A urinary tract infection ( UTI) is an infection that affects a part of the urinary tract.[ Symptoms of a kidney infection, on the other hand, are more systemic and include fever or Abdominal pain usually in addition to the symptoms of a lower UTI.][ Rarely, the urine may appear Hematuria.][ Symptoms may be vague or non-specific at the extremities of age (i.e. in patients who are very young or old).]
The most common cause of infection is Escherichia coli, though other bacteria or fungi may sometimes be the cause.[ Risk factors include female anatomy, sexual intercourse, diabetes, obesity, catheterisation, and family history.][ Although sexual intercourse is a risk factor, UTIs are not classified as sexually transmitted infections (STIs).][
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In uncomplicated cases, UTIs are treated with a short course of such as nitrofurantoin or trimethoprim/sulfamethoxazole.[ Resistance to many of the antibiotics used to treat this condition is increasing.][ In complicated cases, a longer course or intravenous antibiotics may be needed.][ If symptoms do not improve in two or three days, further diagnostic testing may be needed.][ In those who have bacteria or white blood cells in their urine but have no symptoms, antibiotics are generally not needed,]
About 150million people develop a urinary tract infection in a given year.[ They occur most frequently between the ages of 16 and 35years.][ Recurrences are common.]
Signs and symptoms
Lower urinary tract infection is also referred to as a bladder infection. The most common symptoms are dysuria and having to urinate frequently (or an urge to urinate) in the absence of vaginal discharge and significant pain.[ These symptoms may vary from mild to severe][ and in healthy women last an average of sixdays.][ Some pain above the pubic bone or in the lower back may be present. People experiencing an upper urinary tract infection, or pyelonephritis, may experience abdominal pain, fever, or nausea and vomiting in addition to the classic symptoms of a lower urinary tract infection.][ Rarely, the urine may appear Hematuria][ or contain visible pyuria.]
UTIs have been associated with onset or worsening of delirium, dementia, and neuropsychiatric disorders such as depression and psychosis. However, there is insufficient evidence to determine whether UTI causes confusion.
Children
In young children, the only symptom of a urinary tract infection (UTI) may be a fever.[ Because of the lack of more obvious symptoms, when females under the age of two or uncircumcised males less than a year exhibit a fever, a culture of the urine is recommended by many medical associations.][ Infants may feed poorly, vomit, sleep more, or show signs of jaundice.][ In older children, new onset urinary incontinence (loss of bladder control) may occur.][ About 1 in 400 infants of one to three months of age with a UTI also have bacterial meningitis.]
Elderly
Urinary tract symptoms are frequently lacking in the Old age.[ The presentations may be vague and include incontinence, a change in mental status, or fatigue as the only symptoms,][ while some present to a health care provider with sepsis, an infection of the blood, as the first symptoms.][ Diagnosis can be complicated by the fact that many elderly people have preexisting incontinence or dementia.][
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It is reasonable to obtain a urine culture in those with signs of systemic infection that may be unable to report urinary symptoms, such as when advanced dementia is present.[
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Cause
UPEC from the gut is the cause of 80–85% of community-acquired urinary tract infections,[ Rarely they may be due to Virus or fungal infections.][ Chlamydia trachomatis and Mycoplasma genitalium can infect the urethra but not the bladder.]
Intercourse
In young sexually active women, sexual activity is the cause of 75–90% of bladder infections, with the risk of infection related to the frequency of sex.[ The term "honeymoon cystitis" has been applied to this phenomenon of frequent UTIs during early marriage. In Menopause women, sexual activity does not affect the risk of developing a UTI.][ Spermicide use, independent of sexual frequency, increases the risk of UTIs.]
Sex
Women are more prone to UTIs than men because, in females, the urethra is much shorter and closer to the anus.[ Additionally, vaginal atrophy that can sometimes occur after menopause is associated with recurrent urinary tract infections.]
Chronic prostatitis in the forms of chronic prostatitis/chronic pelvic pain syndrome and chronic bacterial prostatitis (not acute bacterial prostatitis or asymptomatic inflammatory prostatitis) may cause recurrent urinary tract infections in males. Risk of infections increases as males age. While bacteria is commonly present in the urine of older males this does not appear to affect the risk of urinary tract infections.
Urinary catheters
Urinary catheterization increases the risk for urinary tract infections. The risk of bacteriuria (bacteria in the urine) is between three and six percent per day and prophylactic antibiotics are not effective in decreasing symptomatic infections.[ The risk of an associated infection occurs linearly for enteric bacteria,]
Male scuba divers using condom catheters and female divers using external catching devices for their are also susceptible to urinary tract infections.
