A42 INULIN PROMOTES POLYPS DEVELOPMENT IN APC MIN/+ MOUSE COLONIZED BY ESCHERICHIA COLI NC101

Background

Colibactin is a genotoxin that induces double-strand DNA breaks and is produced by Escherichia coli strains harboring the pks island. Human and animal studies have shown that colibactin-producing gut bacteria promote carcinogenesis and facilitate the progression of colorectal cancer through cellular senescence and chromosomal abnormalities.

Aims

In this study, we investigated the impact of inulin, a prebiotic able to modulate bacterial metabolism, in a colorectal cancer model, ApcMin/+mice, colonized by colibactin-producing E. coli strain NC101.

Material & methods

Apc Min/+ mice were subjected to oral gavage with PBS (control) or 108 cfu of E. coli NC101 after a week of receiving a 2% dextran sulfate sodium solution in drinking water. Mice were fed a diet supplemented with 10% cellulose (control) or 10% inulin for 4 weeks. During necropsy, the number of polyps in the duodenum, jejunum, ileum, and colon was counted. Tumors in the colon were graded and the erythroid parameters were measured.

Results

We showed that the inulin diet increased the number of polyps in the ileum compared to cellulose. Moreover, mice colonized with E. coli NC101 and on the inulin diet presented severe anemia associated with an increasing number of polyps in the duodenum, jejunum, and ileum compared to mice supplemented with cellulose.

Conclusions

Our results suggest that, in vivo, inulin promotes polyp development in the small intestine of ApcMin/+ mice colonized by pks+ E. coli strain NC101.

Funding Agencies

CIHRNSERC

A34 ANTIBIOTIC TREATMENT AND ORAL IRON SUPPLEMENTATION SHAPE THE COMPOSITION, RECOVERY AND FUNCTION OF THE GUT MICROBIOTA

Background

Colorectal cancer (CRC) induces anemia in a large proportion of patients and is usually treated with oral iron supplementation. Surgery, the main treatment for CRC, is routinely accompanied by prophylactic antibiotics to avoid infection. However, the combined effect of antibiotics and luminal iron in the gut on the microbiota and intestinal homeostasis remains unknown.

Aims

We aim to characterize the dynamics of gut microbiota composition and recovery from antibiotic exposure under iron-sufficient and iron-supplemented diets in mice. We will investigate how microbial shifts induced by antibiotics and iron influence the function of the gut microbiota and metabolites in the gut.

Methods

Mice were subjected to antibiotic treatment with different concentrations of dietary iron. The composition of the gut microbiota and its recovery after these interventions were assessed in stool samples by 16S rRNA sequencing before and after antibiotic exposure and during the recovery period. Gut microbiota functions were inferred by using the PICRUSt2 prediction tool, and short chain fatty acid (SCFA) concentration in feces were assessed by liquid-chromatography mass spectrometry.

Results

Recovery from antibiotics under high luminal iron concentration shifted the gut microbiota toward a Bacteroidetes phylum-dominant composition. Four bacterial species characterized as CRC markers and/or CRC initiators were significantly more abundant, and nitrogen and pentose phosphate metabolism were higher after recovery under oral iron supplementation. Antibiotic exposure induced a long-term increase in SCFAs linked to gut inflammation, propionate and succinate, and was independent of luminal iron concentration. For mice recovering from antibiotics under high luminal iron concentration, they showed a lack of recovery in baseline levels of butyrate, a SCFA that inhibits cancer cell proliferation in the gut.

Conclusions

Gut microbiota recovery from antibiotic exposure under oral iron supplementation is frequent in CRC patients, but is also common in the general population. This study identifies possible deleterious effects of the concomitance of these two disruptive agents of the gut microbiota and may lead to modifications in the management of anemia in patients with CRC.

