Gut microbiome influences on anastomotic leak and recurrence rates following colorectal cancer surgery

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.

Prior antibiotics exposure is associated with an elevated risk of surgical site infections, including anastomotic leakage, after colon cancer but not rectal cancer surgery: A register-based study of 38,839 patients

Gut microbiota composition has been implicated in surgical site complications after colorectal cancer surgery. Antibiotics affect gut microbiota, but evidence for a role in surgical site complications is inconclusive. We aimed to investigate use of prescription antibiotics during the years before surgery in relation to the risk of surgical site infections, including anastomotic leakage, within 30 days after surgery. Cardiovascular/neurological complications and the urinary antiseptic methenamine hippurate, for which there is no clear link with the microbiota, were used as negative controls. We conducted a patient cohort study using complete population data from Swedish national registers between 2005 and 2020. The final study population comprised 26,527 colon cancer and 12,312 rectal cancer cases with a 4.5 year exposure window. In colon cancer patients, antibiotics use was associated with a higher risk of surgical site infections (adjusted odds ratio (aOR) for any versus no use = 1.20, 95% confidence interval (CI) 1.10-1.33) and anastomotic leakage in particular (aOR =1.19, 95% CI 1.03-1.36), both with dose-response relationships for increasing cumulative antibiotics use (Ptrend = <0.001 and Ptrend = 0.047, respectively). Conversely, associations in rectal cancer patients, as well as for the negative controls cardiovascular/neurological complications and methenamine hippurate, were null. In conclusion, prescription antibiotics use up to 4.5 years before colorectal cancer surgery is associated with a higher risk of surgical site infections, including anastomotic leakage, after colon cancer but not rectal cancer surgery. These findings support a role for antibiotics-induced intestinal dysbiosis in surgical site infections.

Oral antibiotic prophylaxis induces changes in the microbiology of surgical site infection after colorectal surgery. A matched comparative study

AIM

Oral antibiotic prophylaxis (OAP) lowers rates of surgical site infection (SSI) and may aid anastomotic healing in colorectal surgery. The aim of this study was to analyse the understudied impact of OAP on SSI microbiology after colorectal surgery.

METHOD

A post hoc analysis was performed on a previous prospective, multicentre study of elective colorectal surgery. For 1000 patients with SSI, this study compared the microbiology of SSIs in procedures without OAP (SSI/OAP-) and with OAP (SSI/OAP+).

RESULTS

There were 340 patients in the SSI/OAP- group and 660 in the SSI/OAP+ group. The use of OAP increased the presence of Gram-positive cocci (GPC) (OR 1.542, 95% CI 1.153-2.062) and fungi (OR 2.037, 95% CI 1.206-3.440), but reduced rates of Gram-negative bacteria (GNB) (OR 1.461, 95% CI 1.022-2.088) and anaerobe isolation (OR 0.331, 95% CI 0.158-0.696). Specifically, it led to increases in the isolation of Enterococcus faecium (OR 1.450, 95% CI 0.812-2.591), methicillin-resistant Staphylococcus aureus (OR 2.000, 95% CI 1.043-3.834) and Candida spp. (OR 2.037, 95% CI 1.206-3.440). In colon surgery with OAP, GPC infections were more likely (OR 1.461, 95% CI 1.022-2.088). In rectal surgery, organ/space SSIs had a higher risk of harbouring GPC (OR 1.860, 95% CI 1.153-2.999) and a lower risk of GNB (OR 0.321, 95% CI 0.200-0.515).

CONCLUSION

OAP reduced the presence of anaerobes and GNB in SSIs, but increased the isolation of GPCs and fungi, with E. faecium and Candida being of particular concern. This information should guide empirical antibiotic therapy for postoperative colorectal SSIs in patients who have received preoperative OAP.

Reducing Postoperative Opioid Use: A Comparison of Open Versus Ultrasound-Guided Regional Anesthesia for Patients Undergoing Open Pancreatoduodenectomy

BACKGROUND

Opioid crisis is a national issue with significant economic burden and marked increase in opioid-related deaths, particularly following surgical procedures. Reducing opioid requirements while maintaining effective analgesia is critically challenging, perioperatively. Multimodal drug regimens and guided regional anesthesia (RA) have been adopted to address this issue. We aimed to assess postoperative opioid consumption in patients undergoing open pancreatoduodenectomy based on the routes of RA administration: open versus ultra-sound guided.

METHODS

This retrospective cohort study was conducted at Emory University Saint Joseph's Hospital, encompassing patients who underwent open pancreatoduodenectomy (PD) from 2020 to 2022 who received ultrasound-guided RA (U-RA) or open RA (O-RA). Patient demographics, surgical details, and postoperative outcomes, including opioid consumption measured in morphine milligram equivalents (MME) at 24, 48, and 72 h, were analyzed. Multivariable linear regression identified predictors of postoperative opioid use.

RESULTS

Of 95 patients, 47 met inclusion criteria: 27 received U-RA and 20 O-RA. Preoperative and intraoperative characteristics were similar between patients receiving O-RA and U-RA. A lower opioid requirement was noted in the O-RA group compared to the U-RA group at all time points. (24 h: 6.5 vs. 18, p = 0.004; 48 h: 18 vs. 37, p = 0.001; 72 h: 30.5 vs. 57, p = 0.002). On multivariable analysis, only route of regional anesthesia was independently associated with reduced opioid use across all time points (24 h: mean difference = -5.75, 95% CI: -11.3, -0.18; 48 h: mean difference = -16.95, 95% CI: -27.5, -6.4; 72 h: mean difference = -20.39, 95% CI: -35.4, -5.3) Patient age, gender, race, obesity, neoadjuvant chemotherapy, small pancreatic duct, and pancreatic fistula were not independently associated with opioid use.

CONCLUSIONS

O-RA may offer a better approach than U-RA in minimizing opioid consumption after open PD. These findings suggest the incorporation of O-RA for upper abdominal surgeries to decrease the necessity of postoperative opioids.

Preventive effect of probiotics on infections following colorectal cancer surgery: An umbrella meta-analysis

BACKGROUND

Postoperative infections remain a significant source of morbidity among patients undergoing colorectal cancer (CRC) surgery. While probiotics have been proposed as a potential strategy to mitigate the risk of these infections, contemporary meta-analyses have produced conflicting findings.

AIM

To synthesize the available evidence regarding the prophylactic efficacy of probiotics in preventing infections following CRC surgery.

METHODS

A comprehensive search of PubMed and Scopus was conducted to identify relevant meta-analyses published up to February 2024. To assess the efficacy of probiotics on outcomes, relative risks (RR) and their corresponding 95%CI were pooled using a random effects model.

RESULTS

This comprehensive umbrella meta-analysis integrated eleven meta-analyses encompassing 11518 participants who fulfilled the inclusion criteria. Probiotics administration resulted in a statistically significant reduction in the incidence of total infections (RR: 0.40, 95%CI: 0.31-0.51; moderate certainty), surgical site infections (RR: 0.56, 95%CI: 0.49-0.63; high certainty), pneumonia (RR: 0.38, 95%CI: 0.30-0.48; high certainty), urinary tract infections (RR: 0.44, 95%CI: 0.31-0.61; moderate certainty), bacteremia (RR: 0.41, 95%CI: 0.30-0.56; high certainty), and sepsis (RR: 0.35, 95%CI: 0.25-0.44; high certainty). However, probiotics did not significantly affect intra-abdominal, central line, or peritoneal infections.

CONCLUSION

Probiotics have demonstrated potential in mitigating postoperative infectious complications among patients undergoing CRC surgery.

