Urinary tract infection in children
Synonyms and keywords: Urinary tract infection in kids

# Overview
In healthy people, urine in the bladder is sterile, no bacteria or other infectious organisms are present. The urethra that carries urine from the bladder out of the body contains no bacteria or too few to cause an infection. However, any part of the urinary tract can become infected. That is why any growth of typical urinary pathogens is considered clinically important if obtained by suprapubic aspiration. An infection anywhere along the urinary tract is called a urinary tract infection (UTI) and it is the 2nd most common infection in children.  UTIs are caused by bacteria that enter the opening of the urethra and move upward to the urinary bladder and sometimes the kidneys. Rarely, in severe infections, bacteria may enter the bloodstream from the kidneys and cause infection of the bloodstream (sepsis) or infection of other organs. During infancy, boys are more likely to develop urinary tract infections. After infancy, girls are much more likely to develop them. children who have UTIs, however, more commonly have various structural abnormalities of their urinary system that make them more susceptible to urinary infection. These abnormalities include vesicoureteral reflux (VUR), which is an abnormality of the ureters that allows urine to pass backward from the bladder up to the kidney, and a number of conditions that block the flow of urine. The risk of renal scarring is greatest in infants and may be progressive if there is a delay in diagnosis and management of urinary tract infections in children. The aims of urinary tract infection management are to provide symptomatic relief and to prevent renal damage. In the meantime to be able to prevent the recurrences of urinary tract infection, evaluation and looking for any structural or functional predisposing factors. Treatment of underlying voiding dysfunction and constipation is important for the successful management of urinary tract infections in children.

# Historical Perspective
Since the early 1970s, occult bacteremia has been the major focus of concern for clinicians evaluating febrile infants who have no recognizable source of infection. With the introduction of effective conjugate vaccines against Haemophilus influenza type b and Streptococcus pneumoniae (which have resulted in dramatic decreases in bacteremia and meningitis), there has been increasing appreciation of the urinary tract as the most frequent site of the occult and serious bacterial infections. Because the clinical presentation tends to be nonspecific in infants and reliable urine specimens for culture cannot be obtained without invasive methods (urethral catheterization or suprapubic aspiration ), diagnosis and treatment may be delayed. Most experimental and clinical data support the concept that delays in the institution of appropriate treatment of pyelonephritis increase the risk of renal damage

# Classification
UTI can be classified by:
1- The sites of infection bladder , kidney , urethra .
2- Severity (complicated versus uncomplicated).
3- Recurrency either first or recurrent based on natural history. That may affect clinical management.

# Pathophysiology
The urinary tract in healthy children is usually sterile. The urethra on the other hand is colonized with bacteria. UTI occurs with the entrance of pathogens into the urinary tract and subsequent adherence to it. Although normal voiding with intermittent urinary outflow usually clears pathogens within the bladder. In conditions with Urinary malformation, urine stasis, impaired urine flow lead to increase reservoir and gives more time to establish the infection and the adherence of bacteria to the uroepithelial mucosa being the main predisposing factors for the development of UTI. Congenital obstructive uropathy, "detrusor sphincter" dyssynergia syndrome is an infrequent bladder emptying that is also a cause of UTI. The second mechanism is the introduction of pathogens by way of a foreign body or instrument. Urinary infection is the third most common nosocomial infection after primary bloodstream infections and pneumonia in intensive care units. A recent prospective study estimates the incidence of nosocomial UTI as 0.6 case/1000 patient/day and newborns and infants are affected disproportionately. The infection is associated frequently with urethral catheterization. Escherichia coli accounts for 80 to 90% of UTI in children. Among febrile infants, unwell children, and older children with urinary symptoms 6%8% will have a UTI. Symptoms and signs of pyelonephritis include fever, chills, rigor, flank pain, and costovertebral angle tenderness. Lower tract symptoms and signs include suprapubic pain, dysuria, urinary frequency, urgency, cloudy urine, malodorous urine, and suprapubic tenderness. A urinalysis and urine culture should be performed when UTI is suspected. While waiting for the culture results, prompt antibiotic therapy is indicated for symptomatic UTI based on clinical findings and positive urinalysis to eradicate the infection and improve clinical outcomes. The prevalence varies with age, peaking in young infants, toddlers, and older adolescents. UTI is more common in female and uncircumcised male infants. During toddler years, toilet training can lead to volitional holding and bladder stasis, promoting UTIs. Over 30% of children with UTI will have recurrent UTI. Common risk factors for recurrence include vesicoureteral reflux (VUR) and the bladderbowel dysfunction. Older non-continent children (eg, developmental delay) also have more recurrent UTIs.

