What is the difference between the gram+ and gram- bacteria ?

See below: Gram negative bacteria do not pick up the gram stain dye. They appear pink under the microscope. They include bacilli like e. Coli and pseudomonas and cocci like neisseria and brucella. Gram positive bacteria pick up the stain and appear dark purple. They include staphylococcus and streptococcus. Each can cause mild and serious disease. They are treated by different types of antibiotics.