Surgical site infections after pancreaticoduodenectomy: Preoperative biliary system interventions and antimicrobial prophylaxis

Surgical site infection following pancreaticoduodenectomy in a referral cancer center in Mexico

BACKGROUND

Pancreaticoduodenectomy is the standard treatment for resectable periampullary cancer. Surgical site infections (SSI) are common complications with increased morbidity. The study aimed to describe the prevalence, risk factors, microbiology, and outcomes of SSI among patients undergoing pancreaticoduodenectomy.

METHODS

We conducted a retrospective study in a referral cancer center between January 2015 and June 2021. We analyzed baseline patient characteristics and SSI occurrence. Culture results and susceptibility patterns were described. Multivariate logistic regression was used to determine risk factors, proportional hazards model to evaluate mortality, and Kaplan-Meier analysis to assess long-term survival.

RESULTS

A total of 219 patients were enrolled in the study; 101 (46%) developed SSI. Independent factors for SSI were diabetes mellitus, preoperative albumin level, biliary drainage, biliary prostheses, and clinically relevant postoperative pancreatic fistula. The main pathogens were Enterobacteria and Enterococci. Multidrug-resistance rate in SSI was high but not associated with increased mortality. Infected patients had higher odds of sepsis, longer hospital stay and intensive care unit stay, and readmission rate. Neither 30-day mortality nor long-term survival was significantly different between infected and non-infected patients.

CONCLUSIONS

SSI prevalence among patients undergoing pancreaticoduodenectomy was high and largely caused by resistant microorganisms. Most risk factors were related to preoperative instrumentation of the biliary tree. SSI was associated with greater risk of unfavorable outcomes; however, survival was unaffected.

Efficacy of perioperative oral care management in the prevention of surgical complications in 503 patients after pancreaticoduodenectomy for resectable malignant tumor: A multicenter retrospective analysis using propensity score matching

BACKGROUND

Pancreaticoduodenectomy has been associated with a high mortality rate and significant postoperative morbidity. Recently, perioperative oral care management has been reported to be effective in preventing postoperative pneumonia and surgical site infection. In this study, we examined the effect of perioperative oral care management in reducing complications after pancreaticoduodenectomy, including surgical site infection.

METHODS

This retrospective multicenter study included 503 patients who underwent pancreaticoduodenectomy at 8 facilities between January 2014 and December 2016. Among these, 144 received perioperative oral management by dentists and dental hygienists (oral management group), whereas the remaining 359 did not (control group). The oral care management program included oral health instructions, removal of dental calculus, professional mechanical tooth cleaning, removal of tongue coating, denture cleaning, instructions for gargling, and tooth extraction. The participants were matched using propensity scores to reduce background bias. Various factors were examined for correlation with the development of complications.

RESULTS

The incidence of organ/space surgical site infection was significantly lower in the oral management group than in the control group (8.0% vs 19.6%, P = .005). Multivariable logistic regression analysis revealed that hypertension and lack of perioperative oral management were independent risk factors for organ/space surgical site infection. Lack of perioperative oral management had an odds ratio of 2.847 (95% confidence interval 1.335-6.071, P = .007).

CONCLUSION

Perioperative oral care management reduces the occurrence of surgical site infections after pancreaticoduodenectomy and should be recommended as a strategy to prevent infections in addition to antibiotic use.

Prevalence of and risk factors for surgical site infections after pancreaticoduodenectomy: a systematic review and meta-analysis

Background

Surgical site infections (SSIs) are one of the most common complications after pancreaticoduodenectomy (PD); however, the global prevalence and risk factors for SSIs after PD remain unknown.

Objectives

To investigate the prevalence of and risk factors for SSIs after PD.

