# Proximity extension assay-based targeted proteomics for biomarker discovery in adult bacterial infections

## TL;DR

This review explores how the Proximity Extension Assay (PEA) can help discover new biomarkers for diagnosing bacterial infections in adults.

## Contribution

The paper provides a systematic scoping review of PEA-based proteomics in adult bacterial infections, highlighting its potential for biomarker discovery.

## Key findings

- Ten studies were identified, mostly from Europe and North America, using plasma samples and immune-focused PEA panels.
- Some proteins were consistently linked to bacterial infections across multiple contexts, while others showed no association.
- Current PEA applications are limited and exploratory, with a need for better-designed studies to support clinical translation.

## Abstract

Bacterial infections remain a major global health burden, causing significant morbidity and mortality. Despite ongoing advances, prompt diagnosis is still hampered by nonspecific host biomarkers and the inherently slow turnaround of traditional microbiological cultures. These limitations often delay the initiation of appropriate treatments. In recent years, affinity-based proteomic approaches have been explored to address this gap. Among them, the Proximity Extension Assay (PEA) has emerged as a promising multiplexed protein quantification tool, capable of simultaneously measuring hundreds of immune and inflammatory proteins with high sensitivity from minimal sample volumes. Such technologies hold the potential to identify novel biomarkers, thereby improving both diagnosis and patient management in bacterial infections.

In this systematic scoping review, we examined studies applying PEA-based proteomics to adult bacterial infections. Out of the records screened, ten studies met inclusion criteria. Most were conducted in Europe and North America, relied primarily on plasma samples, and employed commercially available panels enriched for immune and inflammatory mediators. Study quality varied, with some evidence of variability and potential risk of bias. Across the 379 proteins investigated, a subset of proteins were consistently associated with bacterial infections across multiple clinical contexts, whereas others showed limited or no associations.

Current applications of PEA-based proteomics in adult bacterial infections is limited and largely exploratory. Rather than supporting immediate clinical translation, the available evidence suggests the value of PEA-based approaches for informing biomarker discovery. Future research should prioritize well-designed, longitudinal, and pathogen-stratified studies in clinically relevant settings to strengthen evidence robustness and support the rational development of proteomics-informed diagnostic and translational strategies.