Biliary microbiome in pancreatic cancer: alterations with neoadjuvant therapy

Association of cephalosporin resistance in intraoperative biliary cultures with surgical site infections in patients undergoing pancreaticoduodenectomy. A retrospective cohort study

BACKGROUND

The aim of this study was to assess the incidence of bacterobilia at the time of a pancreaticoduodenectomy (PD) and the association of resistant bacteria in bile to surgical site infections (SSI).

METHODS

This was a retrospective cohort study including patients undergoing PD in a single center between May 2016 and October 2020. Data of preoperative biliary drainage (PBD), intraoperative biliary cultures (IBC) and postoperative complications were analysed to assess the risk factors for resistant bacteria in IBC and SSIs.

RESULTS

Of 361 patients included, 254 (70%) had undergone PBD. Second-generation cephalosporin resistant bacteria were found in IBC of 183 (64%) of all the patients. PBD was the only risk factor for second-generation cephalosporin resistance. The risk for second-generation cephalosporin resistance was more than 20-fold in patients with PBD [n = 170/254 (67%) (OR 22.58 (95% CI, 9.61-53.01), p < 0.001)] compared to patients who did not have PBD (n = 13/107 (12%)). Also, if the time between PBD and surgery was 2 months or more the second-generation cephalosporin resistance in IBC increased the risk for SSIs (OR 4.14 (95% CI, 1.18-14.51), p = 0.027).

CONCLUSION

The second-generation cephalosporin resistance in IBC is common in patients who have undergone PBD. Broad-spectrum antibiotics in prophylaxis may be beneficial for these patients.

Extended antibiotic therapy is associated with a lower rate of clinically relevant postoperative pancreatic fistula after pancreatoduodenectomy in intermediate- and high-risk patients: A single-institution analysis

BACKGROUND

Clinically relevant postoperative pancreatic fistula remains a common complication after pancreatoduodenectomy. The fistula risk score is a validated tool to predict the risk of clinically relevant postoperative pancreatic fistula. To mitigate complications, we have implemented an extended antibiotic pathway for patients at increased risk of clinically relevant postoperative pancreatic fistula (fistula risk score ≥3). We report outcomes after pancreatoduodenectomy in patients at increased risk for clinically relevant postoperative pancreatic fistula who received extended antibiotic therapy compared to those who received standard perioperative antibiotics (single dose before incision).

METHODS

Single-institution analysis of 87 patients who underwent elective pancreatoduodenectomy (2018-2022) with soft gland texture and fistula risk score ≥3 and were treated with (n = 34) or without (n = 53) 10 days of broad-spectrum antibiotics (piperacillin/tazobactam converted to amoxicillin/clavulanic acid at discharge) after surgery. Associations between extended antibiotics and postoperative outcomes were analyzed.

RESULTS

Baseline clinicodemographic factors were similar between cohorts. Patients who received extended antibiotics had shorter index days (6 vs 8 days, P = .004) and 90-day composite length of stay (8.5 vs 12 days, P = .018). Patients who received extended antibiotics had lower rates of clinically relevant postoperative pancreatic fistula (11.8% vs 37.7%; odds ratio = 0.17, 95% confidence interval: 0.04-0.68), wound infections (8.8% vs 30.2%; odds ratio = 0.08, 95% confidence interval: 0.01-0.50), organ space infections (14.7% vs 43.4%; odds ratio = 0.15, 95% confidence interval: 0.04-0.52), and image-guided drain placement (8.8% vs 34.0%; odds ratio = 0.15, 95% confidence interval: 0.04-0.62). There were no Clostridium difficile infections in the extended antibiotic group.

CONCLUSION

Extended antibiotic therapy is associated with a lower rate of clinically relevant postoperative pancreatic fistula and associated complications after pancreatoduodenectomy in patients with a fistula risk score ≥3. These results form the basis of a randomized controlled trial (NCT05753735).

