Changing trend in bile microbiology and antibiotic susceptibilities: over 12 years of experience

Microbiological etiology and current resistance patterns in acute calculous cholecystitis

INTRODUCTION

The current treatment for acute calculous cholecystitis (ACC) is early laparoscopic cholecystectomy, in association with appropriate empiric antibiotic therapy. In our country, the evolution of the prevalence of the germs involved and their resistance patterns have been scarcely described. The aim of the study was to analyze the bacterial etiology and the antibiotic resistance patterns in ACC.

METHODS

We conducted a single-center, retrospective, observational study of consecutive patients diagnosed with ACC between 01/2012 and 09/2019. Patients with a concomitant diagnosis of pancreatitis, cholangitis, postoperative cholecystitis, histology of chronic cholecystitis or carcinoma were excluded. Demographic, clinical, therapeutic and microbiological variables were collected, including preoperative blood cultures, bile and peritoneal fluid cultures.

RESULTS

A total of 1104 ACC were identified, and samples were taken from 830 patients: bile in 89%, peritoneal fluid and/or blood cultures in 25%. Half of the bile cultures and less than one-third of the blood and/or peritoneum samples were positive. Escherichia coli (36%), Enterococcus spp (25%), Klebsiella spp (21%), Streptococcus spp (17%), Enterobacter spp (14%) and Citrobacter spp (7%) were isolated. Anaerobes were identified in 7% of patients and Candida spp in 1%. Nearly 37% of patients received inadequate empirical antibiotic therapy. Resistance patterns were scrutinized for each bacterial species. The main causes of inappropriateness were extended-spectrum beta-lactamase-producing bacteria (34%) and Enterococcus spp (45%), especially in patients older than 80 years.

CONCLUSIONS

Updated knowledge of microbiology and resistance patterns in our setting is essential to readjust empirical antibiotic therapy and ACC treatment protocols.

Acute suppurative terminal cholangitis: Clinical characteristics of a new subtype of acute cholangitis

BACKGROUND

Acute suppurative terminal cholangitis (ASTC) is rarer than acute obstructive cholangitis and is not well studied. To explore this subtype of acute cholangitis, we described our clinical experience with ASTC.

METHODS

We performed a retrospective review of patients with ASTC admitted to our center from September 2014 to August 2020. We analyzed their clinical characteristics, including etiology, clinical manifestations, imaging features, treatment and prognosis.

RESULTS

A total of 32 ASTC patients were included in the analysis. The majority of the patients had a history of biliary operations, and clinical manifestations were occult and atypical. The positive rate of bacterial culture was 46.9%. All the patients had typical imaging features on computed tomography and magnetic resonance imaging. Treatment with effective antibiotics was provided as soon as diagnosis was established. After treatment, most patients had a good outcome. Elevated levels of total bilirubin, aspartate aminotransferase, procalcitonin and gamma-glutamyltransferase were the characteristics of critically ill patients and were associated with relatively poor prognosis.

CONCLUSIONS

Our results demonstrated that ASTC should be recognized as a new subtype of acute cholangitis, and that earlier diagnosis and more personalized treatments are needed.

Prolonged antibiotic prophylaxis after pancreatoduodenectomy: systematic review and meta-analysis

BACKGROUND

Previous studies have reported conflicting results of prolonged antibiotic prophylaxis on infectious complications after pancreatoduodenectomy. This study evaluated the effect of prolonged antibiotics on surgical-site infections (SSIs) after pancreatoduodenectomy.

METHODS

A systematic review and meta-analysis was undertaken of SSIs in patients with perioperative (within 24 h) versus prolonged antibiotic (over 24 h) prophylaxis after pancreatoduodenectomy. SSIs were classified as organ/space infections or superficial SSI within 30 days after surgery. ORs were calculated using a Mantel-Haenszel fixed-effect model.

