Post-streptococcal glomerulonephritis (GN) is a disorder of the kidneys that occurs after infection with certain strains of streptococcus bacteria. Post-streptococcal GN is a form of glomerulonephritis. It is caused by an infection with a type of streptococcus bacteria. The infection does not occur in the kidneys, but in a different part of the body, such as the skin or throat. The strep bacterial infection causes the tiny blood vessels in the filtering units of the kidneys (glomeruli) to become inflamed.