Microbial colonization of pancreatic duct stents: a prospective analysis.

OBJECTIVE: The aim of the study was to analyze the microbial colonization rate as well as the spectrum and number of microorganisms in relation to the indwelling time of pancreatic stents. METHODS: Forty pancreatic stents were prepared according to a standardized protocol and subsequently sonicated to optimize bacterial release from the biofilm on the stents. RESULTS: Two hundred forty-six microorganisms were identified. Thirty-nine of 40 stents were colonized with microorganisms. Aerobic gram-positive microorganisms (106/246 [43%]) accounted for the greatest proportion. The predominant microorganisms were Streptococcus species (46/246 [19%]), which were isolated from 27 (68%) of 40 stents. Stents with a short indwelling time (3-13 days) were mainly colonized with aerobic gram-positive bacteria (82%) and Candida species (63%). In contrast, anaerobes (P < 0.01, 69% vs 18%) and aerobic gram-negative microorganisms (P < 0.01, 93% vs 45%) such as Enterobacteriaceae (P < 0.01, 86% vs 27%) were significantly more present on stents with a long indwelling time (29-93 days), compared with stents with a short indwelling time. CONCLUSIONS: Microbial analysis of pancreatic duct stents revealed a very high colonization rate. Furthermore, the spectrum and number of microorganisms altered with the indwelling time of the stent. However, clinical relevance of our findings remains unclear.

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.