Quantification of major constituents of biofilms in occluded pancreatic stents.

PURPOSE: Biofilms comprise bacterial populations enclosed in a matrix that attaches to surfaces such as medical stents. We characterized the biofilm components in occluding pancreatic stents and investigated potential factors for the formation of the biofilms.

METHODOLOGY: The clinical details of 24 patients (M : F, 15 : 9) undergoing pancreatic stent retrieval were noted and the retrieved stents were processed for the quantification of biofilm proteins and polysaccharides and the molecular identification of bacteria.

RESULTS

The patients' ages ranged from 16 to 62 years. The underlying indications for stent insertion were bile duct stone prophylaxis against post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (n=7; 29.1 %) and pancreatic ductal leaks (n=17; 70.9 %). The retrieved stent sizes were 5 Fr (n=5; 20.8 %) and 7 Fr (n=19; 79.2 %), with a mean insertion duration of 103 days. The polybacteria detected by PCR in 95.8 % of the stents were Pseudomonas (n=8), Staphylococcus (n=8), Serratia (n=5), Aeromonas (n=4), Proteus (n=4), Klebsiella (n=4), Escherichia coli (n=4), Enterococcus (n=4), Streptococcus (n=4), Citrobacter (n=3), Bacillus (n=2), Enterobacter (n=1), Vibrio (n=1) and Clostridium (n=1). Several other organisms were identified by sequencing. The mean protein concentration was 0.585±0.29 mg ml-1 and the mean polysaccharide concentration was 0.054±0.03 mg ml-1. No significant differences were observed in the quantity of proteins and polysaccharides (P=0.933) for various factors, namely gender, presence of cholangitis, indications for stenting, stent sizes and duration of indwelling stents. Age was found to be a significant (P=0.013) factor for protein deposition for those aged >50 years.

CONCLUSION

The majority of the pancreatic stents grew polymicro-organisms, and those from patients aged >50 years showed significant deposition of protein, which is a key element in biofilm formation. Understanding the constituents of the biofilms in pancreatic stents could be very useful in developing future strategies for the prevention of biofilm formation.