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

Clinical significance of perioperative probiotic intervention on recovery following intestinal surgery

Restoring the balance of gut microbiota has emerged as a critical strategy in treating intestinal disorders, with probiotics playing a pivotal role in maintaining bacterial equilibrium. Surgical preparations, trauma, and digestive tract reconstruction associated with intestinal surgeries often disrupt the intestinal flora, prompting interest in the potential role of probiotics in postoperative recovery. Lan et al conducted a prospective randomized study on 60 patients with acute appendicitis, revealing that postoperative administration of Bacillus licheniformis capsules facilitated early resolution of inflammation and restoration of gastrointestinal motility, offering a novel therapeutic avenue for accelerated postoperative recovery. This editorial delves into the effects of perioperative probiotic supplementation on physical and intestinal recovery following surgery. Within the framework of enhanced recovery after surgery, the exploration of new probiotic supplementation strategies to mitigate surgical complications and reshape gut microbiota is particularly intriguing.

Acute perioperative alterations in metabolism: A pilot study using mass spectrometry-based metabolomics

OBJECTIVE

To characterize early physiologic stresses imposed by surgery by applying metabolomic analyses to deeply phenotype pre- and postoperative plasma and urine of patients undergoing elective surgical procedures.

BACKGROUND

Patients experience perioperative stress through depletion of metabolic fuels. Bowel stasis or injury might allow more microbiome-derived uremic toxins to enter the blood, while the liver and kidney are simultaneously clearing analgesic and anesthetic drugs. Metabolomics provides a broad-scale snapshot of small-molecule chemicals generated in vital energetic and detoxification pathways, enabling a mechanistic understanding of surgical stressors.

METHODS

We performed metabolomic analysis of paired preoperative and early-recovery plasma (n = 34) and urine (n = 35) from patients who underwent elective surgeries, spanning cardiovascular, gastrointestinal, hernia, oncologic, and urologic procedures. Mass spectrometry-based metabolomics analyses were performed together with the analysis of select metabolites and macromolecules via conventional clinical assays.

RESULTS

Fuel stress during elective surgery manifested in changes across all major metabolic pathways, encompassing lipolysis, glycolysis-Krebs cycle, ketogenesis, and glycogenolysis. A common signature of enhanced amino acid oxidation and urea-cycle activity emerged, which was especially pronounced in patients given citrulline boluses before visceral procedures. Excretion of amino acid-derived catabolite toxins increased during surgery, notably those derived from gut microbes, as did an extract of disposable surgical plasticware, bis(2-ethylhexyl)phthalate.

CONCLUSION

Elective surgery imposes broad-scale early and measurable metabolic changes. The use of citrulline-enriched preoperative carbohydrate drinks needs further study to limit metabolic burden. Attention to perioperative nutrition and intraoperative control of gut-microbial toxins might reduce metabolic derangements and lead to better postoperative outcomes.

Microbiota modifications in prehabilitation - the next step towards comprehensive preparation for surgery. The scoping review

This scoping review highlights the role of microbiota modifications in prehabilitation for surgical patients. It emphasises the importance of optimising gut microbiota through probiotics, synbiotics, and postbiotics to reduce surgical complications, such as surgical site infections (SSIs). The review highlights that gut dysbiosis, worsened by surgery, stress, antibiotics, and poor diet, can lead to increased infection risk and slower recovery. Evidence from systematic reviews, meta-analyses, and randomised controlled trials suggests that microbiota-targeted interventions can reduce SSIs, enhance immune responses, and promote quicker recovery. The review advocates for an individualised approach to prehabilitation, incorporating microbiota modifications based on patient-specific factors and surgery type. However, it also notes the need for further research to standardise therapeutic regimens and confirm the safety and efficacy of these interventions in clinical practice.

Alterations in the gut microbiota in patients with long-term follow-up after pancreaticoduodenectomy and their association with postoperative fatty liver: A pilot study

BACKGROUND/PURPOSE

Gut microbiota status after pancreaticoduodenectomy (PD) is unclear, and postoperative fatty liver is an important complication after PD. This study evaluated the relationship between postoperative fatty liver and gut microbiota after PD.

METHODS

Fecal samples were collected from patients who had undergone PD and remained stable after 6 months of follow-up. A comprehensive bacterial analysis using 16S rRNA gene amplicon sequencing was performed. The results were compared with those of 85 healthy volunteers. The association between perioperative factors, gut microbiota, and development of fatty liver was investigated.

RESULTS

Twenty-four patients after PD, including 10 in the fatty liver (FL) group and 14 in the normal liver (NL) group were investigated. The β-diversity of the gut microbiota was significantly different between the healthy volunteers and patients after PD, with more Escherichia coli and Streptococcus gallolyticus and less Bifidobacterium catenulatum and Faecalibacterium prausnitzii in the patients with PD. Lactobacillus gasseri was significantly less abundant in the FL group than in the healthy volunteers, although this change was not observed in the NL group.

CONCLUSIONS

The gut microbiota of patients after PD was in dysbiosis at postoperative ≥6 months. Development of fatty liver might be associated with significant differences in gut microbiota.

