Hexidium iodide, a fluorescent nucleic binding acid stain (excitation/emission ~ 518/600 nm), permeants to mammalian cells and selectively stains almost all gram-positive bacteria. Hexidium iodide can bind to the DNA of all bacteria after permeabilization by EDTA[1][2].
Hexidium iodide allows assessment of Gram status by differential absorption through bacterial cell walls, selectively staining gram-positive organisms in suspension[1].
[1]. Shanmugam BK, et al. Biodegradation of tannery dye effluent using Fenton’s reagent and bacterial consortium: A biocalorimetric investigation. J Environ Manage. 2019;242:106-113.
[2]. Holm C, et al. A flow-cytometric gram-staining technique for milk-associated bacteria. Appl Environ Microbiol. 2003;69(5):2857-2863.