Urinary tract infection
A urinary tract infection (UTI) is an infection that affects a part of the urinary tract.[1] Lower urinary tract infections may involve the bladder (cystitis) or urethra (urethritis) while upper urinary tract infections affect the kidney (pyelonephritis).[10] Symptoms from a lower urinary tract infection include suprapubic pain, painful urination (dysuria), frequency and urgency of urination despite having an empty bladder.[1] Symptoms of a kidney infection, on the other hand, are more systemic and include fever or flank pain usually in addition to the symptoms of a lower UTI.[10] Rarely, the urine may appear bloody.[7] Symptoms may be vague or non-specific at the extremities of age (i.e. in patients who are very young or old).[1][11]
"UTI" redirects here. For other uses, see UTI (disambiguation).Urinary tract infection
Acute cystitis, simple cystitis, bladder infection, symptomatic bacteriuria
Most often Escherichia coli[2]
Catheterisation (foley catheter), female anatomy, sexual intercourse, diabetes, obesity, family history[2]
Based on symptoms, urine culture[3][4]
152 million (2015)[8]
196,500 (2015)[9]
The most common cause of infection is Escherichia coli, though other bacteria or fungi may sometimes be the cause.[2] Risk factors include female anatomy, sexual intercourse, diabetes, obesity, catheterisation, and family history.[2] Although sexual intercourse is a risk factor, UTIs are not classified as sexually transmitted infections (STIs).[12] Pyelonephritis usually occurs due to an ascending bladder infection but may also result from a blood-borne bacterial infection.[13] Diagnosis in young healthy women can be based on symptoms alone.[4] In those with vague symptoms, diagnosis can be difficult because bacteria may be present without there being an infection.[14] In complicated cases or if treatment fails, a urine culture may be useful.[3]
In uncomplicated cases, UTIs are treated with a short course of antibiotics such as nitrofurantoin or trimethoprim/sulfamethoxazole.[7] Resistance to many of the antibiotics used to treat this condition is increasing.[1] In complicated cases, a longer course or intravenous antibiotics may be needed.[7] If symptoms do not improve in two or three days, further diagnostic testing may be needed.[3] Phenazopyridine may help with symptoms.[1] In those who have bacteria or white blood cells in their urine but have no symptoms, antibiotics are generally not needed,[15] although during pregnancy is an exception.[16] In those with frequent infections, a short course of antibiotics may be taken as soon as symptoms begin or long-term antibiotics may be used as a preventive measure.[17]
About 150 million people develop a urinary tract infection in a given year.[2] They are more common in women than men, but similar between anatomies while carrying indwelling catheters.[7][18] In women, they are the most common form of bacterial infection.[19] Up to 10% of women have a urinary tract infection in a given year, and half of women have at least one infection at some point in their lifetime.[4][7] They occur most frequently between the ages of 16 and 35 years.[7] Recurrences are common.[7] Urinary tract infections have been described since ancient times with the first documented description in the Ebers Papyrus dated to c. 1550 BC.[20]
Prognosis
With treatment, symptoms generally improve within 36 hours.[19] Up to 42% of uncomplicated infections may resolve on their own within a few days or weeks.[4][103]
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).[74] Recurrent urinary tract infections are defined as at least two infections (episodes) in a six-month time period or three infections in twelve months, can occur in adults and in children.[74]
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.[104]
Epidemiology
Urinary tract infections are the most frequent bacterial infection in women.[19] They occur most frequently between the ages of 16 and 35 years, with 10% of women getting an infection yearly and more than 40–60% having an infection at some point in their lives.[7][4] 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.[7] Pyelonephritis occurs between 20 and 30 times less frequently.[4] They are the most common cause of hospital-acquired infections accounting for approximately 40%.[105] Rates of asymptomatic bacteria in the urine increase with age from two to seven percent in women of child-bearing age to as high as 50% in elderly women in care homes.[39] Rates of asymptomatic bacteria in the urine among men over 75 are between 7–10%.[11] 2–10% of pregnant women have asymptomatic bacteria in the urine and higher rates are reported in women who live in some underdeveloped countries.[99]
Urinary tract infections may affect 10% of people during childhood.[7] Among children, urinary tract infections are most common in uncircumcised males less than three months of age, followed by females less than one year.[28] 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.[28]
History
Urinary tract infections have been described since ancient times with the first documented description in the Ebers Papyrus dated to c. 1550 BC.[20] It was described by the Egyptians as "sending forth heat from the bladder".[106] Effective treatment did not occur until the development and availability of antibiotics in the 1930s before which time herbs, bloodletting and rest were recommended.[20]