Methods

The PubMed, Embase, Cochrane Library, Web of Science, and Science Direct databases were systematically searched from inception to 1 December 2022. Observational studies reporting adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of risk factors for SSIs in patients undergoing PD were included. Two independent reviewers in teams performed data extraction, risk of bias assessment, and level of evidence analysis. The pooled results were estimated using a random-effects model. The I 2 statistic and Q χ 2 statistic were used to assess heterogeneity. Funnel plots, Egger's regression test, and the trim-and-fill method were used to determine publication bias. The primary outcomes were identifying risk factors for SSIs after PD. The secondary outcomes were the pooled prevalence rates of SSIs.

Results

A total of 98 704 patients from 45 studies were included, and 80% of the studies were considered high quality. The estimated pooled prevalence of SSIs was 23% (0.19-0.27, I 2=97%). The prevalence of SSIs was found to be higher in Japan and lower in USA. Preoperative biliary stenting, higher body mass index (BMI), longer operation time, postoperative pancreatic fistula, soft pancreatic texture, perioperative blood transfusion, and cardiac disease were identified as significant risk factors for the development of SSIs after PD. Additionally, broad-spectrum antibiotics were a significant protective factor against SSIs. Subgroup analysis and sensitivity analysis showed that the results were robust.

Conclusion and relevance

The prevalence of SSIs remains high and varies widely among regions. It is necessary to take effective preventive measures and carry out more prospective studies to further verify these results.

Antibiotic prophylaxis after 48 h postoperatively are not associated with decreased surgical site infections and other healthcare associated infections in pancreatic surgery patients: a retrospective cohort study

BACKGROUND

It is controversial whether antibiotic should be used prophylactically 48 h after pancreatic surgery. Hence, the association of antibiotic prophylaxis (AP) after 48 h postoperatively with the incidence of surgical site infections (SSIs) and other healthcare-associated infections (HAIs) in patients receiving pancreatic surgery was evaluated.

METHODS

A retrospective cohort analysis was performed on 1073 patients who underwent pancreatic surgery. These patients were categorized into the non-AP after 48 h postoperatively group (n = 963) and the AP after 48 h postoperatively group (n = 110) based on whether or not they obtained AP from 48 h to 30 days after surgery. Outcomes included SSIs and other HAIs.

RESULTS

The incidence of SSIs in the non-AP after 48 h postoperatively group (98/963, 10.2%) was notably lower than that in the AP after 48 h postoperatively group (22/110, 20.0%) (P = 0.002). Other HAIs incidence was not significantly different between the non-AP after 48 h postoperatively group (77/963, 8.0%) and the AP after 48 h postoperatively group (11/110, 10.0%) (P = 0.468). Multiple regression analysis demonstrated that AP after 48 h postoperatively was a risk factor for SSIs (OR = 2.14, 95% CI 1.28-3.59) but not for other HAIs (OR = 1.24, 95% CI 0.63-2.42) after adjustment for age, gender, and diabetes. Subsequent to adjustment for all confounding factors, AP after 48 h postoperatively was not a influence factor for SSIs (OR = 2.13, 95% CI 0.76-5.99) and other HAIs (OR = 3.69, 95% CI 0.99-13.81).

CONCLUSIONS

AP after 48 h postoperatively following pancreatic surgery was not associated with the lower morbidity rate of SSIs and other HAIs. Nonetheless, this study may facilitate further development of strategies towards standardization of the duration of AP management of pancreatic surgery.

Bile Acids and Microbiota Interplay in Pancreatic Cancer

Evidence suggests the involvement of the microbiota, including oral, intra-tumoral and gut, in pancreatic cancer progression and response to therapy. The gut microbiota modulates the bile acid pool and is associated with maintaining host physiology. Studies have shown that the bile acid/gut microbiota axis is dysregulated in pancreatic cancer. Bile acid receptor expression and bile acid levels are dysregulated in pancreatic cancer as well. Studies have also shown that bile acids can cause pancreatic cell injury and facilitate cancer cell proliferation. The microbiota and its metabolites, including bile acids, are also altered in other conditions considered risk factors for pancreatic cancer development and can alter responses to chemotherapeutic treatments, thus affecting patient outcomes. Altogether, these findings suggest that the gut microbial and/or bile acid profiles could also serve as biomarkers for pancreatic cancer detection. This review will discuss the current knowledge on the interaction between gut microbiota interaction and bile acid metabolism in pancreatic cancer.

