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See a complete list of Specialty Services and Departments at UMMC.Urinary tract infection
Description
An in-depth report on the causes, diagnosis, treatment, and prevention of urinary tract infections.
Alternative Names
Cystitis; UTI
Medications
Antibiotics are the mainstay treatment for all UTIs. A variety of antibiotics are available and choices depend on many factors, including whether the infection is complicated or uncomplicated or primary or recurrent. Treatment decisions are also based on the type of patient (man or woman, a pregnant or nonpregnant woman, child, hospitalized or nonhospitalized patient, person with diabetes.) Treatment should not necessarily be based on the actual bacteria count. For example, if a woman has symptoms, even if bacterial count is low or normal, infection is probably present and antibiotic treatment should be considered.
Bacterial Resistance to Antibiotics. Antibiotic-resistant strains of E. coli, the most common cause of UTIs, are increasing. The prevalence of such bacteria has dramatically increased worldwide, in large part due to widespread use of antibiotics in humans and animal feed. In a 2003 report, 42% of E. coli were resistant to one or more of the 12 antibiotics that researchers investigated. As more bacteria have become resistant to the standard UTI treatment trimethoprim-sulfamethoxazole (TMP-SMX), more doctors have been prescribing quinolone antibiotics to treat UTIs. A 2006 study found that quinolones have now overtaken TMP-SMX as the most commonly prescribed antibiotic for UTIs. Experts are concerned that resistance may develop to these drugs as well.
Specific Antibiotics Used for Most UTIsBeta-Lactams The beta-lactam antibiotics share common chemical features and include penicillins, cephalosporins, and some newer similar drugs. Their primary actions to interfere with bacterial cell walls. Many have been important in the treatment of urinary tract infections. Penicillins (Amoxicillin). Until recent years, the standard treatment for a UTI was 10 days of amoxicillin, a penicillin antibiotic, but it is now ineffective against E. coli bacteria in up to 25% of cases. A combination of amoxicillin-clavulanate (Augmentin) is sometimes given for drug-resistant infections. Amoxicillin or Augmentin may be useful for UTIs caused by gram-positive organisms, including Enterococcus species and S. saprophyticus . Cephalosporins. Antibiotics known as cephalosporins are also alternatives for infections that do not respond to standard treatments or for special populations. They are often classed as:
Other Beta-Lactam Drugs. Other beta-lactam antibiotics have been developed. For example, pivmecillinam (a form of mecillinam), is commonly used in Europe for UTIs. It appears to be safe during pregnancy. Trimethoprim-Sulfamethoxazole ( TMP-SMX) The typical treatment is a 3-day course of the combination drug trimethoprim-sulfamethoxazole, commonly called TMP-SMX (Bactrim, Cotrim, Septra). A 1-day course is somewhat less effective but poses a lower risk for side effects. Longer courses (7 to 10 days) work no better than the 3-day course and have a higher rate of side effects. TMP-SMX should not be used in patients whose infections occurred after dental work or in patients allergic to sulfa drugs. Allergic reactions can be very serious. Trimethoprim (Proloprim, Trimpex) is sometimes used alone in those allergic to sulfa drugs. TMP-SMX can interfere with the effectiveness of oral contraceptives. High rates of bacterial resistance to TMP-SMX exist in many parts of the U.S. Still, even when regional rates approach 30%, cure rates with TMP-SMX reach 80% to 85%. Fluoroquinolones (Quinolones) Fluoroquinolones (also simply called quinolones) are now becoming as widely used as TMP-SMX. These drugs interfere with the bacteria's genetic material so they cannot reproduce. They are the standard alternatives to TMP-SMX. Examples of quinolones include ofloxacin (Floxacin), ciprofloxacin (Cipro), norfloxacin (Noroxin), levofloxacin (Levaquin), gatifloxacin (Tequin), and sparfloxacin (Zagam). These antibiotics are effective against a wide range of organisms but are expensive and, in general, used in the following circumstances:
Pregnant women should not take fluoroquinolone antibiotics. They also have more adverse effects in children than other antibiotics and should not be the first-line option in most situations. Antibiotics Used Specifically for UTIs Nitrofurantoin. Nitrofurantoin (Furadantin, Macrodantin) is a relatively inexpensive antibiotic that is used specifically for urinary tract infections. It is an effective alternative to TMP-SMX or a quinolone. Unlike many of the other drugs, however, it must be given 7 to 10 days, even in cases of simple cystitis. (Shorter course treatments are being investigated.) It is not useful for treating kidney infections. Nitrofurantoin frequently causes stomach upset and interacts with many drugs. Other chronic or serious medical conditions may also affect its use. It should not