, 2015.) have previously demonstrated in both mice and humans that the commensal microbe Enterococcus faecalis selectively colonizes wounded colonic tissues and disrupts the healing process by amplifying collagenolytic matrix-metalloprotease activity toward excessive degradation. Here, we demonstrate for the first time, to our knowledge, a novel collagenolytic virulence mechanism by which E. faecalis is able to bind and locally activate the human fibrinolytic protease plasminogen (PLG), a protein present in high concentrations in healing colonic tissue. E. faecalis-mediated PLG activation leads to supraphysiological collagen degradation; in this study, we demonstrate this concept both in vitro and in vivo. This pathoadaptive response can be mitigated with the PLG inhibitor tranexamic acid (TXA) in a fashion that prevents clinically significant complications in validated murine models of both E. faecalis- and Pseudomonas aeruginosa-mediated colonic perforation. TXA has a proven clinical safety record and is Food and Drug Administration approved for topical application in invasive procedures, albeit for the prevention of bleeding rather than infection. As such, the novel pharmacological effect described in this study may be translatable to clinical trials for the prevention of infectious complications in colonic healing.NEW & NOTEWORTHY This paper presents a novel mechanism for virulence in a commensal gut microbe that exploits the human fibrinolytic system and its principle protease, plasminogen. This mechanism is targetable by safe and effective nonantibiotic small molecules for the prevention of infectious complications in the healing gut.

Bilirubin, urobilinogen, pancreas elastase and bile acid in drain fluid. The GBUP-study: Analysis of biomarkers for a colorectal anastomotic leakage

Purpose

A colorectal anastomotic leakage (CAL) is a major complication after colorectal surgery and leads to high rates of morbidity and prolonged hospital stay. The study aims to evaluate the benefit of using bilirubin, urobilinogen, pancreas elastase and bile acid in the drain fluid (DF) as a predictive marker for the CAL.

Methods

From June 2015 to October 2017 100 patients, who underwent left hemicolectomy (LH), sigma resection (SR), high anterior resection (HAR), low anterior resection (LAR) or reversal of Hartmann's Procedure (ROHP) were included in this monocentric non-randomized prospective clinical trial. During the first four postoperative days (POD) the concentration of bilirubin, urobilinogen, pancreas elastase and bile acid in the DF was measured.

Results

In total 100 patients were recruited. 17 were excluded due to intraoperative decisions to conduct a protective stoma. 6 patients had a CAL. The patients of the control group (n = 77) and the patients who suffered from a CAL (n = 6) had no increased concentration of urobilinogen and pancreas elastase in the DF. The concentration of bile acid in the DF of the patients who suffered from a CAL differed from those of the control group on the 4th POD (p = 0.055).

The concentration of bilirubin in the DF of the patients who suffered from a CAL significantly differed from those of the control group on the 1st POD (p = 0.031) and on the 3rd POD (p = 0.041).

Conclusion

Bilirubin and bile acid in the DF may function as a predictive marker for a CAL.

•

Bilirubin in the DF may function as a predictive marker for a CAL.

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Bile acid in the DF may function as a predictive marker for a CAL.

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Pancreas elastase in the DF did not seem to be a predictive marker for a CAL.

Peritoneal fluid biomarkers in the detection of colorectal anastomotic leaks: a systematic review

PURPOSE

Anastomotic leak (AL) in colorectal surgery leads to significant morbidity, mortality and poorer oncological outcomes. Diagnosis of AL is frequently delayed as current methods of detection are not 100% sensitive or specific. 'Biomarkers', such as cytokines and markers of ischaemia, from the milieu of the anastomosis may aid early detection. This paper aims to review the evidence for their role in AL detection, allowing identification of targets for future research.

METHODS

A systematic review was performed using PubMed, MEDLINE and Cochrane Library databases. Papers concerning detection or prediction of AL with biomarkers were identified. References within the papers were used to identify further relevant articles.