The Combined Effect of Western Diet Consumption and Diclofenac Administration Alters the Gut Microbiota and Promotes Anastomotic Leakage in the Distal Colon

BACKGROUND

Obesity, Western diet (WD) consumption, and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are co-occurring and modifiable factors associated with microbiome dysbiosis and anastomotic leakage. We studied the combined effect of a Western-type diet (WD) and diclofenac, a standard NSAID used in surgical patients, on anastomotic healing and gut microbiota composition following distal colon resection.

METHODS

Forty-two rats were fed a WD for 6 weeks, after which they were randomized to either parenteral diclofenac 3 mg/kg/day or saline started on the day of surgery and continued for three days. The surgical procedure involved distal colon resection with anastomosis. Animals were sacrificed on postoperative day (POD)-3 or POD-5. Anastomotic healing was assessed and correlated with diclofenac treatment and gut microbiota composition, analyzed by 16S rRNA marker gene amplicon sequencing. Mucosal integrity of the anastomosis was evaluated by histological analysis.

RESULTS

Anastomotic leakage rate was 100 percent (8/8) in diclofenac-treated rats and 10 percent (1/10) in saline-treated controls on POD-5. Diclofenac administration in WD-fed animals induced a shift in microbiota composition, characterized by an increase in microbiota diversity on POD-5 and a significant 15-fold, 4-fold, and 16-fold increase of Proteobacteria, Bacteroidetes, and Verrucomicrobia, respectively. Diclofenac use in WD-fed animals caused mucosal erosion on POD-5, a phenomenon not observed in control animals.

CONCLUSIONS

Consumption of a Western diet combined with diclofenac administration shifts the microbiota composition, associated with clinically relevant AL in the distal colon of rats.

Effects of diet and antibiotics on anastomotic healing: A mouse model study with varied dietary fiber and fat, and pre-operative antibiotics

INTRODUCTION

This study investigated the separate impacts of diet and pre-operative antibiotics on gut microbiome and colonic anastomotic healing using a mouse model.

METHODS

Male C57BL/6J mice were fed either low-fat-high-fibre (SD) or high-fat-low-fiber (WD) groups for 6 weeks, then further received either pre-operative antibiotics or a control sham before a colonic anastomotic procedure was performed. After 7 days, the anastomosis was assessed and microbiota composition and biodiversity were analyzed in anastomotic tissue and stool.

RESULTS

WD-fed mice had shorter survival (5.2 ​± ​2.3 vs. 6.9 ​± ​2.3 days, p ​= ​0.022), increased weight loss (5.55 ​± ​3.80g vs. 2.65 ​± ​2.36g, p ​= ​0.03), and reduced biodiversity compared to SD-fed mice. Pre-operative antibiotics improved anastomotic healing scores (1.33 ​± ​0.65 vs. 2.08 ​± ​0.79, p ​= ​0.02) and reduced Enterococcus faecalis growth in tissue and stool (p ​= ​0.02, p ​= ​0.02). Improved anastomotic healing correlated with lower Enterococcus abundance (p ​= ​0.04) and higher collagen III and IV levels (p ​= ​0.01, 0.04) in anastomotic tissue.

CONCLUSION

SD promotes enhanced post-operative recovery and increased microbiome biodiversity, while pre-operative antibiotics enhance anastomotic healing by suppressing Enterococcus faecalis growth, mitigating collagen III/IV degradation.

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.

Applicability of sodium butyrate preparations from a surgeon's and gastroenterologist's perspective

In recent years, much has been written about the possibilities of using exogenous sodium butyrate in the prevention and treatment of gastrointestinal diseases, in prehabilitation, in peri- and postoperative treatment, as well as its local application. It became possible thanks to the development of a special formulation (microencapsulation technique) enabling the delivery of unstable butyrate compounds to the large intestine, where it is used primarily as a source of energy. It also plays a key role in maintaining body homeostasis by maintaining the integrity of the intestinal epithelium and stimulating the intestinal immune system. There is growing evidence of the effectiveness of sodium butyrate in various areas of health. The following article discusses the possibilities of using microencapsulated sodium butyrate in the prevention and treatment of gastrointestinal diseases from the perspective of a gastroenterologist and gastrointestinal surgeon.

Antimicrobial Prophylaxis With Ampicillin-sulbactam Compared With Cefazolin for Esophagectomy: Nationwide Inpatient Database Study in Japan

OBJECTIVE

To assess the effect of antimicrobial prophylaxis with ampicillin-sulbactam (ABPC/SBT) compared with cefazolin (CEZ) on the short-term outcomes after esophagectomy.

BACKGROUND

CEZ is widely used for antimicrobial prophylaxis in esophagectomy without procedure-specific evidence, whereas ABPC/SBT is preferred in some hospitals to target both aerobic and anaerobic oral bacteria.

METHODS

Data of patients who underwent esophagectomy for cancer between July 2010 and March 2019 were extracted from a nationwide Japanese inpatient database. Overlap propensity score weighting was conducted to compare the short-term outcomes [including surgical site infection (SSI), anastomotic leakage, and respiratory failure] between antimicrobial prophylaxis with CEZ and ABPC/SBT after adjusting for potential confounders. Sensitivity analyses were also performed using propensity score matching and instrumental variable analyses.

RESULTS

Among 17,772 eligible patients, 16,077 (90.5%) and 1695 (9.5%) patients were administered CEZ and ABPC/SBT, respectively. SSI, anastomotic leakage, and respiratory failure occurred in 2971 (16.7%), 2604 (14.7%), and 2754 patients (15.5%), respectively. After overlap weighting, ABPC/SBT was significantly associated with a reduction in SSI [odds ratio 0.51 (95% CI: 0.43-0.60)], anastomotic leakage [0.51 (0.43-0.61)], and respiratory failure [0.66 (0.57-0.77)]. ABPC/SBT was also associated with reduced respiratory complications, postoperative length of stay, and total hospitalization costs. The proportion of Clostridioides difficile colitis and noninfectious complications did not differ between the groups. Propensity score matching and instrumental variable analyses demonstrated equivalent results.

CONCLUSIONS

The administration of ABPC/SBT as antimicrobial prophylaxis for esophagectomy was associated with better short-term postoperative outcomes compared with CEZ.

Survival and cancer recurrence after short-course perioperative probiotics in a randomized trial

BACKGROUND & AIMS

The long-term impact of perioperative probiotics remains understudied while mounting evidence links microbiome and oncogenesis. Therefore, we analyzed overall survival and cancer recurrence among patients enrolled in a randomized trial of perioperative probiotics.

METHODS

6-year follow-up of surgical patients participating in a randomized trial evaluating short-course perioperative oral probiotic VSL#3 (n = 57) or placebo (n = 63).

RESULTS

Study groups did not differ in age, preoperative hemoglobin, ASA status, and Charlson comorbidity index. There was a significant difference in preoperative serum albumin (placebo group 4.0 ± 0.1 vs. 3.7 ± 0.1 g/dL in the probiotic group, p = 0.030). Thirty-seven deaths (30.8 %) have occurred during a median follow-up of 6.2 years. Overall survival stratified on preoperative serum albumin and surgical specialty was similar between groups (p = 0.691). Age (aHR = 1.081, p = 0.001), serum albumin (aHR = 0.162, p = 0.001), and surgical specialty (aHR = 0.304, p < 0.001) were the only predictors of overall survival in the multivariate model, while the placebo/probiotic group (aHR = 0.808, p = 0.726) was not predictive. The progression rate among cancer patients was similar in the probiotic group (30.3 %, 10/33) compared to the placebo group (21.2 %, 7/33; p = 0.398). The progression-free survival was not significantly different (unstratified p = 0.270, stratified p = 0.317).

CONCLUSIONS

Perioperative short-course use of VSL#3 probiotics does not influence overall or progression-free survival after complex surgery for visceral malignancy.