be used in pregnant women within 1 to 2 weeks of delivery, in nursing mothers, or in those with kidney disease. Fosfomycin. The antibiotic fosfomycin (Monurol), which comes in an orange-flavored, soluble powder, is proving to be another good alternative. It can be an effective 1-dose treatment for many women, including those who are pregnant. To date, bacterial resistance rates to this antibiotic are very low. Tetracyclines Tetracyclines inhibit bacterial growth. They include doxycycline, tetracycline, and minocycline. Long-term treatment with tetracycline or doxycycline may be used for infections that are caused by Mycoplasma or Chlamydia . Tetracyclines have unique side effects among antibiotics, including skin reactions to sunlight, possible burning in the throat, and tooth discoloration. Aminoglycosides Aminoglycosides (gentamicin, kanamycin, tobramycin, amikacin) are given by injection for very serious bacterial infections. They can be given only in combination with other antibiotics. Gentamicin is the most commonly used aminoglycoside for serious UTIs. They can have very serious side effects, including damage to hearing, sense of balance, and kidneys. |
Treatment for Uncomplicated UTIs
UTIs in low-risk women can often be successfully treated over the phone. In such cases, a health professional provides the patients with 3-day antibiotic regimens without even requiring an office urine test. This course is recommended only for women at low risk for recurrent infection and who do not have symptoms suggesting other problems, such as vaginitis.
Antibiotic Regimen. Oral antibiotic treatment cures 94% of uncomplicated urinary tract infections, although the rate of recurrence remains high. The following antibiotics are commonly used for uncomplicated UTIs:
- The standard regimen has traditionally been a 3-day course of trimethoprim-sulfamethoxazole, commonly called TMP-SMX (Bactrim, Cotrim, Septra). TMP-SMX combines an antibiotic with a sulfa drug. A single dose of TMP-SMX is sometimes prescribed in mild cases, but cure rates are generally lower than with the 3-day regimens.
- Fluoroquinolone antibiotics, also called quinolones, have usually been a second choice. However, in geographic areas that have a high resistance to TMP-SMX, quinolones are now the first-line treatment for UTIs. Ciprofloxacin (Cipro) is the quinolone antibiotic most commonly prescribed. Quinolones are usually given over a 3–day period. Pregnant women should not take these drugs.
- Nitrofurantoin (Furadantin, Macrodantin) is a third option. This drug must be given for longer than 3 days.
- Fosfomycin (Monurol) is not as effective as other antibiotics but may be used during pregnancy. Resistance rates to this drug are very low.
- Many other effective antibiotics are available, including amoxicillin (with or without clavulanate) and cephalosporins. Doxycycline is often effective but cannot be given to children or pregnant women.
After a week of antibiotic treatment, most patients are free of infection. If the symptoms do not clear up within the first few days of therapy, doctors generally suggest that women discontinue their antibiotic and provide a urine sample for culturing in order to identify the specific organism causing the condition.
Treatment for Relapsing Infection. A relapsing infection (caused by treatment failure) occurs within 3 weeks in about 10% of women. Relapse is treated similarly to a first infection but the antibiotics are continued for at least 2 weeks. (Relapsing infections may be due to structural abnormalities, abscesses, or other problems that may require surgery, and such conditions should be ruled out.)
Antibiotic Treatment for Recurrent Infections
Preventive antibiotics may be required for women who experience two or more symptomatic UTIs within 6 months or three or more over the course of a year. A woman's own perception of discomfort can generally guide her decisions on whether to use preventive antibiotics or not. All women should use lifestyle measures to prevent recurrences.
Intermittent Self Treatment. Many, if not most, women with recurrent UTIs can effectively self treat recurrent UTIs without going to a doctor. In general, this requires the following steps:
- As soon as the patient develops symptoms, she takes the antibiotic. Infections that occur less than twice a year are usually treated as if they were an initial attack, with single-dose or three-day antibiotic regimens.
- At that time, she also performs a clean-catch urine test and sends it to the doctor for culturing to confirm the infection.
A doctor should be consulted under the following circumstances:
- If symptoms have not completely resolved within 48 hours
- If there is a change in symptoms
- If the patient suspects that she is pregnant
- If the patient has more than four infections a year
Women who are not good candidates for self-treatment are those with impaired immune systems, previous kidney infections, structural abnormalities of the urinary tract, or a history of infection with antibiotic-resistant bacteria.
