CAREER: A Multi-phase Biosensing Approach towards Point-of-Care Evaluation of Pseudomonas aeruginosa Virulence in Infected Chronic Wounds

Infections from bacteria that are resistant to antibiotics are a major source of healthcare costs ($4.6B annually) and treatment complications that lead to death. More than 2.8 million drug-resistant infections occur each year in the US, with more than 35,000 deaths despite widespread availability of antibiotics, mostly because they are not effective against drug-resistant bacteria.

The likelihood of complication or death is increased for patients with weakened immune systems. The bacteria form complex structures called biofilms that protect themselves from antibiotic treatment. These biofilms are developed through a bacteria cell communication strategy called quorum sensing.

This project seeks to study how quorum sensing can be tracked by an inexpensive, rapid, and flexible sensor that provides information on how quickly bacteria are growing and how fast biofilms are being developed. The sensor developed and used in this study is unique because of its flexibility and ability to measure electrical and chemical activity related to bacteria growth.

The long-term research goal of this project is to make possible the fast (less than 5 minutes) determination of infection so that the correct antibiotics and dosage can be delivered at the most opportune time. Importantly, this sensing approach can also be used in other applications, like water filtering and agriculture. The educational goal of this project is to support research and graduate education for underrepresented students, especially veterans and non-traditional students.

These students often face unique obstacles to participating in traditional undergraduate research experiences, such as work, family, or military commitments. This project will address these challenges through a combination of coursework, research, and workshop experiences designed to expose and engage students in new ideas and job opportunities.

The primary motivation for this project is the development of a strategy to quickly measure bacterial infections in chronic, non-healing wounds for the inhibition of antibiotic resistance/tolerance, which is both an important societal problem and of fundamental scientific interest. More than 2.8 million antimicrobial-resistant infections occur each year in the US, with more than 35,000 deaths despite widespread availability of antibiotics in large part because they are ineffective against resistant strains and biofilms, especially but not only in immune compromised patients.

The research objective of this project is to leverage concentration-dependent quorum sensing (QS) molecules to quantify key transitions in biofilm formation that relate to the progression of virulence in bacterial pathogens. This project focuses on Pseudomonas aeruginosa biofilm formation and virulence, as a model system for other bacterial pathogens commonly found in chronic wounds.

This project uses a nonwoven nanofiber composite electrode design in electrochemical impedance spectroscopy and voltammetric experiments to quantify virulence progression via pyocyanin and 3OC12HSL (QS molecules used to mediate virulence) detection and quantification. The following scientific contributions will result from this work: 1) A directly quantifiable relationship between bacterial concentration (P. aeruginosa), QS molecule concentration (Pyocyanin and AHLs - 3OC12HSL), and stage of biofilm development; 2) Enablement of a flexible, tunable voltametric sensor that offers highly sensitive and specific electrochemical detection of redox species while being easily incorporated into wearable fabrics or wound dressings given its bio-textile design; and 3) The functionalization of nanofiber composite aptasensors, enabling generation of quantifiable electrochemical signals to greatly reduce the Limit of Detection (LOD) and improve specificity.

This work addresses the critical challenge of quantifying species-specific signaling molecules associated with progression of bacterial load (bioburden). The long-term importance of this work is increased understanding of more effective treatment timing, while reducing the risk for development of drug resistance. Understanding the precise moments in which a bacterial pathogen may be advancing in virulence is important for any organism that may be infected by these bacteria, including plants, animals, and humans.

This project is jointly funded by the Biosensing Program and the Established Program to Stimulate Competitive Research (EPSCoR).

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.