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Urinary tract infection
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A urinary tract infection (UTI) is a bacterial infection that affects any part of the urinary tract. Although urine contains a variety of fluids, salts, and waste products, it usually does not have bacteria in it. When bacteria gets into the bladder or kidney and multiply in the urine, they cause a UTI. The most common type of UTI is a bladder infection which is also often called cystitis. Another kind of UTI is a kidney infection, known as pyelonephritis, and is much more serious.
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Encyclopedia
A urinary tract infection (UTI) is a bacterial infection that affects any part of the urinary tract. Although urine contains a variety of fluids, salts, and waste products, it usually does not have bacteria in it. When bacteria gets into the bladder or kidney and multiply in the urine, they cause a UTI. The most common type of UTI is a bladder infection which is also often called cystitis. Another kind of UTI is a kidney infection, known as pyelonephritis, and is much more serious. Although they cause discomfort, urinary tract infections can usually be quickly and easily treated with a short course of antibiotics. Studies have shown that breastfeeding can reduce the risk of UTIs in infants.
Symptoms
For bladder infections
- Frequent urination along with the feeling of having to urinate even though there may be very little urine to pass.
- Nocturia: Need to urinate during the night.
- Urethritis: Discomfort or pain at the urethral meatus or a burning sensation throughout the urethra with urination (dysuria).
- Pain in the midline suprapubic region.
- Pyuria: Pus in the urine or discharge from the urethra.
- Hematuria: Blood in urine.
- Pyrexia: Mild fever
- Cloudy and foul-smelling urine
- Increased confusion and associated falls are common presentations to Emergency Departments for elderly patients with UTI.
- Some urinary tract infections are asymptomatic.
- Protein found in the urine.
For kidney infections
- All of the above symptoms.
- Emesis: Vomiting is common.
- Back, side (flank) or groin pain.
- Abdominal pain or pressure.
- Shaking chills and high spiking fever.
- Night sweats.
- Extreme fatigue.
Epidemiology
UTIs are most common in sexually active women and increase in diabetics and people with sickle-cell disease or anatomical malformations of the urinary tract.
Since bacteria can enter the urinary tract through the urethra (an ascending infection), poor toilet habits can predispose to infection, but other factors (pregnancy in women, prostate enlargement in men) are also important and in many cases the initiating event is unclear.
While ascending infections are generally the rule for lower urinary tract infections and cystitis, the same may not necessarily be true for upper urinary tract infections like pyelonephritis which may be hematogenous in origin.
Allergies can be a hidden factor in urinary tract infections. For example, allergies to foods can irritate the bladder wall and increase susceptibility to urinary tract infections. Urinary tract infections after sexual intercourse can be also be due to an allergy to latex condoms, spermicides, or oral contraceptives. In this case review alternative methods of birth control with your doctor.
Indwelling urinary catheters in women and men who are elderly, over placement of a temporary prostatic stent can be a major cause of UTIs. Also, people experiencing nervous system disorders, people who are convalescing or unconscious for long periods of time, will have an increased risk of urinary tract infection for a number of reasons. Scrupulous aseptic techniques may decrease these associated risks.
The bladder wall is coated with various mannosylated proteins, such as Tamm-Horsfall proteins (THP), which interfere with the binding of bacteria to the uroepithelium. As binding is an important factor in establishing pathogenicity for these organisms, its disruption results in reduced capacity for invasion of the tissues. Moreover, the unbound bacteria are more easily removed when voiding. The use of urinary catheters (or other physical trauma) may physically disturb this protective lining, thereby allowing bacteria to invade the exposed epithelium.
Elderly individuals, both men and women, are more likely to harbor bacteria in their genitourinary system at any time. These bacteria may be associated with symptoms and thus require treatment with an antibiotic. The presence of bacteria in the urinary tract of older adults, without symptoms or associated consequences, is also a well recognized phenomenon which may not require antibiotics. This is usually referred to as asymptomatic bacteriuria. The overuse of antibiotics in the context of bacteriuria among the elderly is a concerning and controversial issue.
Women are more prone to UTIs than males because in females, the urethra is much shorter and closer to the anus than in males, and they lack the bacteriostatic properties of prostatic secretions. Among the elderly, UTI frequency is in roughly equal proportions in women and men.
A common cause of UTI is an increase in sexual activity, such as vigorous sexual intercourse with a new partner. The term "honeymoon cystitis" has been applied to this phenomenon. . In males, frequent masturbation could also lead to the build up of the bacteria if they are not urinated out of the urinary tract after masturbating.
Diagnosis
A patient with dysuria (painful voiding) and urinary frequency generally has a spot mid-stream urine sample sent for urinalysis, specifically the presence of nitrites, leukocytes or leukocyte esterase. If there is a high bacterial load without the presence of leukocytes, it is most likely due to contamination. The diagnosis of UTI is confirmed by a urine culture.
If the urine culture is negative:
A negative urine test can also suggest the presence of unusual bacteria or viruses causing symptoms of UTI.