Postcoital Antibiotics. If recurrent infections are clearly related to sexual activity and episodes recur more than two times within a 6-month period, a single preventive dose taken immediately after intercourse is very effective. Antibiotics for such cases include TMP-SMX, nitrofurantoin, cephalexin, or a fluoroquinolone (such as ciprofloxacin). (Fluoroquinolones are not appropriate during pregnancy.)
Continuous Preventive Antibiotics (Prophylaxis). Continuous preventive (prophylactic) antibiotics are an option for some women who do not respond to other measures. With this approach, low-dose antibiotics are taken continuously for 6 months or longer.
Typical prophylactic regimens include one dose of nitrofurantoin (50 mg), 1/2 tablet of TMP-SMX, or cephalexin (250 mg) daily. Taking the antibiotic at bedtime may be most effective. Studies suggest that continuous prophylactic antibiotics reduces recurrences by up to 95% and may prevent kidney infection.
Adverse effects mostly include gastrointestinal problems and yeast infections. (Taking probiotic supplements or eating yogurt may help prevent yeast infections.) Although there is concern that continuous risk increases the risk for bacteria that are resistant to the antibiotics, studies to date have not reported any significant risk even up to 5 years of use.
Antibiotics for Kidney Infections (Pyelonephritis)
Treating Uncomplicated Kidney Infections. Patients with uncomplicated kidney infections (pyelonephritis) may be treated at home with oral antibiotics. Such patients are healthy and nonpregnant. They typically are experiencing fever, chills, and flank pain. However, they are not nauseous or vomiting and show no symptoms or signs of kidney involvement or complicated infection.
The standard treatment for uncomplicated pyelonephritis is a 14-day course of oral antibiotics, usually trimethoprim-sulfamethoxazole (TMP-SMX) or a fluoroquinolone. Sometimes patients with uncomplicated pyelonephritis are first given an antibiotic injection, if indicated.
Oral amoxicillin or amoxicillin-clavulanate (Augmentin) may be prescribed for women with bacteria (gram-positive organisms, including Enterococcus species and S. saprophyticus ) that do not respond to standard regimens.
A urine culture is may be obtained within 1 week of completion of therapy and again 4 weeks later.
Treating Moderate to Severe Kidney Infections. Patients with moderate to severe acute kidney infection and those with severe symptoms or other complications may need to be hospitalized. In such cases, antibiotics (ceftriaxone and gentamicin) are usually given intravenously for 3 to 5 days or until symptoms are relieved and patients have not shown any signs of fever for 24 to 48 hours.
If fever and back pain persist after 72 hours of antibiotic administration, the doctor will usually order imaging tests to see if abscesses, obstructions, or other abnormalities are present.
Treating Chronic Kidney Infections. Patients with chronic pyelonephritis are often treated with long-term antibiotics, even during periods when they have no symptoms.
Treatments for Interstitial Cystitis
The two approved treatments for interstitial cystitis are pentosan polysulfate (Elmiron), and dimethyl sulfoxide (DMSO). Patients generally prefer Elmiron because it can be taken by mouth. A DMSO solution is instilled into the bladder through a catheter. Elmiron is a type of blood thinner that helps to coat the bladder lining and prevent infections. It may take several months before having an effect on symptoms, but the benefits increase the longer the drug is used.
Doctors sometimes also prescribe other types of medications to help interstitial cystitis symptoms. These drugs include antihistamines, such as hydroxyzine (Atarax), and low doses of the tricyclic antidepressant amitriptyline (Elavil). Drugs that reduce bladder spasms (hyoscine, oxybutynin) are also sometimes used. Other treatments are being investigated, including hyperbaric oxygen therapy. This treatment involves having a patient breathe pure oxygen inside a sealed pressurized chamber.
Some doctors think that interstitial cystitis may be related to immune disorders. Researchers are investigating various drugs that block immune and inflammatory responses.
Treatments for Specific Populations
Treating the Pregnant Woman . Pregnant women should be screened for UTIs, since they are at high risk for UTIs and their complications. The antibiotics used during pregnancy are amoxicillin, ampicillin, nitrofurantoin, or an oral cephalosporin. Fosfomycin (Monurol) is not as effective as others but may be used during pregnancy. Pregnant women should not take fluoroquinolones.
Pregnant women with even asymptomatic bacteriuria (evidence of infection but no symptoms) have a 30% risk for acute pyelonephritis in their second or third trimester. They need screening and treatment for this condition. In such cases, they should be treated with a short course of antibiotics (3 to 5 days). For an uncomplicated UTI, pregnant women may need longer-term antibiotics (7 to 10 days).
