Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Dr. Balentine received his undergraduate degree from McDaniel College in Westminster, Maryland. He attended medical school at the Philadelphia College of Osteopathic Medicine graduating in1983. He completed his internship at St. Joseph's Hospital in Philadelphia and his Emergency Medicine residency at Lincoln Medical and Mental Health Center in the Bronx, where he served as chief resident.
The urine is normally sterile. An infection occurs when bacteria get into the urine and begin to grow. The infection usually starts at the opening of the urethra where the urine leaves the body and moves upward into the urinary tract.
The culprit in at least 90% of uncomplicated infections is a type of bacteria called Escherichia coli, better know as E. coli. These bacteria normally live in the bowel (colon) and around the anus.
These bacteria can move from the area around the anus to the opening of the urethra. The two most common causes of this are poor hygiene and sexual intercourse.
Usually, the act of emptying the bladder (urinating) flushes the bacteria out of the urethra. If there are too many bacteria, urinating may not stop their spread.
The bacteria can travel up the urethra to the bladder, where they can grow and cause an infection.
The infection can spread further as the bacteria move up from the bladder via the ureters.
If they reach the kidney, they can cause a kidney infection (pyelonephritis), which can become a very serious condition if not treated promptly.
The following people are at increased risk of urinary tract infection:
People with conditions that block (obstruct) the urinary tract, such as kidney stones
People with medical conditions that cause incomplete bladder emptying (for example, spinal cord injury or bladder decompensation after menopause)
People with suppressed immune systems: Examples of situations in which the immune system is suppressed are AIDS and diabetes. People who take immunosuppressant
medications such as chemotherapy for cancer also are at increased risk.
Women who are sexually active: Sexual intercourse can introduce larger
numbers of bacteria into the bladder. Infection is more likely in women who have
frequent intercourse. Infection attributed to frequent intercourse is nicknamed
"honeymoon cystitis." Urinating after intercourse seems to decrease the
likelihood of developing a urinary tract infection.
Men with an enlarged prostate: Prostatitis or obstruction of the urethra by an enlarged prostate
can lead to incomplete bladder emptying, thus increasing the risk of infection.
This is most common in older men.
Males are also less likely to develop UTIs because their urethra (tube from
the bladder) is longer. There is a drier environment where a man's urethra meets
the outside world, and fluid produced in the prostate can fight bacteria.
Breastfeeding has been found to decrease the risk for urinary tract infections.
The following special groups may be at increased risk of urinary tract infection:
Very young infants: Bacteria gain entry to the urinary tract via the
bloodstream from other sites in the body.
Young children: Young children have trouble wiping themselves and washing
their hands well after a bowel movement. Poor hygiene has been linked to an
increased frequency of urinary tract infections.
Children of all ages: Urinary tract infection in children
can be (but is not always) a sign of an abnormality in the urinary tract,
usually a partial blockage. An example is a condition in which urine moves
backward from the bladder up the ureters (vesicoureteral reflux).
Hospitalized patients or nursing home residents: Many of these individuals are catheterized for long periods and are thus vulnerable to infection of the urinary tract. Catheterization means that a thin tube (catheter) is placed in the urethra to drain urine from the bladder. This is done for people who have problems urinating or cannot reach a toilet to urinate on their own.