Bile glycoprotein mucin in sludge occluding biliary stent

Aspirin exposure and its association with metal stent patency in malignant distal biliary obstruction: a large international multicenter propensity score-matched study

BACKGROUND AND AIMS

Stent dysfunction is common after ERCP with self-expandable metal stent (SEMS) insertion for malignant distal biliary obstruction (MDBO). Chronic aspirin (acetylsalicylic acid; ASA) exposure has been previously shown to potentially decrease this risk. We aim to further ascertain the protective effect of ASA and to identify other predictors of stent dysfunction.

METHODS

This multicenter retrospective cohort study was conducted at 9 sites in Canada and 1 in the United States. Patients with MDBO who underwent ERCP with SEMS placement between January 2014 and December 2019 were included and divided into 2 cohorts: ASA exposed (ASA-E) and ASA unexposed (ASA-U). Propensity-score matching (PSM) was performed to limit selection bias. Matched variables were age, sex, tumor stage, and type of metal stent. The primary outcome was the hazard rate of stent dysfunction. A multivariable Cox proportional hazards model was used to identify independent predictors of stent dysfunction.

RESULTS

Of 1396 patients assessed, after PSM 496 patients were analyzed (248 ASA-E and 248 ASA-U). ERCP with SEMS placement was associated with a high clinical success of 82.2% in ASA-E and 81.2% in ASA-U cohorts (P = .80). One hundred eighty-four patients had stent dysfunction with a mean stent patency time of 229.9 ± 306.2 days and 245.4 ± 241.4 days in ASA-E and ASA-U groups, respectively (P = .52). On multivariable analysis, ASA exposure did not protect against stent dysfunction (hazard ratio [HR], 1.25; 95% confidence interval [CI], .96-1.63). An etiology of pancreatic cancer (HR, 1.36; 95% CI, 1.15-1.61) predicted stent dysfunction, whereas cancer therapy was protective (HR, .73; 95% CI, .55-.96). Chronic ASA use was not associated with an increased risk for adverse events including bleeding, post-ERCP pancreatitis, and perforation.

CONCLUSIONS

In this large, multicenter study using PSM, chronic exposure to ASA did not protect against stent dysfunction in MDBO. Instead, the analysis revealed that the etiology of pancreatic cancer was an independent predictor of stent dysfunction and cancer therapy was protective.

Aspirin for metal stent in malignant distal common bile duct obstruction (AIMS): study protocol for a multicenter randomized controlled trial

Background

Endoscopic retrograde biliary drainage (ERBD) is the treatment of choice for patients with malignant distal common bile duct (CBD) obstruction. Self-expandable metal stents (SEMS), which are commonly used in unresectable cases, have many clinical advantages, including longer stent patency. Although the expected patency of SEMS is around 8 months, it has recently been reported that the duration of SEMS’ patency in patients using aspirin is prolonged. Our study, therefore, aims to investigate the effect of aspirin on SEMS’ patency.

Methods/design

This is an investigator-initiated, prospective, multicenter, double-blind, randomized placebo-controlled trial that will be conducted from November 2017 in four tertiary centers in South Korea. We intend to include in our study 184 adult (aged ≥ 20 years) patients with malignant distal CBD obstruction for whom ERBD with SEMS was successfully performed. The patients will be randomly allocated to two groups, which will comprise patients who have either taken 100 mg aspirin or a placebo for 6 months after index ERBD. The primary outcome will be the rate of stent dysfunction, and the secondary outcomes will be the duration of patency, the rate of reintervention, and the occurrence of adverse events.

Discussion

The aspirin for metal stents in malignant distal common bile duct obstruction (AIMS) study should determine the efficacy of aspirin in maintaining metal-stent patency in patients with malignant distal CBD obstructive.

Trial registration

ClinicalTrials.gov, ID: NCT03279809. Registered on 5 September 2017.

Aspirin Use Is Associated With Reduced Risk of Occlusion of Metallic Biliary Stents

BACKGROUND & AIMS

Biliary self-expandable metallic stents (SEMSs) are widely used to treat malignant and benign conditions of bile duct. Despite their lower rate of occlusion and longer patency than plastic stents, SEMSs still have significant rates of occlusion. We aimed to identify factors associated with occlusion of biliary SEMS.