Intraoperative esophageal washout reduces free intraluminal tumor cells during resection of carcinomas of the esophagus and cardia

OBJECTIVE

Intraluminally shed viable tumor cells might contribute to anastomotic recurrence in cancer of the esophagus and the cardia. The study aimed to establish a method of esophageal washout and, hence, to reduce intraluminal cancer cells before esophageal anastomosis.

METHODS

Forty-eight consecutive patients with esophago-gastric resection for histologically proven cancer of the esophagus or the cardia were included in a prospective, interventional study. Before transection, the esophagus was clamped proximally to the tumor and rinsed with 1:10 diluted povidone-iodine-solution (10 × 30 ml) applied by a transorally inserted 24F-Foley catheter. The first, fifth and tenth portion of the lavage fluid were sent to cytological examination.

RESULTS

Intraoperative frozen sections confirmed clear proximal resection margins of the esophagus. The cytological examination of the fluid recovered from the esophageal washout revealed malignant cells in 13/48 patients (27%). The presence of malignant cells was significantly less likely in patients with neoadjuvant treatment than in patients without neoadjuvant treatment: 2/23 (9%) vs. 11/25 (44%) (p = 0.009). Repetitive washout reduced the probability of detectable malignant cells from 13 to 8 (62%) patients after 5, and further to 4 patients (30%) after 10 washout maneuvers.

CONCLUSIONS

Free malignant cells may be present in the esophageal lumen following intraoperative manipulation of cancers of the esophagus or cardia. Transoral washout of the esophagus is novel, feasible and enables reduction or even elimination of these tumor cells. The reliability of this procedure raises with increasing washout volume. Esophageal washout might be especially worthwhile in patients who do not receive neoadjuvant therapy.

A Transcriptomic Approach to Understand Patient Susceptibility to Pneumonia After Abdominal Surgery

OBJECTIVE

To describe immune pathways and gene networks altered following major abdominal surgery and to identify transcriptomic patterns associated with postoperative pneumonia.

BACKGROUND

Nosocomial infections are a major healthcare challenge, developing in over 20% of patients aged 45 or over undergoing major abdominal surgery, with postoperative pneumonia associated with an almost 5-fold increase in 30-day mortality.

METHODS

From a prospective consecutive cohort (n=150) undergoing major abdominal surgery, whole-blood RNA was collected preoperatively and at 3 time-points postoperatively (2-6, 24, and 48 h). Twelve patients diagnosed with postoperative pneumonia and 27 matched patients remaining infection-free were identified for analysis with RNA-sequencing.

RESULTS

Compared to preoperative sampling, 3639 genes were upregulated and 5043 downregulated at 2 to 6 hours. Pathway analysis demonstrated innate-immune activation with neutrophil degranulation and Toll-like-receptor signaling upregulation alongside adaptive-immune suppression. Cell-type deconvolution of preoperative RNA-sequencing revealed elevated S100A8/9-high neutrophils alongside reduced naïve CD4 T-cells in those later developing pneumonia. Preoperatively, a gene-signature characteristic of neutrophil degranulation was associated with postoperative pneumonia acquisition ( P =0.00092). A previously reported Sepsis Response Signature (SRSq) score, reflecting neutrophil dysfunction and a more dysregulated host response, at 48 hours postoperatively, differed between patients subsequently developing pneumonia and those remaining infection-free ( P =0.045). Analysis of the novel neutrophil gene-signature and SRSq scores in independent major abdominal surgery and polytrauma cohorts indicated good predictive performance in identifying patients suffering later infection.

CONCLUSIONS

Major abdominal surgery acutely upregulates innate-immune pathways while simultaneously suppressing adaptive-immune pathways. This is more prominent in patients developing postoperative pneumonia. Preoperative transcriptomic signatures characteristic of neutrophil degranulation and postoperative SRSq scores may be useful predictors of subsequent pneumonia risk.

Indocyanine green fluorescence angiography could reduce the risk of anastomotic leakage in rectal cancer surgery: a systematic review and meta-analysis of randomized controlled trials

AIM

Several papers have shown that use of indocyanine green (ICG) decreases incidence of anastomotic leakage (AL) during colonic surgery, but no clear evidence has been found for rectal cancer surgery. Therefore, with this systematic review and meta-analysis of randomized controlled trials (RCTs) we aimed to assess if ICG could also reduce risk of AL in rectal cancer surgery.

METHOD

PubMed, Scopus, CINAHL and Cochrane databases were searched for RCTs assessing the effect of intraoperative ICG on the incidence of AL of the colorectal anastomosis. Pooled relative risk (RR) and pooled risk difference (RD) were obtained using models with random effects. Risk of bias was evaluated with the Rob2 tool and the quality of evidence was assessed using the GRADE Pro tool.

RESULTS

Four RCTs were included for analysis, with a total of 1510 patients (743 controls and 767 ICG patients). The rate of AL was 9% in the ICG group (69/767) and 13.9% (103/743) in the control group (p = 0.003, RR -0.5, 95% CI -0.827 to -0.172, heterogeneity test 0%, p = 0.460). The RD in terms of incidence of AL was significantly decreased by 4.51% (p = 0.031, 95% CI -0.086 to -0.004, heterogeneity test 28%, p = 0.182) when using ICG.

CONCLUSION

Our meta-analysis suggested that use of ICG during rectal cancer surgery could reduce the rate of AL.

Poor prognosis of young male patients with stage III colorectal cancer: A multicenter retrospective study

BACKGROUND AND OBJECTIVES

The number of young patients with colorectal cancer (CRC) is increasing. However, sex-dependent differences in the prognosis of young CRC remain unknown.

METHODS

We investigated patients aged <70 years with stage III CRC treated between January 2000 and December 2010 in 24 Japanese referral hospitals. Patients were divided into subgroups by age of 50 years (early-onset and late-onset groups) and sex, and clinical characteristics and survival outcomes were compared. Risk factors associated with poor survival outcomes were also analyzed.

RESULTS

Among 4758 consecutive patients, 771 (16%) were <50 years. Regardless of sex, there were more patients with rectal cancer and treated with adjuvant chemotherapy in the early-onset group. Among males, tumors in the early-onset group were poorly differentiated (p < 0.001), and patients were diagnosed at an advanced N stage (p = 0.010). Among females, there were more patients with left-sided cancer in the early-onset group (p < 0.001). Relapse-free survival (RFS) and overall survival (OS) were worse in the early-onset group than in the late-onset group (5-year RFS rates: 58% and 63%, p = 0.024; 5-year OS rates: 76% and 81%, p = 0.041, respectively), while there were no age-dependent differences in the survival outcomes of female CRC patients. A multivariate analysis identified age <50 years as one of the independent risk factors associated with poor RFS in male stage III CRC patients (p = 0.032) CONCLUSIONS: Young male patients with stage III CRC showed poorer survival outcomes than their older counterparts. Therefore, age- and sex-related differences in the incidence of CRC recurrence need to be considered.

A Transcriptomic Approach to Understand Patient Susceptibility to Pneumonia After Abdominal Surgery

OBJECTIVE

To describe immune pathways and gene networks altered following major abdominal surgery and to identify transcriptomic patterns associated with postoperative pneumonia.

BACKGROUND

Nosocomial infections are a major healthcare challenge, developing in over 20% of patients aged 45 or over undergoing major abdominal surgery, with postoperative pneumonia associated with an almost 5-fold increase in 30-day mortality.

METHODS

From a prospective consecutive cohort (n=150) undergoing major abdominal surgery, whole-blood RNA was collected preoperatively and at 3 time-points postoperatively (2-6, 24, and 48 h). Twelve patients diagnosed with postoperative pneumonia and 27 matched patients remaining infection-free were identified for analysis with RNA-sequencing.