# Causes
The common pathogenic sources of UTI are bacteria of enteric origin, although other pathogens (fungi, mycobacteria, and viruses) also are encountered.
Bacterial infection:
- Escherichia coli is responsible for over 80% of all mechanisms of UTIs. Pathogens in the urinary tract of a healthy child are usually the result of retrograde migration of enteric bacteria colonizing the peri-urethral area and reflects this flora.
- Other common gram-negative organisms include Klebsiella, Proteus, Enterobacter, and occasionally Pseudomonas. Proteus mirabilis is a common pathogen in males and in children with kidney stones.
- Gram-positive pathogens include group B Streptococcus and Enterococcus in neonates and infants reflecting the colonization status of the mothers, and Staphylococcus saprophyticus in adolescent girls.
Fungal infections:
- are much less common and are usually to those who are immune-compromised, diabetic, on long-term antibiotics or have a long-term indwelling catheter. The fungus Candida is the organism most likely to cause urinary tract yeast infections (candidiasis). Fungi and bacteria may infect the kidneys at the same time.
Viral infection:
- Is more common in immunocompromised patients, particularly those receiving immunosuppressants, than in otherwise healthy children. Adenovirus and BK virus are viral pathogens that may cause hemorrhagic cystitis. 

# Differentiating Urinary tract infection in children from other Diseases
Although fever may be the sole presenting symptom in children younger than 24 months, physical examination findings may point toward an alternative diagnosis, including:
- Otitis media.
- Gastroenteritis.
- Upper respiratory tract infection.
Occult bacteremia should always be considered, although the probability of this diagnosis is much lower than UTI (less than 1 versus 7 percent) in fully immunized children with no other identifiable potential source for fever on physical examination. Urinary calculi, urethritis (including a sexually transmitted infection), dysfunctional elimination, and diabetes mellitus must be considered in verbal children with urinary tract problems.

# Epidemiology and Demographics

## Age/Gender/Race
- Neonates and infants are at higher risk for UTI, and it declines afterward. which coincides with their incompletely developed immunity. Breast milk seems to protect children from UTI and other infections, which have higher IgA levels than non-breastfed children.
- About 8% of girls and 2% of boys experience at least one episode of UTI up to the age of 7. The incidences of UTI in boys and girls younger than 2 years of age are the same. In older children, particularly in sexually active teenagers, there is a female predominance of UTI.
- 15 years. The incidence is greater in girls in this age group and is likely due to short urethra and translocation of fecal bacteria.
- Uncircumcised infant boys are more at risk, between 15 years.
Structural abnormalities, neurologic deficiency, or behavioral voiding dysfunction resulting in residual urine in any part of the urinary tract also may influence the persistence of bacteriuria once established. Race seems to affect the incidence of UTI. In developed countries with adequate medical resources, UTI is more common in white girls than girls of other races. Although UTI occurs in children of all races and ethnicities, the incidence is low in African-American children. the risk for recurrence is proportional to the number of previous infections.

# Risk Factors
- UTIs occur more often in girls, especially when toilet training begins. Girls are more susceptible because their urethras are shorter and closer to the anus. This makes it easier for bacteria to enter the urethra. Uncircumcised boys under 1-year-old also have a slightly higher risk of UTIs.
- The urethra doesnt normally harbor bacteria. But certain circumstances can make it easier for bacteria to enter or remain in your childs urinary tract. The following factors can put your child at a higher risk for a UTI:
Structural deformity or blockage in one of the organs of the urinary tract.
Vesicoureteral reflux, a birth defect that results in the abnormal backward flow of urine.
The use of bubbles in baths (for girls).
Tight-fitting clothes (for girls).
Wiping from back to front after a bowel movement.
Poor toilet and hygiene habits.
Infrequent urination or delaying urination for long periods of time.
- Structural deformity or blockage in one of the organs of the urinary tract.
- Vesicoureteral reflux, a birth defect that results in the abnormal backward flow of urine.
- The use of bubbles in baths (for girls).
- Tight-fitting clothes (for girls).
- Wiping from back to front after a bowel movement.
- Poor toilet and hygiene habits.
- Infrequent urination or delaying urination for long periods of time.

# Natural History, Complications and Prognosis
- Common complications of UTI in children:
Kidney abscess.
Reduced kidney function or kidney failure.
Hydronephrosis, or swelling of the kidneys.
Sepsis, which can lead to organ failure and death.
- Kidney abscess.
- Reduced kidney function or kidney failure.
- Hydronephrosis, or swelling of the kidneys.
- Sepsis, which can lead to organ failure and death.
- Prognosis is generally good with immediate treatment, can expect to fully recover from a UTI. However, some children may require treatment for periods lasting from six months up to two years.
Long-term antibiotic treatment is more likely if the child receives a diagnosis of vesicoureteral reflux or VUR. This birth defect results in the abnormal backward flow of urine from the bladder up the ureters, moving urine toward the kidneys instead of out the urethra. This disorder should be suspected in young children with recurring UTIs or any infant with more than one UTI with fever. Children with VUR have a higher risk of kidney infection. It creates an increased risk of kidney damage and, ultimately, kidney failure. Surgery is an option used in severe cases. Typically, children with mild or moderate VUR outgrow the condition. However, kidney damage or kidney failure may occur into adulthood.