What Is the Role of the Gut Microbiota in Anastomotic Leakage After Colorectal Resection? A Scoping Review of Clinical and Experimental Studies

Background: Anastomotic leakage (AL) still remains a common complication after colorectal anastomosis that leads to increased morbidity and mortality. The gut microbiota has been hypothesized as one of the risk factors associated with anastomotic leakage. The aim of the present study was to summarize all existing clinical and experimental studies that evaluate the impact of intestinal microbiota on anastomotic leakage after colorectal resection. Methods: The present scoping review was designed according to PRISMA recommendations and a systematic search in Medline, Scopus, EMBASE, Clinicaltrials.gov, Google Scholar, and CENTRAL was conducted until September 2024. Results: Overall, 7 clinical and 5 experimental studies were included. A diminished α-diversity of the gut microbiota in patients suffering from AL was demonstrated. Specific microbe genera, such as Lachnospiraceae, Bacteroidaceae, Bifidobacterium, Acinetobacter, Fusobacterium, Dielma, Elusimicronium, Prevotella, and Faecalibacterium, seem to be associated with AL. However, specific genera, like Prevotella, Streptococcus, Eubacterium, Enterobacteriaceae, Klebsiella, Actinobacteria, Gordonibacter, Phocaeicola, and Ruminococcus2, seem to be protective against AL. Experimental studies highlighted that the Western diet seems to affect microbiota diversity and increases the AL rate, whereas anastomotic healing seems to be impaired by high metalloproteinase production and increased collagenase activity. Conclusions: The intestinal microbiota seems to play an important role in anastomotic leakage after colorectal resection. Specific interventions targeting the microbiota's composition and the pathophysiological mechanisms by which it impairs anastomotic healing could diminish the risk for anastomotic leakage and improve clinical outcomes. However, future studies should be based on prospective design and eliminate heterogeneity.

Gut Microbiota and Probiotics in Perioperative Management: A Narrative Review

The human gut is the abode of several complex and diverse microbes. It is a fact that the human brain is interconnected with the spinal cord and sense organs; however, there is also a possibility of a connection between the brain and the gut microbiome. The human gut can be altered in various ways, the principal method being the intake of prebiotics, probiotics and synbiotics. Can this alteration in the gut microbiome be clinically utilised in the perioperative period? We conducted a literature search related to this topic using databases and search engines (Medical Literature Analysis and Retrieval System Online {MEDLINE}, Embase, Scopus, PubMed and Google Scholar). The search revealed some preclinical and clinical studies in animals and humans that demonstrate the alteration of the gut microbiome with the use of anxiolysis, probiotics/prebiotics and other perioperative factors including opioids, anaesthetics and perioperative stress. The significant effects of this alteration have been seen on preoperative anxiety and postoperative delirium/cognitive dysfunction/pain. These effects are described in this narrative review, which opens up newer vistas for high-quality research related to the gut microbiome, gut-brain axis, the related signaling pathways and their clinical application in the perioperative period.

Parenteral Nutrition, Inflammatory Bowel Disease, and Gut Barrier: An Intricate Plot

Malnutrition poses a critical challenge in inflammatory bowel disease, with the potential to detrimentally impact medical treatment, surgical outcomes, and general well-being. Parenteral nutrition is crucial in certain clinical scenarios, such as with patients suffering from short bowel syndrome, intestinal insufficiency, high-yielding gastrointestinal fistula, or complete small bowel obstruction, to effectively manage malnutrition. Nevertheless, research over the years has attempted to define the potential effects of parenteral nutrition on the intestinal barrier and the composition of the gut microbiota. In this narrative review, we have gathered and analyzed findings from both preclinical and clinical studies on this topic. Based on existing evidence, there is a clear correlation between short- and long-term parenteral nutrition and negative effects on the intestinal system. These include mucosal atrophic damage and immunological and neuroendocrine dysregulation, as well as alterations in gut barrier permeability and microbiota composition. However, the mechanistic role of these changes in inflammatory bowel disease remains unclear. Therefore, further research is necessary to effectively address the numerous gaps and unanswered questions pertaining to these issues.

Changes in HLA-B27 Transgenic Rat Fecal Microbiota Following Tofacitinib Treatment and Ileocecal Resection Surgery: Implications for Crohn's Disease Management

