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

Impact of mechanical bowel preparation on the gut microbiome of patients undergoing left-sided colorectal cancer surgery: randomized clinical trial

BACKGROUND

Postoperative complications after colorectal cancer surgery have been linked to the gut microbiome. However, the impact of mechanical bowel preparation using oral preparation agents or rectal enema on postoperative infections remains poorly understood. This study aimed to compare the impact of oral preparation and rectal enema on the gut microbiome and postoperative complications.

METHODS

This open-label pilot RCT was conducted at the National Cancer Institute, Vilnius, Lithuania. Patients with left-side colorectal cancer scheduled for elective resection with primary anastomosis were randomized 1 : 1 to preoperative mechanical bowel preparation with either oral preparation or rectal enema. Stool samples were collected before surgery, and on postoperative day 6 and 30 for 16S rRNA gene sequencing analysis. The primary outcome was difference in β-diversity between groups on postoperative day 6.

RESULTS

Forty participants were randomized to oral preparation (20) or rectal enema (20). The two groups had similar changes in microbiome composition, and there was no difference in β-diversity on postoperative day 6. Postoperative infections occurred in 12 patients (32%), without differences between the study groups. Patients with infections had an increased abundance of bacteria from the Actinomycetaceae family, Actinomyces genus, Sutterella uncultured species, and Enterococcus faecalis species.

CONCLUSION

Mechanical bowel preparation with oral preparation or rectal enema resulted in similar dysbiosis. Patients who experienced postoperative infections exhibited distinct gut microbiome compositions on postoperative day 6, characterized by an increased abundance of bacteria from the Actinomycetaceae family, Actinomyces genus, Sutterella uncultured species, and Enterococcus faecalis species.

REGISTRATION NUMBER

NCT04013841 (http://www.clinicaltrials.gov).

Postoperative delayed gastric emptying: may gut microbiota play a role?

Postoperative delayed gastric emptying is a prevalent complication following surgical procedures, imposing heavy physical and financial burdens on patients. However, current treatment options remain suboptimal. In recent years, an increasing number of studies have highlighted that the gut microbiota and its metabolites are closely associated with postoperative complications. Various factors can disrupt the gut microbiome after surgery. This review discusses the potential mechanisms by which the gut microbiota and their metabolites may contribute to the pathogenesis of postoperative delayed gastric emptying. However, the current knowledge base is limited in terms of fully understanding the exact mechanisms involved. It is therefore evident that further research is required to fully elucidate the role of the gut microbiome in postoperative delayed gastric emptying, with the aim of uncovering new possibilities for preventive measures and therapeutic treatments.

Impact of Pericoronary Microbiota Composition on Course of Recovery after Third Molar Alveotomy

Although the role of microbiota has been investigated in relation to different oral diseases, it is unknown if its composition has any effect on the course of recovery after third molar alveotomy. Our aim was to determine the influence of patient clinical characteristics as well as pericoronary microbiota composition on the course of recovery after a semi-impacted third molar alveotomy. Thirty-six patients were included and samples obtained with paper points, swabs, and tissue samples were analyzed using DNA hybridization and culture methods. Among the 295 organisms detected, the most frequent were Streptococcus spp. (22.4%; 66/295) followed by Fusobacterium spp. (11.9%; 35/295), and T. forsythia (9.1%; 27/295). A comparison of microbiota composition in patients with better and worse recovery did not show significant differences. Worse recovery outcomes were more frequent in patients with a grade 2 self-assessment of oral health (p = 0.040) and better recovery courses were observed in patients with a grade 4 self-assessment (p = 0.0200). A worse recovery course was statistically significant more frequently in patients with previous oral surgical procedures (p = 0.019). Although we demonstrate that worse recovery outcomes were more frequent when certain bacteria were detected, there was no statistically significant difference. Further research is needed to identify microbial profiles specific to the development of worse outcomes after a third molar alveotomy.

Promoting wound recovery through stable intestinal flora: Reducing post-operative complications in colorectal cancer surgery patients

In recent years, the relationship between intestinal flora and post-operative recovery, particularly in colorectal cancer (CRC) surgery patients, it has been hypothesized that intestinal flora stability influences wound healing, reduces complications and improves overall recovery outcomes after surgical interventions. This study examined the relationship between intestinal flora stability and post-operative recovery in patients undergoing CRC surgery. Between May 2020 and 2023, 80 CRC patients from our hospital's Colorectal Surgery Department were enrolled. A random number table was used to divide them into two categories. Both groups were subjected to distinct gastrointestinal preparation protocols. Indicators of clinical therapeutic effect, intestinal flora balance following surgery, post-operative complications and quality of life were evaluated. The observation group, which adhered to a distinct gastrointestinal regimen, demonstrated a statistically significant improvement in post-operative outcomes, with a clinical effectiveness rate of 97.5% compared to the control group's 75%. In addition, the observation group had a lower incidence of intestinal flora imbalance following surgery than the control group. The observation group had lower incidences of intestinal obstruction, infection, anastomotic leakage, incisional tumour implantation and delayed diarrhoea. Using the KPS score and the BMI, post-treatment assessments of the observation group's quality of life revealed significant enhancements in comparison to the control group. Additionally, wound healing rates were superior in the observation group, with a correlation between stable intestinal flora and decreased wound infection rates. The type of post-operative diet influenced the stabilization of the gut flora, with a high-fibre diet producing superior results in both groups. The stability of intestinal flora influences the post-operative rehabilitation of patients undergoing CRC surgery favourably. Appropriate bowel preparation and dietary considerations can reduce post-operative complications, improve wound healing rates and enhance overall quality of life.

