Gonorrhoea bacterial cultures (pale lumps) growing in a petri dish on a nutrient medium (red). This is a culture of Neisseria gonorrhoeae bacteria (also known as Gonococcus bacteria), the cause of the sexually transmitted disease gonorrhoea. They are spherical bacteria that infect the genital mucous membranes of both sexes, causing pain on urination and a discharge of pus from the vagina or penis. Some cases pass unnoticed, while in others complications may develop leading to sterility.