The therapeutic management of Crohn's disease (CD), a chronic relapsing-remitting inflammatory bowel disease (IBD), is highly challenging. Surgical resection is sometimes a necessary procedure even though it is often associated with postoperative recurrences (PORs). Tofacitinib, an orally active small molecule Janus kinase inhibitor, is an anti-inflammatory drug meant to limit PORs in CD. Whereas bidirectional interactions between the gut microbiota and the relevant IBD drug are crucial, little is known about the impact of tofacitinib on the gut microbiota. The HLA-B27 transgenic rat is a good preclinical model used in IBD research, including for PORs after ileocecal resection (ICR). In the present study, we used shotgun metagenomics to first delineate the baseline composition and determinants of the fecal microbiome of HLA-B27 rats and then to evaluate the distinct impact of either tofacitinib treatment, ileocecal resection or the cumulative effect of both interventions on the gut microbiota in these HLA-B27 rats. The results confirmed that the microbiome of the HLA-B27 rats was fairly different from their wild-type littermates. We demonstrated here that oral treatment with tofacitinib does not affect the gut microbial composition of HLA-B27 rats. Of note, we showed that ICR induced an intense loss of bacterial diversity together with dramatic changes in taxa relative abundances. However, the oral treatment with tofacitinib neither modified the alpha-diversity nor exacerbated significant modifications in bacterial taxa induced by ICR. Collectively, these preclinical data are rather favorable for the use of tofacitinib in combination with ICR to address Crohn's disease management when considering microbiota.

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.

Probiotics in Postoperative Pain Management

Postoperative pain is the unpleasant sensory and emotional experience after surgery, its origin being both the inflammatory reaction induced by the surgical trauma on the abdominal wall and the splanchnic pain induced by the activation of nociceptors of the viscera, which are highly sensitive to distension, ischemia, and inflammation. Nowadays, it is well recognized that there is a close relationship between the gut microbiome and pain perception, and that microbiome is highly affected by both anesthesia and surgical manipulation. Thus, efforts to restore the disturbed microbiome via supplementation with beneficial bacteria, namely probiotics, seem to be effective. In this article, the knowledge gained mainly from experimental research on this topic is analyzed, the concluding message being that each probiotic strain works in its own way towards pain relief.

Stoma-free Survival After Rectal Cancer Resection With Anastomotic Leakage: Development and Validation of a Prediction Model in a Large International Cohort

OBJECTIVE

To develop and validate a prediction model (STOMA score) for 1-year stoma-free survival in patients with rectal cancer (RC) with anastomotic leakage (AL).

BACKGROUND

AL after RC resection often results in a permanent stoma.

METHODS

This international retrospective cohort study (TENTACLE-Rectum) encompassed 216 participating centres and included patients who developed AL after RC surgery between 2014 and 2018. Clinically relevant predictors for 1-year stoma-free survival were included in uni and multivariable logistic regression models. The STOMA score was developed and internally validated in a cohort of patients operated between 2014 and 2017, with subsequent temporal validation in a 2018 cohort. The discriminative power and calibration of the models' performance were evaluated.

RESULTS

This study included 2499 patients with AL, 1954 in the development cohort and 545 in the validation cohort. Baseline characteristics were comparable. One-year stoma-free survival was 45.0% in the development cohort and 43.7% in the validation cohort. The following predictors were included in the STOMA score: sex, age, American Society of Anestesiologist classification, body mass index, clinical M-disease, neoadjuvant therapy, abdominal and transanal approach, primary defunctioning stoma, multivisceral resection, clinical setting in which AL was diagnosed, postoperative day of AL diagnosis, abdominal contamination, anastomotic defect circumference, bowel wall ischemia, anastomotic fistula, retraction, and reactivation leakage. The STOMA score showed good discrimination and calibration (c-index: 0.71, 95% CI: 0.66-0.76).

CONCLUSIONS

The STOMA score consists of 18 clinically relevant factors and estimates the individual risk for 1-year stoma-free survival in patients with AL after RC surgery, which may improve patient counseling and give guidance when analyzing the efficacy of different treatment strategies in future studies.

Controlling Intestinal Infections and Digestive Disorders Using Probiotics

After consumption, probiotics provide health benefits to the host. Probiotics and their metabolites have therapeutic and nutritional properties that help to alleviate gastrointestinal, neurological, and cardiovascular problems. Probiotics strengthen host immunity through various mechanisms, including improved gut barrier function, receptor site blocking, competitive exclusion of pathogens, and the production of bioactive molecules. Emerging evidence suggests that intestinal bowel diseases can be fatal, but regular probiotic consumption can alleviate disease symptoms. The use and detailed description of the health benefits of probiotics to consumers in terms of reducing intestinal infection, inflammation, and digestive disorders are discussed in this review. The well-designed and controlled studies that examined the use of probiotics to reduce life-threatening activities caused by intestinal bowel diseases are also covered. This review discussed the active principles and potency of probiotics as evidenced by the known effects on host health, in addition to providing information on the mechanism of action.

Dysbiosis of gut microbiota during fecal stream diversion in patients with colorectal cancer

BACKGROUND

The effect of fecal stream diversion on the gut microbiota is still uncertain. The present study was designed to assess the effect of fecal stream diversion on the composition of the gut microbiota in patients with colorectal cancer. We included patients undergoing left-sided colorectal cancer surgery with (ileostomy group) or without (control group) diverting ileostomy. Fecal samples were collected from 10 patients in each group before surgery (t1) and after ileostomy repair in the ileostomy group and 6-12 months after the initial surgery in the control group (t2). The fecal microbiota was assessed using 16S rRNA sequencing, and changes in the composition of the fecal microbiota were compared between the two groups.