Tailored Pre-Operative Antibiotic Prophylaxis to Prevent Post-Operative Surgical Site Infections in General Surgery

The average American today undergoes three inpatient and two outpatient surgical procedures during one's life, each of which carries with it a risk of post-operative infection. It has long been known that post-operative infections cause significant morbidity in the immediate peri-operative period, but recent evidence suggests that they can have long-term consequences as well, increasing a patient's risk of infectious complications in unrelated surgeries performed months or even years later. While there are several theories on the origin of this association, including bacterial colonization of a post-operative infectious wound site, antimicrobial resistance from curative courses of antibiotics, subclinical immunosuppression, or the creation of an inflammatory "pathobiome" following an infectious insult, it is ultimately still unclear why patients who experience a single post-operative infection seem to be at a significantly higher risk of experiencing subsequent ones. Regardless, this association has significant implications for the routine use of pre-operative antibiotic prophylaxis. Indeed, while the prescription of antibiotics pre-operatively has dramatically reduced the rate of post-operative infections, the chosen prophylaxis regimens are typically standardized according to national guidelines, are facing increasing antimicrobial resistance patterns, and have been unable to reduce the risk of post-operative infection to acceptably low levels for certain surgeries. As a result, some clinicians have speculated that tailoring pre-operative antibiotic prophylaxis according to a patient's prior infectious and operative history could improve efficacy and further reduce the rate of post-operative infections. The purpose of this review is to describe the evidence for the link between multiple post-operative infections and explore the efficacy of individualized pre-operative prophylaxis.

Longitudinal dynamics of gut bacteriome and mycobiome interactions pre- and post-visceral surgery in Crohn's disease

Introduction

Alterations of the gut microbiome are involved in the pathogenesis of Crohn's disease (CD). The role of fungi in this context is unclear. This study aimed to determine postoperative changes in the bacterial and fungal gut communities of CD patients undergoing intestinal resection, and to evaluate interactions between the bacteriome and mycobiome and their impact on the patients' outcome.

Methods

We report a subgroup analysis of a prospective cohort study, focusing on 10 CD patients whose fecal samples were collected for bacterial 16S rRNA and fungal ITS2 genes next-generation sequencing the day before surgery and on the 5th or 6th postoperative day.

Results

No significant differences in bacterial and fungal diversity were observed between preoperative and postoperative stool samples. By in-depth analysis, significant postoperative abundance changes of bacteria and fungi and 17 interkingdom correlations were detected. Network analysis identified 13 microbial clusters in the perioperative gut communities, revealing symbiotic and competitive interactions. Relevant factors were gender, age, BMI, lifestyle habits (smoking, alcohol consumption) and surgical technique. Postoperative abundance changes and identified clusters were associated with clinical outcomes (length of hospital stay, complications) and levels of inflammatory markers.

Conclusions

Our findings highlight the importance of dissecting the interactions of gut bacterial and fungal communities in CD patients and their potential influence on postoperative and disease outcomes.

Gut Microbiota in Diagnosis, Therapy and Prognosis of Cholangiocarcinoma and Gallbladder Carcinoma-A Scoping Review

Cancers of the biliary tract are more common in Asia than in Europe, but are highly lethal due to delayed diagnosis and aggressive tumor biology. Since the biliary tract is in direct contact with the gut via the enterohepatic circulation, this suggests a potential role of gut microbiota, but to date, the role of gut microbiota in biliary tract cancers has not been elucidated. This scoping review compiles recent data on the associations between the gut microbiota and diagnosis, progression and prognosis of biliary tract cancer patients. Systematic review of the literature yielded 154 results, of which 12 studies and one systematic review were eligible for evaluation. The analyses of microbiota diversity indices were inconsistent across the included studies. In-depth analyses revealed differences between gut microbiota of biliary tract cancer patients and healthy controls, but without a clear tendency towards particular species in the studies. Additionally, most of the studies showed methodological flaws, for example non-controlling of factors that affect gut microbiota. At the current stage, there is a lack of evidence to support a general utility of gut microbiota diagnostics in biliary tract cancers. Therefore, no recommendation can be made at this time to include gut microbiota analyses in the management of biliary tract cancer patients.

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.

