Single-tube two-step RPA-CRISPR/Cas12b platform for detection of Pseudomonas aeruginosa

Abstract

Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen of significant clinical and public health concern, necessitating the development of rapid and reliable detection methods. Traditional diagnostic approaches, which rely on culture-dependent techniques and biochemical identification, are often labor-intensive, time-consuming, and technically demanding. This study describes a novel single-tube, two-step, rapid detection platform that integrates recombinase polymerase amplification (RPA) with clustered regularly interspaced short palindromic repeats-associated protein Cas12b technology. Through systematic experimental optimization, the study identified an optimal RPA primer pair (F2-R1) and single-guide ribonucleic acid 553 that targets the lasR gene of P. aeruginosa , with reaction conditions optimized at 42°C and a primer concentration of 10 μM. The RPA-clustered regularly interspaced short palindromic repeats/Cas12b fluorescence detection system (RPA-Cas12b-Fluo) demonstrated a sensitivity threshold of 10 copies of deoxyribonucleic acid (DNA) per reaction and a bacterial detection limit of 50 colony-forming units (CFU) per reaction. When coupled with a lateral flow strip (RPA-Cas12b-LFS), the sensitivity was slightly reduced but remained robust, achieving detection limits of 10² copies and 200 CFU per reaction. Specificity assays confirmed a high discriminatory capacity for P. aeruginosa with no cross-reactivity observed against P. fluorescens , P. putida , or six common foodborne pathogens, thereby validating the specificity profile of the platform. The applicability of the method was further validated by analyzing 20 water samples, which demonstrated 100% concordance with the national standard culture method. These findings have significant implications for improving outbreak surveillance and mitigating the risk of foodborne transmission associated with P. aeruginosa .