what causes frequent uti
1 Infection of the urethra (urethritis). 2  This type of UTI can occur when GI bacteria spread from the anus to the urethra. 3  Also, because the female urethra is close to the vagina, sexually transmitted infections, such as herpes, gonorrhea, chlamydia and mycoplasma, can cause urethritis.he most common UTIs occur mainly in women and affect the bladder and urethra. 1  Infection of the bladder (cystitis). 2  Infection of the urethra (urethritis). 3  Symptoms. 4  Risk factors.