title: Biliary endoprosthesis: a prospective analysis of bacterial colonization and risk factors for sludge formation.
abstract: 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.
authors.affiliation: II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, München, Germany; Institut für Medizinische Mikrobiologie und Hygiene, Technische Universität München, München, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Schneider
authors.affiliation: Institut für Medizinische Statistik und Epidemiologie, Technische Universität München, München, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Hapfelmeier
authors.affiliation: II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Fremd
authors.affiliation: II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Schenk
authors.affiliation: Klinik für Orthopädie und Sportorthopädie, Technische Universität München, München, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Obermeier
authors.affiliation: Klinik für Orthopädie und Sportorthopädie, Technische Universität München, München, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Burgkart
authors.affiliation: Institut für Medizinische Mikrobiologie und Hygiene, Technische Universität München, München, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Forkl
authors.affiliation: Institut für Medizinische Mikrobiologie und Hygiene, Technische Universität München, München, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Feihl
authors.affiliation: Institut für Medizinische Mikrobiologie und Hygiene, Technische Universität München, München, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Wantia
authors.affiliation: II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Bruno
authors.initials: B
authors.lastname: Neu
authors.affiliation: II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Monther
authors.initials: M
authors.lastname: Bajbouj
authors.affiliation: II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: von Delius
authors.affiliation: II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Roland M
authors.initials: RM
authors.lastname: Schmid
authors.affiliation: II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Hana
authors.initials: H
authors.lastname: Algül
authors.affiliation: II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, München, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Weber
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001659:Biliary Tract / Q000382:microbiology; D001662:Biliary Tract Surgical Procedures; D018441:Biofilms; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D016983:Enterococcus / Q000502:physiology; D005260:Female; D006801:Humans; D007709:Klebsiella / Q000502:physiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections / Q000382:microbiology*; D012307:Risk Factors; D015607:Stents / Q000382:microbiology*; D055815:Young Adult