Funding Agencies

CIHR Bourse de Mérite Rougier-Armandie en recherche médicale de la Faculté de médecine

A229 PROMOTION OF COLONIC ANASTOMOTIC HEALING WITH PERIOPERATIVE SUPPLEMENTATION WITH OLIGOSACCHARIDES

Background

Colorectal resection is a standard procedure in the management of colorectal cancer (CRC) and inflammatory bowel disease. Anastomotic leak (AL) is a major complication in colorectal resections, and the gut microbiota may play a role in the healing and development of AL. Short-chain fatty acids (SCFAs), namely butyrate, have been involved in anastomotic healing when administered into the bowel via enema. Due to the mechanical stress associated with enemas after the confection of a fresh and fragile anastomosis, other butyrate-increasing strategies are required.

Aims

To promote anastomotic healing and prevent AL by using inulin and galacto-oligosaccharides (GOS) supplementation to modulate the microbiota toward a butyrate-producing profile.

Methods

Mice were fed diets supplemented with inulin, GOS or cellulose, as a non-fermentable control, for two weeks and underwent a proximal colonic anastomosis under general anesthesia. Healing of the anastomosis, both macroscopically and microscopically, was assessed six days after surgery. Epithelial proliferation, mucus production and integrity of the gut barrier were assessed.

Results

Inulin and GOS supplementation increased SCFAs in the colon and were associated with better postoperative weight recovery and macroscopic anastomotic healing. Microscopically, mucosal continuity was promoted by inulin and GOS. Mucus production was found to be similar in all groups. The gut barrier was found to be improved with inulin and GOS as shown by less bacterial translocation.

Conclusions

Inulin and GOS may prevent AL and promote anastomotic healing. This effect appears to be mediated by improved mucosal proliferation.

Funding Agencies

CIHRNatural Sciences and Engineering Research Council of Canada; Institut du cancer de Montréal; Fonds de recherche du Québec en santé

Oligosaccharides increase the genotoxic effect of colibactin produced by pks+ Escherichia coli strains

BACKGROUND

Colibactin is a genotoxin that induces DNA double-strand breaks that may lead to carcinogenesis and is produced by Escherichia coli strains harboring the pks island. Human and animal studies have shown that colibactin-producing gut bacteria promote carcinogenesis and enhance the progression of colorectal cancer through cellular senescence and chromosomal abnormalities. In this study, we investigated the impact of prebiotics on the genotoxicity of colibactin-producing E. coli strains Nissle 1917 and NC101.

METHODS

Bacteria were grown in medium supplemented with 20, 30 and 40 mg/mL of prebiotics inulin or galacto-oligosaccharide, and with or without 5 μM, 25 μM and 125 μM of ferrous sulfate. Colibactin expression was assessed by luciferase reporter assay for the clbA gene, essential for colibactin production, in E. coli Nissle 1917 and by RT-PCR in E. coli NC101. The human epithelial colorectal adenocarcinoma cell line, Caco-2, was used to assess colibactin-induced megalocytosis by methylene blue binding assay and genotoxicity by γ-H2AX immunofluorescence analysis.

RESULTS

Inulin and galacto-oligosaccharide enhanced the expression of clbA in pks+ E. coli. However, the addition of 125 μM of ferrous sulfate inhibited the expression of clbA triggered by oligosaccharides. In the presence of either oligosaccharide, E. coli NC101 increased dysplasia and DNA double-strand breaks in Caco-2 cells compared to untreated cells.

CONCLUSION

Our results suggest that, in vitro, prebiotic oligosaccharides exacerbate DNA damage induced by colibactin-producing bacteria. Further studies are necessary to establish whether oligosaccharide supplementation may lead to increased colorectal tumorigenesis in animal models colonized with pks+ E. coli.

High-grade neuroendocrine small-cell carcinoma of the anal canal: Long-term remission with chemoradiotherapy

Primary small-cell carcinoma of the anal canal is an exceedingly rare tumor with a poor prognosis even when aggressive therapy is initiated. We present the case of a 53-year-old male patient who presented with chronic anal pain. Examination under general anesthesia revealed the presence of a mass in the anal canal. A biopsy was performed, and histopathological examination showed a high-grade neuroendocrine small-cell carcinoma. Assessment with endoscopic ultrasound showed an invasion of the internal anal sphincter. The patient was treated with a chemoradiotherapy (CRT) regimen consisting of cisplatin and etoposide, combined to radiotherapy. The patient achieved long-term remission with CRT. This is one of the first reports in the literature of a case of a high-grade neuroendocrine small-cell carcinoma of the anal canal where long-term remission was achieved with non-surgical management of a tumor invading the anal sphincter. This favorable evolution with CRT suggests that remission could still be achieved with anal small-cell carcinomas. More cases are however required to validate this approach.