RESULTS

Research has taken place in small cohorts with varying definitions of AL. Lactate has consistently been shown to be elevated in patients with intra-abdominal complications and ALs. pH on post-operative day 3 showed excellent specificity. Despite mixed results, a meta-analysis found that the cytokines tumour necrosis factor-α and interleukin-6 were elevated early in AL. Detection of bacteria in drain fluid by RT-PCR has good specificity but a high rate of false positives.

CONCLUSIONS

Peritoneal cytokines, lactate and pH have the potential to identify AL early. The consistency of the results for lactate and pH, alongside the fact that they are easy, quick and inexpensive to test, makes them the most attractive targets. Studies in larger cohorts with standardized definitions of AL are required to clarify their usefulness. Emerging biosensor technology may facilitate the development of small, low-cost and degradable intra-abdominal devices to measure peritoneal fluid biomarkers.

Systematic review of the role of biomarkers in diagnosing anastomotic leakage following colorectal surgery

BACKGROUND

Anastomotic leakage (AL) following colorectal surgery can be difficult to diagnose owing to varying clinical presentations. This systematic review aimed to assess biomarkers as potential diagnostic tests for preclinical detection of AL.

METHODS

A comprehensive literature review was conducted according to PRISMA guidelines. All published studies evaluating biomarkers, both systemic and peritoneal, in the context of AL following colorectal surgery were included. Studies were sought in three electronic databases (MEDLINE, PubMed and Embase) from January 1990 to June 2016.

RESULTS

Thirty-six studies evaluated 51 different biomarkers in the context of AL after colorectal surgery. Biomarkers included markers of ischaemia and inflammation, and microbiological markers, and were measured in both peritoneal drain fluid and the systemic circulation. The most commonly evaluated peritoneal drain fluid biomarkers were interleukin (IL) 6, IL-10 and tumour necrosis factor. Significantly raised drain levels in the early postoperative period were reported to be associated with the development of AL. C-reactive protein, procalcitonin and leucocytes were the most commonly evaluated systemic biomarkers with significant negative and positive predictive values. Associated area under the curve values ranged from 0·508 to 0·960.

CONCLUSION

Peritoneal drain fluid and systemic biomarkers are poor predictors of AL after colorectal surgery. Combinations of these biomarkers showed improvement in predictive accuracy.

Novel insight into the role of microbiota in colorectal surgery

Recent literature undeniably supports the idea that the microbiota has a strong influence on the healing process of an intestinal anastomosis. Understanding the mechanisms by which the bacterial community of the gut influences intestinal healing could open the door for new preventive and therapeutic approaches. Among the different mechanisms, data have shown that the production of specific reactive oxygen species (ROS) and the activation of specific formyl peptide receptors (FPRs) regulate intestinal wound healing. Evidence suggests that specific gut microbes such as Lactobacillus spp and Akkermansia muciniphila help to regulate healing processes through both ROS-dependent and FPR-dependent mechanisms. In this review, we will discuss the current knowledge and future perspectives concerning the impact of microbiota on wound healing. We will further review available evidence on whether mechanical bowel preparation and the use of specific antibiotics are beneficial or harmful procedures, an ongoing matter of debate. These practices have a profound effect on the gut microbiota composition at the level of both the mucosal and the luminal compartments. Therefore, a key question remains unanswered: should we continue to prepare the gut before surgical intervention? Current knowledge and data do not clearly support the use of one technique or another to avoid complications such as anastomotic leak. There is an urgent need for appropriate interventions with a deep microbiota analysis to investigate both the surgical technical benefits of a proper anastomosis compared with the potential effect of the gut microbes (beneficial vs harmful) on the processes of wound healing and anastomotic leakage reduction.