METHODS

We performed a retrospective study of consecutive patients who underwent endoscopic retrograde cholangiopancreatography with biliary SEMS placement at the Cleveland Clinic Foundation from March 2011 to April 2016. We collected clinical, endoscopic, radiographic, and surgical data from medical records and performed multivariable analysis to identify factors associated with SEMS patency. Subjects that received minimal daily dose of 81 mg at the time of stent placement until the end of follow-up were assigned to the aspirin exposure group (n = 157) and compared with subjects with no aspirin exposure (n = 436). Patients were followed for a median 81 days. The primary outcome was hazard ratio for SEMS occlusion requiring an interventional maneuver for biliary drainage.

RESULTS

We analyzed data from patients receiving a total of 593 biliary SEMS for treatment of malignant and benign conditions of bile duct. Stent occlusion was observed in 126 cases. Multivariable analysis showed that daily use of aspirin (81 mg or more) was associated with 51% lower risk of stent occlusion than in patients without daily use of aspirin (hazard ratio, 0.49; 95% confidence interval, 0.32-0.75). Furthermore, SEMSs had a longer duration of stent patency in patients in the aspirin exposure group (434.4 days) versus the no aspirin exposure group (339.9 days) (P < .001). Stricture location limited to distal bile duct (in comparison with strictures involving proximal extrahepatic duct) was associated with lower risk of stent occlusion (hazard ratio, 0.39; 95% CI, 0.22-0.71).

CONCLUSIONS

In an analysis of a large cohort of subjects with metallic biliary stent placement for malignant and benign conditions of bile duct, we associated daily use of aspirin (81 mg or more) with lower risk of SEMS occlusion and longer stent patency duration.

Epidemiology and Resistance Patterns of Bacterial and Fungal Colonization of Biliary Plastic Stents: A Prospective Cohort Study

Background

Plastic stents used for the treatment of biliary obstruction will become occluded over time due to microbial colonization and formation of biofilms. Treatment of stent-associated cholangitis is often not effective because of inappropriate use of antimicrobial agents or antimicrobial resistance. We aimed to assess the current bacterial and fungal etiology of stent-associated biofilms, with particular emphasis on antimicrobial resistance.

Methods

Patients with biliary strictures requiring endoscopic stent placement were prospectively enrolled. After the retrieval of stents, biofilms were disrupted by sonication, microorganisms were cultured, and isolates were identified by matrix-associated laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and/or biochemical typing. Finally, minimum inhibitory concentrations (MICs) were determined for various antimicrobial agents. Selected stents were further analyzed by fluorescence in situ hybridization (FISH).

Results

Among 120 patients (62.5% males, median age 64 years) with biliary strictures (35% malignant, 65% benign), 113 double pigtail polyurethane and 100 straight polyethylene stents were analyzed after a median indwelling time of 63 days (range, 1–1274 days). The stent occlusion rate was 11.5% and 13%, respectively, being associated with a significantly increased risk of cholangitis (38.5% vs. 9.1%, P<0.001). Ninety-five different bacterial and 13 fungal species were detected; polymicrobial colonization predominated (95.8% vs. 4.2%, P<0.001). Enterococci (79.3%), Enterobacteriaceae (73.7%), and Candida spp. (55.9%) were the leading pathogens. Candida species were more frequent in patients previously receiving prolonged antibiotic therapy (63% vs. 46.7%, P = 0.023). Vancomycin-resistant enterococci accounted for 13.7%, extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae with co-resistance to ciprofloxacin accounted for 13.9%, and azole-resistant Candida spp. accounted for 32.9% of the respective isolates.

Conclusions

Enterococci and Candida species play an important role in the microbial colonization of biliary stents. Therefore, empirical antimicrobial treatment of stent-associated cholangitis should be guided toward enterococci, Enterobacteriaceae, streptococci, anaerobes, and Candida. To determine causative pathogens, an accurate microbiological analysis of the extracted stent(s) may be helpful.

Spectral and morphological classification of different chronic and acute Taiwanese gallstones via FTIR, SEM and ESEM-EDX microanalyses

BACKGROUND

Gallstone disease is one of the leading upper gastrointestinal surgical problems in different countries.

AIMS

To analyze the chronic gallstones and acute gallbladder sludge retrieved from 36 Taiwanese patients.