Intratumoral microorganisms in tumors of the digestive system

Tumors of the digestive system pose a significant threat to human health and longevity. These tumors are associated with high morbidity and mortality rates, leading to a heavy economic burden on healthcare systems. Several intratumoral microorganisms are present in digestive system tumors, and their sources and abundance display significant heterogeneity depending on the specific tumor subtype. These microbes have a complex and precise function in the neoplasm. They can facilitate tumor growth through various mechanisms, such as inducing DNA damage, influencing the antitumor immune response, and promoting the degradation of chemotherapy drugs. Therefore, these microorganisms can be targeted to inhibit tumor progression for improving overall patient prognosis. This review focuses on the current research progress on microorganisms present in the digestive system tumors and how they influence the initiation, progression, and prognosis of tumors. Furthermore, the primary sources and constituents of tumor microbiome are delineated. Finally, we summarize the application potential of intratumoral microbes in the diagnosis, treatment, and prognosis prediction of digestive system tumors. Video Abstract.

Microbiome as a biomarker and therapeutic target in pancreatic cancer

Studying the effects of the microbiome on the development of different types of cancer has recently received increasing research attention. In this context, the microbial content of organs of the gastrointestinal tract has been proposed to play a potential role in the development of pancreatic cancer (PC). Proposed mechanisms for the pathogenesis of PC include persistent inflammation caused by microbiota leading to an impairment of antitumor immune surveillance and altered cellular processes in the tumor microenvironment. The limited available diagnostic markers that can currently be used for screening suggest the importance of microbial composition as a non-invasive biomarker that can be used in clinical settings. Samples including saliva, stool, and blood can be analyzed by 16 s rRNA sequencing to determine the relative abundance of specific bacteria. Studies have shown the potentially beneficial effects of prebiotics, probiotics, antibiotics, fecal microbial transplantation, and bacteriophage therapy in altering microbial diversity, and subsequently improving treatment outcomes. In this review, we summarize the potential impact of the microbiome in the pathogenesis of PC, and the role these microorganisms might play as biomarkers in the diagnosis and determining the prognosis of patients. We also discuss novel treatment methods being used to minimize or prevent the progression of dysbiosis by modulating the microbial composition. Emerging evidence is supportive of applying these findings to improve current therapeutic strategies employed in the treatment of PC.

Roles of microbiota in pancreatic cancer development and treatment

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with poor prognosis. This is due to the fact that most cases are only diagnosed at an advanced and palliative disease stage, and there is a high incidence of therapy resistance. Despite ongoing efforts, to date, the mechanisms underlying PDAC oncogenesis and its poor responses to treatment are still largely unclear. As the study of the microbiome in cancer progresses, growing evidence suggests that bacteria or fungi might be key players both in PDAC oncogenesis as well as in its resistance to chemo- and immunotherapy, for instance through modulation of the tumor microenvironment and reshaping of the host immune response. Here, we review how the microbiota exerts these effects directly or indirectly via microbial-derived metabolites. Finally, we further discuss the potential of modulating the microbiota composition as a therapy in PDAC.

Neoadjuvant therapy does not impact the biliary microbiome in patients with pancreatic cancer

BACKGROUND

Pancreatic adenocarcinoma (PDAC) often impinges on the biliary tree and obstruction necessitates stent placement increasing the risk of surgical site infections (SSIs). We sought to explore the impact of neoadjuvant therapy on the biliary microbiome and SSI risk in patients undergoing resection.

METHODS

A retrospective analysis was performed on 346 patients with PDAC who underwent resection at our institution from 2008 to 2021. Univariate and multivariate methods were utilized for analysis.

RESULTS

Biliary stenting rates were similar between groups but resulted in increased bile culture positivity (97% vs. 15%, p < 0.001). Culture positivity did not differ between upfront resection or neoadjuvant chemotherapy (NAC) (77% vs. 80%, p = 0.60). NAC-alone versus neoadjuvant chemoradiotherapy did not impact biliary positivity (80% vs. 79%, p = 0.91), nor did 5-fluorouracil versus gemcitabine-based regimens (73% vs. 85%, p = 0.19). While biliary stenting increased incisional SSI risk (odds ratios [OR]: 3.87, p = 0.001), NAC did not (OR: 0.83, p = 0.54). Upfront resection, NAC, and chemoradiotherapy were not associated with biliary organism-specific changes or antibiotic resistance patterns.

CONCLUSIONS

Biliary stenting is the greatest predictor for positive biliary cultures and SSIs in resected PDAC patients. Neither NAC nor radiotherapy impact bile culture positivity, speciation, rates, or antibiotic resistance patterns, and perioperative antibiotic prophylaxis should not differ.