RESULTS

Alpha diversity analysis revealed that the complexity of fecal microbiota decreased between t1 and t2 only in the ileostomy group. Beta diversity analysis also showed dissimilarity between t1 and t2 only in the ileostomy group. The composition of the microbiota was similar between the two groups at t1. However, at t2, the ileostomy group had lower proportion of beneficial bacteria (Lachnospiraceae, 3.8% vs. 29.9%, p < 0.001; Ruminococcaceae, 0.6% vs. 18.4%, p < 0.001; Blautia, 0.1% vs. 9.1%, p < 0.001; Faecalibacterium, 0.2% vs. 7.5%, p < 0.001) and a higher proportion of harmful bacteria (Proteobacteria, 17.9% vs. 5.1%, p = 0.006; Clostridium, 16.2% vs. 1.1%, p = 0.013; Streptococcus, 17.7% vs. 1.6%, p = 0.002) than the control group.

CONCLUSIONS

Fecal stream diversion was closely associated with less diversity and dysbiosis of the gut microbiota.

Alterations of gut microbiome following gastrointestinal surgical procedures and their potential complications

Intestinal microorganisms play a crucial role in shaping the host immunity and maintaining homeostasis. Nevertheless, alterations in gut bacterial composition may occur and these alterations have been linked with the pathogenesis of several diseases. In surgical practice, studies revealed that the microbiome of patients undergoing surgery changes and several post-operative complications seem to be associated with the gut microbiota composition. In this review, we aim to provide an overview of gut microbiota (GM) in surgical disease. We refer to several studies which describe alterations of GM in patients undergoing different types of surgery, we focus on the impacts of peri-operative interventions on GM and the role of GM in development of post-operative complications, such as anastomotic leak. The review aims to enhance comprehension regarding the correlation between GM and surgical procedures based in the current knowledge. However, preoperative and postoperative synthesis of GM needs to be further examined in future studies, so that GM-targeted measures could be assessed and the different surgery complications could be reduced.

Effect of preoperative immunonutrition on fecal microbiota in colon cancer patients: a secondary analysis of a randomized controlled trial

BACKGROUND/OBJECTIVES

This study aimed to evaluate the effect of preoperative immunonutrition on the composition of fecal microbiota following a colon cancer surgery.

MATERIALS/METHODS

This study was a secondary analysis of a randomized controlled trial assessing the impact of preoperative immunonutrition on the postoperative outcomes of colon cancer surgery. Patients with primary colon cancer were enrolled and randomly assigned to receive additional preoperative immunonutrition or a normal diet alone. Oral nutritional supplementation (400 mL/day) with arginine and ω-3 fatty acids were administered to patients in the immunonutrition group for 7 days prior to surgery. Thirty-two fecal samples were collected from 16 patients in each group, and the composition of fecal microbiota was compared between the 2 groups.

RESULTS

At the phylum level, no significant difference was observed in the composition of microbiota between the 2 groups (Firmicutes, 69.1% vs. 67.5%, P = 0.624; Bacteroidetes, 19.3% vs. 18.1%, P = 0.663; Actinobacteria, 6.7% vs. 10.6%, P = 0.080). The Firmicutes/Bacteroidetes ratio (4.43 ± 2.32 vs. 4.55 ± 2.51, P = 0.897) was also similar between the 2 groups. At the genus level, the proportions of beneficial bacteria such as Faecalibacterium spp. (8.1% vs. 6.4%, P = 0.328) and Prevotella spp. (6.9% vs. 4.8%, P = 0.331) were higher, while that of Clostridium spp. was lower (0.5% vs. 1.2%, P = 0.121) in the immunonutrition group, but the difference was not significant.

CONCLUSIONS

Immunonutrition showed no significant association with the composition of fecal microbiota. The relationship between immunonutrition and the fecal microbiota should be investigated further in large-scale studies.

Gut Microbiota Modulation of Short Bowel Syndrome and the Gut-Brain Axis

Short bowel syndrome (SBS) is a condition that results from a reduction in the length of the intestine or its functional capacity. SBS patients can have significant side effects and complications, the etiology of which remains ill-defined. Thus, facilitating intestinal adaptation in SBS remains a major research focus. Emerging data supports the role of the gut microbiome in modulating disease progression. There has been ongoing debate on defining a "healthy" gut microbiome, which has led to many studies analyzing the bacterial composition and shifts that occur in gastrointestinal disease states such as SBS and the resulting systemic effects. In SBS, it has also been found that microbial shifts are highly variable and dependent on many factors, including the anatomical location of bowel resection, length, and structure of the remnant bowel, as well as associated small intestinal bacterial overgrowth (SIBO). Recent data also notes a bidirectional communication that occurs between enteric and central nervous systems called the gut-brain axis (GBA), which is regulated by the gut microbes. Ultimately, the role of the microbiome in disease states such as SBS have many clinical implications and warrant further investigation. The focus of this review is to characterize the role of the gut microbiota in short bowel syndrome and its impact on the GBA, as well as the therapeutic potential of altering the microbiome.