RESULTS

Compared to preoperative sampling, 3639 genes were upregulated and 5043 downregulated at 2 to 6 hours. Pathway analysis demonstrated innate-immune activation with neutrophil degranulation and Toll-like-receptor signaling upregulation alongside adaptive-immune suppression. Cell-type deconvolution of preoperative RNA-sequencing revealed elevated S100A8/9-high neutrophils alongside reduced naïve CD4 T-cells in those later developing pneumonia. Preoperatively, a gene-signature characteristic of neutrophil degranulation was associated with postoperative pneumonia acquisition ( P =0.00092). A previously reported Sepsis Response Signature (SRSq) score, reflecting neutrophil dysfunction and a more dysregulated host response, at 48 hours postoperatively, differed between patients subsequently developing pneumonia and those remaining infection-free ( P =0.045). Analysis of the novel neutrophil gene-signature and SRSq scores in independent major abdominal surgery and polytrauma cohorts indicated good predictive performance in identifying patients suffering later infection.

CONCLUSIONS

Major abdominal surgery acutely upregulates innate-immune pathways while simultaneously suppressing adaptive-immune pathways. This is more prominent in patients developing postoperative pneumonia. Preoperative transcriptomic signatures characteristic of neutrophil degranulation and postoperative SRSq scores may be useful predictors of subsequent pneumonia risk.

Modulating Gut Microbiota Prevents Anastomotic Leak to Reduce Local Implantation and Dissemination of Colorectal Cancer Cells after Surgery

PURPOSE

Anastomotic leak (AL) is a major complication in colorectal cancer surgery and consists of the leakage of intestinal content through a poorly healed colonic wound. Colorectal cancer recurrence after surgery is a major determinant of survival. We hypothesize that AL may allow cancer cells to escape the gut and lead to cancer recurrence and that improving anastomotic healing may prevent local implantation and metastatic dissemination of cancer cells.

EXPERIMENTAL DESIGN

We investigated the association between AL and postoperative outcomes in patients with colorectal cancer. Using mouse models of poor anastomotic healing, we assessed the processes of local implantation and dissemination of cancer cells. The effect of dietary supplementation with inulin and 5-aminosalicylate (5-ASA), which activate PPAR-γ in the gut, on local anastomotic tumors was assessed in mice undergoing colonic surgery. Inulin and 5-ASA were also assessed in a mouse model of liver metastasis.

RESULTS

Patients experiencing AL displayed lower overall and oncologic survival than non-AL patients. Poor anastomotic healing in mice led to larger anastomotic and peritoneal tumors. The microbiota of patients with AL displays a lower capacity to activate the antineoplastic PPAR-γ in the gut. Modulation of gut microbiota using dietary inulin and 5-ASA reinforced the gut barrier and prevented anastomotic tumors and metastatic spread in mice.

CONCLUSIONS

Our findings reinforce the hypothesis that preventing AL is paramount to improving oncologic outcomes after colorectal cancer surgery. Furthermore, they pave the way toward dietary targeting of PPAR-γ as a novel way to enhance healing and diminish cancer recurrence.

Role of Microbiome in the Outcomes Following Surgical Repair of Perianal Fistula: Prospective Cohort Study Design and Preliminary Results

BACKGROUND

Anal fistulae are common, predominantly cryptoglandular, and almost invariably require surgical treatment. Recurrences are common for procedures other than fistulotomy regardless of technique and adequacy of repair. Growing evidence supports the pivotal role of specific intestinal bacteria in anastomotic failures after bowel resection. Anal crypts harbor colonic microbiota suggesting that similar mechanisms to anastomotic healing might prevail after anal fistula repair and hence influence healing. This study aims at assessing the potential role of the intestinal microbiome in the clinical outcomes after surgical repair of cryptoglandular anal fistula.

METHODS

This is a pilot prospective cohort study enrolling patients with anal fistula undergoing endoanal advancement flap. For microbiome analysis, stool samples are taken via rectal swab before the procedure; additionally, a portion of the fistula is collected intraoperatively after fistulectomy. Samples from groups with treatment failure are compared to samples from patients who healed after surgical repair. Alpha and beta diversities and differential abundance of microbial taxa are determined and compared between groups with DADA2 analytical pipeline.

RESULTS

Five patients have been enrolled to date (one female, four male). At median follow-up of 6 months (2-11), one patient experienced disease recurrence at 3 months. DNA from the 5 rectal swab and tissue samples was extracted, showing increased relative abundance of Enterococcus faecalis in samples from the patient who developed a recurrent fistula but not in those without recurrence.

CONCLUSION

These very preliminary data suggest that intestinal microbiome may represent a crucial determinant of the surgical outcomes after anal fistula surgery.

Diet-induced shifts in the gut microbiota influence anastomotic healing in a murine model of colonic surgery

Host diet and gut microbiota interact to contribute to perioperative complications, including anastomotic leak (AL). Using a murine surgical model of colonic anastomosis, we investigated how diet and fecal microbial transplantation (FMT) impacted the intestinal microbiota and if a predictive signature for AL could be determined. We hypothesized that a Western diet (WD) would impact gut microbial composition and that the resulting dysbiosis would correlate with increased rates of AL, while FMT from healthy, lean diet (LD) donors would reduce the risk of AL. Furthermore, we predicted that surgical outcomes would allow for the development of a microbial preclinical translational tool to identify AL. Here, we show that AL is associated with a dysbiotic microbial community characterized by increased levels of Bacteroides and Akkermansia. We identified several key taxa that were associated with leak formation, and developed an index based on the ratio of bacteria associated with the absence and presence of leak. We also highlight a modifiable connection between diet, microbiota, and anastomotic healing, potentially paving the way for perioperative modulation by microbiota-targeted therapeutics to reduce AL.

Results of the Eighth Scientific Workshop of ECCO: Pathophysiology and Risk Factors of Postoperative Crohn's Disease Recurrence after an Ileocolonic Resection

Postoperative recurrence [POR] after an ileocolonic resection with ileocolonic anastomosis is frequently encountered in patients with Crohn's disease. The 8th Scientific Workshop of ECCO reviewed the available evidence on the pathophysiology and risk factors for POR. In this paper, we discuss published data on the role of the microbiome, the mesentery, the immune system and the genetic background. In addition to investigating the causative mechanisms of POR, identification of risk factors is essential to tailor preventive strategies. Potential clinical, surgical and histological risk factors are presented along with their limitations. Emphasis is placed on unanswered research questions, guiding prevention of POR based on individual patient profiles.

Anastomotic leak in colorectal cancer surgery: Contribution of gut microbiota and prediction approaches

AIM

To monitor prospectively the occurrence of colorectal anastomotic leakage (CAL) in patients with colon cancer undergoing resectional surgery, characterizing the microbiota in both faeces and mucosal biopsies of anastomosis. In a second stage, we investigated the ability to predict CAL using machine learning models based on clinical data and microbiota composition.

METHOD

A total of 111 patients were included, from whom a faecal sample was obtained, as well as biopsy samples from proximal and distal sites in the healthy margins of the tumour piece. The microorganisms present in the samples were investigated using microbial culture and 16S rDNA massive sequencing. Collagenase and protease production was determined, as well as the presence of genes responsible for expressing enzymes with these activities. Machine learning analyses were developed using clinical and microbiological data.

RESULTS

The incidence of CAL was 9.0%, and CAL was associated with collagenase/protease-producing Enterococcus. Significant differences were found in the microbiota composition of proximal and distal biopsy samples, but not in faecal samples, among patients who developed CAL. Clinical predictors of CAL were 5-day C-reactive protein and heart disease, whereas 3-day C-reactive protein and diabetes were negative predictors.