# Diagnosis
Fever is the most common presentation of UTI in young children, for this reason, the American Academy of Pediatrics (AAP) recommends UTI be ruled out in any child 2 months to 2 years of age with unexplained fever.
- In younger children, the presence of upper respiratory infections, otitis media, or gastroenteritis does not eliminate the possibility of a UTI. In this age group, recurrent abdominal pain could be a symptom of recurrent UTI and should be evaluated promptly.
- In older children, fever is usually the presenting symptom of UTI. Besides fever, children may have vomiting, loose stools, and abdominal pain. This age group could present with more specific symptoms of either cystitis or pyelonephritis. These may include dysuria, frequency, new-onset incontinence flank pain, and fever.
- Adolescent girls may have urethritis from an STD. Hence, for proper diagnosis, laboratory evaluation is mandatory.

## Symptoms
- Consider a diagnosis of urinary tract infection in all infants and children with:
-unexplained fever of 100.4F (38C) or higher after 24 hours.
-symptoms and signs suggestive of urinary tract infection, including.
- fever
- specific symptoms, such as frequency, dysuria, loin tenderness,hesitancy, dysfunctional voiding, changes to continence, hematuria, and offensive or cloudy urine.
- non-specific symptoms, such as lethargy, irritability, malaise, failure to thrive, vomiting, poor feeding, abdominal pain.

## Physical Examination
The physical examination of children with UTI can be nonspecific. With the advent of ultrasonography, occasionally an anatomically abnormal genitourinary organ may be found during the initial evaluation (eg, hydronephrosis, xanthogranulomatous kidney, protruding ureterocele). An old-fashioned examination, however, still may reveal subtle information suggestive of the neurogenic bladder (eg, spinal anomalies, sacral dimples/pits/fat pads).

## Laboratory Findings
Urinalysis
- A small amount of the childs urine must be collected for this test. Babies and small children who are not toilet trained will have a small, thin, flexible tube called a catheter placed into the urethra to get a urine sample.
- This is needed because urine from collection bags, which can be taped around a babys diaper area, is often contaminated, or mixed, with germs and other substances found on the babys skin.
- If urine is contaminated, test results will not be accurate.
Parents may help preschoolers catch a clean urine sample in a special container, and older children and teens can do it by themselves.
A health care professional will look at the sample under a microscope for bacteria and white blood cells, which the body produces to fight infection. Bacteria also can be found in the urine of healthy children, so a bladder infection is diagnosed based on both your childs symptoms and lab test results.
Urine culture
- This laboratory test usually takes 24 to 48 hours.
- The sample is analyzed to identify the type of bacteria causing the UTI, how much of it exists, and appropriate antibiotic treatment.

## Imaging tests
- Ultrasound is recommended if the child
Is younger than age 2 and has a bladder infection with a fever.
Has had repeated bladder infections at any age.
Has high blood pressure, poor growth or a family history of kidney or bladder problems doesnt get better with treatment.
- Is younger than age 2 and has a bladder infection with a fever.
- Has had repeated bladder infections at any age.
- Has high blood pressure, poor growth or a family history of kidney or bladder problems doesnt get better with treatment.
- Voiding cystourethrogram (VCUG). The voiding cystourethrogram uses x-rays of the bladder and urethra to show how urine flows. A catheter is used to fill the childs bladder with a special dye. Then x-ray pictures are taken before and after your child urinates. A VCUG can show if urine flows backward from the bladder into the ureters or kidneys, a condition called vesicoureteral reflux (VUR).

## Other Diagnostic Studies
- Urinary tract infection may also be diagnosed using DMSA is a nuclear test in which pictures of the kidneys are taken after the intravenous (IV) injection of radioactive material called an isotope.
- CT scan and MRI of the kidney and the bladder.

# Treatment

## Medical Therapy
Currently, a second or third-generation cephalosporin and amoxicillin-clavulanate are drugs of choice in the treatment of acute uncomplicated UTI. Parenteral antibiotic therapy is recommended for infants   2 months and any child who is toxic-looking, hemodynamically unstable, immunocompromised, unable to tolerate oral medication, or not responding to oral medication. A combination of intravenous ampicillin and intravenous/intramuscular gentamycin or a third-generation cephalosporin can be used in those situations. Routine antimicrobial prophylaxis is rarely justified, but continuous antimicrobial prophylaxis should be considered for children with frequent febrile UTI.
Prophylactic antibiotics do not reduce the risk of recurrent UTIs, even in children with mild to moderate vesicoureteral reflux.
- The length of treatment depends on
How severe the infection is.
Whether a childs symptoms and infection go away.
Whether a child has repeated bladder infections.
Whether the child has vesicoureteral reflux or another problem in the urinary tract.
- How severe the infection is.
- Whether a childs symptoms and infection go away.
- Whether a child has repeated bladder infections.
- Whether the child has vesicoureteral reflux or another problem in the urinary tract.

## Surgery
The surgical opinion is sought only when medical management has failed. Failure is defined as either recurrent infections and pyelonephritis or poor renal growth.

## Prevention
- Drinking enough liquids.
- Following good bathroom and diapering habits.
- Wearing loose-fitting clothes.
- Avoid constipation.
Getting treated for related health problems may help prevent a UTI.