Harnessing the Microbiome to Reduce Pancreatic Cancer Burden

Pancreatic cancer mortality is expected to rise in the next decades. This aggressive malignancy has a dismal prognosis due to late diagnosis and resistance to treatment. Increasing evidence indicates that host-microbiome interactions play an integral role in pancreatic cancer development, suggesting that harnessing the microbiome might offer promising opportunities for diagnostic and therapeutic interventions. Herein, we review the associations between pancreatic cancer and the intratumoral, gut and oral microbiomes. We also explore the mechanisms with which microbes influence cancer development and the response to treatment. We further discuss the potentials and limitations of using the microbiome as a target for therapeutic interventions, in order to improve pancreatic cancer patient outcomes.

Impact of Extended Antibiotic Use After Pancreaticoduodenectomy for Patients with Preoperative Metallic Biliary Stenting Treated with Neoadjuvant Chemotherapy

INTRODUCTION

Pancreaticoduodenectomy (PD) remains a complex surgical procedure with infectious complications affecting nearly 50% of patients. Patients who undergo biliary drainage with stent placement prior to neoadjuvant treatment (NAT) reportedly have higher infection rates following PD. The aim of the current study is to evaluate the differences in postoperative infectious complication rates based on the duration of post operative prophylactic antibiotics in patients with indwelling metal biliary stent who had NAT.

METHODS

A retrospective institutional pancreatic cancer database was queried for patients who had a metal biliary stent placed prior to NAT initiation, followed by subsequent PD between 2014 and 2021. Duration of postoperative prophylactic antibiotics was defined as short (SC: ≤ 24 h) or extended (EC: > 24 h-7 days). The primary outcome of interest was surgical site infection (SSI).

RESULTS

Two hundred and ninety-five (n = 295) patients were identified of which the majority (n = 205, 69.5%) received a short course of antibiotics postoperatively. Baseline characteristics were similar between the two cohorts including age, sex, BMI, and comorbidity index. EC patients received more NAT cycles (4 vs. 3, p < 0.001) and underwent an open PD more frequently (61.8% vs. 41.0%, p < 0.001). SSI occurred in 64 (21.7%) patients; SC cohort: 54, 26.3% vs. EC cohort:10, 11.1%, (p = 0.003). Additionally, the SC cohort demonstrated a higher incidence of major complications (Clavien-Dindo ≥ 3: 51 [24.9%] vs. 13 [14.4%], p = 0.045). On the logistic regression model examining factors associated with SSI, higher BMI (continuous variable) was associated with increased odds of SSI (OR: 1.05 [95%CI: 1.00, 1.10, p = 0.040), while EC was protective (OR: 0.36 [95%CI: 0.17, 0.75], p = 0.007).

CONCLUSIONS

These data suggest that an extended course of perioperative antibiotic correlates with reductions in SSI and major morbidity following PD in patients with a metallic biliary stent placed prior to NAT course. These results require validation in a future randomized clinical trial examining a larger cohort of patients with further emphasis on the types of perioperative antibiotics administered.

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.

Effect of preoperative biliary stent on postoperative complications after pancreaticoduodenectomy for cancer: Neoadjuvant versus upfront treatment

BACKGROUND

Limited data are available regarding the effect of preoperative biliary stent, during long-course neoadjuvant chemotherapy, on postoperative complications. The aim of the study is to analyze whether the association of neoadjuvant chemotherapy and biliary stent increases overall and infectious complications after pancreaticoduodenectomy.

METHODS

Data for 538 consecutive pancreatic ductal adenocarcinoma patients who underwent pancreaticoduodenectomy between 2015 and 2020 were retrospectively analyzed. Four groups of patients were identified: neoadjuvant chemotherapy + biliary stent (171 patients), neoadjuvant chemotherapy-no biliary stent (65 patients), upfront surgery + biliary stent (184 patients), and upfront surgery-no biliary stent (118 patients). Median neoadjuvant chemotherapy duration was 6 months. The main outcome of the study was the occurrence of postoperative infections.