New challenges in cholangiocarcinoma candidates for elective surgery: harnessing the microbiome dysbiosis

BACKGROUND

The gut microbiota, composed by several species of microorganisms, works to preserve the liver-gut homeostasis and plays an important role during digestion and absorption of nutrients, and in the immune response of the host. In this review, we analyzed the influence of microbiota in patients with cholangiocarcinoma (CCA) who were candidates for elective surgery.

METHODS

A literature review was conducted to identify papers that provided empiric evidence to support that the altered microbiota composition (dysbiosis) is related also to CCA development.

RESULTS

Bacteria such as Helicobacter pylori, Helicobacter hepaticus, and Opisthorchis viverrini increase the risk of CCA. The most abundant genera were Enterococcus, Streptococcus, Bacteroides, Klebsiella, and Pyramidobacter in CCA's biliary microbiota. Additionally, levels of Bacteroides, Geobacillus, Meiothermus, and Anoxybacillus genera were significantly higher. An enrichment of Bifidobacteriaceae, Enterobacteriaceae, and Enterococcaceae families has also been observed in CCA tumor tissue. Microbiota is related to postoperative outcomes in abdominal surgery. The combination of caloric restriction diets in liver cancer or CCA increases the effect of the chemotherapy treatment.

CONCLUSION

The correct use of nutrition for microbiota modulation according to each patient's needs could be a therapeutic tool in combination with elective surgery and chemotherapy to diminish side effects and improve prognosis. Further investigations are needed to fully understand the mechanisms by which they are related.

Interaction between the intestinal flora and the severity of diversion colitis after low anterior resection of rectal cancer

Background

Diversion colitis (DC) is nonspecific inflammation of the distal intestinal mucosa following disruption of colonic continuity with colonic dysfunction. The colonscopic score is a good tool for differentiating the severity of patients with DC. At present, no studies have analyzed the pathogenesis of DC from the perspective of the diversity and and differences of intestinal flora.

Methods

Retrospective study: Clinical information were collected from patients with low rectal cancer admitted to the Department of Anorectal Surgery, Changzheng Hospital, from April 2017 to April 2019. These patients underwent laparoscopic low anterior resection (LAR) combined with terminal ileum enterostomy (dual-chamber). We used chi-square test to comparethe clinical baseline information, clinical symptoms, and colonscopic characteristics between different severity of DC. Propsective oberservational study: We recruited 40 patients with laparoscopic anterior low resection combined with terminal ileum enterostomy and they were further classified into mild group and severe group according to the scores of colonscopic examinations for DC. 16s-rDNA sequencing was carried out to analyze the diversity and and differences of intestinal flora in the intestinal lavage fluid of the two groups.

Results

In retrospective study, we found that age, BMI, history of diabetes, and symptoms associated with the stoma state were the independent risk factors that affect DC severity (P<0.05). Meanwhile, age, BMI, history of diabetes and colonscopic score were found to be independent risk factors affecting the severity of diarrhea after ileostomy closure surgery(P<0.05), which was consistent with our results of differentiating the severity of DC under endoscopy; In propsective oberservational study, 40 patients with low rectal cancer recruited by sample size calculation, 23 were in the mild group and 17 in the severe group. The results of 16s-rDNA sequencing showed that intestinal flora with high enrichment values primarily consisted of Bifidobacteriales and Prevotella in mild group, whereas that in the severe group consisted of Providencia and Dorea. The functional predictions on such two types of intestinal flora were mainly focused on lipid synthesis, glycan synthesis, metabolism, and amino acid metabolism pathways.

Conclusion

After ileostomy closure surgery, a series of severe clinical symptoms might appear in DC patients. There are significant differences in local and systemic inflammatory responses, composition of intestinal flora between DC patients with different colonscopic scores, which provide a basis for the clinical interventional treatment for DC in patients with permanent stoma.

The Role of Probiotics in Inflammation Associated with Major Surgery: A Narrative Review

Background: Gut microbiota is well-known for its ability to maintain intestinal homeostasis. However, the disruption of this homeostasis, known as dysbiosis, leads to multiple consequences, including local and systemic inflammation. Surgery-induced inflammation is a major concern for patients, as it leads to many infectious and non-infectious complications. Objective: The purpose of this review was to explore the role of probiotics and symbiotics in surgery-induced inflammation and to determine if their use is effective in combatting inflammation and its complications Methods and Materials: A literature search was conducted, and articles published only in English, until December 2022 were included. The results are reported in the form of a narrative review. Results: The perioperative use of probiotics and/or symbiotics results in lower risk of infectious complications, including reduced rates of surgical site infections, respiratory and urinary tract infections, shorter hospital stays, and fewer days of antibiotic administration. It also contributes to reducing non-infectious complications, as it mitigates systemic and local inflammation via maintenance of the intestinal barrier, improves intestinal mobility, and is associated with lower rates of postoperative pain and anastomotic leak. Conclusions: Restoring gut microbiota after disruptions caused by surgery may accelerate local healing processes, attenuate systemic inflammation, and may thus prove beneficial to certain populations.