Others
A predisposition for bladder infections may run in families.[ This is believed to be related to genetics.][ Other risk factors include diabetes,][ being circumcise,][ In children UTIs are associated with vesicoureteral reflux (an abnormal movement of urine from the urinary bladder into or ) and constipation.][
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Persons with spinal cord injury are at increased risk for urinary tract infection in part because of chronic use of catheter, and in part because of urination dysfunction.[
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Pathogenesis
The bacteria that cause urinary tract infections typically enter the bladder via the urethra. However, infection may also occur via the blood or lymph.[ It is believed that the bacteria are usually transmitted to the urethra from the bowel, with females at greater risk due to their anatomy.][ After gaining entry to the bladder, E. Coli are able to attach to the bladder wall and form a biofilm that resists the body's immune response.][
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Escherichia coli is the single most common microorganism, followed by Klebsiella and Proteus spp., to cause urinary tract infection. Klebsiella and Proteus spp., are frequently associated with stone disease. The presence of Gram positive bacteria such as Enterococcus and Staphylococcus is increased.
The increased resistance of urinary pathogens to quinolone antibiotics has been reported worldwide and might be the consequence of overuse and misuse of quinolones.
Diagnosis
In straightforward cases, a diagnosis may be made and treatment given based on symptoms alone without further laboratory confirmation.[ In complicated or questionable cases, it may be useful to confirm the diagnosis via urinalysis, looking for the presence of , white blood cells (leukocytes), or leukocyte esterase.][ As symptoms can be vague and without reliable tests for urinary tract infections, diagnosis can be difficult in the elderly.][
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Based on pH
Normal urine pH is slightly acidic, with usual values of 6.0 to 7.5, but the normal range is 4.5 to 8.0. A urine pH of 8.5 or 9.0 is indicative of a urea-splitting organism, such as Proteus, Klebsiella, or Ureaplasma urealyticum; therefore, an asymptomatic patient with a high pH means UTI regardless of the other urine test results. Alkaline pH also can signify struvite kidney stones, which are also known as "infection stones".[ Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License .]
Classification
A urinary tract infection may involve only the lower urinary tract, in which case it is known as a bladder infection. Alternatively, it may involve the upper urinary tract, in which case it is known as pyelonephritis. If the urine contains significant bacteria but there are no symptoms, the condition is known as asymptomatic bacteriuria.[ If a urinary tract infection involves the upper tract, and the person has diabetes mellitus, is pregnant, is male, or immunocompromised, it is considered complicated.][ Otherwise if a woman is healthy and premenopausal it is considered uncomplicated.][ In children when a urinary tract infection is associated with a fever, it is deemed to be an upper urinary tract infection.]
Children
To make the diagnosis of a urinary tract infection in children, a positive urinary culture is required. Contamination poses a frequent challenge depending on the method of collection used, thus a cutoff of 105CFU/mL is used for a "clean-catch" mid stream sample, 104CFU/mL is used for catheter-obtained specimens, and 102CFU/mL is used for suprapubic aspirations (a sample drawn directly from the bladder with a needle). The use of "urine bags" to collect samples is discouraged by the World Health Organization due to the high rate of contamination when cultured, and catheterization is preferred in those not toilet trained. Some, such as the American Academy of Pediatrics recommends renal ultrasound and voiding cystourethrogram (watching a person's urethra and urinary bladder with real time x-rays while they urinate) in all children less than two years old who have had a urinary tract infection. However, because there is a lack of effective treatment if problems are found, others such as the National Institute for Health and Care Excellence only recommends routine imaging in those less than six months old or who have unusual findings.[
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Differential diagnosis
In women with cervicitis (inflammation of the cervix) or vaginitis (inflammation of the vagina) and in young men with UTI symptoms, a Chlamydia trachomatis or Neisseria gonorrhoeae infection may be the cause.
Hemorrhagic cystitis, characterized by hematuria, can occur secondary to a number of causes including: infections, radiation therapy, underlying cancer, medications and toxins.[ Medications that commonly cause this problem include the chemotherapeutic agent cyclophosphamide with rates of 2–40%.][ Signs and symptoms are similar to a bladder infection.]
Prevention
A number of measures have not been confirmed to affect UTI frequency including: urinating immediately after intercourse, the type of underwear used, personal hygiene methods used after urinating or defecating, or whether a person typically bathes or showers.[ There is similarly a lack of evidence surrounding the effect of holding one's urine, tampon use, and Douche.][ In those with frequent urinary tract infections who use spermicide or a diaphragm as a method of contraception, they are advised to use alternative methods.][ In those with benign prostatic hyperplasia urinating in a sitting position appears to improve bladder emptying]
Using urinary catheters as little and as short of time as possible and appropriate care of the catheter when used prevents catheter-associated urinary tract infections.[ Evidence does not support a significant decrease in risk when silver-alloy catheters are used.]
Medications
For those with recurrent infections, taking a short course of antibiotics when each infection occurs is associated with the lowest antibiotic use.[ A prolonged course of daily antibiotics is also effective.][ Medications frequently used include nitrofurantoin and trimethoprim/sulfamethoxazole.][ Some recommend against prolonged use due to concerns of antibiotic resistance.]