RELEVANCE FOR PATIENTS

This case presentation suggests that long-term remission can still be achieved using CRT and without an extensive surgical resection in patients with small-cell carcinoma of the anal canal.

Minimally invasive management of a paraduodenal hernia with intestinal malrotation

Paraduodenal hernias (PDHs) are rare entities that may present with acute or subacute symptoms, and which pose challenges to prompt diagnosis and treatment. The minimally invasive management of these hernias is emerging as a new compelling approach to optimize surgical recovery. We present the case of a 42-year-old female patient who presented with acute abdominal pain and symptoms of bowel obstruction. Abdominal imaging suggested the presence of a left PDH. Laparoscopic exploration was performed. Intestinal malrotation was noted with incarceration of a small bowel loop in the Landzert fossa. The incarcerated bowel loop was freed and primary repair of the hernial defect was performed. PDHs are usually congenital and involve a herniation of abdominal content into the left mesocolon, between the mesocolon and the posterior abdominal wall. Minimally invasive treatment, consisting of adhesiolysis and repair of the hernial defect, seems to be a valid and safe option.

Raoultella ornithinolytica: Emergence and Resistance

Raoultella ornithinolytica is an encapsulated Gram-negative, oxidase-negative, catalase-positive, aerobic, non-motile rod that belongs to the Enterobacteriaceae family. This bacterium was initially classified in the genus Klebsiella as Klebsiella ornithinolytica, until the creation of the genus Raoultella in 2001. R. ornithinolytica is usually found in water environments and soil, and due to its ability to convert histidine to histamine, it has been associated with histamine poisoning in humans. R. ornithinolytica is an emerging entity in human infections, with several reports of virulent infections in comorbid at-risk patients. Increasing reports are potentially due to better and more precise identification tools. The objective of this article is to provide a comprehensive review of reported cases of R. ornithinolytica infections, the emergent virulence of described multiresistant strains, and an overview of currently used identification methods.

Anisakiasis in a Canadian patient with incarcerated epigastric hernia

Anisakiasis is human zoonotic parasitic infection caused by a nematode parasite called Anisakis. This infection is usually reported in Asian countries where consumption of raw seafood is common. Very few cases have been reported in North America. We present the case of a female Canadian patient with an Anisakis larvae in an incarcerated ventral hernia. Cases of Anisakis infections are exceedingly rare in western countries, with very few previous reports describing extra-gastrointestinal cases. Diagnosis is often difficult since the symptoms of anisakiasis are not pathognomonic. As the larvae cannot survive in the body, conservative treatment might be effective in intestinal anisakiasis and surgery is usually performed when complications are encountered. Preventive measures are crucial and include educating the public about the risks of raw fish consumption and the importance of visually inspecting consumed fish and freezing it before ingestion to kill the larvae and prevent the infection.

Prospective study of the changes in pharmacokinetics of immunosuppressive medications after laparoscopic sleeve gastrectomy