CONCLUSION

Biopsy samples from surgical margins, rather than faecal samples, are the most appropriate samples for exploring the contribution of the intestinal microbiota to CAL. Enterococci are only enriched in the anastomosis after surgery, and their collagenases and proteases are involved in the degradation of the anastomotic scar.

Prediagnostic Prescription Antibiotics Use and Survival in Patients with Colorectal Cancer: A Swedish National Register-Based Study

BACKGROUND

Antibiotics use is associated with higher colorectal cancer risk, but little is known regarding any potential effects on survival.

METHODS

We conducted a nationwide cohort study, using complete-population data from Swedish national registers between 2005 and 2020, to investigate prediagnostic prescription antibiotics use in relation to survival in colorectal cancer patients.

RESULTS

We identified 36,061 stage I-III and 11,242 stage IV colorectal cancer cases diagnosed between 2010 and 2019. For stage I-III, any antibiotics use (binary yes/no variable) was not associated with overall or cancer-specific survival. Compared with no use, moderate antibiotics use (total 11-60 days) was associated with slightly better cancer-specific survival [adjusted HR (aHR) = 0.93; 95% confidence interval (CI), 0.86-0.99)], whereas very high use (>180 days) was associated with worse survival [overall survival (OS) aHR = 1.42; 95% CI, 1.26-1.60, cancer-specific survival aHR = 1.31; 95% CI, 1.10-1.55]. In analyses by different antibiotic types, although not statistically significant, worse survival outcomes were generally observed across several antibiotics, particularly macrolides and/or lincosamides. In stage IV colorectal cancer, inverse relationships between antibiotics use and survival were noted.

CONCLUSIONS

Overall, our findings do not support any substantial detrimental effects of prediagnostic prescription antibiotics use on cancer-specific survival after colorectal cancer diagnosis, with the possible exception of very high use in stage I-III colorectal cancer. Further investigation is warranted to confirm and understand these results.

IMPACT

Although the study findings require confirmation, physicians probably do not need to factor in prediagnostic prescription antibiotics use in prognosticating patients with colorectal cancer.

Identification of host gene-microbiome associations in colorectal cancer patients using mendelian randomization

BACKGROUND

There are many studies indicating that alterations in the abundance of certain gut microbiota are associated with colorectal cancer (CRC). However, a causal relationship has not been identified due to confounding factors such as lifestyle, environmental, and possible reverse causal associations between the two. Furthermore, certain host gene mutations can also contribute to the development of CRC. However, the association between genes and gut microbes in patients with CRC has not been extensively studied.

METHODS

We conducted a two-sample Mendelian randomization (MR) study to reveal the causal relationship between gut microbiota and CRC. We obtained SNPs associated with gut microbiome abundance as instrumental variables (IVs) from a large-scale, multi-ethnic GWAS study, and extracted CRC-related datasets from an East Asian Population genetic consortia GWAS (AGWAS) study and FinnGen consortium, respectively. We analyzed a total of 166 bacterial features at four taxonomic levels, including order, family, genus, and species. The inverse-variance-weighted (IVW), weighted median, MR-Egger, and simple median methods were applied to the MR analysis, and the robustness of the results were tested using a series of sensitivity analyses. We extracted IVs of gut microbiota with direct causal association with CRC for SNP annotation to identify the genes in which these genetic variants were located to reveal the possible host gene-microbiome associations in CRC patients.

RESULTS

The findings from our MR analysis based on CRC-associated GWAS datasets from AGWAS revealed causal relationships between 6 bacterial taxa and CRC at a locus-wide significance level (P < 1 × 10-5). The IVW method found that family Porphyromonadaceae, genera Anaerotruncus, Intestinibacter, Slackia, and Ruminococcaceae UCG004, and species Eubacterium coprostanoligenes group were positively associated with CRC risk, which was generally consistent with the results of other complementary analyses. The results of a meta-analysis of the MR estimates from the AGWAS and the FinnGen datasets showed that family Porphyromonadaceae and genera Slackia, Anaerotruncus, and Intestinibacter replicated the same causal association. Sensitivity analysis of all causal associations did not indicate significant heterogeneity, horizontal pleiotropy, or reverse causal associations. We annotated the SNPs at a locus-wide significance level of the above intestinal flora and identified 24 host genes that may be related to pathogenic intestinal microflora in CRC patients.

CONCLUSION

This study supported the causal relationship of gut microbiota on CRC and revealed a possible correlation between genes and pathogenic microbiota in CRC. These findings suggested that the study of the gut microbiome and its further multi-omics analysis was important for the prevention and treatment of CRC.

Selective Decontamination with Oral Antibiotics in Colorectal Surgery: 90-day Reintervention Rates and Long-term Oncological Follow-up

BACKGROUND

Oral antibiotics (OAB) in colorectal surgery have been shown to reduce surgical site infections (SSIs) and possibly anastomotic leakage. However, evidence on long-term follow-up, reintervention rates and 5-year oncological follow-up is lacking. The current study aims at elucidating this knowledge gap.

METHODS

This study evaluated the long-term effectiveness of perioperative 'Selective decontamination of the digestive tract' (SDD) in colorectal cancer surgery. The primary outcome was anastomotic leakage within 90 days, secondary outcomes included infectious complications, reinterventions, readmission, hospital stay, and 5-year overall and disease-free-survival. Statistical analysis including univariate and multivariate analysis was performed to identify predictors of 90-day outcomes, and Kaplan-Meier survival analysis was used for the 5-year survival outcomes.

RESULTS

In total 455 patients were analyzed, 228 participants in the SDD group and 227 in the control group. Anastomotic leakage rate was not statistically different between the SDD and control group (6.6% versus 9.7%). One or more infectious complications occurred in 15.4% of patients in the SDD group and in 28.2% in the control group (OR 0.46, 95% C.I. 0.29 - 0.73). In the SDD group 8,8% of patients required a reintervention compared to 16,3% of patients in the control group (OR 0.47, 95% C.I. 0.26 - 0.84). After multivariable analysis SDD remained significant in reducing both infectious complications and reinterventions after 90-days follow-up. There was no difference between SDD and control group in 5-year overall survival and disease-free-survival.

CONCLUSION

SDD as OAB is effective in reducing 90-days postoperative infectious complications and reinterventions. As such, SDD as standard OAB in elective colorectal surgery is highly recommended.

Impact of Anastomotic Leak on Long-term Oncological Outcomes After Restorative Surgery for Rectal Cancer: A Retrospective Cohort Study

BACKGROUND

Anastomotic leak after restorative surgery for rectal cancer is a major complication and may lead to worse long-term oncological and survival outcomes.

OBJECTIVE

The purpose of this study was to identify risk factors associated with anastomotic leak and to assess the perioperative and long-term oncological impact of anastomotic leak in our cohort of patients with rectal cancer.

DESIGN

A retrospective analysis was performed on data from the prospectively maintained Cabrini Monash colorectal neoplasia database. Patients who had undergone rectal cancer resection and subsequently received anastomosis between November 2009 and May 2020 were included in this study. Patient and tumor characteristics, technical risk factors, and short-term and perioperative as well as long-term oncological and survival outcomes were assessed.

SETTINGS

The study was conducted in 3 tertiary hospitals.

PATIENTS

A total of 693 patients met the inclusion criteria for this study.

MAIN OUTCOME MEASURES

Univariate analyses were performed to assess the relationship between anastomotic leak and patient and technical risk factors, as well as perioperative and long-term outcomes. Univariate and multivariate proportional HR models of overall and disease-free survival were calculated. Kaplan-Meier survival analyses assessed disease-free and overall survival.

