Use of proton pump inhibitors, biliary drainage following pancreatic surgery, and anatomical location all affect pancreatic microbiome diversity and bacterial load, according to study findings published in PLoS One.
Researchers in Amsterdam conducted a prospective cohort study of 51 patients who underwent pancreatic surgery between August 2018 and September 2020 to examine the relationship between the pancreatic microbiome and patient characteristics as well as the duodenal microbiome. They collected pancreatic biopsies from all 51 patients in addition to 22 duodenal fluids, 21 duodenal swabs, and 11 duodenal tissues, then used the IS-pro assay to assess bacterial DNA in each sample.
The pancreatic microbiome was comprised predominantly of proteobacteria followed by firmicutes, actinobacteria, fusobacteria, and verrucomicrobia (FAFV) and bacteriodetes, respectively. The most common bacterial strains found within the pancreatic tissues included Escherichia coli, Enterobacter-Klebsiella, Enterococcus faecalis and Streptococcus mitis.
The median bacterial load was significantly higher in patients who underwent biliary drainage compared with those who did not (54,618 vs. 5623.5; P =.007). The researchers noted that proteobacteria load was particularly higher following biliary drainage (9119.0 vs. 2067.1; P =.003). Bacteriodetes (59.2 vs. 27.6; P =.070) and FAFV (6093.8 vs. 2234.2; P =.070) loads also tended to be higher in patients who underwent biliary drainage, but these higher loads did not reach statistical significance.
Patients demonstrated higher abundance of Enterococcus faecalis (12.5% vs 5.9%), E coli (12.1% vs 7.8%) and Enterobacter/Klebsiella (10.6% vs <0.1%) following biliary drainage compared with those who did not.
In contrast, Staphylococcus epidermidis was less abundant after biliary drainage compared with patients who did not undergo this procedure (1.9% vs. 15.5%), indicating that biliary drainage following pancreatic surgery significantly affected the microbiome diversity and load in the pancreatic tissues.
Use of proton pump inhibitors (PPIs) also increased bacterial loads in pancreatic tissues. Patients receiving PPIs demonstrated higher total bacterial loads than those who did not use them (115,964.7 vs. 8495.8), including more FAFV (66,862.9 vs. 1890.1), more proteobacteria (24,245.9 vs. 2951.4), and more bacteriodetes (542.5 vs. 25.8).
The researchers compared the microbiomes of tissues taken from different regions of the pancreas, such as the head and tail. They found that the head of the pancreas contained a greater bacterial load than the tail (21,193.4 vs. 2096.8) as well as increased FAFV (5225.7 vs. 19.0) regardless of biliary drainage.
Lastly, they found that the pancreatic microbiome weakly correlated with the duodenal microbiome in all of the types of samples (ie, fluid, tissue, or swab).
The study is limited by patient disease heterogeneity, which prevented multivariate analysis, short follow-ups of less than 1 year, lack of control samples, and the inability to compare pre- and post-biliary drainage microbiome changes.
“Biliary drainage, use of proton pump inhibitors, and anatomic location of the pancreatic biopsy influence the pancreatic microbiome,” the study authors conclude. “Furthermore, the duodenal microbiome does not suffice as a surrogate for the pancreatic microbiome,” they add.
Disclosures: Several study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see original source for full list of disclosures.
Zwart ES, Jeleniewski S, Boyd LNC, et al. Factors that influence the pancreatic and duodenal microbiome in patients undergoing pancreatic surgery. PLoS One. 2022;17(12):e0278377. doi:10.1371/journal.pone.0278377