uti's, or 'bladder infections' are generally caused by normal bacteria that lives on the skin or migrates from the ano-rectal region and finds its way into the opening of the urethra and up into the urinary tract. women get these because the short length of the urethra (the tube that carries urine from the bladder to the outside) (short relative to men) is less of a protective barrier. for women the length of th urethra is about one inch, give or take. in the man it varies from around four inches to (insert your own joke here). (the bacteria do not like the environment of the urethra, and don't live long there, but once they get into the bladder, it is bacterial paradise, and they grow and thrive, causing infection. typically the bacteria originates on the woman's body, but can come from the man's body. a 'communicable' aspect is the act of intercourse, when performed frequently or vigorously, can temporarily damage the opening of the female urethra, allowing easier access for bacteria, or the act can directly introduce bacteria to the opening of the utethra. so, yes, bacteria from a man can be transmitted to a woman's uretheral opening, but the woman has plenty of bacteria on her own body that can cause the infection. and the act of sex can mechanically break down some of the natural protective barrier to infection. in these manners, the woman can 'catch' a uti from a man, but it is not like a man has a uti which he directly transmits to the woman through intimate contact. as far as the other direction, male bladder infections are extremely rare, as the length of the male urethra is a very effective barrier. but it does happen. sadly the only case i have ever seen involved my very own peepee. it allowed me to develop incredible empathy to my sisters when they are suffering from this malady. with antibiotics, uti's are nearly always effectively treated, and symptoms resolve within seven to ten days. the above applies to otherwise healthy, non-immune compromised sexually active adults. there are different considerations for elderly people, immunocompromised patients, post surgical patients, and patients who have had instrumentation of the urinary tract.