RESULTS

Anastomotic leak rate was 3.75%. Males had an increased risk of anastomotic leak, as did patients with hypertension and ischemic heart disease. Patients who experience an anastomotic leak were more likely to require reoperation and hospital readmission and were more likely to experience an inpatient death. Disease-free and overall survival were also negatively impacted by anastomotic leaks.

LIMITATIONS

This is a retrospective analysis of data from only 3 centers with the usual limitations. However, these effects have been minimized because of the high quality and completeness of the prospective data collection.

CONCLUSIONS

Anastomotic leaks after restorative surgery negatively affect long-term oncological and survival outcomes for patients with rectal cancer. See Video Abstract at http://links.lww.com/DCR/C81 .

IMPACTO DE LA FUGA ANASTOMTICA EN LOS RESULTADOS ONCOLGICOS A LARGO PLAZO TRAS CIRUGA RESTAURADORA PARA EL CNCER DE RECTO UN ESTUDIO DE COHORTE RETROSPECTIVO

ANTECEDENTES:La fuga anastomótica tras una cirugía restauradora para el cáncer de recto es una complicación mayor y puede conducir a peores resultados oncológicos y de supervivencia a largo plazo.OBJETIVO:El propósito de este estudio fue identificar los factores de riesgo asociados con la fuga anastomótica y evaluar el impacto oncológico perioperatorio y a largo plazo de la fuga anastomótica en nuestra cohorte de pacientes con cáncer de recto.DISEÑO:Se realizó un análisis retrospectivo de datos obtenidos de la base de datos Cabrini Monash sobre neoplasia colorrectal la cual es mantenida prospectivamente. Se incluyeron en este estudio pacientes que fueron sometidos a una resección del cáncer de recto y que posteriormente recibieron una anastomosis entre noviembre de 2009 y mayo de 2020. Se evaluaron las características del paciente y del tumor, los factores de riesgo relacionados a la técnica, los resultados oncológicos y de supervivencia perioperatorio, así como los resultados a corto y largo plazo.AJUSTES:El estudio se realizó en tres hospitales terciarios.PACIENTES:Un total de 693 pacientes cumplieron con los criterios de inclusión para este estudio.PRINCIPALES MEDIDAS DE RESULTADO:Se realizaron análisis univariados para evaluar la relación entre la fuga anastomótica y aquellos factores relacionados al paciente, a la técnica, así como los resultados perioperatorios y a largo plazo. Se calcularon modelos de razón de riesgo proporcional univariante y multivariante de supervivencia global y libre de enfermedad. Los análisis de supervivencia de Kaplan-Meier evaluaron la supervivencia libre de enfermedad y la supervivencia global.RESULTADOS:La tasa de fuga anastomótica fue del 3,75%. Los hombres tenían un mayor riesgo de fuga anastomótica al igual que aquellos pacientes con hipertensión y cardiopatía isquémica. Los pacientes que sufrieron una fuga anastomótica tuvieron mayores probabilidades de requerir una reintervención y reingreso hospitalario, así como también tuvieron mayores probabilidades de sufrir una muerte hospitalaria. La supervivencia libre de enfermedad y general también se vio afectada negativamente por las fugas anastomóticas.LIMITACIONES:Este es un análisis retrospectivo de datos de solo tres centros con las limitaciones habituales. Sin embargo, estos efectos han sido minimizados debido a la alta calidad y la exhaustividad de la recopilación prospectiva de datos.CONCLUSIONES:Las fugas anastomóticas después de una cirugía restauradora afectan negativamente los resultados oncológicos y de supervivencia a largo plazo para los pacientes con cáncer de recto. Consulte Video Resumen en http://links.lww.com/DCR/C81 . (Traducción-Dr. Osvaldo Gauto ).

Indole metabolites and colorectal cancer: Gut microbial tryptophan metabolism, host gut microbiome biomarkers, and potential intervention mechanisms

Tryptophan (Trp) functions in host-disease interactions. Its metabolism is a multi-pathway process. Indole and its derivatives are Trp metabolites unique to the human gut microbiota. Changes in Trp metabolism have also been detected in colorectal cancer (CRC). Here, combined with the existing CRC biomarkers, we ascribed it to the altered bacteria having the indole-producing ability by making a genomic prediction. We also reviewed the anti-inflammatory and possible anti-cancer mechanisms of indoles, including their effects on tumor cells, the ability to repair the gut barrier, regulation of the host immune system, and provide resistance against oxidative stress. Indole and its derivatives, along with related bacteria, could be targeted as auxiliary strategies to restrain cancer development in the future.

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 Influence of the Microbiome on Metastatic Colorectal Cancer

The microbiome (bacteria, viruses, and fungi) that exist within a patient's gastrointestinal tract and throughout their body have been increasingly understood to play a critical role in a variety of disease, including a number of cancer histologies. These microbial colonies are reflective of a patient's overall health state, their exposome, and germline genetics. In the case of colorectal adenocarcinoma, significant progress has been made in understanding the mechanism the microbiome plays beyond mere associations in both disease initiation and progression. Importantly, this improved understanding holds the potential to further identify the role these microbes play in colorectal cancer. We hope this improved understanding will be able to be leveraged in the future through either biomarkers or next-generation therapeutics to augment contemporary treatment algorithms through the manipulation of a patient's microbiome-whether through diet, antibiotics, prebiotics, or novel therapeutics. Here we review the role of the microbiome in the setting of patients with stage IV colorectal adenocarcinoma in both the development and progression or disease as well as response to therapeutics.

The Debate between the Human Microbiota and Immune System in Treating Aerodigestive and Digestive Tract Cancers: A Review

The human microbiota comprises a group of microorganisms co-existing in the human body. Unbalanced microbiota homeostasis may impact metabolic and immune system regulation, shrinking the edge between health and disease. Recently, the microbiota has been considered a prominent extrinsic/intrinsic element of cancer development and a promising milestone in the modulation of conventional cancer treatments. Particularly, the oral cavity represents a yin-and-yang target site for microorganisms that can promote human health or contribute to oral cancer development, such as Fusobacterium nucleatum. Moreover, Helicobacter pylori has also been implicated in esophageal and stomach cancers, and decreased butyrate-producing bacteria, such as Lachnospiraceae spp. and Ruminococcaceae, have demonstrated a protective role in the development of colorectal cancer. Interestingly, prebiotics, e.g., polyphenols, probiotics (Faecalibacterium, Bifidobacterium, Lactobacillus, and Burkholderia), postbiotics (inosine, butyrate, and propionate), and innovative nanomedicines can modulate antitumor immunity, circumventing resistance to conventional treatments and could complement existing therapies. Therefore, this manuscript delivers a holistic perspective on the interaction between human microbiota and cancer development and treatment, particularly in aerodigestive and digestive cancers, focusing on applying prebiotics, probiotics, and nanomedicines to overcome some challenges in treating cancer.

Early and late anastomotic leak after colorectal surgery: A systematic review of the literature

The aim of this study was to review and to assess the quality of the scientific articles regarding early and late anastomotic leak (AL) after colorectal surgery and their risk factors. An electronic systematic search for articles on Colorectal Surgery, AL and its timing was undertaken using the MEDLINE database via PubMed, Cochrane and Embase. The selected articles were thoroughly reviewed and assessed for methodological quality using a validated methodology quality score (MINCIR score). This review was registered in the PROSPERO registry under ID: CRD42022303012. 9 articles were finally reviewed in relation to the topic of early and late anastomotic leak. There is a lack of consensus regarding the exact cut-off in time to define early and late anastomotic leak, but it is clear that they are two differentiated entities. The first, occurring in relation to technical factors; whereas the latter, is related to impaired healing.