Laparoscopic sleeve gastrectomy induces weight loss via the creation of a restrictive gastric tube for early satiety and is associated with an accelerated gastric transit time. A prospective, single-dose pharmacokinetic study was performed, prior to and after laparoscopic sleeve gastrectomy, for tacrolimus, extended-release tacrolimus, mycophenolate mofetil, and enteric-coated mycophenolate sodium. The study included 12 morbidly obese patients in chronic renal failure. The median decrease in body mass index was 8.8 kg/m² with an excess body weight loss of 54.9%. The AUC₂₄ of all drugs were increased after laparoscopic sleeve gastrectomy by 46%, 55%, 77%, and 74%, respectively. The maximum concentrations were increased for tacrolimus, extended-release tacrolimus, and mycophenolate mofetil by 43%, 46%, and 65%. The apparent total clearances were decreased for tacrolimus, mycophenolate mofetil, and enteric-coated mycophenolate sodium by 36%, 57%, and 38%. Laparoscopic sleeve gastrectomy can be associated with significant changes in pharmacokinetics of the drugs evaluated. The mechanism is likely decreased apparent drug clearance due to an increased drug exposure (from a more distal site of intestinal absorption with decreased intestinal metabolism), or decreased clearance (liver metabolism). Adapting the monitoring of immunosuppression will be important to avoid overdosing and potential side effects.

Giant splenic cyst and solid pseudopapillary tumour of the pancreas managed with distal pancreatectomy and splenectomy

Solid pseudopapillary tumours of the pancreas and giant splenic cysts are very rare entities, and their coexistence in a young female patient has not been previously reported in the literature. We present the case of a 27-year-old woman who presented with abdominal pain and two masses on abdominal imaging. A mass located in the right upper quadrant was biopsied, and histological and immunohistochemical analysis showed a solid pseudopapillary tumour of the pancreas. A giant cystic splenic lesion was also noted. The patient underwent a distal pancreatectomy and splenectomy in our referral centre. Margins were negative on histopathological examination. Negative surgical margins were achieved with distal pancreatectomy and splenectomy despite the large size of the pancreatic tumour. The management of solid pseudopapillary tumours of the pancreas is often challenging and the concomitant presence of a giant splenic cyst poses additional challenges to the surgical management of such tumours.

Gastric necrosis late after a Collis-Nissen procedure

A Nissen procedure is an efficient surgical approach to treat gastroesophageal reflux disease. It is sometimes combined with a Collis gastroplasty to lengthen the functional distal esophagus to allow a 360° Nissen fundoplication without tension. We present the case of a 76-year-old female patient, with a history of a Collis-Nissen procedure, who developed extensive gastric necrosis after ingesting a significant quantity of maize. She underwent an urgent total gastrectomy with Roux-en-Y esophagojejunostomy. The cause of ischemia and necrosis in this case is believed to be an insufficient blood supply due to excessive intraluminal pressure. Necrosis of the gastric cavity is usually more likely to be due to venous insufficiency as veins’ walls are less resistant to compression than arterial vessels. Gastric necrosis after a Collis-Nissen procedure is exceedingly rare, and symptoms of such a complication are usually vague and not pathognomonic, which might delay surgical care and increase morbidity.

Current evidence on the relation between gut microbiota and intestinal anastomotic leak in colorectal surgery

BACKGROUND

Anastomotic leak (AL) is a major complication in colorectal surgery. It worsens morbidity, mortality and oncological outcomes in colorectal cancer. Some evidence suggests a potential effect of the intestinal microbiome on wound healing. This review aims to provide a comprehensive review on historical and current evidence regarding the relation between the gastrointestinal microbiota and AL in colorectal surgery, and the potential microbiota-modifying effect of some perioperative commonly used measures.

DATA SOURCES

A comprehensive search was conducted in Pubmed, Medline and Embase for historical and current clinical and animal studies addressing perioperative intestinal microbiota evaluation, intestinal healing and AL.

CONCLUSIONS

Evidence on microbes' role in AL is mainly derived from animal experiments. The microbiota's composition and implications are poorly understood in surgical patients. Elaborate microbiota sequencing is required in colorectal surgery to identify potentially beneficial microbial profiles that could lead to specific perioperative microbiome-altering measures and improve surgical and oncological outcomes.