In cases where infections are related to intercourse, taking antibiotics afterwards may be useful.[ In post-menopausal women, topical vaginal estrogen has been found to reduce recurrence.][ As opposed to topical creams, the use of vaginal estrogen from Pessary has not been as useful as low dose antibiotics.]
Children
The evidence that preventive antibiotics decrease urinary tract infections in children is poor.
Male circumcision
Circumcision of boys has been observed to exhibit a strong protective effect against UTIs, with some research suggesting as much as a 90% reduction in symptomatic UTI incidence among male infants, if they are circumcised.
Dietary supplements
When used as an Adjuvant therapy to antibiotics and other standard treatments, cranberry supplements decrease the number of UTIs in people who get them frequently.
Mannose is often marketed as a dietary supplement that prevents UTIs; however, there is little evidence supporting its use. A randomised controlled trial compared daily d-mannose with a placebo (fructose) among women with recurrent urinary tract infections over 6 months. D-mannose offered no benefit over placebo in reducing UTIs.
As of 2015, probiotics require further study to determine if they are beneficial for UTI.
Treatment
The mainstay of treatment is . Phenazopyridine is occasionally prescribed during the first few days in addition to antibiotics to help with the burning and urgency sometimes felt during a bladder infection.
Fosfomycin can be used as an effective treatment for both UTIs and complicated UTIs including acute pyelonephritis.
Gepotidacin was approved for medical use in the United States in March 2025.
Uncomplicated
Uncomplicated infections can be diagnosed and treated based on symptoms alone.
Fluoroquinolones are not recommended as a first treatment.
The combination sulopenem etzadroxil/probenecid (Orlynvah) was approved for medical use in the United States in October 2024.
Complicated
Complicated UTIs are more difficult to treat and usually requires more aggressive evaluation, treatment, and follow-up.
Asymptomatic bacteriuria
Those who have bacteria in the urine but no symptoms should not generally be treated with antibiotics.
Pregnant women
Urinary tract infections, even asymptomatic presence of bacteria in the urine, are more concerning in pregnancy due to the increased risk of kidney infections.
Pyelonephritis
Pyelonephritis is treated more aggressively than a simple bladder infection using either a longer course of oral antibiotics or intravenous antibiotics.[ Seven days of the oral fluoroquinolone ciprofloxacin is typically used in areas where the resistance rate is less than 10%. If the local antibiotic resistance rates are greater than 10%, a dose of intravenous ceftriaxone is often prescribed.][ Trimethoprim/sulfamethoxazole or amoxicillin/clavulanate orally for 14 days is another reasonable option.][ Complications such as ureteral obstruction from a kidney stone may be considered if symptoms do not improve following two or three days of treatment.][
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Prognosis
With treatment, symptoms generally improve within 36hours.[ Up to 42% of uncomplicated infections may resolve on their own within a few days or weeks.]
15–25% of adults and children have chronic symptomatic UTIs including recurrent infections, persistent infections (infection with the same pathogen), a re-infection (new pathogen), or a relapsed infection (the same pathogen causes a new infection after it was completely gone).
Cystitis refers to a urinary tract infection that involves the lower urinary tract (bladder). An upper urinary tract infection which involves the kidney is called pyelonephritis. About 10–20% of pyelonephritis will go on and develop scarring of the affected kidney. Then, 10–20% of those develop scarring will have increased risk of hypertension in later life.
Epidemiology
Urinary tract infections are the most frequent bacterial infection in women.[ They occur most frequently between the ages of 16 and 35years, with 10% of women getting an infection yearly and more than 40–60% having an infection at some point in their lives.][ Recurrences are common, with nearly half of people getting a second infection within a year. Urinary tract infections occur four times more frequently in females than males.][ Pyelonephritis occurs between 20 and 30 times less frequently.][ They are the most common cause of hospital-acquired infections accounting for approximately 40%.][ Rates of asymptomatic bacteria in the urine among men over 75 are between 7–10%.][ 2–10% of pregnant women have asymptomatic bacteria in the urine and higher rates are reported in women who live in some underdeveloped countries.]
Urinary tract infections may affect 10% of people during childhood.[ Among children, urinary tract infections are most common in uncircumcised males less than three months of age, followed by females less than one year.][ Estimates of frequency among children, however, vary widely. In a group of children with a fever, ranging in age between birth and two years, 2–20% were diagnosed with a UTI.][
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Veterinary medicine
Domestic Cat are less susceptible to bacterial urinary tract infections than domestic Dog.
History
Urinary tract infections have been described since ancient times with the first documented description in the Ebers Papyrus dated to c. 1550 BC.[ It was described by the Egyptians as "sending forth heat from the bladder".][
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See also
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Urinary anti-infective agent
External links