RESULTS

No differences among the 4 groups were observed for pancreaticoduodenectomy-specific complications (ie, POPF, DGE, PPH). Infectious complications, in particular surgical site infections, were more frequent in neoadjuvant chemotherapy + biliary stent group (P = 0.001). At multivariate analysis, biliary stent was significantly associated with postoperative infectious complications in the overall cohort (odds ratio 1.996, confidence interval 95% 1.29-3.09, P = .002) and in neoadjuvant chemotherapy patients (odds ratio 5.974, 95% confidence interval 2.52-14.13, P < .001). Biliary stent significantly increased the comprehensive complication index by 9.5% (95% confidence interval 0.04-0.64, P = 0.024) in the overall cohort and 18.9% (95% confidence interval 0.22-1.23, P = .005) in the neoadjuvant chemotherapy group. The presence of multidrug-resistant microorganisms in intraoperative bile culture was not influenced by long-course neoadjuvant chemotherapy.

CONCLUSION

In neoadjuvant chemotherapy patients, biliary stent increased the occurrence of postoperative infectious complications and surgical site infections, while the incidence of multidrug-resistant bacteria in intraoperative bile culture was similar between groups.

Association of the Microbiota and Pancreatic Cancer: Opportunities and Limitations

The human body is thoroughly colonized by a wide variety of microorganisms, termed microbiota. Pancreatic cancer, one of the most aggressive forms of cancer, is no exception. The microbiota of pancreatic cancer largely influences and even dominates the occurrence, development and outcome of pancreatic cancer in many ways. Studies have shown that microbiota could change the malignant phenotype and prognosis of pancreatic cancer by stimulating persistent inflammation, regulating the antitumor immune system, changing the tumor microenvironment and affecting cellular metabolism. This is why the association of the microbiota with pancreatic cancer is an emerging area of research that warrants further exploration. Herein, we investigated the potential microbial markers of pancreatic cancer, related research models, the mechanism of action of microbiota in pancreatic cancer, and pancreatic cancer-microbiota-related treatment.

Human Colonic Microbiota and Short-Term Postoperative Outcomes in Colorectal Cancer Patients: A Pilot Study

Despite the advances in surgical techniques and perioperative care, the complication rates after colorectal cancer surgery have remained stable. Recently, it has been suggested that colon microbiota may be implicated in several pathways that can lead to impaired colonic homeostasis and, thereby, to the development of complications after colorectal surgery. The aim of this study was to evaluate the potential impact of colonic dysbiosis on postoperative course. This prospective human clinical study recruited patients operated on for left colon, sigmoid colon or rectal cancer. Colon mucosa and fecal samples were collected to study mucosa associated microbiota (MAM) and luminal microbiota (LM), accordingly. Preliminary analysis for the first 25 consecutive patients with V3–V4 16S rRNA metagenomic analysis was performed. Bacterial composition and abundance in patients who developed postoperative complications over a 90-day follow-up period were compared to those without postoperative complications. Abundance and distribution of genera in MAM differed significantly when compared to LM with a significant impact on neoadjuvant therapy on bacterial composition. Preliminary analysis revealed no statistically significant differences in LM nor in MAM composition when individuals with and without postoperative surgical complications were compared. In cases of postoperative complications, LM and MAM showed significantly decreased diversity. Composition of the colonic microbiota is altered by neoadjuvant therapy. Results on the impact of colonic dysbiosis on postoperative complications are pending the end of the present study, with 50 patients enrolled.

Role of biliary stent and neoadjuvant chemotherapy in the pancreatic tumor microbiome

BACKGROUND

Intra-tumor microbiota have been implicated in pancreatic ductal adenocarcinoma (PDAC) development, treatment response and post-treatment survivorship. Moreover, therapeutic interventions targeting microbiota may improve the response to chemotherapy and immunotherapy, further emphasizing the critical need to understand the origins of and growth of bacteria within the pancreatic tumor microenvironment. Here, we studied the role of several clinical factors on the bacterial colonization of PDAC.

RESULTS

We obtained matched tumor and normal pancreatic tissue specimens from 27 patients who had undergone surgical resection for PDAC between 2011 and 2015 from the University of Minnesota Biological Materials Procurement Network (BioNet). We found that 26 (48%) out of 54 pancreatic tissue samples harbored detectable bacterial communities using real-time PCR targeting the 16S rRNA gene. Bacterial colonization was detected significantly more frequently in samples from patients who had pancreatic head tumors, underwent Whipple procedure, or had preoperative biliary stent placement. There was also a significantly greater relative abundance of microbiota from the family Enterobacteriaceae among samples from patients who underwent biliary stent placement or neoadjuvant treatment with a combination of Gemcitabine and Paclitaxel.