Pelvic Aggressive Angiomyxoma: Major Challenges in Diagnosis and Treatment

Aggressive pelvic angiomyxoma is a very rare mesenchymal tumor that is usually diagnosed in premenopausal female patients. The current mainly reported treatment is wide surgical excision. Other treatment options, such as radiotherapy and hormonal therapy, have been suggested as potential alternatives. A 61-year-old postmenopausal female patient presented with hematuria that led to the identification of a perirectal mass on abdominopelvic imaging. A 46-year-old female patient presented with a perineal mass of unknown etiology. Despite extensive investigations, the diagnosis could not be confirmed before surgical resection in both patients. Surgical excisions were performed and revealed the presence of an aggressive angiomyxoma with positive estrogen and progesterone tumoral receptors in both cases. Radiological and clinical recurrence was noted in one patient. Tumor regression was noted in this patient after treatment with a luteinizing hormone-releasing hormone (LHRH) agonist with long-term remission. The diagnosis of a perirectal aggressive angiomyxoma is an exceedingly rare event. Preoperative biopsy and pathological diagnosis are challenging and often yields poor results. Its slow growth and expression of hormonal receptors make noninvasive therapeutic strategies, such as radiotherapy, gonadotropin-releasing hormone agonists, or even watchful waiting, valid options in selected patients. Due to the lack of reported cases, the best treatment has yet to be elucidated.

Combined Mucinous and Neuroendocrine Tumours of the Appendix Managed with Surgical Cytoreduction and Oxaliplatin-based Hyperthermic Intraperitoneal Chemotherapy

Appendiceal neoplasms account for 1% of appendectomy specimens. Common subtypes include mucinous cystadenoma, adenocarcinoma, and neuroendocrine tumors (NETs). The simultaneous presence of appendicular mucinous and NETs is a rare event. Depending on the tumors’ morphological distribution in the affected organ, they are qualified as either “collision” or “combined” tumours. We herein present the case of a 50-year-old male who presented with acute appendicitis and who was subsequently found to have pseudomyxoma peritonei (PMP) due to a perforated combined mucinous and neuroendocrine tumours. The patient was treated by right hemicolectomy and cytoreductive surgery (CRS) with oxaliplatin-based hyperthermic intraperitoneal chemotherapy (HIPEC). He was cancer free 20 months later. Due to the limited clinical experience with this presentation, no formal recommendations exist as to its management other than those applicable to each cancer alone. The efficacity of treatment on the long-term prognosis on these combined tumors is yet to be elucidated.

Cholecystocolonic fistula with a giant colonic gallstone: the mainstay of treatment in an acute setting

A cholecystoenteric fistula (CEF) is a rare complication of cholelithiasis with cholecystitis. Cholecystocolonic fistulas (CCFs) account for 8–26.5% of all CEFs. CCFs can cause colonic bleeding, obstruction or perforation, with such complications being mainly reported in the narrower sigmoid colon. Colonic biliary ileus, or obstruction due to the colonic gallstone impaction, is extremely rare in the proximal colon and its best management is yet to be elucidated. We present the case of a 73-year-old male patient with multiple comorbidities and previous abdominal surgeries who presented with hematochezia and intestinal obstructive symptoms. Imaging revealed a giant 5 × 7 cm² gallstone in the proximal transverse colon. Laparotomy and stone extraction via colotomy were performed. Complicated proximal colonic gallstones are exceedingly rare with several operative and non-operative treatments already described. A time-saving surgery in a patient with serious comorbidities is reasonable when compared to a more extensive procedure including enterolithotomy, cholecystecomy and fistula closure.

Ectopic jejunal pancreas with pancreatitis mistaken for a post-transplant lymphoproliferative disease in an immunosuppressed kidney transplant patient

An ectopic pancreas, also known as pancreatic rest or heterotopic pancreas, consists of pancreatic tissue found in a location with no continuity with the anatomic pancreas. This lesion can occasionally cause gastrointestinal obstruction, ulceration or become inflamed and cause ectopic pancreatitis. We present the case of a 29-year-old immunocompromised female patient due to a previous kidney transplant. She presented with nausea and vague abdominal discomfort and was admitted for investigation and treatment of an acute kidney injury. A small bowel mass of unknown etiology was incidentally found on abdominal computed tomography imaging. Due to the high suspicion of a post-transplant lymphoproliferative disease, a surgical exploration took place and revealed the presence of a pancreatic rest with chronic pancreatitis. Ectopic pancreas diagnosis is challenging and surgical exploration is warranted when a neoplastic process is suspected.

