Proteomic identification of PA2146 as a biofilm marker of on endoscope channel material.

STUDY BACKGROUND AND AIMS

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 biofilms on endoscope channel material.

METHODS

Three genetically unrelated 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.

RESULTS

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.

CONCLUSION

PA2146 expression increases during 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.