The possible role of gut microbiota dysbiosis in the pathophysiology of delirium in older persons

Delirium is a clinical syndrome characterized by an acute change in attention, awareness and cognition with fluctuating course, frequently observed in older patients during hospitalization for acute medical illness or after surgery. Its pathogenesis is multifactorial and still not completely understood, but there is general consensus on the fact that it results from the interaction between an underlying predisposition, such as neurodegenerative diseases, and an acute stressor acting as a trigger, such as infection or anesthesia. Alterations in brain insulin sensitivity and metabolic function, increased blood-brain barrier permeability, neurotransmitter imbalances, abnormal microglial activation and neuroinflammation have all been involved in the pathophysiology of delirium. Interestingly, all these mechanisms can be regulated by the gut microbiota, as demonstrated in experimental studies investigating the microbiota-gut-brain axis in dementia. Aging is also associated with profound changes in gut microbiota composition and functions, which can influence several aspects of disease pathophysiology in the host. This review provides an overview of the emerging evidence linking age-related gut microbiota dysbiosis with delirium, opening new perspectives for the microbiota as a possible target of interventions aimed at delirium prevention and treatment.

Dietary Impacts on Changes in Diversity and Abundance of the Murine Microbiome during Progression and Treatment of Cancer

The intestinal microbial population is recognized for its impact on cancer treatment outcomes. Little research has reported microbiome changes during cancer progression or the interplay of disease progression, dietary sugar/fat intake, and the microbiome through surgery and chemotherapy. In this study, the murine gut microbiome was used as a model system, and changes in microbiome diversity, richness, and evenness over the progression of the cancer and treatment were analyzed. Mice were categorized into four diet cohorts, combinations of either high or low sucrose and high or low omega-3 fatty acids, and two treatment cohorts, saline vehicle or chemotherapy, for a total of eight groups. Fecal samples were collected at specific timepoints to assess changes due to diet implementation, onset of cancer, lumpectomy, and chemotherapy. Akkermansia muciniphila abundance was very high in some samples and negatively correlated with overall Amplicon Sequence Variant (ASV) richness (r(64) = -0.55, p = 3 × 10-8). Throughout the disease progression, ASV richness significantly decreased and was impacted by diet and treatment. Alpha-diversity and differential microbial abundance were significantly affected by disease progression, diet, treatment, and their interactions. These findings help establish a baseline for understanding how cancer progression, dietary macronutrients, and specific treatments impact the murine microbiome, which may influence outcomes.

Examining the Role of Microbiota-Centered Interventions in Cancer Therapeutics: Applications for Urothelial Carcinoma

Modern advances in genomic and molecular technologies have sparked substantial research on the human intestinal microbiome over the past decade. A deeper understanding of the microbiome has illuminated that dysbiosis, or a disruption in the microbiome, is associated with inflammatory disease states and carcinogenesis. Novel therapies that target the microbiome and restore healthy flora may have value in dampening the immunopathologic state induced by dysbiosis. A narrative review of the literature on the use of microbiota-centered interventions (MCIs) was conducted. Several randomized clinical trials show that MCIs can augment response to immune checkpoint inhibitor (ICI) therapy in patients with metastatic cancer. Clinical trials have also demonstrated that modulation of the intestinal microbiome can enhance recovery and reduce infectious complications in the surgical management of colorectal adenocarcinoma. Overall, these major discoveries suggest future clinical applications of MCIs for a wide range of immune-mediated conditions. These results may also translate to improved patient outcomes in systemic immunotherapy for urothelial carcinoma as well as in patients recovering from radical cystectomy (RC), which is complicated by high infection rates. Further research is needed to evaluate the optimal bacterial composition of microbiota-centered therapies and the specific cellular changes that lead to improved tumor antigen recognition after microbiota-centered therapies.

Morbidity and Mortality of Neutropenic Patients in Visceral Surgery: A Narrative Review

Leukocytes are essential for the function of the immune system and cell–cell interaction in the human body, but hematological diseases as well as chemotherapeutic treatments due to cancer lead to occasionally or even permanent leukocyte deficiency. Normally, more than 50% of leukocytes are neutrophilic granulocytes, and leukopenia is, therefore, mostly characterized by a decrease in neutrophilic granulocytes. The consequence of neutropenia is increased susceptibility to infection, but also healing disorders are suggestable due to the disturbed cell–cell interaction. While there is no surgical treatment for leucocyte disorders, patients suffering from neutropenia are sometimes in need of surgery for other reasons. Less is known about the morbidity and mortality of this patients, which is why this narrative review critically summarizes the results of recent research in this particular field. The results of this review suggest that neutropenic patients in need of emergency surgery have a higher mortality risk compared to non-neutropenic patients. In contrast, in elective surgery, there was not a clear tendency for a higher mortality risk of neutropenic patients. The role of neutrophilic granulocytes in inflammation and immunity in surgical patients is emphasized by the results, but most of the evaluated studies showed methodological flaws due to small sample sizes or risk of bias. Further research has to evaluate the risk for postoperative complications, particularly of infectious complications such as surgical site infections, in neutropenic patients undergoing elective surgery, and should address the role of neutrophilic function in postoperative morbidity and mortality.