CONCLUSIONS

These findings suggest that biliary stent placement and neoadjuvant chemotherapy are associated with specific alterations that promote the infiltration and growth of intra-tumor bacteria in the setting of PDAC. Further studies exploring whether specific bacterial communities could contribute to increased chemoresistance will be essential for optimizing medical therapies in the future.

Neoadjuvant Treatment for Pancreatic Adenocarcinoma: A False Promise or an Opportunity to Improve Outcome?

Simple Summary

Pancreatic cancer usually presents late when it has spread to distant sites. In a small proportion of patients, the cancer can be removed by surgery. Surgery is usually followed by chemotherapy, as studies have shown that this improves survival. However, due to complications after surgery and a decline in fitness, some patients do not start their chemotherapy and many do not complete the planned course. The cancer returns in the majority of patients. Chemotherapy or a combination of chemotherapy and radiotherapy before surgery are being investigated to improve survival. The best treatment regime and patient selection for different treatment strategies remains to be defined and is discussed here.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) has an aggressive tumor biology and is associated with poor survival outcomes. Most patients present with metastatic or locally advanced disease. In the 10–20% of patients with upfront resectable disease, surgery offers the only chance of cure, with the addition of adjuvant chemotherapy representing an established standard of care for improving outcomes. Despite resection followed by adjuvant chemotherapy, at best, 3-year survival reaches 63.4%. Post-operative complications and poor performance mean that around 50% of the patients do not commence adjuvant chemotherapy, and a significant proportion do not complete the intended treatment course. These factors, along with the advantages of early treatment of micrometastatic disease, the ability to downstage tumors, and the increase in R0 resection rates, have increased interest in neo-adjuvant treatment strategies. Here we review biomarkers for early diagnosis of PDAC and patient selection for a neo-adjuvant approach. We also review the current evidence for different chemotherapy regimens in this setting, as well as the role of chemoradiotherapy and immunotherapy, and we discuss ongoing trials.

Micro- and Mycobiota Dysbiosis in Pancreatic Ductal Adenocarcinoma Development

BACKGROUND

Dysbiosis of the intestinal flora has emerged as an oncogenic contributor in different malignancies. Recent findings suggest a crucial tumor-promoting role of micro- and mycobiome alterations also in the development of pancreatic ductal adenocarcinoma (PDAC).

METHODS

To summarize the current knowledge about this topic, a systematic literature search of articles published until October 2020 was performed in MEDLINE (PubMed).

RESULTS

An increasing number of publications describe associations between bacterial and fungal species and PDAC development. Despite the high inter-individual variability of the commensal flora, some studies identify specific microbial signatures in PDAC patients, including oral commensals like Porphyromonas gingivalis and Fusobacterium nucleatum or Gram-negative bacteria like Proteobacteria. The role of Helicobacter spp. remains unclear. Recent isolation of Malassezia globosa from PDAC tissue suggest also the mycobiota as a crucial player of tumorigenesis. Based on described molecular mechanisms and interactions between the pancreatic tissue and the immune system this review proposes a model of how the micro- and the mycobial dysbiosis could contribute to tumorigenesis in PDAC.

CONCLUSIONS

The presence of micro- and mycobial dysbiosis in pancreatic tumor tissue opens a fascinating perspective on PDAC oncogenesis. Further studies will pave the way for novel tumor markers and treatment strategies.

Clinical implications of bile cultures obtained during pancreatoduodenectomy: a cohort study and meta-analysis

BACKGROUND

The association between intraoperative bile cultures and infectious complications after pancreatoduodenectomy remains unclear. This cohort study and meta-analysis aimed to determine the predictive role of intraoperative bile cultures in abdominal infectious complications after pancreatoduodenectomy.

METHODS

The cohort study included 114 patients undergoing pancreatoduodenectomy. Regression analyses were used to estimate the odds to develop an organ space infection (OSI) or isolated OSI (OSIs without a simultaneous complication potentially contaminating the intraabdominal space) after a positive bile culture. A systematic review and meta-analysis was performed on abdominal infectious complications (Mantel-Haenszel fixed-effect model).