Surgical Site Infections in Patients of Periampullary Carcinoma Undergoing Delayed Bile Duct Division (COMBILAST) in Whipple’s Procedure: A Prospective Cohort Study

Surgical site infections (SSIs) following a pancreaticoduodenectomy have been a significant cause of morbidity and even mortality. A modified sequence of the Whipple procedure, using the COMBILAST technique, may reduce SSIs and the patient’s hospital stay. This prospective cohort study included 42 patients undergoing Whipple’s pancreaticoduodenectomy for a periampullary malignancy. The modified sequence pancreaticoduodenectomy technique, COMBILAST, was used to estimate the incidence of SSI and explore other advantages. Of the 42 patients, seven (16.7%) developed superficial SSIs, and two patients (4.8%) had an additional deep SSI. Positive intraoperative bile culture had the strongest association with SSI (OR: 20.25, 95% CI: 2.12, 193.91). The mean operative duration was 391.28 ± 67.86 min, and the mean blood loss was 705 ± 172 mL. A total of fourteen (33.3%) patients had a Clavien–Dindo grade of III or higher. Three (7.1%) patients died of septicemia. The average length of a hospital stay was 13.00 ± 5.92 days. A modified sequence of the Whipple procedure, using the COMBILAST technique, seems promising in reducing SSIs and the patient’s hospital stay. As the approach is only a modification of the operative sequence, it does not compromise the oncological safety of the patient. Moreover, it has an added surgical advantage in reducing the chance of injury to the aberrant or accessory right hepatic artery.

Effectiveness of discharge education for patients undergoing general surgery: A systematic review and meta-analysis

BACKGROUND

There is some evidence to suggest that discharge education may reduce the risk of postoperative complications, however, a critical evaluation of the body of evidence is needed.

OBJECTIVE

To assess the effect of discharge education interventions versus standard education given to general surgery patients prior to, or up to 30-days of hospital discharge on clinical and patient-reported outcomes.

DESIGN

Systematic review and meta-analysis. Clinical outcomes were 30-day surgical site infection incidence and re-admission up to 28 days. Patient-reported outcomes included patient knowledge, self-confidence, satisfaction, and quality of life.

SETTING

Participants were recruited from hospitals.

PARTICIPANTS

Adult general surgical patients.

METHODS

MEDLINE (Pubmed), CINAHL (EBSCO), EMBASE (Elsevier) and the Cochrane Library were searched in February 2022. Randomised controlled trials and non-randomised studies of interventions published between 2010 and 2022, with adults undergoing general surgical procedures receiving discharge education on surgical recovery, including wound management, were eligible for inclusion. Quality appraisal was undertaken using the Cochrane Risk of Bias 2 and the Risk of Bias Assessment Tool for Nonrandomised Studies. The Grading of Assessment, Development, Recommendations, and Evaluation was used to assess the certainty of the body of evidence based on the outcomes of interest.

RESULTS

Ten eligible studies (eight randomised control trials and two non-randomised studies of interventions) with 965 patients were included. Six randomised control trials assessed the effect of discharge education interventions on 28-day readmission (Odds ratio 0.88, 95 % confidence interval 0.56-1.38). Two randomised control trials assessed the effect of discharge education interventions on surgical site infection incidence (Odds ratio = 0.84, 95 % confidence interval 0.39-1.82). The results of the non-randomised studies of interventions were not pooled due to heterogeneity in outcome measures. The risk of bias was either moderate or high for all outcomes, and the body of evidence using GRADE was judged as very low for all outcomes studied.