Predicting Value of Serum Procalcitonin, C-Reactive Protein, Drain Fluid Culture, Drain Fluid Interleukin-6, and Tumor Necrosis Factor-α Levels in Anastomotic Leakage after Rectal Resection

BACKGROUND

Anastomotic leak is the most dreaded septic complication of colorectal surgical procedures. Death is proportional to the time between occurrence and diagnosis of the leakage. Biomarkers, which may help to predict anastomotic leakage before appearance of its clinical features, may be beneficial in preventing adverse outcomes. This study investigates a biomarker that might be useful to predict rectal anastomotic leakage before its clinical presentation.

PATIENTS AND METHODS

Serum procalcitonin and C-reactive protein (CRP) levels, bacterial proliferation, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels of drain fluid were evaluated in 50 consecutive patients who underwent low anterior resection without diverting ostomy for rectal carcinoma.

RESULTS

Anastomotic leakage occurred in seven of 50 (14%) patients. Serum CRP and procalcitonin levels at post-operative day three were higher in patients with anastomotic leakage (p = 0.01, p = 0.02 respectively). Drain TNF-α values were increased 63.2% on post-operative day five when compared with post-operative day three in patients with anastomotic leakage, but were decreased in patients without leakage. There was no statistical difference for drain IL-6 levels between groups. The bacterial proliferation rate of drain fluid culture in the leakage group was 42.9% at post-operative day three and 85.7% at post-operative day five (p = 0.29 and p = 0.0001, respectively).

CONCLUSIONS

High serum CRP and procalcitonin values on post-operative day three are alarming, and assessment of anastomotic leakage by abdominal imaging with rectal contrast is suggested. In addition, increasing levels of TNF-α and bacterial proliferation in drain fluid are predictive, whereas IL-6 is not.

The role of the microbiota in surgical recovery

PURPOSE OF REVIEW

The purpose of this review is to highlight new research findings in the complex bidirectional crosstalk that occurs between the intestinal microbiome and the host immune system in the context of surgical recovery and outcomes.

RECENT FINDINGS

Significant evidence has been generated emphasizing the central role of the intestinal microbiome on surgical outcomes such as wound healing, surgical site infections and anastomotic leak. Current preventive strategies, including the use of some parenteral antibiotics, may actually exacerbate the problem by selecting for drug-resistant pathogens.

SUMMARY

A delicate balance exists between the human host and its microbial counterparts that is directly related to postsurgical healing. This balance can be easily altered in favor of the pathogen through perioperative and surgical interventions leading to intestinal dysbiosis and loss of colonization resistance. Current strategies to prevent infectious complications with the escalating use of broader and more powerful antibiotics are not an evolutionarily stable strategy. A more complete understanding of the ecological and molecular interactions of the host with its microbiome is necessary to uncover new therapeutic strategies that preserve the composition and function of the intestinal microbiome and constrain virulent pathogens through the course of surgical injury.

Integrated approach to colorectal anastomotic leakage: Communication, infection and healing disturbances

Colorectal anastomotic leakage (CAL) remains a major complication after colorectal surgery. Despite all efforts during the last decades, the incidence of CAL has not decreased. In this review, we summarize the available strategies regarding prevention, prediction and intervention of CAL and categorize them into three categories: communication, infection and healing disturbances. These three major factors actively interact during the onset of CAL. We aim to provide an integrated approach to CAL based on its etiology. The intraoperative air leak test, intraoperative endoscopy, radiological examinations and stoma construction mainly aim to detect and to prevent communication between the intra- and extra-luminal content. Other strategies including postoperative drainage, antibiotics, and infectious-parameter evaluation are intended to detect and prevent anastomotic or peritoneal infection. Most currently available interventions for CAL focus on the control of communication and infection, while strategies targeting the healing disturbances such as lifestyle changes, oxygen therapy and evaluation of metabolic biomarkers still lack wide clinical application. This simplified categorization may contribute to an integrated understanding of CAL. We strongly believe that this integrated approach should be taken into consideration during clinical practice. An integrated approach to CAL could contribute to a better understanding of the etiology of CAL and eventually better patient outcome.