Conservative management of pelvic sepsis with severe shock and multiple organ dysfunction syndrome after rubber-band ligation of internal haemorrhoids: surgery is not the only option

Rubber-band ligation (RBL) is a safe and cost-effective approach to internal haemorrhoids. Potential side effects include pain, bleeding, urinary retention and occasionally pelvic sepsis and systemic inflammatory response syndrome (SIRS). At-risk patients are mainly those with immunocompromising conditions. Although aggressive surgical debridement or diverting colostomy appear to be obvious options when patients' life is threatened, their superiority to conservative measures has not been proven. We present the case of a 58-year-old female patient who presented 48 h after a RBL with pelvic pain, dysuria and leukocytosis. Her condition deteriorated rapidly that ventilator and inotropic support were required for a severe SIRS for almost 10 days. Laparoscopic exploration and imaging showed a rectosigmoiditis, ascites and superficial rectal necrosis with no transmural damage requiring an emergent surgery. Conservative management could possibly be a valid option in post-RBL pelvic sepsis even when severe associated multiple organ failure is present.

Sodium polystyrene sulfonate crystals in the gastric wall of a patient with upper gastrointestinal bleeding and gastric perforation: an incidental finding or a pathogenic factor?

Sodium polystyrene sulfonate, or Kayexalate, is an ion-exchange resin used to treat hyperkalemia. It is sometimes used with sorbitol, an osmotic laxative that prevents constipation. Small and large bowel necrosis and perforation due to Kayexalate were previously reported. However, no previous cases of gastric perforation were described. We present a case of gastric perforation in a 48-year-old patient, with chronic kidney disease (CKD), lung transplant under chronic corticosteroids, and two previous Nissen fundoplications. He presented with sudden epigastralgia, hematemesis and hemodynamic instability. Esophagogastroduodenoscopy was not able to localize the site of bleeding. Surgical exploration revealed perforation of the lesser curvature of the stomach. Antrectomy with a Billroth II reconstruction was performed. Pathological examination revealed no abnormalities except fibrinoleukocytic debris with Kayexalate crystals in the gastric wall. Kayexalate is believed to be a trigger for the gastric injury in a patient with tissues impaired by corticosteroids, CKD and immunosuppressors.

Tracing the Pathway from Drift-Wave Turbulence with Broken Symmetry to the Production of Sheared Axial Mean Flow

This study traces the emergence of sheared axial flow from collisional drift-wave turbulence with broken symmetry in a linear plasma device-the controlled shear decorrelation experiment. As the density profile steepens, the axial Reynolds stress develops and drives a radially sheared axial flow that is parallel to the magnetic field. Results show that the nondiffusive piece of the Reynolds stress is driven by the density gradient, results from spectral asymmetry of the turbulence, and, thus, is dynamical in origin. Taken together, these findings constitute the first simultaneous demonstration of the causal link between the density gradient, turbulence, and stress with broken spectral symmetry and the mean axial flow.

Community-acquired infection to Raoultella ornithinolytica presenting as appendicitis and shock in a healthy individual

Raoultella ornithinolytica and Raoultella planticola are histamine-producing bacteria that are usually found in fish and water. They are associated with scombroid syndrome that presents with vomiting and flushing. A wide range of infections with these germs is reported, but mainly in fragile hospitalized patients with multiple comorbidities. We report the case of a 54-year-old healthy patient who presented with 24-hours abdominal pain, vomiting, flushing and shock. The abdominal examination showed guarding in the right lower quadrant (RLQ), and the abdominal CT scan images showed a thickened terminal ileum and a distended appendix. The patient underwent a surgical exploration revealing a normal terminal ileum but an inflamed appendicular base. Raoultella ornithinolytica was found in blood cultures and in the liquid retrieved from the RLQ. To the best of our knowledge, this is the first report of a severe life-threatening intra-abdominal presentation due to a community-acquired R. ornithinolytica infection.