RESULTS

Ten studies were included in the qualitative analysis, of which 8 reporting on 1170 patients were included in the quantitative analysis. The duration of prolonged antibiotic prophylaxis varied between 2 and 10 days after surgery. Four studies reporting on 782 patients showed comparable organ/space infection rates in patients receiving perioperative and prolonged antibiotics (OR 1.35, 95 per cent c.i. 0.94 to 1.93). However, among patients with preoperative biliary drainage (5 studies reporting on 577 patients), organ/space infection rates were lower with prolonged compared with perioperative antibiotics (OR 2.09, 1.43 to 3.07). Three studies (633 patients) demonstrated comparable superficial SSI rates between patients receiving perioperative versus prolonged prophylaxis (OR 1.54, 0.97 to 2.44), as well as in patients with preoperative biliary drainage in 4 studies reporting on 431 patients (OR 1.60, 0.89 to 2.88).

CONCLUSION

Prolonged antibiotic prophylaxis is associated with fewer organ/space infection in patients who undergo preoperative biliary drainage. However, the optimal duration of antibiotic prophylaxis after pancreatoduodenectomy remains to be determined and warrants confirmation in an RCT.

Suggested use of empirical antibiotics in acute cholecystitis based on bile microbiology and antibiotic susceptibility

BACKGROUND

Bacterial infection is common in acute cholecystitis (AC). To identify appropriate empirical antibiotics, we investigated AC-associated microorganisms and their susceptibilities to antibiotics. We also compared preoperative clinical findings of patients grouped according to specific microorganisms.

METHODS

Patients who underwent laparoscopic cholecystectomy for AC between 2018 and 2019 were enrolled. Bile cultures and antibiotic susceptibility tests were performed, and clinical findings of patients were noted.

RESULTS

A total of 282 patients were enrolled (147 culture-positive and 135 culture-negative). The most frequent microorganisms were Escherichia (n = 53, 32.7%), Enterococcus (n = 37, 22.8%), Klebsiella (n = 28, 17.3%), and Enterobacter (n = 18, 11.1%). For Gram-negative microorganisms, second-generation cephalosporin (cefotetan: 96.2%) was more effective than third-generation cephalosporin (cefotaxime: 69.8%). Vancomycin and teicoplanin (83.8%) were the most effective antibiotics for Enterococcus. Patients with Enterococcus had higher rates of CBD stones (51.4%, p = 0.001) and biliary drainage (81.1%, p = 0.002), as well as higher levels of liver enzymes, than patients with other microorganisms. Patients with ESBL-producing bacteria had higher rates of CBD stones (36.0% vs. 6.8%, p = 0.001) and biliary drainage (64.0% vs. 32.4%, p = 0.005) than those without.

DISCUSSION

Preoperative clinical findings of AC are related to microorganisms in bile samples. Periodic antibiotic susceptibility tests should be conducted to select appropriate empirical antibiotics.

Incidence of bactibilia and related factors in patients who undergo cholecystectomy

Purpose

In general, bile is normally sterile. However, there are reports bactibilia may occur in certain instances, though the causal factors are unclear. We analyzed possible preoperative predictors of bactibilia upon cholecystectomy.

Methods

Bile samples were collected during cholecystectomies from November 2018 to November 2019. A total of 428 open or laparoscopic cholecystectomies were performed. Preoperative, intraoperative, and postoperative variables were compared between the culture-positive and culture-negative groups.

Results

One hundred fifty-seven patients (36.7%) were culture-positive. Gram-negative bacteria (95 [61.0%]) were more common. Escherichia coli (38 [40.0%]) and Enterobacter (22 [23.2%]) were the most common species. In univariate analysis, age of ≥70 years (P < 0.001), male sex (P < 0.001), high American Society of Anesthesiologists physical status grades (P = 0.001), diabetes mellitus (P = 0.002), jaundice (P = 0.007), high Tokyo Guideline grades (P = 0.008), percutaneous transhepatic gallbladder drainage (PTGBD; P < 0.001), endoscopic retrograde cholangiopancreatography (ERCP; P < 0.001) were identified as a risk factors for bactibilia. In multivariate analysis, age of ≥70 years (hazard ratio [HR], 2.874; 95% confidence interval [CI], 1.769-4.670; P = 0.001), ERCP (HR, 9.001; 95% CI, 4.833-16.75; P < 0.001), and PTGBD (HR, 2.866; 95% CI, 1.440-4.901; P = 0.002) were independent risk factors for bactibilia.

