Acridine orange stain is a rapid, reliable, and sensitive fluorescent stain used with flow cytometry or fluorescence microscopy in various applications including: 

• Confirming the presence of microorganisms in blood smears 
• Counting the total number of microbes in a sample by binding with the nucleic acid of living as well as dead bacteria
• Visualizing nucleic acids on polyacrylamide and agarose gels
• Measuring cellular content of DNA vs. RNA in individual cells 
• Detecting DNA damage in infertile sperm cells
• Measuring DNA denaturation
• Detecting apoptosis
• Studying mitochondria and lysosomal content by flow cytometry
• Detecting cell wall deficient bacteria such as mycoplasmas that are difficult to visualize in Gram stain due to their inability to retain Gram stain dyes
• Diagnosing bacterial infections such as meningitis