CONCLUSIONS

The impact of discharge education on the clinical and patient-reported outcomes of patients undergoing general surgery cannot be determined due to the uncertainty of the evidence base. Despite the increased use of web-based interventions to deliver discharge education to general surgery patients, larger samples in more rigorous multicentre randomised control trials with parallel process evaluations are needed to better understand the effect of discharge education on clinical and patient-reported outcomes.

REGISTRATION

PROSPERO CRD42021285392.

TWEETABLE ABSTRACT

Discharge education may reduce the likelihood of surgical site infection and hospital readmission but the body of evidence is inconclusive.

Microbiota in the Natural History of Pancreatic Cancer: From Predisposition to Therapy

Early microbiome insights came from gut microbes and their role among intestinal and extraintestinal disease. The latest evidence suggests that the microbiota is a true organ, capable of several interactions throughout the digestive system, attracting specific interest in the biliopancreatic district. Despite advances in diagnostics over the last few decades and improvements in the management of this disease, pancreatic cancer is still a common cause of cancer death. Microbiota can influence the development of precancerous disease predisposing to pancreatic cancer (PC). At the same time, neoplastic tissue shows specific characteristics in terms of diversity and phenotype, determining the short- and long-term prognosis. Considering the above information, a role for microbiota has also been hypothesized in the different phases of the PC approach, providing future revolutionary therapeutic insights. Microbiota-modulating therapies could open new issues in the therapeutic landscape. The aim of this narrative review is to assess the most updated evidence on microbiome in all the steps regarding pancreatic adenocarcinoma, from early development to response to antineoplastic therapy and long-term prognosis.

An anti-bacterial and anti-cancer fibrous membrane with multiple therapeutic effects for prevention of pancreatic cancer recurrence

Adjuvant systemic chemotherapy with gemcitabine (GEM) is recognized as the standard of care to improve the prognosis of patients with resected pancreatic cancer (PC); however, it is greatly limited by poor absorption of chemotherapy agents. Moreover, surgical site infection and Gammaproteobacteria-induced GEM resistance further decrease the chemotherapy efficacy and increase the risk of recurrence and even mortality. Here, we develop an implantable anti-bacterial and anti-cancer fibrous membrane (AAFM) to inhibit PC recurrence in a well-coordinated manner. Our AAFM can be readily prepared via simple co-electrospinning of GEM and poly-L-lactic acid (PLLA) and subsequent tannic acid (TA)-mediated in-situ generation of silver nanoparticles (AgNPs). The resultant membrane presents highly porous fibrous morphology and appropriate mechanical performance. Most importantly, we find the surface-deposited TA/AgNP complexes can exert multiple therapeutic effects: (1) they can act as a fence to extend GEM diffusion route, achieving a sustained drug release; (2) they can fight the pathogenic microorganisms in the local microenvironment and prevent infectious complications and alleviate Gammaproteobacteria-induced chemotherapy resistance; (3) they can combat residual cancer cells to synchronously strengthen the effectiveness of GEM-based chemotherapy. Altogether, our AAFM provides a proof-of-concept demonstration of the integrated anti-cancer and anti-bacterial strategy for enhanced therapeutic efficacy and will inspire the design of other high-performance implants for prevention of tumor relapse.

Risk Factors for Delayed Gastric Emptying After Pancreaticoduodenectomy

OBJECTIVES

Delayed gastric emptying (DGE) is a complication that affects the length of hospitalization and associated cost after pancreaticoduodenectomy (PD). The reported risk factors for DGE were controversial. This study aimed to identify risk factors for the development of DGE after PD.

METHODS

The patients who underwent PD between October 2010 and October 2020 were retrospectively examined. Multivariate analysis was performed to predict the variables causing DGE.

RESULTS

In total, 225 patients underwent PD. The pylorus preserving PD was applied to 151 patients (67%), whereas standard PD to 74 (33%). The DGE was detected in 26 patients (11.5%). The majority of cases were classified as grade A (57.7%), whereas 38.4% as grade B and 3.9% as grade C. In the multivariate analysis, diabetes mellitus (odds ratio [OR], 3.48; 95% confidence interval [CI], 1.45-8.34; P = 0.05), the preoperative biliary stent (OR, 2.5; 95% CI, 1.04-5.99; P = 0.039), and the pylorus resection (OR, 3.05; 95% CI, 1.28-7.25; P = 0.012) were independently associated with DGE.