The Colorectal Anastomosis: A Timeless Challenge

Colorectal anastomosis is a sophisticated problem that demands an elaborate discussion and an elegant solution. "Those who forget the past are condemned to repeat it." George Santayana, Life of Reason , 1905.

Role of transanal drainage tubes in preventing anastomotic leakage after low anterior resection: a meta-analysis of randomized controlled trials

BACKGROUND

The transanal drainage tube (TDT) is thought to reduce the incidence of anastomotic leakage (AL) in patients with low anterior resection (LAR). However, results from different clinical trials are inconsistent, although nearly all meta-analyses agree on the efficacy. In contrast to results of many previous studies, 2 recent independent randomized controlled trials (RCTs) suggest that the use of TDT does not prevent AL. We performed a meta-analysis including only RCTs to compare patients with TDTs vs. those without TDTs in terms of AL rate.

METHODS

A systematic literature search was performed in the PubMed, Embase, Cochrane Library databases, Clinicaltrials.gov and WHO/ICTRP from inception until February 14, 2022. RCTs that evaluated the role of TDTs in AL prevention in patients who underwent LAR for rectal cancer were included. A meta-analysis was performed according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines. Data were extracted by two authors independently, and random-effects models were implemented. The main outcome was AL, and the secondary outcome was the grade of AL.

RESULTS

Three RCTs were included involving a total of 1115 participants (559 patients in the TDT group and 556 in the non-TDT group). No significant difference in the AL rate was detected (RR = 0.69, 95% confidence interval (CI) 0.42-1.15, p = 0.15, I2 = 21%, very low certainty evidence). The incidence of grade C AL was possibly lower in the TDT group (RR = 0.33, 95% CI 0.11-1.01, p = 0.05, very low certainty evidence), while the rate of grade B AL was similar between the two groups (RR = 1.17, 95% CI 0.66-2.08, p = 0.59, very low certainty evidence).

CONCLUSIONS

The present meta-analysis suggests that TDTs are not effective in reducing the overall incidence of AL, but possibly have a potential benefit in reducing the occurrence of grade C AL in patients with LAR. Based on the current limited data and existing heterogeneity, the inclusion of larger populations and the identification of more uniform indications for TDT need to be addressed in future studies.

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.

Fluorescence angiography likely protects against anastomotic leak in colorectal surgery: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

Observational studies have shown that fluorescence angiography (FA) decreases the incidence of anastomotic leak (AL) in colorectal surgery, but high-quality pooled evidence was lacking. Therefore, we aimed at confirming this preliminary finding using a systematic review and meta-analysis of randomised controlled trials (RCTs) in the field.

METHODS

MEDLINE, Embase and CENTRAL were searched for RCTs assessing the effect of intra-operative FA versus standard assessment of bowel perfusion on the incidence of AL of colorectal anastomosis. The systematic review complied with the PRISMA 2020 and AMSTAR2 recommendations and was registered in PROSPERO. Pooled relative risk (RR) and pooled risk difference (RD) were obtained using models with random effects. Heterogeneity was assessed using the Q-test and quantified using the I2 value. Certainty of evidence was assessed using the GRADE Pro tool.

RESULTS

One hundred and eleven articles were screened, 108 were excluded and three were kept for inclusion. The three included RCTs compared assessment of the perfusion of the bowel during creation of a colorectal anastomosis using FA versus standard practice. In meta-analysis, FA was significantly protective against AL (3 RCTs, 964 patients, RR: 0.67, 95% CI: 0.46 to 0.99, I2: 0%, p = 0.04). The RD of AL was non-significantly decreased by 4 percentage points (95%CI: - 0.08 to 0, I2: 8%, p = 0.06) when using FA. Certainty of evidence was considered as moderate.

CONCLUSION

The effect of FA on prevention of AL in colorectal surgery exists but is potentially of small magnitude. Considering the potential magnitude of effect of FA, we advise that future RCTs have an adequate sample size, include a cost-benefit analysis of the technique and better define the subpopulation who could benefit from FA.

Implantation of an Impedance Sensor for Early Detection of Gastrointestinal Anastomotic Leaks

INTRODUCTION

Accurate early diagnosis of a gastrointestinal anastomotic leak remains a challenge. When an anastomotic leak develops, the electrical properties of the tissue undergoing inflammatory processes change, resulting from the extravasation of inflammatory fluid and cellular infiltration. The method described here intends to provide a novel early anastomotic leak warning system based upon measurable changes in tissue impedance nearby an acute inflammatory process.

METHODS

A biodegradable Mg-alloy was compared with a nonabsorbable stainless steel (STS) electrode connected to a wireless recording system for impedance measurement. In vitro measurements were made in physiological solutions and small animal (eight mice) and large animal (eight pigs) models with an anastomotic leak simulated by an open colotomy. Measurements were made at 10 mm intervals from the open colon at baseline and up to 120 min comparing these with a sutured colonic wound and normal tissue.

RESULTS

In-vitro biodegradable magnesium electrode impedance evaluation showed good sensitivity to different media due to its environmental corrosion properties. The impedance of an acidic environment (1.06 ± 0.02 kΩ for citric acid) was twice that of phosphate-buffered saline (PBS) (0.64 ± 0.008 kΩ) with a distinction between Normal Saline (0.42 ± 0.013 kΩ) and PBS (0.64 ± 0.008 kΩ). This was in contrast to the performance characteristics of the control STS electrodes, where impedance in an acidic environment was lower than saline or PBS (citric acid:0.76 ± 0.01 kΩ versus PBS: 1.32 ± 0.014 kΩ). In a mouse model simulating an anastomotic leak, there was a significant increase in impedance after 120 min when compared with controls (99.7% increase versus 9.6% increase, respectively; P < 0.02). This effect was confirmed in a pig model when relative impedance measurements of the leak and control groups were compared (1.86 ± 0.46 versus 1.07 ± 0.02, respectively; P < 0.027).

CONCLUSIONS

Electrophysiological measurement shows diagnostic sensitivity for a gastrointestinal leak with potential clinical utility in the postoperative detection of early intra-abdominal sepsis. Further investigation of biodegradable tissue sensors capable of monitoring an early anastomotic leak is required.

Shenhuang Plaster Application Improves Gastrointestinal Motility in Mice with Postoperative Ileus through Intestinal Microbiota

Postoperative ileus (POI) is a common surgical complication, and its incidence remains high. Shenhuang Plaster (SHP) is a famous traditional Chinese medicine with a definite curative effect on postoperative intestinal dysfunction; however, the mechanisms involved in these effects are unclear. Accordingly, in this study, we constructed a POI mouse model and used the intestinal flora as the target to explore the regulatory effect of SHP on gastrointestinal motility. The results illustrated that SHP applied at the Shenque acupoint promoted the recovery of gastrointestinal motility, relieved intestinal villus atrophy and basal damage caused by POI, protected the integrity of intestinal tissue morphology, and alleviated the inflammatory response in the intestinal tissue of POI model mice. In addition, we clarified the role of the intestinal flora in the occurrence and development of POI, further evaluated the changes in the intestinal flora in each group of mice, and analysed the regulatory effect of SHP on the intestinal flora in mice with POI. The results suggested that SHP might improve gastrointestinal motility disorder in POI mice by effectively regulating intestinal flora.

