Isolated microorganisms in plastic biliary stents placed for benign and malignant diseases

Biliary stenting is a well-established method to treat patients with malignant and benign biliary diseases. However, occlusion of plastic biliary stents is considered as a drawback and bacterial colonization seems to be the key factor in this process.

During a 3-year period, 51 plastic biliary stents were extracted from 42 patients. Twenty three stents were inserted for treating malignant and 28 for benign diseases. Stent samples were taken under a strict protocol, and were immediately sent to microbiological laboratory for culturing.

A polymicrobial growth was present in nearly all stents. The most frequently isolated organisms were Enterococcus spp (74%), Escherichia coli (E. coli) (62%), and Klebsiella spp (58%). E. coli was more frequently encountered in benign vs. malignant disease (78% vs. 43%, P<0.05). Klebsiella spp, Pseudomonas spp, and Candida spp were more frequently isolated in occluded vs. non-occluded stents, 68% vs. 37%, 22% vs. 0 and 40% vs. 6% respectively (P<0.05). E. coli and Pseudomonas spp had 34% and 50% resistance rate to quinolones respectively. Enterobacter spp expressed Amp-C derepression in 35%. Enterococcus spp, Klebsiella spp and Pseudomonas spp had a low resistance rate.

Enterococcus spp, E. coli and Klebsiella spp are the most frequently associated organisms in plastic biliary stents. In occluded stents Pseudomonas spp and Candida spp should be taken into account. Quinolones may not be adequate for the treatment of cholangitis associated with stent occlusion. In patients under chemotherapy for malignancy and stent occlusion-related biliary sepsis, antifungal and enterococcal covering should be considered.