Conclusion

Among patients who underwent cholecystectomy, those who were elderly, symptomatic, and underwent preoperative drainage were more likely to have bactibilia. In such cases, surgeons should take care to prevent bile leakage during surgery and consider administering appropriate antibiotics.

Korean Guidelines for Use of Antibiotics for Intra-abdominal Infections in Adults

The guidelines are intended to provide practical information for the correct use of antibiotics for intra-abdominal infections in Korea. With the aim of realizing evidence-based treatment, these guidelines for the use of antibiotics were written to help clinicians find answers to key clinical questions that arise in the course of patient care, using the latest research results based on systematic literature review. The guidelines were prepared in consideration of the data on the causative pathogens of intra-abdominal infections in Korea, the antibiotic susceptibility of the causative pathogens, and the antibiotics available in Korea.

The biliary microbiome in ischaemic-type biliary lesions can be shaped by stenting but is resilient to antibiotic treatment

This study aims to characterize the biliary microbiome as neglected factor in patients with ischaemic-type biliary lesions (ITBL) after liver transplantation. Therefore, the V1-V2 region of the 16S rRNA gene was sequenced in 175 bile samples. Samples from patients with anastomotic strictures (AS) served as controls. Multivariate analysis and in silico metagenomics were applied cross-sectionally and longitudinally. The microbial community differed significantly between ITBL and AS in terms of alpha and beta diversity. Both, antibiotic treatment and stenting were associated independently with differences in the microbial community structure. In contrast to AS, in ITBL stenting was associated with pronounced differences in the biliary microbiome, whereas no differences associated with antibiotic treatment could be observed in ITBL contrasting the pronounced differences found in AS. Bacterial pathways involved in the production of antibacterial metabolites were increased in ITBL with antibiotic treatment. After liver transplantation, the biliary tract harbours a complex microbial community with significant differences between ITBL and AS. Fundamental changes in the microbial community in ITBL can be achieved with biliary stenting. However, the effect of antibiotic treatment in ITBL was minimal. Therefore, antibiotics should be administered wisely in order to reduce emerging resistance of the biliary microbiome towards external antibiotics.

Evaluation of bile sterility in patients undergoing liver resection

Introduction: Surgery remains the mainstay of treatment for liver tumors. Significant differences in complication rates between liver surgery centers have been reported ranging from 4.1% up to 47.7%. There have been little papers or studies on the impact of bile infection on postoperative complications in patients undergoing surgery for liver cancer. Aim: The aim of our study was to assess the etiology of bile infections in patients following liver resection and to evaluate its impact on complications and perioperative mortality. Materials and methods: The studied material consisted of 69 patients undergoing surgery for liver tumors at the Department of General and Transplant Surgery of the Medical University of Lodz between 2011 and 2013, when the intraoperative bile cultures were available. Results: The intraoperative bile cultures were positive for bacteria in 12 cases (18.75%), while in other cases the bile was sterile (n = 52). In 41.61% of cases, a methicillin-resistant strain was identified. Two patients presented with jaundice, associated with abdominal pain in one patient; other patients complained of abdominal pain only (jaundice: 16.67%; abdominal pain: 91.67%). In both cases, jaundice was not accompanied by any other typical symptoms of cholangitis; also, palliative surgery was performed in both cases. In patients with confirmed bile infection, jaundice was significantly more common (16.67% vs 0.00%; p = 0.033). Patients with sterile bile cultures reported weight loss significantly more often compared to patients with bile infection (26.90% vs 0.00%; p = 0.042). The hospital stay was longer in patients with bile infection (p = 0.138), whereas the hospitalization was significantly longer in patients infected with methicillin-resistant strains compared to both patients with sterile bile and those with bile infection with non-resistant strains. Conclusions: The causes and real incidence of asymptomatic bile infection remain unknown. Routine bile cultures in patients undergoing liver surgery may prevent complications by early modification of antibiotic regime considering the antibiogram, and identification of the most common causes of asymptomatic bile infection may translate to better preoperative antibiotic prophylaxis.

