Imaging of Staphylococcus aureus Infections and Biofilms Using a Selective Covalent Probe for the Unique Serine
Emily C Woods1, Tulsi Upadhyay1, Ki Wan Park2
1Department of Pathology, Stanford University School of Medicine, Stanford, United States.
Abstract:
Staphylococcus aureus is the leading cause of soft tissue infections which can often be treated with antibiotics. However, it can also cause significant mortality and morbidity from systemic infections and infections of surgical implants. Implant infections typically require invasive surgery, and treatment often necessitates removal of the implant because S. aureus biofilms are extremely difficult to eradicate with antibiotic treatment alone. Therefore, there is a significant need for improved diagnostic tools for rapid, noninvasive confirmation of S. aureus infections. We recently developed an activity-based probe containing an oxadiazolone electrophile that selectively and covalently labels the S. aureus-specific serine hydrolase, FphE. Here we describe a Cy5-labeled version of the probe, JJ-OX-012, and its characterization as an imaging agent for detecting biofilms both in vitro and in vivo. The probe labeled S. aureus biofilms in vitro, with virtually no background labeling of bacteria that lack FphE expression, such as Escherichia coli. Furthermore, using a mouse surgical implant infection model, we demonstrate that JJ-OX-012 can be used for noninvasive fluorescent imaging to detect S. aureus biofilms in vivo. Overall, these findings support the potential for using covalent probes targeting FphE as imaging agents for rapid detection and diagnosis of staphylococcal infections in vivo.
Insights
A new probe, JJ-OX-012, can detect Staphylococcus aureus biofilms in vitro and in vivo. This imaging agent targets the FphE enzyme, offering a potential new tool for diagnosing staphylococcal infections.
Area of Science:
- Biochemistry
- Microbiology
- Medical Imaging
Background:
- Staphylococcus aureus causes soft tissue infections and serious systemic or implant-associated infections.
- Current treatments for S. aureus implant infections are often ineffective due to biofilm formation, necessitating implant removal.
- Rapid, noninvasive diagnostic tools are needed for S. aureus infections.
Purpose of the Study:
- To develop and characterize a novel imaging agent for detecting Staphylococcus aureus biofilms.
- To evaluate the efficacy of a Cy5-labeled activity-based probe (JJ-OX-012) targeting the S. aureus-specific enzyme FphE.
Main Methods:
- Development of a Cy5-labeled oxadiazolone probe (JJ-OX-012) targeting the serine hydrolase FphE.
- In vitro testing of JJ-OX-012 for labeling S. aureus biofilms.
- In vivo evaluation of JJ-OX-012 using a mouse surgical implant infection model.
Main Results:
- JJ-OX-012 selectively labeled S. aureus biofilms in vitro with minimal background.
- Escherichia coli, lacking FphE expression, showed no significant labeling.
- Noninvasive in vivo fluorescent imaging successfully detected S. aureus biofilms in a mouse model.
Conclusions:
- The covalent probe JJ-OX-012 functions as an effective imaging agent for S. aureus biofilms.
- Targeting FphE with activity-based probes shows promise for rapid, noninvasive diagnosis of staphylococcal infections.
- Further development of FphE-targeting probes could significantly improve clinical diagnostics for S. aureus infections.
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