what causes bladder infections in females
1 Infection of the bladder (cystitis). 2  This type of UTI is usually caused by Escherichia coli (E. coli), a type of bacteria commonly found in the gastrointestinal (GI) tract. 3  However, sometimes other bacteria are responsible. 4  Sexual intercourse may lead to cystitis, but you don't have to be sexually active to develop it.