Intrace Medical has developed a NIR-fluorescent probe targeting Gramm-positive bacteria that potentially allows in vivo imaging of bacteria infection.
Gram-positive bacteria are differentiated from Gram-negative bacteria based on the structure of their cell walls. In Gram-positive bacteria, the cell wall is composed of a thick peptidoglycan layer.1 Many antibiotics have been established to treat Gram-positive infections. Vancomycin is a commonly used glycopeptide antibiotic that acts on inhibiting bacterial cell wall synthesis. In order to create an imaging agent, we attach the near infra-red fluorescence imaging dye Indocyanine Green (ICG) to vancomycin.
ICG is approved by the United States Food and Drug administration (FDA) for ophthalmologic angiography to determine cardiac output and liver blood flow and function. This dye is also used in cancer patients for the detection of solid tumors, localization of lymphnodes, and for angiography during reconstructive surgery, visualization of retinal and choroidal vasculature, and photodynamic therapy.[i]2-3 In cancer diagnostics and therapeutics, ICG could be used as both an imaging dye and a hyperthermia agent.
ICG is a tricarbocyanine-type dye with NIR-absorbing properties (peak absorption around 800 nm) and little absorption in the visible range thus exhibit low autofluorescence, tissue absorbance, and scatter at NIR wavelengths (700-900 nm).