Correlation between Colon Perfusion and Postoperative Fecal Output through a Transanal Drainage Tube during Laparoscopic Low Anterior Resection

In order to prevent anastomotic leakage (AL) following rectal surgery, various solutions—such as intraoperative indocyanine green (ICG) angiography and transanal drainage tubes (TDT)—have been proposed. This study investigated the relationship between intestinal perfusion and fecal volume through TDT in laparoscopic low anterior resection (LAR). A total of 59 rectal cancer patients who underwent laparoscopic LAR with both intraoperative ICG angiography and postoperative TDT placement were retrospectively analyzed. The relationship between intestinal perfusion and fecal volume through TDT was examined. Based on the ICG fluorescence, the transection site was shifted more proximally in 20 cases (33.9%). Symptomatic AL occurred in seven patients (11.8%). The AL rate of the patients whose daily fecal volume exceeded 100 mL/day in 2 or more days was significantly higher than that of those whose daily fecal volume exceeded it in 0 or 1 day (44.4% vs. 6.0%; p < 0.01). Univariate and multivariate analyses showed that the need for a proximal shift of the transection site was significantly associated with a high fecal volume. The quantitative analysis of ICG fluorescence indicated that Fmax (the fluorescence difference between the baseline and maximum) was significantly associated with fecal volume through TDT.

Changes of Intestinal Microflora in Colorectal Cancer Patients after Surgical Resection and Chemotherapy

OBJECTIVE

The change of bacterial flora structure in colorectal cancer (CRC) patients after treatment is not clear. The aim of this study was to explore the change and function of intestinal microflora in CRC before and after treatment.

METHOD

The 16S conserved region V3+V4 of intestinal flora obtained from CRC patients was sequenced and analyzed. Alpha and beta diversity indices were used to analyze the abundance and structure of gut flora. FAPROTAX, BugBase, and Tax4Fun software were used to analyze the species phenotypes and Kyoto Encyclopedia of Genes and Genomes Ontology (KO) function pathways.

RESULTS

Total abundance and structure of species in CRC patients were significantly increased compared with healthy people (control group) (P < 0.05), but there was no significant difference between CRC patients before and after treatment (P > 0.05). There was significant difference in relative abundance of bacteria at different levels (phylum, class, order, family, genus, and species) between the CRC group with after operation (CRC_O group) and chemotherapy (CRC_C group) treatment, particularly Prevotellaceae_UCG-001, Akkermansia, Fusicatenibacter, Tyzzerella_4, Megamonas, etc. in genus level. The KO function analysis showed that most of the bacteria with differences were mainly involved in the biosynthesis of lipopolysaccharide (Megamonas, Megasphaera, and Ruminococcus torques_group), protein digestion and absorption, renin-angiotensin system pathway (Akkermansia, Eubacterium_ruminantium_group, and Eubacterium_nodatum_group genus), adipocytokine signaling pathway and peroxisome pathway (Tyzzerella_4, Phascolarctobacterium, Ruminococcus_gnavus_group), and so on.

CONCLUSION

The abundance of intestinal microflora in CRC patients was increased significantly contrasted to healthy people, and surgery and chemotherapy were hard to reduce this phenomenon. Megamonas was involved in lipopolysaccharide biosynthesis and carcinogenesis in colorectal cancer. Surgery and drug treatment did not reduced lipopolysaccharide biosynthesis but increased the number of probiotic Akkermansia population and reduced the pathogenic bacteria Tyzzerella_4, participate in adipocytokine signaling pathway, and affect metabolism.

OUP accepted manuscript

Background

Methods

Results

Conclusion

Association between the urogenital microbiome and surgical treatment response in women undergoing midurethral sling operation for mixed urinary incontinence

BACKGROUND

The urogenital microbiome is associated with urgency and mixed urinary incontinence symptoms and differential treatment responses to pharmacotherapy for urgency urinary incontinence.

OBJECTIVE

This study aimed to describe whether the preoperative urinary and vaginal microbiomes were associated with surgical treatment responses at 12 months after a midurethral sling operation in women with mixed urinary incontinence.

STUDY DESIGN

This cohort study compared the preoperative microbiome compositions of urine and vaginal samples from a subset of women undergoing a midurethral sling operation in the Effects of Surgical Treatment Enhanced With Exercise for Mixed Urinary Incontinence trial (NCT01959347) and compared the microbiota in women who were surgical responders vs surgical nonresponders. Twelve-month objective response was defined as a ≥70% reduction from baseline urinary incontinence episodes on a 3-day diary. Subjective response was defined as a change from baseline in the Urogenital Distress Inventory scores. Bacterial abundance and beta diversity were assessed using 16S ribosomal RNA sequencing. The primary differential abundance analysis described predominant bacterial operational taxonomic units associated with responders vs nonresponders using unadjusted and age-adjusted linear models.

RESULTS

Objective nonresponders (n=28) compared with responders (n=72) were older (58.5±10.7 vs 51.6±10.2 years) and more likely postmenopausal without hormone use (odds ratio, 6.4; 95% confidence interval, 1.8-22.6). Vaginal and urinary microbiota beta diversities were associated with age (P<.05) for both responders and nonresponders. Overall, predominant operational taxonomic units (genera) were Lactobacillus, Gardnerella, Tepidimonas, Escherichia, Streptococcus, and Prevotella. Operational taxonomic units from baseline urine samples were not significantly associated (P threshold=.05) with surgical treatment responses. A greater abundance of baseline vaginal Lactobacillus was associated with an objective response (P=.04) and Prevotella with an objective nonresponse (P=.01). Adjusting for age, only a greater abundance of baseline vaginal Prevotella was associated with an objective nonresponse (P=.01). Moreover, less abundant vaginal operational taxonomic units were associated with objective and subjective responses and persistent urinary incontinence symptoms (P<.05).

CONCLUSION

Women meeting a 70% reduction of urinary incontinence treatment episodes (objective responders) had greater vaginal Lactobacillus at the time of the surgical procedure; however, controlling for age diminished this association. Women not meeting a 70% reduction of urinary incontinence episodes 1 year after a midurethral sling operation had greater vaginal Prevotella at the time of the midurethral sling operation. Further research is needed to determine whether therapy altering the vaginal microbiome may impact surgical treatment responses in women with mixed urinary incontinence.

The differences between fecal microbiota and intestinal fluid microbiota in colon polyps: An observational study

Generally, intestinal microbiota can be classified into intestinal cavity microbiota and mucosal microbiota, among which, the former is the default type. This study aimed to identify the differences between fecal microbiota and intestinal fluid microbiota in colon polys.This study enrolled patients with colon polys who met the Rome-III criteria to carry out 16s rDNA gene sequencing. Then, both fresh feces as well as intestinal fluid was sampled. Thereafter, α/β diversities, together with the heterogeneities with regard to microbial function and structure were assessed among those intestinal fluid and fresh feces samples collected.According to bioinformatics analysis, difference in α-diversity was not statistically significant between intestinal fluid microbiota and fecal microbiota among patients with colorectal polyps (CPs). Non-metric multidimensional scaling analysis of β-diversity revealed that differences were of statistical significance between both groups. In addition, linear discriminant analysis effect size analysis displayed great heterogeneities in intestinal microbiota of both groups, including Firmicutes, Clostridia, and Phascolarctobacterium. At the phylum level, difference (P = .016) in Spirochaetes was statistically significant between the intestinal fluid group and fecal group. At the family level, differences in Bacteroidaceae, Micrococcaceae, F16, Spirocheatacae, Enterobacteriaceae, Cardiobacteriaceae, Turkish Spirobacteriaceae, Bifidobacteriaceae, and Dethiosulfovibrionaceae were statistically significant between the 2 groups. At the genus level, there were statistical differences between the 2 groups in terms of Bacteroidetes, Rothia, Actinobacillus, F16, Treponema, Oscillospira, Turicibacter, Sharpea, Heamophilus, Veillonella, and Cardiobacterium.There are statistical differences in the composition between intestinal microbiota and fecal microbiota in CP patients, both of which are equally important and indispensable for analyzing the intestinal microbiota in CP patients.

Bowel decontamination before colonic and rectal surgery

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