CONCLUSIONS

We demonstrated that implementation of the preoperative stent, pylorus resection, and diabetes mellitus are independent risk factors for DGE. Pylorus preservation should remain the standard of care in PD.

Optimizing Nanopore Sequencing for Rapid Detection of Microbial Species and Antimicrobial Resistance in Patients at Risk of Surgical Site Infections

Surgical site infections (SSI) are a significant burden to patients and health care systems. We evaluated the use of Nanopore sequencing (NS) to rapidly detect microbial species and antimicrobial resistance (AMR) genes present in intraoperative bile aspirates. Bile aspirates from 42 patients undergoing pancreatic head resection were included. Three methods of DNA extraction using mechanical cell lysis or protease cell lysis were compared to determine the optimum method of DNA extraction. The impact of host DNA depletion, sequence run duration, and use of different AMR gene databases was also assessed. To determine clinical value, NS results were compared to standard culture (SC) results. NS identified microbial species in all culture positive samples. Mechanical lysis improved NS detection of cultured species from 60% to 76%, enabled detection of fungal species, and increased AMR predictions. Host DNA depletion improved detection of streptococcal species and AMR correlation with SC. Selection of AMR database influenced the number of AMR hits and resistance profile of 13 antibiotics. AMR prediction using CARD and ResFinder 4.1 correctly predicted 79% and 81% of the bile antibiogram, respectively. Sequence run duration positively correlated with detection of AMR genes. A minimum of 6 h was required to characterize the biliary microbes, resulting in a turnaround time of 14 h. Rapid identification of microbial species and AMR genes can be achieved by NS. NS results correlated with SC, suggesting that NS may be useful in guiding early antimicrobial therapy postsurgery. IMPORTANCE Surgical site infections (SSI) are a significant burden to patients and health care systems. They increase mortality rates, length of hospital stays, and associated health care costs. To reduce the risk of SSI, surgical patients are administered broad-spectrum antibiotics that are later adapted to target microbial species detected at the site of surgical incision. Use of broad-spectrum antibiotics can be harmful to the patient. We wanted to develop a rapid method of detecting microbial species and their antimicrobial resistance phenotypes. We developed a method of detecting microbial species and predicting resistance phenotypes using Nanopore sequencing. Results generated using Nanopore sequencing were similar to current methods of detection but were obtained in a significantly shorter amount of time. This suggests that Nanopore sequencing could be used to tailor antibiotics in surgical patients and reduce use of broad-spectrum antibiotics.

Antibiotic Prophylaxis for Hepato-Biliopancreatic Surgery—A Systematic Review

Background: Surgical site infections (SSIs) are among the most important determinants of morbidity after HBP surgery. Their frequency after HPB surgery is variable, from 1–2% after elective cholecystectomy to 25% after PD. Methods: A systematic review was performed to assess the role of antimicrobial prophylaxis (AP) in HPB elective surgery. Articles published between 2015 and 2021 were obtained; those before 2015 were not included because they antedate the WHO guidelines on SSI prevention. We conducted three different research methods for liver resection, elective cholecystectomy and pancreatic and biliary surgery regarding patients requiring preoperative biliary drainage. Results: Hepatic surgery, improvement in surgical technique and perioperative management lead to a very low SSI. One preoperative 2 g cefazolin dose may be adequate for surgical prophylaxis. From preoperative biliary drainage, we can derive that patients’ homeostasis rather than AP plays a paramount role in reducing postoperative morbidity. The time from biliary drainage could be an essential element in decision making for surgical prophylaxis. In the case of low-risk cholecystectomy, it is not easy to draw definitive conclusions about the effect of AP. Data from the literature are inconsistent, and some risk factors cannot be predicted before surgery. Conclusion: in our opinion, a strict preoperative cefazolin dose strategy can be reasonable in HBP surgery until a large-scale, multicentric RCT brings definitive conclusions.

