Urinary Tract Infections
Bacterial Invasion of the Urethra, Bladder, and Kidney
Urinary tract infections can be mild or serious with symptoms that depend on the portion of the urinary tract involved.
The urinary tract, from the kidney to the opening of the urethra (urethral meatus), is usually sterile. Now and then, bacteria and other pathogens may be present and cause urinary tract infections (UTIs). They occur mostly in women, though certain men may be prone to urinary tract infections.
Causes
The vast majority of urinary tract infections are caused by bacteria, including the intestinal bacterium E. coli and other gram-negative bacteria like Klebsiella, Pseudomonas aeruginosa, and Proteus mirabilis. The gram-positive bacterium Staphylococcus saprophyticus may also be a culprit. Lesser common pathogens include fungi and sexually transmitted diseases (STDs).
Clinical Presentation
Whatever the cause (etiology), the clinical manifestations of a urinary tract infection depend on which portion of the urinary tract is involved. Urethritis is often accompanied by burning with urination (dysuria) and urethral discharge, especially when it involves sexually transmitted diseases caused by Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis. Cystitis, or inflammation of the urinary bladder, manifests itself as urinary frequency and urgency. Pyelonephritis is a serious infection of the kidneys, which can present with pain in the flanks, particularly with percussion.
Most of the time, urinary tract infections occur because the pathogen ascends the urinary tract from the urethral meatus. Indwelling urethral catheters and conditions that involve urinary outflow obstruction can predispose one to a urinary tract infections, which in this case would be called a complicated urinary tract infection. Infections that involve no urinary tract obstruction are called uncomplicated urinary tract infections.
Gender Involvement
Women are more likely to have urinary tract infections than men because of anatomic factors like shorter urethra and proximity of the urethra to the anus in conjunction with lack of hygiene. Use of antibiotics and spermicides may also play a role because they alter the vaginal flora and allow for other bacteria like E. coli to colonize. Men who are prone to urinary tract infections include those with AIDS and those who engage in vaginal intercourse with a woman colonized with pathogens or unprotected anal intercourse.
Treatment and Prevention
Antibiotics are the treatment for any type of urinary tract infection, and the specific drug depends on the pathogen involved. Women can prevent further urinary tract infections by drinking cranberry juice, wiping from front to back after toileting, and urinating after sexual intercourse. Women may also consider being careful with feminine products, such as douches and powders, because of potential irritation of the urethra.