Treating Women with Diabetes. Women with diabetes have more frequent and more severe UTIs than women without the disease. Many experts recommend that patients with diabetes and UTI, even an uncomplicated infection, be treated with antibiotics for 7 to 14 days. People with diabetes have higher than average rates of asymptomatic bacteriuria, but it is unclear whether they should be screened and treated for this condition. A 2003 study indicated that treating this condition had little value in these women and did not prevent complications.
Treating Urethritis in Men. Urethritis in men has typically been treated with a 7-day regimen of doxycycline. Some research suggests that a single dose of azithromycin may be just as effective while causing fewer side effects. One-dose treatment also improves compliance, so cure rates may even be better than with a long-term regimen. However, once an infection spreads to the prostate gland it is harder to treat, so most doctors still prefer the longer regimen. Patients with urethritis should also be tested for an accompanying sexually transmitted disease such as gonorrhea.
Treating Children with UTIs. Children with UTIs are generally treated with TMP-SMX or cephalexin (Keflex). These drugs are usually taken by mouth in either liquid or pill form. Doctors sometimes give them as a shot or IV. Children usually respond to treatment within a few days. Antibiotic resistance to cephalosporin antibiotics such as cephalexin is increasing, and some doctors prefer to prescribe an aminoglycoside antibiotic. Gentamicin (Garamycin) is the aminoglycoside antibiotic that is most commonly used. It is given intravenously.
Vesicoureteral reflux (VUR) is a concern for children with UTIs. About a third of children with UTIs develop this condition, in which urine backs up into the kidneys. VUR can lead to kidney infection (pyelonephritis), which can cause kidney damage. Either long-term antibiotics or surgery are options to correct vesicoureteral reflux (VUR) and prevent infection. Many experts recommend surgery over antibiotics, especially due to concerns of antibiotic resistance. Antibiotic treatment usually continues for years with the idea that the condition will resolve when the child has grown. However, a 2006 study suggested that long-term antibiotics are not useful for preventing VUR. Furthermore, the study found that mild-to-moderate VUR does not increase the likelihood of UTIs or pyelonephritis.
Children with acute kidney infection are treated with oral cefixime (Suprax) or a short course (2 to 4 days) of an intravenous (IV) antibiotic (typically gentamicin, given in one daily dose). An oral antibiotic then follows the IV.
Management of Catheter-Induced Urinary Tract InfectionsPreventing Catheter-Induced Infections Catheter-induced urinary tract infections are very common and preventive measures are extremely important. Catheters should not be used unless absolutely necessary, and they should be removed as soon as possible. Reducing the risk for infections during long-term catheter use, however, remains problematic. Catheter Coatings. Catheter coatings, such as silver nitrate, antibiotics, and other substances, are being tested and are showing some benefits, but the problem is still not resolved. One promising catheter (LoFric) uses a so-called hydrophilic coating consisting of PVP (polyvinyl pyrrolidone) and salt. It attracts water to the catheter surface, putting up a water barrier to reduce friction. In a 2003 study, it was associated with significantly fewer UTIs. Intermittent Use of Catheters. If a catheter is required for long periods, it is best to use it intermittently if possible (as opposed to an indwelling catheter). Some doctors recommend replacing it every 2 weeks to reduce the risk of infection and irrigating the bladder with antibiotics between replacements. Daily Hygiene. A typical catheter is one that has been preconnected and sealed and uses a drainage bag system. To prevent infection, some of the following tips may be helpful:
Antibiotics for Catheter-Induced Infections Patients using catheters who develop UTIs with symptoms should be treated for each episode with antibiotics and the catheter should be removed, if possible. A major problem in treating catheter-related UTIs is that the organisms involved are constantly changing. Because there are likely to be multiple species of bacteria, experts generally recommend an antibiotic that is effective against a wide variety of microorganisms. These medications include those in the fluoroquinolone group and drug combinations such as ampicillin plus gentamicin or imipenem plus cilastatin. Although high bacteria counts in the urine (bacteriuria) occur in most catheterized patients, administering antibiotics to prevent a UTI is rarely recommended. Many catheterized patients do not develop symptomatic urinary tract infections even with high bacteria counts. If bacteriuria occurs without symptoms, antibiotic therapy has little benefit if the catheter is to remain in place for a long period. |
Catheterization is accomplished by inserting a catheter (a hollow tube, often with and inflatable balloon tip) into the urinary bladder. This procedure is performed for urinary obstruction, following surgical procedures to the urethra, in unconscious patients (due to surgical anesthesia, coma, etc.), or for any other problem in which the bladder needs to be kept empty (decompressed) and urinary flow assured. Catheterization in males is slightly more difficult and uncomfortable than in females because of the longer urethra.
- Review Date: 6/16/2006
- Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital
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