The Role of Targeted Versus Standard Antibiotic Prophylaxis in Pancreatoduodenectomy in Reducing Postoperative Infectious Complications: A Systematic Review and Meta-analysis

INTRODUCTION

Infectious complications are common after pancreatoduodenectomy, which in turn are associated with preoperative biliary drainage. Current guidelines recommend a first-generation cephalosporin as perioperative antibiotic prophylaxis. However, some studies support the use of targeted antibiotics. The aim of this systematic review and meta-analysis is to evaluate the role of prophylactic targeted antibiotics compared to standard antibiotics in reducing postoperative infections after pancreatoduodenectomy.

METHODS

A search from MEDLINE, EMBASE, and Cochrane library from 1946 to July 2020 was conducted. Studies were included if they compared targeted antibiotics with standard perioperative antibiotics while including outcome data on surgical site infections (SSI). Targeted therapy was defined as perioperative antibiotics targeting organisms prevalent in bile instrumentation or by culture data obtained from the patient or institution. Outcomes assessed were the rate of SSIs and their microbiology profile. Analyses included demographic data, perioperative antibiotics, postoperative outcomes including microbiology data, and meta-analysis was performed where applicable.

RESULTS

Seven studies were included, with a total of 849 patients undergoing pancreatoduodenectomy. Targeted antibiotics were associated with a significantly lower rate of postoperative SSI compared to standard antibiotic therapy [21.1% vs 41.9%; risk ratios (RR) 0.55, 95% confidence interval 0.37-0.81]. Wound/incisional site infections and organ space infections were lower in patients receiving targeted antibiotic prophylaxis (RR 0.33, P = 0.0002 and RR 0.54, P = 0.0004, respectively). Enterococcus species were the most common bacteria reported.

CONCLUSION

There was a significant reduction in overall SSI rates when targeted antibiotics was used. Current standard antibiotic prophylaxis is inadequate in covering microbes prevalent in postoperative infections developing after pancreatoduodenectomy.

The Role of Microbiota in Primary Sclerosing Cholangitis and Related Biliary Malignancies

Primary sclerosing cholangitis (PSC) is an immune-related cholangiopathy characterized by biliary inflammation, cholestasis, and multifocal bile duct strictures. It is associated with high rates of progression to end-stage liver disease as well as a significant risk of cholangiocarcinoma (CCA), gallbladder cancer, and colorectal carcinoma. Currently, no effective medical treatment with an impact on the overall survival is available, and liver transplantation is the only curative treatment option. Emerging evidence indicates that gut microbiota is associated with disease pathogenesis. Several studies analyzing fecal and mucosal samples demonstrate a distinct gut microbiome in individuals with PSC compared to healthy controls and individuals with inflammatory bowel disease (IBD) without PSC. Experimental mouse and observational human data suggest that a diverse set of microbial functions may be relevant, including microbial metabolites and bacterial processing of pharmacological agents, bile acids, or dietary compounds, altogether driving the intrahepatic inflammation. Despite critical progress in this field over the past years, further functional characterization of the role of the microbiota in PSC and related malignancies is needed. In this review, we discuss the available data on the role of the gut microbiome and elucidate important insights into underlying pathogenic mechanisms and possible microbe-altering interventions.

Pancreatoduodenectomy within 2 weeks after endoscopic retrograde cholangio-pancreatography increases the risk of organ/space surgical site infections: a 5-year retrospective cohort study in a high-volume centre

BACKGROUND

Organ/space surgical site infections (OSSI) after pancreaticoduodenectomy (PD) are not rare events. The role of diagnosis and treatment for pancreatic and biliary diseases with an endoscopic retrograde cholangio-pancreatography (ERCP) procedure is currently controversial. However, the ERCP procedure might play a role in surgical outcomes after PD.

METHODS

We conducted a retrospective cohort study for patients who underwent PD in the First Affiliated Hospital with the Nanjing Medical University from 1st September 2012 to 31st January 2018. The relationship between ERCP exposure and OSSI after PD was analyzed by univariate and forward stepwise multivariate logistic regression model.

