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Urinary tract infection
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 get 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 are usually quickly and easily treated by seeing a doctor promptly.
Additional recommended knowledge
Symptoms & Signs
For Bladder Infections
For Kidney Infections
Since bacteria can enter the urinary tract through the urethra (an ascending infection), poor toilet habits can predispose to infection, but other factors are also important: (pregnancy in women, prostate enlargement in men) 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. Keep track of your diet and have allergy testing done to help eliminate foods that may be a problem. 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.
The use of urinary catheters in both men and women who are elderly, people experiencing nervous system disorders and people who are convalescing or unconscious for long periods of time may result in an increased risk of urinary tract infection for a variety of reasons. Scrupulous aseptic technique may decrease this risk.
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.[clarify] 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 men and women.
A common cause of UTI is an increase in sexual activity, such as vigorous sexual intercourse with a new partner. The term "honeymoon cystitis", although somewhat demeaning, has been applied to this phenomenon.
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:
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, MRI and CAT scan technology.
Most uncomplicated UTIs can be treated with oral antibiotics such as trimethoprim, cephalosporins, nitrofurantoin, or a fluoroquinolone (e.g. ciprofloxacin, levofloxacin). These are usually taken for 3 days in young adults, and 5 days in elderly. Whilst co-trimoxazole was previously internationally used (and continues to be used in the U.S.), the additional of the sulphonamide gave little additional benefit compared to the trimethoprim component alone, but was responsible for its both high incidence of mild allergic reactions and rare but serious complications.
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. The gold-standard imaging modality is CT scan.
As an at-home treatment, increased water-intake, frequent voiding, the avoidance of sugars and sugary foods, drinking unsweetened cranberry juice, as well as taking vitamin C with the last meal of the day can shorten the time duration of the infection. Sugars and alcohol can feed the bacteria causing the infection, and worsen pain and other symptoms. Vitamin C at night raises the acidity of the urine, which retards the growth of bacteria in the urinary tract. However, if pain is in the back region (suggesting kidney infection) or if pain persists, if there is fever, or if blood is present in the urine, doctor care is recommended.
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).
Researchers at Center for Genomic Sciences, Allegheny Singer Research Institute, and the Department of Microbiology and Immunology, Drexel University College of Medicine have shown that biofilms are responsible for chronic infections and, from a clinical perspective, traditional antibiotic therapy will never be a successful treatment against biofilm bacteria.
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:
The following measures seem sensible, but have not been studied:
|Tumors of the kidney||Renal cell carcinoma - Wilms' tumor (children)|
|See also congenital conditions (Q60-Q64, 753)|