In severe infection, characterized by fever, rigors or flank pain, urea and creatinine measurements may be performed to assess whether renal function has been affected.
Most cases of lower urinary tract infections in females are benign and do not need exhaustive laboratory work-ups. However, UTI in young infants must receive some imaging study, typically a retrograde urethrogram, to ascertain the presence/absence of congenital urinary tract anomalies. Males too must be investigated further. Specific methods of investigation include x-ray, Nuclear Medicine, MRI and CAT scan technology.
Treatment
Uncomplicated UTIs
Most uncomplicated UTIs can be treated with oral antibiotics such as trimethoprim, cephalosporins, nitrofurantoin, or a fluoroquinolone (e.g., ciprofloxacin or levofloxacin). Trimethoprim is one widely used antibiotic for UTIs and is usually taken for 7 days. It is often recommended that trimethoprim be taken at night to ensure maximal urinary concentrations and increase its effectiveness. Trimethoprim/sulfamethoxazole was previously internationally used (and continues to be used in the U.S. and Canada), the additional of the sulfonamide gave little additional benefit compared to the trimethoprim component alone. It however is responsible for a high incidence of mild allergic reactions and rare but serious complications. A three day treatment of trimethoprim/sulfamethoxazole or ciprofloxacin is usually all that is needed.
Though there is anecdotal evidence of benefits, and many doctors recommend them as part of a treatment or preventive regimen, there are no clinical trials on humans proving benefits of cranberry juice, cranberry supplements, or D-mannose in the treatment or prevention of UTIs>
Complicated UTIs
An infection of the urinary tract is considered complicated if there is simultaneous evidence of a metabolic disease, functional/anatomical abnormality of the urinary tract, or more severe infection of the urinary tract, especially with
"resistant pathogens".
In some cases, a urinary tract infection may lead to an infection in the bloodstream (sepsis, septicemia) that can be life-threatening.
Case reports cited primarily in women having period in which a blood-soaked tampon may provide an excellent breeding ground for the bacteria which causes Toxic Shock Syndrome (TSS), and is a significant cause of urinary tract infections. TSS is a variant of septic shock and bacteremic shock. It presents with a sepsis-like picture.
Pyelonephritis
If the patient has symptoms consistent with pyelonephritis, intravenous antibiotics may be indicated. Regimens vary, usually Aminoglycosides (such as Gentamicin) are used in combination with a beta-lactam, such as Ampicillin or Ceftriaxone. These are continued for 48 hours after fever subsides. The patient may then be discharged home on oral antibiotics for a further 5 days.
If the patient makes a poor response to IV antibiotics (marked by persistent fever, worsening renal function), then imaging is indicated to rule out formation of an abscess either within or around the kidney, or the presence of an obstructing lesion such as a stone or tumor. Ref: http://www.merck.com/mmhe/sec17/ch190/ch190w.html
Children
For simple UTIs children often respond well to a 3 day course of antibiotics.
Recurrent UTIs
- See also Prevention (below)
Patients with recurrent UTIs may need further investigation. This may include ultrasound scans of the kidneys and bladder or intravenous urography (X-rays of the urological system following intravenous injection of iodinated contrast material). If there is no response to treatments, interstitial cystitis may be a possibility.
During cystitis, uropathogenic Escherichia coli (UPEC) subvert innate defenses by invading superficial umbrella cells and rapidly increasing in numbers to form intracellular bacterial communities (IBCs).
Prevention
The following are measures that studies suggest may reduce the incidence of urinary tract infections. These may be appropriate for people, especially women, with recurrent infections:
- Do not delay urination when it is necessary.
- Cleaning the urethral meatus (the opening of the urethra) after intercourse has been shown to be of some benefit; however, whether this is done with an antiseptic or a placebo ointment (an ointment containing no active ingredient) does not appear to matter.
- It has been advocated that cranberry juice can decrease the incidence of UTI (some of these opinions are referenced in External Links section). A specific type of tannin found only in cranberries and blueberries prevents the adherence of certain pathogens (eg. E. coli) to the epithelium of the urinary bladder. A review by the Cochrane Collaboration of randomized controlled trials states "some evidence from trials to show cranberries (juice and capsules) can prevent recurrent infections in women. Many people in the trials stopped drinking the juice, suggesting it may not be a popular intervention".
- For post-menopausal women, a randomized controlled trial has shown that intravaginal application of topical estrogen cream can prevent recurrent cystitis. In this study, patients in the experimental group applied 0.5 mg of estriol vaginal cream nightly for two weeks followed by twice-weekly applications for eight months.
- Often long courses of low dose antibiotics are taken at night to help prevent otherwise unexplained cases of recurring cystitis.
- Acupuncture has been shown to be effective in preventing new infections in recurrent cases. One study showed that urinary tract infection occurrence was reduced by 50% for 6 months. However, this study has been criticized for several reasons. Acupuncture appears to reduce the total amount of residual urine in the bladder . All of the studies are done by one research team without independent reproduction of results.
See also
External links
- NIH articles on Urinary Tract Infections in and in .
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