RESULTS

Of the 1,365 patients who underwent PD, 136 developed OSSI (10.0%). We found that ERCP exposure before PD (EEBPD) was significantly associated with an increased incidence rate of post-operative pancreas fistula (POPF) [24.2% (23/95) vs. 14.9% (189/1,270), risk ratio (RR) =1.63, 95% confidence interval (CI), 1.11-2.38, P=0.015]. Hypertension, a higher level of preoperative low-density lipoprotein (LDL) and creatinine (Cr) were associated with elevated risks of post-operative OSSI [adjusted odds ratio (Adj-OR) (95% CI) were 1.59 (1.09-2.32), 1.70 (1.16-2.51), 1.99 (1.36-2.92)], whereas a preoperatively higher level of aspartate aminotransferase (AST) would decrease the risk [Adj-OR (95% CI), 0.62 (0.42-0.91)]. Remarkably, EEBPD would significantly increase and more than double the OSSI risk [Adj-OR (95% CI), 2.56 (1.46-4.47)] especially if it was within 14 days before surgery (Spearman =-0.698, P<0.001).

CONCLUSIONS

ERCP, as an independent risk factor, significantly increased the risk of post-operative OSSI after PD if it is performed within 14 days prior to surgery. Our findings would assist clinical decision-making, and improve OSSI control and prevention.

Antibiotic selection based on microbiology and resistance profiles of bile from gallbladder of patients with acute cholecystitis

With the progression of acute cholecystitis, antimicrobial therapy becomes important for infection control. Current antibiotic recommendations were mostly based on reports of patients with acute cholangitis whose bile specimens were sampled from the biliary tract. However, as most infections of acute cholecystitis are limited to the gallbladder, direct sampling from the site increases the probability of identifying the causative pathogen. We investigated 321 positive bile cultures from 931 patients with acute cholecystitis who underwent laparoscopic cholecystectomy between January 2003 and December 2017. The frequency of enterococci declined (P = 0.041), whereas that of Enterobacteriales (P = 0.005), particularly Escherichia (P = 0.008), increased over time. The incidence of ciprofloxacin-resistant Enterobacteriales showed a significant increasing trend (P = 0.031). Vancomycin-resistant E.faecium, carbapenem-resistant Enterobacteriales, and extended-spectrum beta-lactamase-producing Enterobacteriales were recently observed. In grade I and II acute cholecystitis, there were no significant differences in perioperative outcomes in patients with and without early appropriate antimicrobial therapy. In conclusion, the changing incidence of frequently isolated microorganisms and their antibiotic resistance over time would be considered before selecting antibiotics for the treatment of acute cholecystitis. Surgery might be a crucial component of infection control in grade I and II acute cholecystitis.

Differences in Bile Microbiology and Antibiotic Resistances between Liver Transplant Recipients and Non-Transplant Patients

Background: Treatment of biliary infection in liver transplant (LT) recipients is a challenge, especially because of ineffectiveness of the antibiotic agents otherwise recommended for non-transplant populations. We aimed to understand the factors underlying the choice of antibiotic therapy. Patients and Methods: A total of 373 bile cultures from LT recipients with biliary complications (n = 127; LT group) and from a non-transplant population that underwent cholecystectomy for acute cholecystitis (n = 246; non-transplant group) between January 2009 and December 2018, were investigated. Results: Polymicrobial cultures (13.4% vs. 1.6%; p < 0.001), Enterococcus faecium (26.0% vs. 8.5%; p < 0.001), and Pseudomonas (13.4% vs. 4.1%; p = 0.001) in the LT group, and non-faecium enterococci (3.9% vs. 18.3%; p < 0.001) and Enterobacteriales (40.2% vs. 54.9%; p = 0.007), especially Escherichia (11.0% vs. 29.7%; p < 0.001), in the non-transplant group, showed higher abundance. Most of the antibiotic agents recommended as initial antibiotic therapy for the non-transplant population as per previous guidelines were not effective in LT recipients. The incidences of Enterococcus faecium (14.9% vs. 32.5%; p = 0.029) in the LT recipients with model for end-stage liver disease (MELD) score >12 and non-faecium enterococci (8.5% vs. 1.3%; p = 0.042) in those with MELD score ≤12 were higher than those in the other group. The incidence of Enterobacteriales increased over time after LT (p = 0.048) and was similar to that in the non-transplant group after one year of LT. Bile micro-organisms in LT recipients, resistant to most antibiotic agents, especially soon after LT changed over time and became similar to those in the non-transplant group after one year of LT. Conclusions: Antibiotic therapy for biliary infection in LT recipients should be different from that in non-transplant populations, considering clinical factors such as the time interval after LT and MELD score.