METHODS

FTIR microspectroscopy was used to classify the types of gallstones, and an ESEM-EDX microanalysis was first applied to determine the microstructural features and elemental compositions of the various gallstones. Bacteria presented on the surface of gallstones were also detected by SEM.

RESULTS

Four types of gallstones were obtained from these 36 Taiwanese patients: calcium bilirubinate (CaBR) stones (30.6%), cholesterol stones (19.4%), mixed stones including 6 subtypes (47.2%), and acute gallbladder sludge (2.8%) made of CaBR and protein/insoluble biomaterials. Bacteria imprints and bacterial discharges or bacterial biofilms were also found on the surface of gallstones and acute sludge under a SEM observation. ESEM-EDX results revealed that calcium was found to be the main constituent of all of the types of stones except cholesterol stones, and aluminum was also presented in most of the stones and sludge samples. Chloride was only detected in the acute gallbladder sludge.

CONCLUSION

FTIR spectra, morphological features, and elemental compositions of the acute gallbladder sludge were different from those of the chronic gallstones.

Biliary endoprosthesis: a prospective analysis of bacterial colonization and risk factors for sludge formation

Bacterial colonization of biliary stents is one of the driving forces behind sludge formation which may result in stent occlusion. Major focus of the study was to analyze the spectrum and number of microorganisms in relation to the indwelling time of stents and the risk factors for sludge formation. 343 stents were sonicated to optimize the bacterial release from the biofilm and identified by matrix-associated laser desorption/ionization-time of flight mass spectrometer (MALDI-TOF). 2283 bacteria were analyzed in total. The most prevalent microorganisms were Enterococcus species (spp.) (504;22%), followed by Klebsiella spp. (218;10%) and Candida spp. (188;8%). Colonization of the stents mainly began with aerobic gram-positive bacteria (43/49;88%) and Candida spp. (25/49;51%), whereas stents with an indwelling time>60 days(d) showed an almost equal colonization rate by aerobic gram-negative (176/184;96%) and aerobic gram-positive bacteria (183/184;99%) and a high proportion of anaerobes (127/184;69%). Compared to stents without sludge, more Clostridium spp. [(P = 0.02; Odds Ratio (OR): 2.4; 95% confidence interval (95%CI): (1.1-4.9)]) and Staphylococcus spp. [(P = 0.03; OR (95%CI): 4.3 (1.1-16.5)] were cultured from stents with sludge. Multivariate analysis revealed a significant relationship between the number of microorganisms [P<0.01; OR (95%CI): 1.3(1.1-1.5)], the indwelling time [P<0.01; 1-15 d vs. 20-59 d: OR (95%CI): 5.6(1.4-22), 1-15 d vs. 60-3087 d: OR (95% CI): 9.5(2.5-35.7)], the presence of sideholes [P<0.01; OR (95%CI): 3.5(1.6-7.9)] and the occurrence of sludge. Stent occlusion was found in 70/343(20%) stents. In 35% of cases, stent occlusion resulted in a cholangitis or cholestasis. In conclusion, microbial colonization of the stents changed with the indwelling time. Sludge was associated with an altered spectrum and an increasing number of microorganisms, a long indwelling time and the presence of sideholes. Interestingly, stent occlusion did not necessarily lead to a symptomatic biliary obstruction.

Management of an occluded biliary metallic stent

In patients with a malignant biliary obstruction who require biliary drainage, a self-expandable metallic stent (SEMS) provides longer patency duration than a plastic stent (PS). Nevertheless, a stent occlusion by tumor ingrowth, tumor overgrowth and biliary sludge may develop. There are several methods to manage occluded SEMS. Endoscopic management is the preferred treatment, whereas percutaneous intervention is an alternative approach. Endoscopic treatment involves mechanical cleaning with a balloon and a second stent insertion as stent-in-stent with either PS or SEMS. Technical feasibility, patient survival and cost-effectiveness are important factors that determine the method of re-drainage and stent selection.

