# Proteomic identification of PA2146 as a biofilm marker of Pseudomonas aeruginosa on endoscope channel material

## TL;DR

This study identifies a protein, PA2146, as a potential biomarker for Pseudomonas aeruginosa biofilms on endoscopes, which could improve detection and safety.

## Contribution

The study introduces PA2146 as a novel proteomic marker for P. aeruginosa biofilms on endoscope materials.

## Key findings

- PA2146 was identified as a protein marker present in P. aeruginosa biofilms on endoscope surfaces.
- The protein's presence was confirmed by MALDI-TOF MS and LC-MS/MS, and its absence in strains lacking the gene verified its origin.
- PA2146 expression increases during biofilm development, suggesting its potential for contamination detection.

## Abstract

Pseudomonas aeruginosa can persistently contaminate endoscopes by forming biofilms within internal channels, complicating both detection and eradication. Current microbiological surveillance methods have limited efficacy and may yield false-negative results. This study aimed to identify proteomic markers of P. aeruginosa biofilms on endoscope channel material.

Three genetically unrelated P. aeruginosa isolates from contaminated duodenoscopes and two reference strains (ATCC 27853 and PAO1) were used. Biofilms were grown on disinfected endoscope biopsy channel rings and incubated for 24, 48, and 72 h. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was employed to analyze temporal changes in protein spectra. Peaks of interest were further characterized by liquid chromatography–tandem mass spectrometry (LC-MS/MS) and whole-genome sequencing to identify associated proteins. To further confirm the origin of these peaks, strains naturally lacking the corresponding genes were analyzed.

MALDI-TOF MS revealed distinct time- and strain-specific spectral profiles, with two notable peaks at approximately 2723 m/z and 5450 m/z. LC-MS/MS identified the 5450 m/z peak as PA2146, corresponding to a 5449.1 Da protein after in vivo methionine cleavage. The 2723 m/z peak was confirmed as its doubly charged ion. Both peaks were absent in strains naturally lacking PA2146, confirming it as the source.

PA2146 expression increases during P. aeruginosa biofilm development on endoscope channel surfaces, indicating its potential as a biomarker for contamination. MALDI-TOF MS could enhance biofilm detection in endoscope surveillance. Further research should assess the clinical utility of proteomic approaches for improving endoscopic microbiological safety.