Microbiota Phenotype Promotes Anastomotic Leakage in a Model of Rats with Ischemic Colon Resection

Anastomotic leakage (AL) is a major cause of morbidity and mortality after colorectal surgery, but the mechanism behind this complication is still not fully understood. Despite the advances in surgical techniques and perioperative care, the complication rates have remained steady. Recently, it has been suggested that colon microbiota may be involved in the development of complications after colorectal surgery. The aim of this study was to evaluate the association of gut microbiota in the development of colorectal AL and their possible virulence strategies to better understand the phenomenon. Using 16S rRNA sequencing of samples collected on the day of surgery and the sixth day following surgery, we analyzed the changes in tissue-associated microbiota at anastomotic sites created in a model of rats with ischemic colon resection. We discovered a trend for lower microbial diversity in the AL group compared to non-leak anastomosis (NLA). There were no differences in relative abundance in the different types of microbial respiration between these groups and the high abundance of the facultative anaerobic Gemella palaticanis is a marker species that stands out as a distinctive feature.

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.

Perioperative Probiotics Application for Preventing Postoperative Complications in Patients with Colorectal Cancer: A Systematic Review and Meta-Analysis

Background and Objectives: Perioperative probiotic administration in patients who undergo gastrointestinal surgery can reduce postoperative infectious complications. This systematic review and meta-analysis aimed to evaluate the effect of probiotics on postoperative outcomes in patients who underwent colorectal cancer surgery. Materials and Methods: For this study, we followed the protocol published by PROSPERO (registration number: CRD42021247277). We included studies on patients undergoing open, laparoscopic, or robotic colorectal cancer surgery for curative intent. We conducted a comprehensive search with online databases (trial registries and ClinicalTrials.gov), other literature sources, and conference proceedings, with no language restriction, up until 12 August 2022. We assessed risk of bias, extracted data, and conducted statistical analyses by using a random-effects model and interpreted the results based on the Cochrane Handbook for Systematic Reviews of Interventions. We rated the certainty of evidence (CoR) according to the GRADE approach. Results: We identified 20 published full-text studies. The use of probiotics probably results in little to no difference in perioperative mortality (risk ratio (RR): 0.17, 95% CI: 0.02 to 1.38; I2 = 0%; moderate CoE) and may result in reducing the overall postoperative infectious complications (RR: 0.45, 95% CI: 0.27 to 0.76; I2 = 38%; low CoE) after colorectal cancer surgery. Probiotics may result in little to no difference in probiotics-related adverse events (RR: 0.73, 95% CI: 0.45 to 1.19; I2 = 0%; low CoE). While probiotics may result in reducing the overall postoperative complications (RR: 0.47, 95% CI: 0.30 to 0.74; I2 = 8%; low CoE), it may result in little to no difference in hospital length of stay (LOS) (MD: -1.06, 95% CI: -1.64 to -0.47; I2 = 8%; low CoE) and postoperative quality of life (QOL) (MD: +5.64, 95% CI: 0.98 to 10.3; low CoE). Conclusions: Perioperative probiotic administration may reduce complications, including overall infectious complications, in patients undergoing colorectal cancer surgery without any additional adverse effects. In addition, probiotics may have similar effects on perioperative mortality; procedure-related complications such as anastomotic leakage, and hospital LOS; or improve the QOL. Thus, probiotics may be considered a beneficial supplement to routine perioperative care for colorectal cancer surgery.

Mechanical bowel preparation with or without oral antibiotics for rectal resection for cancer (REPCA trial): a study protocol for a multicenter randomized controlled trial

BACKGROUND

There is still a lack of randomized trials assessing the clinical value of mechanical bowel preparation (MBP) and oral antibiotics (OA) before rectal surgery. Existing studies are inconsistent regarding OA. The aim of this study is to examine the role of MBP with or without OA (using Alfa Normix^®) on postoperative complications in patients undergoing rectal resection for cancer.

METHODS

We are conducting a prospective multicenter randomized controlled trial comparing MBP (Moviprep^®) with OA (Alfa Normix^®) versus MBP alone in patients undergoing elective rectal resection for cancer. Patients with rectal or rectosigmoid cancer are randomized in a 1:1 allocation ratio. The primary endpoint is incisional surgical site infection (SSI) assessed within 30 days after surgery. Secondary endpoints are anastomotic leakage (AL), organ/space SSI, other postoperative complications, intraoperative complications, operation time, bowel preparation quality, bowel preparation adherence. Intention-to-treat and per protocol analyses will be performed.

CONCLUSIONS

The results of the REPCA trial will demonstrate whether MBP + OA is superior to MBP alone in rectal cancer surgery. This trial might influence current preoperative practice and improve postoperative outcomes.

Study of Correlation between Intestinal Microbiota and Traditional Chinese Medicine Syndrome of Patients with Colon Cancer

Objective

This research aims to study the material basis of the formation and specific bacteria of traditional Chinese medicine (TCM) syndrome from the characteristics of the intestinal microbiota of patients with colon cancer (CC) before and after the operation.