Proton Pump Inhibitors Increase the Risk of Early Biliary Infection After Placement of Percutaneous Transhepatic Biliary Stents

PURPOSE

To investigate the association between the use of proton pump inhibitors (PPIs) and the risk of early biliary infection (EBI) after the placement of percutaneous transhepatic biliary stents (PTBS) in patients with unresectable malignant biliary obstruction (MBO).

MATERIALS AND METHODS

A total of 136 patients with unresectable MBO (82 males and 54 females) treated with PTBS were included in this multicenter retrospective study. PPIs were prescribed to MBO patients with dyspepsia. The risk factors for EBI were identified by univariate and multivariate analyses. The association between the use of PPIs and EBI was assessed by logistic analyses.

RESULTS

A total of 72 (53%) patients were regular users of PPIs, and 33 (24%) patients developed EBI after PTBS. Univariate and multivariate analyses revealed that diabetes (hazard ratio [HR], 20.3; 95% confidence interval [CI], 5.6-72.9; P <.001), biliary stones (HR, 20.3; 95% CI, 5.6-72.9; P <.001) and PPIs (HR, 4.0; 95% CI, 1.2-12.8; P =.020) were risk factors for EBI. Further analyses of the correlation between the duration of PPIs use and EBI demonstrated that a prolonged use of PPIs significantly increased the risk of EBI (PPIs for <15 days vs 15-30 days: HR, 10.2; 95% CI, 3.1-33.3; P <.001; and PPIs <15 days vs ≥30 days; HR, 20.4; 95% CI, 2.2-192.3; P <.001).

CONCLUSION

The use of PPIs increased the risk of EBI after PTBS in patients with unresectable MBO. Furthermore, the risk of EBI increased with a prolonged duration of PPIs use.

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.

Mortality analysis of Aeromonas hydrophila infection in hepato-biliary pancreatic surgery: Multicenter retrospective observational study

BACKGROUND/PURPOSE

Aeromonas hydrophila can cause lethal infectious complications after surgery. There have been no large cohort studies of this specific to the hepato-biliary-pancreatic (HBP) field. We investigate the postoperative influence of A hydrophila infection after HBP surgery.

METHODS

We retrospectively reviewed patients who underwent HBP surgery between 2008 and 2017 at eight university hospitals. Patients with A hydrophila isolation during perioperative management were extracted, and their postoperative courses were investigated.

RESULTS

Bacterial culture examination of 10 074 patients was performed as perioperative management. Among them, 76 patients (0.75%) had A hydrophila isolation, most of whom underwent pancreatoduodenectomy (n = 38) or hepatectomy with biliary reconstruction (n = 14). There were seven mortalities after these two procedures (13.5%), five within 3 days after the onset of infection. Bile (n = 48) and abdominal drainage fluid (n = 29) were major sites of A hydrophila isolation. Typical prophylactic antibiotics, cefazolin or flomoxef, were mostly resistant. There was no mortality among patients that received sensitive antibiotics prophylactically.

CONCLUSIONS

Isolation of A hydrophila was low in our cases of HBP surgery, but the condition of some patients deteriorated rapidly by this infection. Although there could be several bacterial infections during management of HBP surgery, A hydrophila should not be overlooked. Preparation of appropriate prophylactic antibiotics may prevent or reduce mortality.

Role of the biliary microbiome in gallstone disease

Gallstone disease is caused by multiple pathogenic factors and is common worldwide. Most studies have focused on the significance of the biliary microbiome in gallstone pathogenesis. Areas covered: In this study, the epidemiology of gallstone diseases and the existence, composition, origin, and mechanisms of the biliary microbiota were reviewed. Mechanisms involved in promoting the formation of different types of gallstones were also emphasized. The antibiotic susceptibility of the biliary microbiota is briefly discussed because it may guide clinical strategies. Expert commentary: The biliary microbiome facilitates the formation of brown pigment stones. Although glycoprotein (mucin) may be pivotal for many promoting substances to coagulate and integrate relevant components, new mechanisms involving prostaglandins, oxysterols, oxygen free radicals, and lipopolysaccharides have been discovered. Furthermore, specific bacterial species such as Helicobacter and Salmonella are involved in the pathogenesis of cholesterol gallstones. Recently, metabolomics of the biliary microbiome has been used to determine the detailed mechanisms that promote gallstone formation. Previously, the bacterial effects involved in the pathogenesis of brown pigment stones have not been analyzed in detail. Whether the administration of antibiotics is related to prophylaxis for gallstone formation and gallstone-associated infections remains unclear.

