A Novel Nonantibiotic Gut-directed Strategy to Prevent Surgical Site Infections

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.

Bowel cleansing, dysbiosis, and postoperative infection: the dots are starting to connect

When preparing the bowel for surgery using purgative cleansing of either oral polyethylene glycol versus 0.9% normal saline enemas, the degree of dysbiosis is the same and is temporary recovering toward normal by postoperative day 30. When examining all infections, independent of treatment group, it appears that many infections arise from among the gut microbiota

Preventing Surgical Site Infections in the Era of Escalating Antibiotic Resistance and Antibiotic Stewardship

Importance

According to the Centers for Disease Control and Prevention and governing bodies within the American College of Surgeons, the administration of antibiotics as prophylaxis against infection prior to a planned elective procedure is, with rare exception, routinely recommended. The goal of "getting to zero" infections remains a high priority for policymakers, practitioners, and certainly for patients.

Observations

Despite the many advances in surgical technique, skin decontamination, sterile procedure, and enhanced recovery programs, surgical site infections continue to adversely affect procedures as diverse as dental implant surgery, joint arthroplasty, and major abdominal surgery. Although surgical site infection rates are at historically low levels, progress has stalled in recent reporting periods and such infections remain disabling, costly, and occasionally lethal. Stakeholders in the field, including surgeons, infectious diseases specialists, and industry, advocate for strategies emphasizing greater levels of intraoperative sterility or broader-spectrum antibiotic coverage as the most appropriate path forward.

Conclusions and Relevance

The current emphasis on ever-increasing levels of intraoperative sterility and extended-spectrum antibiotic use are not sustainable long-term solutions. Continuing to escalate these approaches may contribute to unintended consequences including antimicrobial resistance. Principles of antimicrobial stewardship and microbiome sciences can be applied to inform a more effective and sustainable approach to infection prevention in the field of surgery.

Classification and Risk Factors for Surgical Site Infections in Radical Cystectomy: A 16-Year Analysis

Introduction: Surgical site infection (SSI) is a substantial cause of peri-operative morbidity among patients undergoing radical cystectomy (RC). The purpose of this study was to identify the risk factors of SSI after RC and to classify and characterize treatment of SSIs. Methods: We retrospectively analyzed peri-operative characteristics and SSI, for patients undergoing RC from 2007 to 2022. Patients were stratified by SSI versus no SSI and differences were assessed. Uni-variable/multi-variable logistic regression analyses were performed to identify factors associated with SSI. SSIs were categorized by the Centers for Disease Control and Prevention (CDC) type: Superficial incisional, deep incisional, and organ/space confined. Results: Three hundred and ninety-eight patients had RC, 279 open, and 119 robotic; 78 (19.6%) developed SSI. Cohorts were similar demographically. Length of stay (LOS) was longer in the SSI cohort (8.8 d versus 12.4 d, p < 0.001), and body mass index (BMI) was greater in patients with SSI (24.34 vs. 25.39, p = 0.0003). On uni-variable analysis, age, gender, Charlson Comorbidity Index, diabetes mellitus, diversion, odds ratio (OR) time, blood loss, and open versus robotic technique were not substantial SSI predictors. BMI was an independent risk factor for SSI on both uni-variable (OR: 1.07, 95% confidence interval [CI]: 1.018-1.115, p = 0.0061) and multi-variable analysis (OR: 1.06, 95% CI: 1.009-1.109, p = 0.02) for 10 (12.8%) and 24 (30.8%) superficial and deep-incisional SSIs, respectively. Superficial wound SSI was treated conservatively with 60% receiving antibiotic agents and no procedural intervention. Deep SSIs received antibiotic agents and 50% required surgical intervention. There were 44 (56.4%) organ/space SSIs, and the most common treatment was antibiotic agents (100%) and IR drain placement (30, 68.2%). Conclusion: In patients undergoing RC, BMI was an independent risk factor for SSI. Type of the surgical procedure, robotic versus open, was not predictive of SSI. LOS was longer for patients with SSI. SSI was managed differently depending on CDC classification.

What Is the Role of the Gut in Wound Infections?

Emerging evidence suggest a major role for the gut microbiome in wound infections. A Trojan Horse mechanism of surgical site infections has been hypothesized to occur when pathogens in the gut, gums, and periodontal areas enter an immune cell and silently travel to the wound site where they release their infectious payload. Genetic tracking of microbes at the strain level is now possible with genetic sequencing techniques and can clarify the origin of microbes that cause wound infections. An emerging field of dietary prehabilitation to modulate the microbiome before surgery is being described to improve infection-related outcomes from surgery.

Rationale for Colonic Pre-Habilitation Prior to Restoration of Gastrointestinal Continuity

The emergence of the gut microbiome as a complex ecosystem that plays a key role in human heath and disease has touched virtually every aspect of medical and surgical care. With the advent of next-generation technology to interrogate the microbiome at the level of its membership, community structure and production of metabolites, applying measures by which the gut microbiome can be manipulated to the advantage of both the patient and provider is now possible. Among the many proposed methods, the most practical and promising is dietary pre-habilitation of the gut microbiome prior to high-risk anastomotic surgery. In this review, we will outline the scientific rationale and molecular underpinning that support dietary pre-habilitation as a practical and deliverable method to prevent complications after high-risk anastomotic surgery.

Rationale behind phosphate therapy to modulate the gut microbiome and protect against surgery-related infection

Despite major advances in infection control and the ever increasing use of broader spectrum antibiotics in surgery, postoperative infections continue to occur under the best of care and in the best institutions. Postoperative infections, also termed "surgical site infections (SSIs), can range from superficial wound infections to deep organ space infections. SSIs can be superficial and only require medical treatment (i.e antibiotics), whereas others such as deep organ space infections resulting from an anastomotic leak can require multiple surgeries leading to sepsis and occasionally shock and death. Many if not most stakeholders in the field including surgeons, infectious disease specialists, infection control nurses, etc., in general advocate the use of prophylactic antibiotics and the enforcement of greater levels of sterility reasoning that all postoperative infections must arise from some type of direct contamination event. In this piece, the alternative view is presented that today, in the era of mandated asepsis protocols, enhanced recovery programs, and enforcement of prophylactic antibiotics in all cases, many if not most postoperative infections and SSIs occur from pathogens endogenous to the patient not from sources exogenous to the patient. It is also suggested that applying broader antibiotic coverage in elective surgery is neither an evolutionarily stable strategy nor inexorable in the context of emerging knowledge in the field of gut ecology. Here this concept is reviewed and the rationale behind using agents that preserve the gut microbiome and attenuate pathogen virulence in lieu of applying broader spectrum antibiotics and greater levels of sterility.