Methods

A cross-sectional study was conducted on 84 patients with CC and 24 healthy controls. A total of 168 and 24 stool samples were collected from CC patients before and after the operation and healthy controls. DNA was extracted from 192 stool samples and then amplified using PCR. The V3-V4 high variable areas were analyzed by 16s rDNA sequencing.

Results

The community diversity, in descending order, was the healthy control group and postoperative and preoperative groups of CC patients. The abundance of beneficial bacteria was postoperative group of CC patients > healthy control group > preoperative group of CC patients. Among the comparisons of the intestinal microbiota of preoperative groups of CC patients with different TCM syndromes, the community diversity in descending order was damp heat accumulation (DHA), spleen deficiency and dampness (SDD), spleen and kidney yang deficiency (SKYD), liver and kidney yin deficiency (LKYD), and deficiency of qi and blood (QBD), respectively. Specific microbiome analysis showed that the differences in the abundance of 42 taxons were statistically significant among the preoperative groups of CC patients with the five TCM syndromes and the healthy control group. While comparing the intestinal microbiota of postoperative groups with the five TCM syndromes, the community diversity in descending order is DHA, SDD, LKYD, SKYD, and QBD. Specific microbiome analysis showed that the differences in the abundance of 46 taxons were statistically significant among the postoperative groups of CC patients with the five TCM syndromes and the healthy control group. Streptococcus and Streptococcus mutans showed no statistical significance between the preoperative group and postoperative groups of CC with DHA syndrome (P > 0.05). Bacteroides at phylum and genus levels showed that there was no statistical significance between the preoperative group and the postoperative group of CC with SKYD syndrome (P > 0.05).

Conclusions

Before and after surgery, with the deterioration of TCM syndrome: DHA ⟶ SDD ⟶ SKYD ⟶ LKYD ⟶ QBD, the number of beneficial bacteria in CC patients' intestines decreased while the number of pathogenic bacteria increased, and the community structure of intestinal microbiota tends to be unitized, indicating a serious intestinal microbiological disorder. After radical surgery and perioperative intervention, the intestinal microbiota diversity and community structure of postoperative CC patients were closer to those of healthy people than preoperative. However, they were still imbalanced. The intestinal microbiota of CC patients with different TCM syndromes differs significantly, which is important for understanding the pathogenesis of CC in TCM. The DHA and SKYD syndromes in CC patients before and after surgery showed significant differences in the microbial structure. Streptococcus and Streptococcus mutans were the specific species with a significant difference in CC patients with DHA syndrome, while bacteroides were the specific species in CC patients with SKYD syndrome.

Gut bacterial dysbiosis and instability is associated with the onset of complications and mortality in COVID-19

There is a growing debate about the involvement of the gut microbiome in COVID-19, although it is not conclusively understood whether the microbiome has an impact on COVID-19, or vice versa, especially as analysis of amplicon data in hospitalized patients requires sophisticated cohort recruitment and integration of clinical parameters. Here, we analyzed fecal and saliva samples from SARS-CoV-2 infected and post COVID-19 patients and controls considering multiple influencing factors during hospitalization. 16S rRNA gene sequencing was performed on fecal and saliva samples from 108 COVID-19 and 22 post COVID-19 patients, 20 pneumonia controls and 26 asymptomatic controls. Patients were recruited over the first and second corona wave in Germany and detailed clinical parameters were considered. Serial samples per individual allowed intra-individual analysis. We found the gut and oral microbiota to be altered depending on number and type of COVID-19-associated complications and disease severity. The occurrence of individual complications was correlated with low-risk (e.g., Faecalibacterium prausznitzii) and high-risk bacteria (e.g., Parabacteroides ssp.). We demonstrated that a stable gut bacterial composition was associated with a favorable disease progression. Based on gut microbial profiles, we identified a model to estimate mortality in COVID-19. Gut microbiota are associated with the occurrence of complications in COVID-19 and may thereby influencing disease severity. A stable gut microbial composition may contribute to a favorable disease progression and using bacterial signatures to estimate mortality could contribute to diagnostic approaches. Importantly, we highlight challenges in the analysis of microbial data in the context of hospitalization.

Changes in the gut bacterial communities in colon cancer surgery patients: an observational study

Background

Colon surgery has been shown to modulate the intestinal microbiota. Our objective was to characterize these changes using state-of-the-art next generation sequencing techniques.

Methods

We performed a single-centre prospective observational cohort study to evaluate the changes in the gut microbiota, i.e., taxon distribution, before and after elective oncologic colon surgery in adult patients with different antimicrobial prophylaxis regimens (standard prophylaxis with cefuroxime/metronidazole versus carbapenems for extended-spectrum beta-lactamase-producing Enterobacterales [ESBL-E] carriers). We obtained rectal samples on the day of surgery, intraoperative luminal samples, and rectal or stoma samples 3 days after surgery. We performed metataxonomic analysis based on sequencing of the bacterial 16S rRNA gene marker. Similarities and differences between bacterial communities were assessed using Bray–Curtis similarity, visualised using principal coordinates analysis and statistically tested by PERMANOVA. Comparison of taxa relative abundance was performed using ANCOM.

