UTI: urinary tract infection

by Tamara Dickinson, RN, CURN, CCCN, BCIA-PMDB

What is urinary tract infection (UTI)?

Urinary Tract Infections (UTIs) are common and affect men and women of all ages. Acute cystitis (infection of the bladder) is one of the most frequent problems treated with antibiotics and encountered in primary care.

Definition and classification of Urinary Tract Infections

Urinary tract infection (UTI) is the product of the urothelial (lining of the urethra) response to bacteria in the urine (bacteriuria) and creates white blood cells in the urine (pyuria). Bacteria in the urine can be symptomatic or asymptomatic but the addition of the white blood cells generally indicates infection. Bacterial colonization usually involves bacteriuria without pyuria¹. Urinary tract infections (UTIs) are typically defined or classified by their site and can involve the upper or lower urinary tract.

Acute bacterial cystitis refers to bladder involvement and is associated with dysuria (painful urination), frequency, urgency and/or suprapubic discomfort (just above the pubic bone). Acute bacterial cystitis is the most common form of UTI².

UTIs can be complicated or uncomplicated. Uncomplicated implies the infection is occurring in a healthy patient with a normal urinary tract and responds well to antibiotic therapy. Complicating factors include a functional or structural abnormality of the urinary tract or some other compromising comorbidity (co-existing condition) such as diabetes, catheterizations, pregnancy or those with compromised immune systems and may not respond to simple treatment. UTIs can be classified as isolated infections, unresolved bacteriuria (has not resolved, possibly due to resistance of the organism to the chosen antibiotic) or as bacterial persistence or reinfection². More than three UTIs in a twelve month period indicates recurrent infections².

Images of the male and female urinary tracts that show the kidney, ureter, bladder, prostate, and urethra.

Incidence and Epidemiology (Patterns in the Population) of Urinary Tract Infections

UTIs are common and affect men and women of all ages. Acute cystitis is one of the most frequent problems treated with antibiotics and encountered in primary care³. These infections are most commonly seen in women, possibly due to the shorter urethra and proximity of the meatus (the opening of the urine channel to the outside) to the perineum and rectal area. Bacteria are believed to generally ascend from the rectal area contaminating the urine. As ascending bacteria are believed to be the primary culprit, it makes sense that E. coli is the most common pathogen. In the sexually active female, there seems to be some increased incidence associated with sexual activity possibly due to milking of bacteria from the vaginal area or urethra into the bladder². Older men and their obstructive processes (enlarged prostate) and/or voiding dysfunction may contribute to their incidence of UTIs. It is estimated that 20-50% of women will have a UTI during their lifetime² and UTIs may account for some seven million office visits a year⁴. The financial impact of community acquired UTIs was estimated at approximately $1.6 billion annually in the United States⁵.

Diagnosis and Evaluation of Urinary Tract Infections

The basic symptoms of a UTI may include frequency, urgency, dysuria, suprapubic discomfort and/or foul smelling urine. The probability of acute, uncomplicated cystitis in women with these symptoms is 50-90%⁶. Differential diagnoses (other options requiring investigation) would include vaginitis, urethritis and sexually transmitted diseases. Infections involving the upper tracts generally also include fever, chills, and flank pain. Urine dipsticks are considered accurate, particularly in regards to assessment for nitrites and leukocyte esterase¹, both of which may be present in the urine during a UTI. Urine micro analysis assesses for white blood cells, red blood cells and bacteria. A urinalysis is a prompt identification of bacteria and white blood cells when UTI is the presumptive diagnosis. The gold standard for UTI diagnosis has been identifying the pathogen in the presence of clinical symptoms via a urine culture³. Urine cultures do remain the absolute method of confirmation; however, routine cultures for uncomplicated acute cystitis are not necessary⁷. Proper teaching regarding the collection of the specimen is crucial to decreasing contaminates and improving accuracy. Imaging studies are not typically indicated in the diagnosis and treatment of an uncomplicated UTI.

When should I see my doctor for a urinary tract infection?

You should see your doctor if you have any of these urinary tract infection symptoms or signs:

burning feeling when you urinate (painful urination)
frequent or intense urges to urinate, even when you have little urine to pass
pain in your back or lower abdomen
cloudy, dark, bloody, or unusual-smelling urine
fever or chills

Women are more likely to get urinary tract infections than men. When men get UTIs, however, they’re often serious and hard to treat. Urinary tract infections can be especially dangerous for older people and pregnant women, as well as for those with diabetes and those who have difficulty urinating.

What will happen at the doctor's office when I have a urinary tract infection?

The health care provider may ask you how much fluid you drink, and if you have pain or a burning feeling when you urinate, or if you have difficulty urinating. Women may be asked about the type of birth control they use. You'll need to urinate into a cup so the urine can be tested. In addition, your doctor may need to take pictures of your kidneys with an x ray or ultrasound and look into your bladder with an instrument called a cystoscope.

Urine tests. Your urine will be checked with a microscope for bacteria and infection-fighting cells. The doctor may order a urine culture. In this test, bacteria from the urine are allowed to grow in a lab dish so the exact type of bacteria can be seen and the precise type of medicine you need can be chosen.
Images. The doctor may use either x rays, ultrasound, or a computerized tomography (CT) scan to view your bladder or kidneys. These pictures can show stones, blockage, or swelling.
Cystoscope. The urethra and bladder can be seen from the inside with a cystoscope, which is a thin tube with lenses like a microscope. The tube is inserted into the urinary tract through the urethra.