RESULTS

The positive bile culture rate was 61%, predominantly in patients after preoperative biliary drainage (98% vs 26%, p < 0.001). OSIs occurred in 35 patients (31%) and isolated OSIs in nine patients (8%) and were not associated with positive bile cultures (OSIs: odds ratio = 0.6, 95% CI = 0.25-1.23, isolated OSIs: odds ratio = 0.77, 95% CI = 0.20-3.04). In the meta-analysis, 15 studies reporting on 2047 patients showed no association between positive bile cultures and abdominal infectious complications (pooled odds ratio = 1.3, 95% CI = 0.98-1.65).

CONCLUSION

Given the rare occurrence of isolated OSIs and similar odds for patients with positive and negative bile cultures to develop abdominal infectious complications, routine performance of bile cultures should be reconsidered.

Different Biliary Microbial Flora Influence Type of Complications after Pancreaticoduodenectomy: A Single Center Retrospective Analysis

BACKGROUND

Bacterobilia is associated with postoperative morbidity after pancreaticoduodenectomy (PD), mostly due to infectious complications. The aim of this study was to investigate the prevalence of bacteria species isolated from intraoperative biliary cultures, and related complications after PD.

METHODS

An ANOVA test was used to assess the prevalence of isolated bacterial species and postoperative complications. The odds ratio was computed to evaluate the association between biliary cultures and each complication, Endoscopic Retrograde CholangioPancreatography (ERCP) and each complication, ERCP and biliary cultures, Delayed Gastric Emptying (DGE) and Postoperative Pancreatic Fistula (POPF).

RESULTS

Positive biliary cultures were found in 162/244 (66%) PDs. Different prevalences of polymicrobial biliary culture were detected in patients with postoperative complications. In SSIs, a significant prevalence of biliary culture positive for E. coli, Klebsiella pneumoniæ and Enterococcus fæcalis (p < 0.001) was detected. Prevalences of polymicrobial biliary cultures with Escherichia coli, Klebsiella pneumoniæ, Enterococcus fæcalis and Enterococcus fæcium were significantly associated with POPF (p < 0.001). Biliary culture positive for Escherichia coli, Enterococcus fæcalis and Enterococcus fæcium showed a higher prevalence of intra-abdominal collection and DGE (p < 0.001). Notably, Escherichia coli was significantly associated with DGE as a unique complication (OR = 2.94 (1.30-6.70); p < 0.01).

CONCLUSIONS

Specific prevalences of polymicrobial bacterobilia are associated with major complications, while monomicrobial Escherichia coli bacterobilia is associated with DGE as a unique complication after PD.

Microbiome and pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) incidence and related-deaths are increasing worldwide. PDAC is characterized by poor prognosis due to late diagnosis, high metastatic capacity and resistance to therapy. This is partially due to its specific microenvironment, where the stroma is prominent over tumor cells. Besides the oral and gut microbiota, the intratumor microbiome, i.e. the bacterial and fungal microorganisms present within the tumor, was recently introduced as a new partner of the tumor microenvironment of PDAC modulating pancreatic carcinogenesis, intratumor immune infiltrates, and response to chemotherapy. In this review, we propose an overview of current knowledge about the roles of bacteria and fungi in PDAC development and biology, and discuss potential therapeutic implications.

The Great ESKAPE: Exploring the Crossroads of Bile and Antibiotic Resistance in Bacterial Pathogens

Throughout the course of infection, many pathogens encounter bactericidal conditions that threaten the viability of the bacteria and impede the establishment of infection. Bile is one of the most innately bactericidal compounds present in humans, functioning to reduce the bacterial burden in the gastrointestinal tract while also aiding in digestion. It is becoming increasingly apparent that pathogens successfully resist the bactericidal conditions of bile, including bacteria that do not normally cause gastrointestinal infections. This review highlights the ability of Enterococcus, Staphylococcus, Klebsiella, Acinetobacter, Pseudomonas, Enterobacter (ESKAPE), and other enteric pathogens to resist bile and how these interactions can impact the sensitivity of bacteria to various antimicrobial agents. Given that pathogen exposure to bile is an essential component to gastrointestinal transit that cannot be avoided, understanding how bile resistance mechanisms align with antimicrobial resistance is vital to our ability to develop new, successful therapeutics in an age of widespread and increasing antimicrobial resistance.