Results

We included 27 patients between March 27, 2019 and September 17, 2019. The median age was 63.6 years (IQR 56.4–76.3) and 44% were females. Most (81%) patients received standard perioperative prophylaxis as they were not ESBL carriers. There was no significant association between ESBL carriage and differences in gut microbiome. We observed large and significant increases in the genus Enterococcus between the preoperative/intraoperative samples and the postoperative sample, mainly driven by Enterococcus faecalis. There were significant differences in the postoperative microbiome between patients who received standard prophylaxis and carbapenems, specifically in the family Erysipelotrichaceae.

Conclusion

This hypothesis-generating study showed rapid changes in the rectal microbiota following colon cancer surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13099-021-00477-7.

Fecal Microbiome Changes and Specific Anti-Bacterial Response in Patients with IBD during Anti-TNF Therapy

Inflammatory bowel diseases (IBD) are chronic disorders of the gastrointestinal tract that have been linked to microbiome dysbiosis and immune system dysregulation. We investigated the longitudinal effect of anti-TNF therapy on gut microbiota composition and specific immune response to commensals in IBD patients. The study included 52 patients tracked over 38 weeks of therapy and 37 healthy controls (HC). To characterize the diversity and composition of the gut microbiota, we used amplicon sequencing of the V3V4 region of 16S rRNA for the bacterial community and of the ITS1 region for the fungal community. We measured total antibody levels as well as specific antibodies against assorted gut commensals by ELISA. We found diversity differences between HC, Crohn's disease, and ulcerative colitis patients. The bacterial community of patients with IBD was more similar to HC at the study endpoint, suggesting a beneficial shift in the microbiome in response to treatment. We identified factors such as disease severity, localization, and surgical intervention that significantly contribute to the observed changes in the gut bacteriome. Furthermore, we revealed increased IgM levels against specific gut commensals after anti-TNF treatment. In summary, this study, with its longitudinal design, brings insights into the course of anti-TNF therapy in patients with IBD and correlates the bacterial diversity with disease severity in patients with ulcerative colitis (UC).

Current Insights: The Impact of Gut Microbiota on Postoperative Complications in Visceral Surgery-A Narrative Review

Postoperative complications are a major problem occurring in up to 50% of patients undergoing major abdominal surgery. Occurrence of postoperative complications is associated with a significantly higher morbidity and mortality in affected patients. The most common postoperative complications are caused by an infectious genesis and include anastomotic leakage in case of gastrointestinal anastomosis and surgical site infections. Recent research highlighted the importance of gut microbiota in health and disease. It is plausible that the gut microbiota also plays a pivotal role in the development of postoperative complications. This narrative review critically summarizes results of recent research in this particular field. The review evaluates the role of gut microbiota alteration in postoperative complications, including postoperative ileus, anastomotic leakage, and surgical site infections in visceral surgery. We tried to put a special focus on a potential diagnostic value of pre- and post-operative gut microbiota sampling showing that recent data are inhomogeneous to identify a high-risk microbial profile for development of postoperative complications.

Effects of Perioperative Probiotics and Synbiotics on Pancreaticoduodenectomy Patients: A Meta-Analysis of Randomized Controlled Trials

Post-pancreaticoduodenectomy infections cause mortality, morbidity, and prolonged antibiotic use. Probiotics or synbiotics may be advantageous for preventing postoperative infections, but their benefits on pancreaticoduodenectomy outcomes are controversial. This study evaluated the efficacy of probiotics and synbiotics in pancreaticoduodenectomy. The Embase, Web of Science, PubMed, and Cochrane Library databases were comprehensively searched for randomized controlled trials (RCTs) that evaluated the effects of probiotics or synbiotics on pancreaticoduodenectomy as of April 16, 2021. Outcomes included perioperative mortality, postoperative infectious complications, delayed gastric emptying, hospital stay length, and antibiotic-use duration. The results were reported as mean differences (MDs) and relative risks (RRs) with 95% confidence intervals (CI). Six RCTs involving 294 subjects were included. Probiotic or synbiotic supplementation did not reduce the perioperative mortality (RR, 0.34; 95% CI, 0.11, 1.03), but reduced the incidences of postoperative infection (RR, 0.49; 95% CI, 0.34, 0.70) and delayed gastric emptying (RR, 0.27; 95% CI, 0.09, 0.76) and also reduced the hospital stay length (MD, -7.87; 95% CI, -13.74, -1.99) and antibiotic-use duration (MD, -6.75; 95% CI, -9.58, -3.92) as compared to the controls. Probiotics or synbiotics can prevent infections, reduce delayed gastric emptying, and shorten the hospital stay and antibiotic-use durations in patients undergoing pancreaticoduodenectomy. These findings are clinically important for promoting recovery from pancreaticoduodenectomy, reducing the incidences of antibiotic resistance and iatrogenic infections, and reducing the medical burden.