A urinary tract infection occurs when bacteria invade and multiply in the urinary organs. The urinary tract is made up of the kidneys, ureter, urethra and bladder. Bacteria can infect any of these organs. In males, bacteria can also infect the reproductive organs, such as the prostate, testes, scrotum and epididymis.
Bacteria
Most urinary tract infections are caused by a type of bacteria called Escherichia coli, or E. coli, according to the National Kidney and Urologic Diseases Information Clearinghouse. E. coli usually live in the large intestine, but they can enter the urinary tract by first clinging to the urethra. As the bacteria multiply, they can spread, causing a urinary tract infection. Other types of bacteria, such as chlamydia and mycoplasma, can also cause urinary tract infections. Unlike E. coli, chlamydia and mycoplasma are sexually transmitted and usually only affect the urethra and reproductive organs.
Kidney Stones
The main cause of urinary tract infections in men is blockage in the urinary tract. One type of blockage is kidney stones. A kidney stone is a crystal-like mass that forms in the kidneys or other parts of the urinary tract, notes the National Kidney and Urologic Diseases Information Clearinghouse. Small stones can travel in the urine through the urinary tract, eventually leaving the body. But if a stone is too big, it can get stuck in the urinary tract causing a blockage. Bacteria can begin to grow and build up, leading to an infection.
Benign Prostate Hyperplasia
Benign prostatic hyperplasia, also called BPH, is the enlargement of the prostate. The prostate is a walnut-sized gland located near the bladder and urethra. It is common for the prostate to grow as a man ages. The prostate has its first growth period during puberty, and then again when a man is in his mid-20s. The final growth period occurs when a man reaches his senior years. It is during these later years that BPH occurs and can cause urinary tract problems.
As the prostate gets bigger, it presses against the urethra. In men, the urethra is the tube that connects the bladder to the penis. When it is time to urinate, urine in the bladder travel down the urethra to the penis. With BPH, since the urethra is being "pinched off" by the prostate, urine builds up in the bladder, causing the bladder to weaken. A weakened bladder makes it difficult to get rid of the urine. Built-up urine along with a narrowed urethra can cause a blockage, where bacteria can multiply, leading to a urinary tract infection.
Catheters
Blockage in the urinary tract can also be caused by bacteria growing on a catheter. A catheter is a flexible tube that is inserted into the body to drain fluids, such as urine. A urinary catheter is usually inserted if a person is unable to urinate on his own. If it is left in the body for a long time, bacteria can begin to grow on it, eventually entering the urinary tract. Most urinary tract infections associated with a catheter is caused by bacteria. At times the presence of a fungus, called Candida, may also result in an infection.
