Urinary tract infection

A **urinary tract infection** (**UTI**) is an infection caused by bacteria in the urinary tract.  

The urinary tract is made up of the kidneys, ureters, the urinary bladder, and urethra. Symptoms of a UTI may affect the urinary tract. They can cause painful urination (peeing), as well as urinating often (polyuria) or wanting to urinate (or both).  

Women get urinary tract infections more often than men. Half of women have an infection at some point in their lives. It is common for a person to have many UTI infections in their life. One cause of UTIs is sexual intercourse. Diagnosis in young, healthy women can be based on symptoms alone. Sometimes urine needs to be tested. A person with frequent infections can take low-dose antibiotics to prevent future infections.

## Mechanism
The bacteria that cause urinary tract infections usually go into the bladder from the urethra. It is believed these bacteria come from the bowel. Females are at greater risk because they have a short urethra that is close to their anus). After entering the bladder, *E. Coli* are able to stick to the bladder wall. They form a biofilm, which is a coating of microorganisms, that resists the body's immune response.

* Urethra: The tube that extends from the bladder to the exterior of the body to excrete pee is known as the urethra. It is possible for bacteria to enter the urethra and grow there, which can result in urethritis, an infection of the urethra.
* Bladder: Urine is stored in the bladder, a hollow, muscular structure. The illness known as cystitis, which is a bladder infection, can develop as a result of bacteria ascending the urethra and entering the bladder.
* Ureters: The kidneys and bladder are linked by two tubes called ureters. Urethritis, a disease where UTIs develop in the ureters, is possible but less often than infections of the urethra or bladder.
* Kidneys: The kidneys are essential organs that filter waste and extra fluid from the circulation to create urine. Pyelonephritis is a more dangerous illness that can develop when bacteria enter the urinary system and go up to the kidneys. Pyelonephritis is a kidney infection

## Cause 
*E. coli* is the cause of 80–85% of urinary tract infections. *Staphylococcus saprophyticus* is the cause in 5–10% of cases. In rare cases, viral or fungal infections cause urinary tract infections Other bacterial causes of UTI include:
**Klebsiella*
**Proteus*
**Pseudomonas*,
**Enterobacter*
These bacterial causes are not common and usually happen when the person has an abnormal urinary system or the person has a urinary catheterization (tube inserted into the bladder.

### Gender
Sexual intercourse is the cause of 75–90% of bladder infections in young, sexually active women. The risk of infection is related to how often they have sex. As a woman's estrogen (a hormone) levels decrease with menopause, the risk of urinary tract infections increases due to the loss of protective vaginal flora (good bacteria that live in the vagina).
*  using a catheter only when necessary
* making sure everything is very clean () when putting the catheter in
* making sure that nothing blocks the catheter.

### Others
Bladder infections are more common in some families. Other risk factors include diabetes, In children, UTIs are linked to vesicoureteral reflux (an abnormal movement of urine from the bladder into ureters or kidneys) and constipation.

### In children
In young children, fever can be the only symptom of a urinary tract infection (UTI). Many medical associations recommend a urine culture for females younger than two years old or uncircumcised males who are younger than a year and have a fever. 

Infants with UTI sometimes eat poorly, vomit, sleep more, or show signs of jaundice ( a yellow coloring of the skin). 

Older children can have new urinary incontinence (loss of bladder control). However, phenazopyridine is no longer commonly recommended due to safety concerns. It can cause methemoglobinemia, which means there is higher than normal level of methemoglobin in the blood. Acetaminophen can be used for fevers.

### Uncomplicated UTI
Simple infections can be diagnosed and treated based on symptoms alone. A three-day treatment with trimethoprim, TMP/SMX, or a fluoroquinolone is usually enough. Nitrofurantoin needs 5–7&nbsp;days. With treatment, symptoms should improve within 36&nbsp;hours.

### Pyelonephritis
Pyelonephritis (kidney infection) 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 geographic areas where the resistance rate is less than 10%. If the local resistance rates are greater than 10%, a dose of intravenous ceftriaxone often is prescribed. People with more severe symptoms are sometimes admitted a hospital for ongoing antibiotics. A number of vaccines were being developed as of 2011. Gastrointestinal (stomach) upset occurs in more than 30% of people who regularly drink cranberry juice or take capsules. As of 2011, probiotics used intravaginally (in the vagina) require further study to determine if they are helpful. It is rare for people who have no problems with their kidneys to develop kidney problems from frequent UTIs. Having frequent urinary tract infections as a child causes less than a third of a percent (0.33%) of chronic kidney disease in adults.

## Diagnosis
 (rod-shaped bacteria, here shown as black and bean-shaped) shown between white blood cells as seen by looking at urine through a microsope. These changes show a urinary tract infection.]]
In most cases, UTIs can be diagnosed just from the symptoms and there is no need for laboratory testing. Urinalysis (testing the urine) can be used to confirm the diagnosis in complicated cases. The urine is tested for urinary nitrites, white blood cells (leukocytes), or leukocyte esterase. Another test, urine microscopy, looks for red blood cells, white blood cells, or bacteria. Urine culture is considered positive if it shows a bacterial colony count of greater than or equal to 103 colony-forming units per mL of a typical bacteria that causes infections of the urinary tract. Cultures can also be used to test which antibiotic will work. However, women with negative cultures can still improve with antibiotic treatment.

### In children
To diagnose a urinary tract infection in children, a positive urinary culture is required. Contamination poses a frequent challenge so a cutoff of 105&nbsp;CFU/mL is used for a "clean-catch" mid-stream sample, 104&nbsp;CFU/mL is used for catheter-obtained specimens, and 102&nbsp;CFU/mL is used for suprapubic aspirations (a sample drawn directly from the bladder through the stomach wall with a needle). The World Health Organization does not like the use of “urine bags” to collect samples because there is a high rate of contamination when that urine is cultured. Catheterization is preferred if an individual is unable to use a toilet. Some medical groups, such as the American Academy of Pediatrics, recommend renal ultrasound and voiding cystourethrogram (watching a person's urethra and urinary bladder with real time X-rays while they urinate) in all children who are younger than 2 years old and have had a urinary tract infection.Other medical groups such as the National Institute for Clinical Excellence recommend routine imaging only in babies younger than 6 months old or who have unusual findings. Vaginitis may also be due to a yeast infection. Interstitial cystitis (chronic pain in the bladder) can be the cause for people who have UTI symptoms many times, but whose urine cultures remain negative and do not improved with antibiotics. Prostatitis (inflammation of the prostate) may also be considered in the differential diagnosis.

## Likelihood
Urinary tract infections are the most frequent bacterial infection in women. They occur most frequently between the ages of 16 and 35&nbsp;years. 10% of women get an infection yearly; 60% have an infection at some point in their lives. Nearly half of people get a second infection within a year. Urinary tract infections occur four times more frequently in females than males. Rates of asymptomatic bacteria in the urine increase with age from 2% to 7% in women of childbearing age to as high as 50% in elderly women in care homes.

Urinary tract infections can affect 10% of people during childhood. The Egyptians described a urinary tract infection as "sending forth heat from the bladder." Herbs, bloodletting, and rest were the common treatments until the 1930s, when antibiotics became available. A kidney infection during pregnancy may result in premature birth or pre-eclampsia (a state of high blood pressure, kidney dysfunction, or seizures).

## References