BacteriSense on the ASK


BacteriSense™ 645 is a fluorescent targeted agent that was developed specifically for detecting bacterial infections. It is a near-infrared labeled fluorescent in vivo imaging agent that targets infection caused by both Gram positive and Gram negative bacteria. It works by binding to negatively charged lipids on the bacterial cell membrane and is highly specific to bacterial cellular membranes. The fast clearing time enables the imaging of an infection every day. In addition, this agent is also suitable for imaging in vitro using general fluorescence microscopes. BacteriSense 645 is ideally suited for studying infectious diseases. Specifically, it can be used to study superficial and deep tissue bacterial infections. In addition, it can be used to determine the efficacy of antibiotic treatments.

Figure 1: BacteriSense 645 mechanism of action. The fluorescent agent binds to the negatively charged lipids on the bacterial cell membrane.

Figure 2: BacteriSense 645 agents have a rapid clearance time and 45 minute half-life.

Products and catalog numbers

ProductCatalog NumberEx/Em wavelength
Molecular weight (g/mol)Validated ExperimentsApplicationsStorage and Stability
BacteriSense™ 645NEV10080635/6561010In vivo
Flow cytometry
In vitro microscopy
Infectious DiseaseTechnical Data Sheet

Using BacteriSense 645 in vivo

The recommended procedure for in vivo imaging with BacteriSense 645 is intravenous administration and imaging 1 hour post injection.

Route of InjectionMouse Dose (25 g)Rat Dose (250 g)Blood t 1/2Tissue t 1/2Optimal imaging timeOptimal Re-injection Time (complete clearance)Route of Metabolism/ background tissueFMT and IVIS settings
IV5 nmol15-50 nmol15 min infected; 45 min uninfected3 h1-4 h1 dbladder, liverFMT 635/655

IVIS 640/660 with spectral unmixing

In Vivo Imaging:

Figure 3: Eighteen SKH-1 E female mice (aged 6-8 weeks) were injected intramuscularly with 105 to 108 CFUs of E. coli in the flank region. Twenty-four hours after the bacteria injection, the mice were injected with 5 nmoles of BacteriSense™ 645. The mice were then imaged one hour following agent injection on FMT® Quantitative Pre-clinical Imaging System. The amount of total fluorescence corresponds well with the amount of E. coli injected into the mice.

Figure 4: Five SKH-1 E female mice (aged 6-8 weeks) were injected intramuscularly with 108 CFUs of E. coli on left thigh. Mice were injected with 5 nmoles of the BacteriSense™ 645 agent at various times after the bacteria injection (1, 23, 47, 72 hours). One hour post-agent injection, the mice were imaged on an FMT system in planar reflectance mode (at 2, 24, 48, and 72 hours). The severity of the bacterial infection can be easily tracked over time using this agent.

BacteriSense 645 can be paired with existing PKI imaging agents to detect associated inflammatory processes of bacterial infections.

Using BacteriSense 645 in vitro

BacteriSense 645 has been validated in both gram negative and gram positive bacteria. Two examples are E. coli and S. epidermidis.

Flow cytometry and in vitro microscopy

We have validated BacteriSense 645 for use with fluorescence microscopes and flow cytometers.  Here is a brief protocol with a recommended concentration of agent to use:

  1. Grow bacteria to OD600 = 0.3-0.5.  Centrifuge at 3500 rpm for 4 min and resuspend in TES buffer.  
  2. Incubate cells with 10 μM BacteriSense 645 for 5 min - 1 h at RT.  
  3. Centrifuge at 3500 rpm for 4 min and resuspend in PBS. 
  4. Flow cytometry filter settings: 705/70
    Fluorescence microscopy filter: Cy5; 100x objective
Figure 5: A culture of either gram positive or gram negative bacteria was grown to OD600 = 0.3. The cultures were then centrifuged pellets were resuspended in 1 mL TES buffer. BacteriSense™ 645 agent was added to bacterial pellets at a concentration of 10 mM. The pellets were then resus­pended and incubated for 1 hour. The labeled bacteria were centrifuged and resuspended in 400 mL of TES buffer and images of the labeled bacteria were taken using PerkinElmer Volocity® software with a Hamamatsu Orca camera.

Application notes and posters

  • Poster: In vivo imaging and quantification of bacterial infection using a new red fluorescently labeled agent


Please visit our Citations Library for references using BacteriSense 645 on the IVIS or on the FMT.