The urinary tract is comprised of the kidneys, ureters, bladder, and urethra. A urinary tract infection (UTI) is an infection caused by pathogenic organisms (for example, bacteria, fungi, or parasites) in any of the structures that comprise the urinary tract. However, this is the broad definition of urinary tract infections; many authors prefer to use more specific terms that localize the urinary tract infection to the major structural segment involved such as urethritis (urethral infection), cystitis (bladder infection), ureter infection, and pyelonephritis (kidney infection). Other structures that eventually connect to or share close anatomic proximity to the urinary tract (for example, prostate, epididymis, and vagina) are sometimes included in the discussion of UTIs because they may either cause or be caused by UTIs. Technically, they are not UTIs and will be only be briefly mentioned in this article.
UTIs are common, leading to between seven and 10 million doctor visits per year. Although some infections go unnoticed, UTIs can cause problems that range from dysuria (pain and/or burning when urinating) to organ damage and even death. The kidneys are the active organs that produce about 1.5 quarts of urine per day. They help keep electrolytes and fluids (for example, potassium, sodium and water) in balance, assist in the removal of waste products (urea), and produce a hormone that aids in the formation of red blood cells. If kidneys are injured or destroyed by infection, these vital functions can be damaged or lost.
While most investigators state that UTIs are not transmitted from person to person, other investigators dispute this and say UTIs may be contagious and recommend that sex partners avoid relations until the UTI has cleared. There is general agreement that sexual intercourse can cause a UTI. This is mostly thought to be a mechanical process whereby bacteria are introduced into the urinary tracts during the sexual act. There is no dispute about the transmission of UTIs caused by sexually transmitted disease (STD) organisms; these infections (for example, gonorrhea and chlamydia) are easily transmitted between sex partners and are very contagious. Some of the symptoms of UTIs and sexually transmitted diseases can be similar (pain and foul smell).
Infertility The most common causes of UTI infections (about 80%) are E. coli bacterial strains that usually inhabit the colon. However, many other bacteria can occasionally cause an infection (for example, Klebsiella, Pseudomonas, Enterobacter, Proteus, Staphylococcus, Mycoplasma, Chlamydia, Serratia and Neisseria spp.), but are far less frequent causes than E. coli. In addition, fungi (Candida and Cryptococcus spp.) and some parasites (Trichomonas and Schistosoma) also may cause UTIs; Schistosoma causes other problems, with bladder infections as only a part of its complicated infectious process. In the U.S., most infections are due to Gram-negative bacteria with E. coli causing the majority of infections.
The UTI symptoms and signs may vary according to age, sex, and location of the infection in the tract. Some individuals will have no symptoms or mild symptoms and may clear the infection in about two to five days. Many people will not spontaneously clear the infection; one of the most frequent symptoms and signs experienced by most patients is a frequent urge to urinate, accompanied by pain or burning on urination. The urine often appears cloudy and occasionally dark, if blood is present. The urine may develop an unpleasant odor. Women often have lower abdominal discomfort or feel bloated and experience sensations like their bladder is full. Women may also complain of a vaginal discharge, especially if their urethra is infected, or if they have an STD. Although men may complain of dysuria, frequency, and urgency, other symptoms may include rectal, testicular, penile, or abdominal pain. Men with a urethral infection, especially if it is caused by an STD, may have a pus-like drip or discharge from their penis. Toddlers and children with UTIs often show blood in the urine, abdominal pain, fever, and vomiting along with pain and urgency with urination.
Symptoms and signs of a UTI in the very young and the elderly are not as diagnostically helpful as they are for other patients. Newborns and infants may develop fever or hypothermia, poor feeding, jaundice, vomiting, and diarrhea. Unfortunately, the elderly often have mild symptoms or no symptoms of a UTI until they become weak, lethargic, or confused.
Location of the infection in the urinary tract usually results in certain symptoms. Urethral infections usually have dysuria (pain or discomfort when urinating). STD infections may cause a pus-like fluid to drain or drip from the urethra. Cystitis (bladder infection) symptoms include suprapubic pain, usually without fever and flank pain. Ureter and kidney infections often have flank pain and fever as symptoms. These symptoms and signs are not highly specific, but they do help the physician determine where the UTI may be located.
Treatment for a UTI should be designed for each patient individually and is usually based on the patient's underlying medical conditions, what pathogen(s) are causing the infection, and the susceptibility of the pathogen(s) to treatments. Patients who are very ill usually require intravenous (IV) antibiotics and admission to a hospital; they usually have a kidney infection (pyelonephritis) that may be spreading to the bloodstream. Other people may have a milder infection (cystitis) and may get well quickly with oral antibiotics. Still others may have a UTI caused by pathogens that cause STDs and may require more than a single oral antibiotic. The caregivers often begin treatment before the pathogenic agent and its antibiotic susceptibilities are known, so in some individuals, the antibiotic treatment may need to be changed. In addition, pediatric patients and pregnant patients should not use certain antibiotics that are commonly used in adults. For example, ciprofloxacin (Cipro) and other related quinolones should not be used in children or pregnant patients due to side effects. However, penicillins and cephalosporins are usually considered safe for both groups if the individuals are not allergic to the antibiotics. Patients with STD-related UTIs usually require two antibiotics to eliminate STD pathogens. The less frequent or rare fungal and parasitic pathogens require specific antifungal or antiparasitic medications; these more complicated UTIs should often be treated in consultation with an infectious disease expert.
All antibiotics prescribed should be taken even if the person's symptoms disappear early. Reoccurrence of the UTI and even antibiotic resistance of the pathogen may happen in individuals who are not adequately treated.
Over-the-counter (OTC) medicines offer relief from the pain and discomfort of UTIs but they don't cure UTIs. OTC products like AZO or Uristat contain the medicine, phenazopyridine (Pyridium and Urogesic), which works in the bladder to relieve pain. This medication turns urine an orange-red color, so patients should not be worried when this occurs. This medication can also turn other body fluids orange, including tears, and can stain contact lenses.
Currently, there are no commercially available vaccines for UTIs, either recurrent or first-time infections. One of the problems in developing a vaccine is that so many different organisms can cause infection; a single vaccine would be difficult to synthesize to cover them all. Even with E. coli causing about 80% of all infections, the subtle changes in antigenic structures that vary from strain to strain further complicates vaccine development even for E. coli. Researchers are still investigating ways to overcome the problems in UTI vaccine development; injected, oral, mucosal, and nasal preparations are being investigated.
Many methods have been suggested to reduce or prevent UTIs. Some of these are considered home remedies and have been discussed (see above home remedies section). There are other suggestions that may help prevent UTIs. Good hygiene for males and females is useful; for females, wiping from front to back helps keep pathogens that may reside or pass through the anal opening away from the urethra; for males, retracting the foreskin before urinating reduces the chance of urine lingering at the urethral opening and acting as a culture media for pathogens. Incomplete bladder emptying and resisting the normal urge to urinate can allow pathogens to survive and replicate easier in a non-flowing system. Some clinicians recommend washing before and urinating soon after sex to reduce the chance of urethritis/cystitis. Many clinicians suggest that anything that causes a person irritation in the genital area (for example, tight clothing, deodorant sprays, or other feminine products like bubble bath) may encourage UTI development. Wearing underwear that is somewhat adsorptive (for example, cotton) may help wick away urine drops that otherwise may be areas for pathogen growth.