The effect of intraoperative wound protector use on the risk of surgical site infections in patients undergoing pancreatoduodenectomy: a systematic review and meta-analysis

AIMS

To evaluate the effect of intraoperative wound protectors on the risk of surgical site infection (SSI) in patients undergoing pancreatoduodenectomy.

METHODS

In compliance with PRISMA statement standards, electronic databases were searched to identify all studies comparing wound protector use with no wound protector use in patients undergoing pancreatoduodenectomy. SSI (superficial or deep) was considered primary outcome measure. The secondary outcome measures included superficial SSI, deep SSI, and organ-space SSI. Random effects modelling was applied to calculate pooled outcome data. The certainty of evidence was assessed using GRADE system.

RESULTS

A total of 12159 patients from four studies were included. The included populations in both groups were comparable in terms of baseline characteristics. The use of wound protector was associated with lower risk of superficial or deep SSI (OR: 0.55, 95% CI 0.43-0.70, P<0.00001), superficial SSI (OR: 0.59, 95% CI 0.46-0.76, P<0.0001), and organ-space SSI (OR: 0.80, 95% CI 0.72-0.90, P=0.0002). There was no difference between the two groups in terms of the risk of deep SSI (OR: 0.68, 95% CI 0.43-1.06, P=0.09) although this may be subject to type 2 error.

CONCLUSIONS

The results of current study suggests that the use of intraoperative wound protector during pancreatoduodenectomy may reduce the risk of postoperative SSI. The quality of the available evidence is moderate with high certainty. While evidence from future randomised controlled trials could increase the robustness of our conclusions, we do not hesitate to recommend the use of wound protectors during pancreatoduodenectomy based on the current evidence.

Worldwide incidence of surgical site infections in general surgical patients: A systematic review and meta-analysis of 488,594 patients

BACKGROUND

Establishing worldwide incidence of general surgical site infections (SSI) is imperative to understand the extent of the condition to assist decision-makers to improve the planning and delivery of surgical care. This systematic review and meta-analysis aimed to estimate the worldwide incidence of SSI and identify associated factors in adult general surgical patients.

MATERIALS AND METHODS

A systematic review was undertaken using MEDLINE (Ovid), CINAHL (EBSCO), EMBASE (Elsevier) and the Cochrane Library to identify cross-sectional, cohort and observational studies reporting SSI incidence or prevalence. Studies of less than 50 participants were excluded. Data extraction and quality appraisal were undertaken independently by two review authors. The primary outcome was cumulative incidence of SSI occurring up to 30 days postoperative. The secondary outcome was the severity/depth of SSI. The I² statistic was used to explore heterogeneity. Random effects models were used in the presence of substantial heterogeneity. Subgroup, meta-regression sensitivity analyses were used to explore the sources of heterogeneity. Publication bias was assessed using Hunter's plots and Egger's regression test.

RESULTS

Of 2091 publications retrieved, 62 studies were included. Of these, 57 were included in the meta-analysis across six anatomical locations with 488,594 patients. The pooled 30-day cumulative incidence of SSI was 11% (95% CI 10%-13%). No prevalence data were identified. SSI rates varied across anatomical location, surgical approach, and priority (i.e., planned, emergency). Multivariable meta-regression showed SSI is significantly associated with duration of surgery (estimate 1.01, 95% CI 1.00-1.02, P = .014).

CONCLUSIONS

and Relevance: 11 out of 100 general surgical patients are likely to develop an infection 30 days after surgery. Given the imperative to reduce the burden of harm caused by SSI, high-quality studies are warranted to better understand the patient and related risk factors associated with SSI.