Primary sclerosing cholangitis is characterised by intestinal dysbiosis independent from IBD

OBJECTIVE

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease often leading to end-stage liver disease. Its pathogenesis remains largely unknown, although frequent concomitant IBD hints towards common factors underlying gut and bile duct inflammation. Considering the mounting evidence on the involvement of the intestinal microbiota in initiating and determining IBD phenotype, we investigated intestinal microbiota composition in patients with PSC.

DESIGN

Stool samples were collected from 147 individuals (52 patients with PSC, 52 age, gender and body mass index-matched healthy volunteers, 13 UC and 30 patients with Crohn's disease). An independent validation cohort of 14 PSC and 14 matched controls was recruited. 16S rDNA sequencing of faecal DNA was performed (Illumina MiSeq).

RESULTS

The microbiota of patients with PSC was characterised by decreased microbiota diversity, and a significant overrepresentation of Enterococcus (p=3.76e-05), Fusobacterium (p=3.76e-05) and Lactobacillus (p=0.0002) genera. This dysbiosis was present in patients with PSC with and without concomitant IBD and was distinct from IBD, and independent of treatment with ursodeoxycholic acid. A decision tree based on abundances of these three genera allowed reliable classification in the validation cohort. In particular, one operational taxonomic unit belonging to the Enterococcus genus was associated with increased levels of serum alkaline phosphatase (p=0.048), a marker of disease severity.

CONCLUSIONS

We here present the first report of PSC-associated faecal dysbiosis, independent from IBD signatures, suggesting the intestinal microbiota could be a contributing factor in PSC pathogenesis. Further studies are needed to confirm these findings and assess causality.

Cholesterol gallstones and bile host diverse bacterial communities with potential to promote the formation of gallstones

The prevalence of cholesterol gallstones has increased in recent years. Bacterial infection correlates with the formation of gallstones. We studied the composition and function of bacterial communities in cholesterol gallstones and bile from 22 cholesterol gallstone patients using culture-dependent and culture-independent methods. Altogether fourteen and eight bacterial genera were detected in cholesterol gallstones and bile, respectively. Pseudomonas spp. were the dominant bacteria in both cholesterol gallstones and bile. As judged by diversity indices, hierarchical clustering and principal component analysis, the bacterial communities in gallstones were different from those in bile. The gallstone microbiome was considered more stable than that of bile. The different microbial communities may be partially explained by differences in their habitats. We found that 30% of the culturable strains from cholesterol gallstones secreted β-glucuronidase and phospholipase A2. Pseudomonas aeruginosa strains showed the highest β-glucuronidase activity and produced the highest concentration of phospholipase A2, indicating that Ps. aeruginosa may be a major agent in the formation of cholesterol gallstones.

Perioperative antibiotics covering bile contamination prevent abdominal infectious complications after pancreatoduodenectomy in patients with preoperative biliary drainage

BACKGROUND

Although bile contamination caused by preoperative biliary drainage (PBD) is a risk factor for infectious complications after pancreatoduodenectomy, the appropriate perioperative antibiotic regimen remains unclear. We evaluated a perioperative antibiotic strategy targeting bile contamination associated with PBD procedures for preventing abdominal infectious complications after pancreatoduodenectomy.

METHODS

Consecutive patients (n = 254) underwent pancreatoduodenectomy at a single center. Perioperative antibiotics were mainly cefazolin in non-PBD cases (n = 116) and cefozopran in internal-PBD cases (n = 87). They were based on preoperative bile cultures in 51 of the external-PBD cases. Intraoperative bile cultures were examined prospectively. Morbidity and abdominal infectious complication rates were evaluated.