Collagen degradation and MMP9 activation by Enterococcus faecalis contribute to intestinal anastomotic leak

Even under the most expert care, a properly constructed intestinal anastomosis can fail to heal, resulting in leakage of its contents, peritonitis, and sepsis. The cause of anastomotic leak remains unknown, and its incidence has not changed in decades. We demonstrate that the commensal bacterium Enterococcus faecalis contributes to the pathogenesis of anastomotic leak through its capacity to degrade collagen and to activate tissue matrix metalloproteinase 9 (MMP9) in host intestinal tissues. We demonstrate in rats that leaking anastomotic tissues were colonized by E. faecalis strains that showed an increased collagen-degrading activity and also an increased ability to activate host MMP9, both of which contributed to anastomotic leakage. We demonstrate that the E. faecalis genes gelE and sprE were required for E. faecalis-mediated MMP9 activation. Either elimination of E. faecalis strains through direct topical antibiotics applied to rat intestinal tissues or pharmacological suppression of intestinal MMP9 activation prevented anastomotic leak in rats. In contrast, the standard recommended intravenous antibiotics used in patients undergoing colorectal surgery did not eliminate E. faecalis at anastomotic tissues nor did they prevent leak in our rat model. Finally, we show in humans undergoing colon surgery and treated with the standard recommended intravenous antibiotics that their anastomotic tissues still contained E. faecalis and other bacterial strains with collagen-degrading/MMP9-activating activity. We suggest that intestinal microbes with the capacity to produce collagenases and to activate host metalloproteinase MMP9 may break down collagen in the intestinal tissue contributing to anastomotic leak.

Improving the outcomes in oncological colorectal surgery

During the last several decades, colorectal cancer surgery has experienced some major perioperative improvements. Preoperative risk-assessment of nutrition, frailty, and sarcopenia followed by interventions for patient optimization or an adapted surgical strategy, contributed to improved postoperative outcomes. Enhanced recovery programs or fast-track surgery also resulted in reduced length of hospital stay and overall complications without affecting patient safety. After an initially indecisive start due to uncertainty about oncological safety, the most significant improvement in intraoperative care was the introduction of laparoscopy. Laparoscopic surgery for colon and rectal cancer is associated with better short-term outcomes, whereas long-term outcomes regarding survival and recurrence rates are comparable. Nevertheless, long-term results in rectal surgery remain to be seen. Early recognition of anastomotic leakage remains a challenge, though multiple improvements have allowed better management of this complication.

Intestinal anastomotic injury alters spatially defined microbiome composition and function

BACKGROUND

When diseased intestine (i.e., from colon cancer, diverticulitis) requires resection, its reconnection (termed anastomosis) can be complicated by non-healing of the newly joined intestine resulting in spillage of intestinal contents into the abdominal cavity (termed anastomotic leakage). While it is suspected that the intestinal microbiota have the capacity to both accelerate and complicate anastomotic healing, the associated genotypes and functions have not been characterized.

RESULTS

Using 16S rRNA amplicon sequencing of samples collected on the day of surgery (postoperative day 0 (POD0)) and the 6th day following surgery (postoperative day 0 (POD6)), we analyzed the changes in luminal versus tissue-associated microbiota at anastomotic sites created in the colon of rats. Results indicated that anastomotic injury induced significant changes in the anastomotic tissue-associated microbiota with minimal differences in the luminal microbiota. The most striking difference was a 500-fold and 200-fold increase in the relative abundance of Enterococcus and Escherichia/Shigella, respectively. Functional profiling predicted the predominance of bacterial virulence-associated pathways in post-anastomotic tissues, including production of hemolysin, cytolethal toxins, fimbriae, invasins, cytotoxic necrotizing factors, and coccolysin.

CONCLUSION

Taken together, our results suggest that compositional and functional changes accompany anastomotic tissues and may potentially accelerate or complicate anastomotic healing.