Characterization of the complex bacterial communities colonizing biliary stents reveals a host-dependent diversity

This study provides a comprehensive survey of the spatial and temporal bacterial composition of biliary stent biofilms. The bacterial diversity, distribution and dynamics of 59 biliary and 4 pancreatic stent communities from 40 patients being treated at two different hospitals, which implant stents either simultaneously or consecutively, were characterized by single-strand conformation polymorphism (SSCP) analysis. Fifty-one phylotypes belonging to 5 bacterial phyla and 24 bacterial families were detected across 63 stents. This is a much broader diversity than previously detected through culture-dependent methods, particularly in regard to the diversity of obligate anaerobes. Stent bacterial diversity was patient-dependent and more similar when stents were implanted simultaneously rather than consecutively. Stent bacterial community composition differed between hospitals specifically because of the difference in abundance of Bifidobacteria. Co-colonization of Veillonella sp., Streptococcus anginosus and organisms closely related to Fusobacterium nucleatum revealed a potentially important attachment and survival strategy that has yet to be reported in biliary stents. This work reveals a more complete survey of the identities of bacterial species that form biofilms in biliary stents, their co-colonization patterns and the natural variation in species composition between different patients, hospitals and locations along the stent. Consideration of the community composition from individual patients will allow tailoring of prophylactic antibiotic treatments and thus will make the management of stent biofilms more effective.

Can pigment gallstones be induced by biliary stricture and prevented by medicine in Guinea pigs?

AIM: To determine the relationship between biliary stricture and pigment gallstone formation, and the prevention of pigment gallstones with medicine.

METHODS: One hundred and eighteen male guinea pigs were randomly divided into four groups: stricture group (S, n = 30) underwent partial ligation of common bile duct, and fed on regular chow; S plus medicine group (S+M, n = 27) underwent the same operation but fed on medicinal chow (0.3 g chenodeoxycholic acid, 0.5 g glucurolactone, and 0.5 g aspirin were mixed up in 1.2 kg regular chow); medicinal control group (C+M, n = 30) was free of operation, and fed on medicinal chow; and control group (C, n = 31) was free of operation and fed on regular chow. One week later, laparotomy was performed, and the bile of gallbladder was collected, measured, and cultured.

RESULTS: Gallstones were identified. Pigment gallstones were induced by biliary stricture in 95% (22/23) of S group. In the S+M group, the incidence of gallstone was reduced to 55% (11/20, vs S group, P < 0.01). The changes of indirect bilirubin and ionized calcium in the bile were consistent with gallstone incidences.

CONCLUSION: Biliary stricture can cause pigment gallstone formation in guinea pigs, and the medicines used can lower the incidence of gallstones. The bilirubin and ionized calcium play important roles in pigment gallstone formation.

Plastic biliary stent occlusion: factors involved and possible preventive approaches

Endoscopic biliary stenting is today the most common palliative treatment for patients suffering from obstructive jaundice associated with malignant hepatobiliary tumors or benign strictures. However, recurrent jaundice, with or without cholangitis, is a major complication of a biliary endoprosthesis insertion. Thus, stent removal and replacement with a new one frequently occurs as a consequence of device blockage caused by microbial biofilm growth and biliary sludge accumulation in the lumen. Factors and mechanisms involved in plastic stent clogging arising from epidemiological, clinical and experimental data, as well as the possible strategies to prevent biliary stent failure, will be reviewed and discussed.

Inhibition of bacterial adherence on the surface of stents and bacterial growth in bile by bismuth dimercaprol

Bacterial infection and biofilm formation on the surface of biliary stents is believed to be one of the main factors in stent occlusion. This study explored the role of the new reagent, bismuth dimercaprol, in preventing bacterial adherence and bacterial biofilm formation on the surface of biliary stents. Sterile porcine bile preparations, infected separately with Escherichia coli, Klebsiella pneumoniae, Enterobacter, and Enterococcus, were used as the perfusion media in an in vitro perfusion system. The bacterial growth in the media and the bacterial adherence on the surface of stents were tested when different concentrations of bismuth dimercaprol were used in the perfusion media. BisBAL (5 microM) did not inhibit the growth of any of the tested bacterial species. It did, however, significantly decrease the amount of bacteria adhering to the surface of stents for all bacterial strains except Escherichia coli. Bismuth dimercaprol (20 microM) significantly inhibited the growth of Escherichia coli, Klebsiella pneumoniae, and Enterobacter and, thereby, significantly decreased the amount of these bacteria adhering to the surface of stents. The unique bactericidal and anitbiofilm activities of bismuth thiols might contribute to delaying the process of biliary stent occlusion if the effective concentrations of bismuth thiols could be delivered to the target sites. The feasibility of this application of bismuth thiols deserves further investigation.