Cystoscope. The prism in the cystoscope reflects light so the doctor can see inside the bladder.

Treatment of Urinary Tract Infections

Antibiotic therapy for the treatment of UTIs must eliminate bacteria in the urine, which makes drug levels in the urine very important. When choosing a drug and the duration of its use, it is important to consider the known or probable pathogen, if it is complicated or uncomplicated, side effects of the antibiotic and cost of the treatment. Bowel flora (intestinal bacteria) is commonly associated with UTIs and can colonize in the urinary tract, but even resistant E. coli is often susceptible to nitrofurantoin or quinolones.

Trimetrhoprim/Sulfamethoxazole (TMP/SMX) has been one of the most widely used drugs over time. It is inexpensive and has minimal side effects, including those related to the bowel flora and gastrointestinal upset. It is, however, associated with a higher incidence of patient allergy/sensitivity.
Nitrofurantoin is effective against most common urinary pathogens and is rapidly excreted in the urine. It has minimal side effects and has been used for prophylaxis for more than forty years¹.
First generation cephalosporins work well against gram positive organisms (such as E. coli and Klebsiella pneumoniae) and also can be useful during pregnancy.
Ampicillin and amoxicillin were widely used in the past but increased incidence or resistance and affects on normal bowel and vaginal flora can lead to adverse side effects such as gastrointestinal upset and candidal vaginitis (or a vaginal yeast infection).
Fluroquinolones have a broad spectrum of coverage which makes them ideal for empiric treatment (treatment given without doing a urine culture or before those results are received). Initially, resistance seemed to be rare; but due to increase in use, resistance appears to be on the rise.

There is much controversy over the commonplace use of these agents due to concerns over increased bacterial resistance and the cost of the agents themselves³.

Duration of the treatment is related to the complicated status of the infection, the concentration the drug can achieve in the urine, and any impairment of the patient's defense mechanisms. Approximately 90% of women are asymptomatic within 72 hours of starting treatment¹.

Prevention of Urinary Tract Infections

Females should be taught to wipe from front to back after toileting to avoid extra contamination by potential ascending bacteria. Females should also pass urine before and after sexual intercourse to impede bacteria spreading into the bladder. Adequate and appropriate fluid intake is also important for everyone.

How can I prevent more urinary tract infections?

Changing some of your daily habits may help you avoid urinary tract infections.

Drink lots of fluid to flush the bacteria from your system. Water is best. Try for 6 to 8 glasses a day.
Drink cranberry juice or take vitamin C. Both increase the acid in your urine so bacteria can't grow easily. Cranberry juice also makes your bladder wall slippery, so bacteria can't stick to it.
Urinate frequently and go when you first feel the urge. Bacteria can grow when urine stays in the bladder too long.
Urinate shortly after sex. This can flush away bacteria that might have entered your urethra during sex. Drinking a glass of water will also help.
After using the toilet, always wipe from front to back, especially after a bowel movement.
Wear cotton underwear and loose-fitting clothes so that air can keep the area dry. Avoid tightfitting jeans and nylon underwear, which trap moisture and can help bacteria grow.
For women, using a diaphragm or spermicide for birth control can lead to urinary tract infections by increasing bacteria growth. If you have trouble with UTIs, consider modifying your birth control method. Unlubricated condoms or spermicidal condoms increase irritation, which may help bacteria grow. Consider switching to lubricated condoms without spermicide or using a nonspermicidal lubricant.

Conclusion
Uncomplicated acute cystitis is easily treatable with antibiotic therapy. Patients with complicated cystitis, unresolved UTIs or recurrent UTIs should be referred to a specialist for further evaluation.

References

Schaeffer AJ & Schaeffer EM. Infections of the Urinary Tract in Campbell-Walsh Urology 9th edition (Wein A, editor); 2006.
Goldmann HB. Evaluation and Management of Recurrent Urinary Tract Infection. in Office Urology: The Clinician's Guide (Kursh ED and Ulchaker JC, editors); 2001.
Schmiemann G, Kniehl E, Gebhardt K, Matejczyk M, Hummers-Pradier E. The Diagnosis of Urinary Tract Infection: A Systematic Review. Dtsch Arztebl Int 2010; 107 (21): 361-7.
Foxman B, Barlow R, D'Arcy H, Gillespie B, Sobel JD. Urinary Tract Infection: Self Reported Incidence and Estimated Costs. Ann Epidemiol 2000; 10:509-515.
Foxman B; Epidemiology of urinary tract infections: Incidence, morbidity, and economic costs. Am J Med 2002; 113(Suppl 1A): 5S-13S.
Bent S, Nallamothu BK, Simel DL, Fihn SD, Saint S. Does this woman have an acute uncomplicated urinary tract infection?. JAMA 2002; 287: 2701-2710.
Grover M, Bracamonte J, Kanodia A, Bryan M, Donahue S, Warner MA, Edwards F, Weaver A. Assessing Adherence to Evidence Based Guidelines for the Diagnosis and Management of Uncomplicated Urinary Tract Infections. Mayo Clinic Proceedings; Feb 2007; 82 (2): 181-185.

This article has been reviewed by a member of the Wellness Partners Editorial Board.

Posted December 2010