Outcomes after Surgery among Patients Diagnosed with One or More Multi-Drug-Resistant Organisms

Background: Infections with multi-drug-resistant organisms (MDROs) may be difficult to treat and prolong patient hospitalization and recovery. Multiple MDRO coinfections may increase the complexity of clinical management. However, association between multiple MDROs and outcomes of patients who undergo surgery is unknown. Patients and Methods: We performed a retrospective, cross-sectional analysis of the 2016 National Inpatient Sample for identified by International Classification of Disease, 10th Revision Clinical Modification (ICD-10-CM) diagnosis codes associated with multi-drug-resistant organisms: methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), multi-drug-resistant gram-negative bacilli, and Clostridioides difficile infection (CDI). Admitted patients with diagnosis codes for MDROs were cross-matched with codes for common general surgery procedures. Outcomes of interest included length of stay and mortality. Weighted univariable and multivariable analyses accounting for the survey methodology were performed. Results: Of 1,550,224 patients undergoing surgery in 2016, 39,065 (3%) admissions were diagnosed with an MDRO and 1,176 (0.1%) were associated with dual MDROs diagnoses. Patients diagnosed with one MDRO were hospitalized three times longer (17.3 days; 95% confidence interval [CI], 16.8-17.7) and patients diagnosed with two MDROs five times longer (31.6 days; 95% CI, 27.0-36.2; p < 0.0001) than undiagnosed patients (6.1 days; 95% CI, 6.1-6.1; all p < 0.0001). On multivariable analysis, the strongest predictor of mortality was a diagnosis of two MDRO infections (odds ratio [OR], 4.8; 95% CI, 3.16-7.21; p < 0.0001). The second strongest predictor was diagnosis of single MDRO infection (OR, 2.9; 95% CI, 2.64-3.20; p < 0.0001). Conclusion: Presence of an MDRO was associated with increased odds of mortality and length of stay in admitted surgical patients. Interventions to reduce MDRO infection among surgical patients may reduce hospital length of stay and mortality.

Effect of bacterial contamination in bile on pancreatic cancer cell survival

BACKGROUND

Introduction of gut flora into the biliary system is common owing to biliary stenting in patients with obstructing pancreatic head cancer. We hypothesize that alteration of biliary microbiome modifies bile content that modulates pancreatic cancer cell survival.

METHODS

Human bile samples were collected during pancreaticoduodenectomy. Bacterial strains were isolated from contaminated (stented) bile and identified using 16S ribosomal RNA sequencing. Human pancreatic cancer cells (AsPC1, CFPAC, Panc1) were treated for 24 hours with sterile (nonstented) bile, contaminated (stented) bile, and sterile bile preincubated with 10⁶ colony forming unit of live bacteria isolated from contaminated bile or a panel of bile acids for 24 hours at 37°C, and evaluated using CellTiter-Blue Cell Viability Assay (Promega Corp. Madison, WI). Human bile (30-50 μl/mouse) was coinjected intraperitoneally with 10⁵ Panc02 mouse pancreatic cancer cells in C57BL6/N mice to evaluate the impact of bile on peritoneal metastasis 3 to 4 weeks after tumor challenge.

RESULTS

While all bile samples significantly reduced peritoneal metastasis of Panc02 cells in mice, some contaminated bile samples had diminished antitumor effect. All sterile bile (n = 4) reduced pancreatic cancer cell survival in vitro. Only 40% (2/5) of contaminated bile samples had significant effect. Preincubation of sterile bile with live Enterococcus faecalis or Streptococcus oralis modified the antitumor effect of sterile bile. These changes were not observed with culture media preincubated with live bacteria, suggesting live gut bacteria can modify the antitumor components present in bile. Conjugated bile acids were more potent than unconjugated cholic acid in reducing pancreatic cancer cell survival.

CONCLUSION

Alteration of bile microbiome from biliary stenting has a direct impact on pancreatic cancer cell survival. Further study is warranted to determine if this microbiome shift alters tumor microenvironment.