RESULTS

The incidence of positive intraoperative bile cultures was significantly higher in the internal-PBD (85 %) and external-PBD (90 %) cases than in the non-PBD cases (26 %) (p < 0.001). The 91 % susceptibility to cefazolin for non-PBD was significantly higher than the 61 % for internal-PBD or 45 % for external-PBD (p < 0.001). Overall morbidity rates (23, 23, and 25 %) and abdominal infectious complications (13, 17, and 14 %) did not differ among the non-PBD, internal-PBD, and external-PBD cases, respectively. Only susceptibility to perioperative antibiotics of biliary microorganisms classified as resistant was a significant independent risk factor for abdominal infectious complications (p = 0.003).

CONCLUSIONS

A perioperative antibiotic strategy particular to PBD procedures is valid for covering biliary microorganisms during pancreatoduodenectomy. Perioperative antibiotics covering bile contamination may prevent abdominal infectious complications after pancreatoduodenectomy in patients with and without PBD.

The use of proton pump inhibitors and the spectrum and number of biliary pathogens in patients with acute cholangitis

BACKGROUND

Knowledge of the bacterial spectrum for acute cholangitis is essential for adequate empiric antibiotic treatment.

AIM

To analyse the relation of proton pump inhibitors (PPI) with biliary pathogens in patients with acute cholangitis.

METHODS

This retrospective study identified 278 patients with 318 acute cholangitis episodes using an endoscopic database. The relationship between PPI and microbiological outcomes was assessed by logistic and poisson regression analysis for binary and count data.

RESULTS

In total, 882 pathogens were isolated, of which, 120 cholangitis episodes occurred with PPI; 198 cholangitis episodes without PPI. Multivariate poisson regression analysis showed that PPI use resulted in a 23% increase in the number of biliary pathogens [3.14 vs. 2.55 (Δ = 0.59), P < 0.01], whereas stent therapy, previous interventional procedures (endoscopic retrograde cholangiography/percutaneous transhepatic cholangiography), genesis, age and sex showed no significant association with the number of biliary pathogens. Significantly, more cholangitis episodes with more than one pathogen isolated occurred during PPI treatment [103/120 (86%) vs. 151/198 (76%), P = 0.04]. Analysis of intrinsic anti-microbial resistance patterns was performed: Anti-microbial combination therapies were significantly more required to cover all isolated pathogens in cholangitis episodes with PPI than in cholangitis episodes without PPI (44/120 vs. 46/198, P = 0.01). Additionally, PPI use was associated with a significantly higher incidence of oropharyngeal flora in the biliary tract (53/120 vs. 61/198, P = 0.02).

CONCLUSIONS

Proton pump inhibitors seem to influence biliary pathogens by increasing the number and broadening the spectrum of biliary pathogens. However, the findings of this hypothesis-generating study need to be tested by confirmatory studies.

Pseudomonas aeruginosa bacteremia in patients with liver cirrhosis: a comparison with bacteremia caused by Enterobacteriaceae

Background

This study was performed to detect risk factors for Pseudomonas aeruginosa bacteremia in patients with liver cirrhosis.

Methods

A retrospective case–control study was designed to identify risk factors for P. aeruginosa bacteremia in cirrhotic patients. The cases were cirrhotic patients with P. aeruginosa bacteremia and the controls were cirrhotic patients with Enterobacteriaceae bacteremia.

Results

Sixty-one cases and the same number of controls were enrolled. In a multivariate analysis, younger age {adjusted odds ratio (aOR) per one year: 0.96, 95% confidence interval: 0.93 - 0.99}, nosocomial acquisition (aOR 3.87, 95% confidence interval: 1.50 - 9.94), preexisting biliary disease (aOR 4.79, 95% confidence interval: 1.92 - 10.47), and recent exposure to immunosuppressive agent (aOR 3.10, 95% confidence interval: 1.23 - 7.82) were associated with P. aeruginosa bacteremia. In the case group the frequency of appropriate initial antibiotic regimens was considerably lower than in the control group: 29.5% vs. 65.6% (P <0.01). However, thirty day mortality did not differ significantly between cases and controls (19.7% vs. 24.6%).

Conclusions

Nosocomial acquisition, preexisting biliary disease, and recent use of immunosuppressive agents are strong predictive factors for P. aeruginosa bacteremia in cirrhotic patients.