Site-specific localized labeling for efficient bio-sensing of drug resistant bacterial strains

Abstract

β-lactam antibiotics are a crucial class of drugs widely used to target bacterial infections. However, the frequent use and misuse of β-lactam antibiotics has resulted in the emergence of antibiotic resistance – a severe threat to global health – which is present dominantly through the production of β-lactamase. In response, our group sought to develop optical imaging probes that would enable the rapid and selective intracellular identification and imaging of β-lactamase activity in real-time. We hope the optical imaging probes would serve as a tool for diagnostic microbiology – to screen and identify resistant bacterial strains – to administer controlled antibiotic therapy and to enable more in-depth research in antibiotic resistance mechanisms.

In our study, we designed two optical imaging probes: (1) Upconversion nanoparticles (UCNP)-based optical probe (2) Metabolic optical probe for covalent labeling of the bacterial peptidoglycan. The UCNP-based optical probe was observed to have achieved a 150-fold fluorescence enhancement when cleaved with a Class A β-lactamase. The UCNP-based optical probe has also displayed selectivity for resistant bacterial strains and has viable in vitro activity in preliminary mammalian cell fluorescence imaging studies conducted.

The metabolic optical imaging probe was observed to have achieved a 200-fold fluorescence enhancement when cleaved with a Class C β-lactamase. The metabolic optical probe has also shown specificity for resistant bacterial strains, displaying greater selectivity for Class C β-lactamase-producing bacterial strains over Class A β-lactamase-producing bacterial strains in fluorescence bacterial imaging studies conducted.