UTI & VUR

Dr.Praful Bambharoliya

Urinary tract infections (UTI) are a common and important clinical problem in childhood.

Upper urinary tract infections (ie, acute pyelonephritis) may lead to renal scarring, hypertension, and end-stage renal disease.

Difficult on clinical grounds to distinguish cystitis from pyelonephritis, particularly in young children (those younger than 2 years)

The risk of having a UTI before the age of 14 yrs

-1- 3% in boys - 3-10% in girls . In girls, the first UTI usually occurs by the

age of 5 yr, with peaks during infancy and toilet training.

In boys, most UTIs occur during the 1st yr of life; more common in uncircumcised boys.

During the 1st yr of life, -M : F ratio is 2.8–5.4 : 1. Beyond 1–2 yr, -M : F ratio of 1 : 10.

Infection of the urinary tract is identified by growth of a significant number of organisms of a single species in the urine, in the presence of symptoms.

Recurrent UTI, defined as the recurrence of symptoms with significant bacteriuria in patients who have recovered clinically following treatment, is common in girls.

Definition:

Escherichia coli is the most common bacterial cause of UTI (80%)

Other gram-negative bacterial pathogens include Klebsiella, Proteus, Enterobacter, and Citrobacter.

Gram-positive bacterial pathogens include Staphylococcus saprophyticus, Enterococcus, and, rarely, Staphylococcus aureus.

Microbiology

Viruses (eg, adenovirus, enteroviruses) and fungi (eg, Candida spp, Aspergillus spp, Cryptococcus neoformans, endemic mycoses) are less common causes of UTI in children

Viral UTI are usually limited to the lower urinary tract.

Risk factors for fungal UTI include immunosuppression and long-term use of broad-spectrum antibiotic therapy, and indwelling urinary catheter

The result of ascending infection. Colonization of the periurethral area by

uropathogenic enteric pathogens is the first step in the development of a UTI.

In E. Coli: pili, hair-like appendages on the cell surface aid in attaching to epithelium.

In the kidney, the bacterial inoculum generates an intense inflammatory response, which may ultimately lead to renal scarring.

Pathogenesis

Female gender   Uncircumcised male    Vesicoureteral reflux    Toilet training    Voiding dysfunction    Obstructive uropathy    Urethral instrumentation    Wiping from back to front in females   

Risk Factors

  Tight clothing    Pinworm infestation    Constipation    Bacteria with P fimbriae    Anatomic abnormality (labial adhesion)    Neuropathic bladder    Sexual activity    Pregnancy

The 3 basic forms of UTI 1. Pyelonephritis2. Cystitis3. Asymptomatic bacteriuria

Clinical manifestations:

Clinical pyelonephritis is characterized by any or all of the following: abdominal or flank pain, fever, malaise, nausea, vomiting, and, occasionally, diarrhea.

In newborns show nonspecific symptoms :poor feeding, irritability, and weight loss.

Pyelonephritis is the most common serious bacterial infection in infants <2 yrs of age who have fever without a focus .

Pyelonephritis

Acute lobar nephronia (acute lobar nephritis) is a localized renal bacterial infection involving >1 lobe that represents either a complication of pyelonephritis or an early stage in the development of a renal abscess.

Renal abscess may occur following a pyelonephritis or may be secondary to a primary bacteremia (S. aureus).

Perinephric abscesses may be secondary to contiguous infection in the perirenal area (e.g., vertebral osteomyelitis, psoas abscess) or pyelonephritis that dissects to the renal capsule.

It indicates that there is bladder involvement.

Symptoms include dysuria, urgency, frequency, suprapubic pain, incontinence, and malodorous urine.

Cystitis does not cause fever and does not result in renal injury.

Cystitis

It refers to a condition that results in a positive urine culture without any manifestations of infection.

It is most common in girls. The incidence is 1–2% in preschool and

school-age girls and 0.03% in boys. The incidence declines with increasing age.

Asymptomatic bacteriuria

The diagnosis of UTI is based on positive culture of a properly collected specimen of urine.

While urinalysis enables a provisional diagnosis of UTI, a specimen must be obtained for culture prior to therapy with antibiotics

Diagnosis:

Significant pyuria is defined as >10 leukocytes per mm3 in a fresh uncentrifuged sample, or >5 leukocytes per high power field in a centrifuged sample.

Leukocyturia might occur in conditions such as fever, glomerulonephritis, renal stones or presence of foreign body in the urinary tract.

Rapid dipstick based tests, which detect leukocyte esterase and nitrite, are useful in screening for UTI.

A combination of these tests has moderate sensitivity and specificity for detecting UTI, and is diagnostically as useful as microscopy

A clean-catch midstream specimen is used to minimize contamination by periurethral flora. Contamination can be minimized by washing the genitalia with soap and water.

Antiseptic washes and forced retraction of the prepuce are not advised.

In neonates and infants, urine sample is obtained by either suprapubic aspiration or transurethral bladder catheterization.

Both techniques are safe and easy to perform.

Collection of specimen for culture

The urine specimen should be promptly plated within one hour of collection.

If delay is anticipated, the sample can be stored in a refrigerator at 4ºC for up to 12-24 hours.

Cultures of specimens collected from urine bags have high false positive rates, and are not recommended.

If the culture shows >50,000 colonies of a single pathogen (suprapubic or catheter sample), or if there are 10,000 colonies and the child is symptomatic, the child is considered to have a UTI.

In a bag sample,if the urinalysis result is positive, the patient is symptomatic, and there is a single organism cultured with a colony count >100,000, there is a presumed UTI.

With acute renal infection, leukocytosis, neutrophilia, and elevated ESR and CRP are common.

With a renal abscess, the white blood cell count is markedly elevated to >20,000–25,000/mm3. Because sepsis is common in pyelonephritis, particularly in infants and in any child with obstructive uropathy, blood cultures should be considered.

The patient’s age, features suggesting toxicity and dehydration, ability to retain oral intake and the likelihood of compliance with medication(s) help in deciding the need for hospitalization.

Therapy should be prompt to reduce the morbidity of infection, minimize renal damage and subsequent complications.

Treatment:

Children less than 3 months of age and those with complicated UTI should be hospitalized and treated with parenteral antibiotics.

The choice of antibiotic should be guided by local sensitivity patterns.

A third generation cephalosporin is preferred. Therapy with a single daily dose of an

aminoglycoside may be used in children with normal renal function.

Intravenous therapy is given for the first 2-3 days followed by oral antibiotics once the clinical condition improves.

Children with simple UTI and those above 3 months of age are treated with oral antibiotics

The duration of therapy -14 days for infants and children with

complicated UTI - 7-10 days for uncomplicated UTI

Evaluation after the first UTI

General Measures: Adequate fluid intake and frequent voiding constipation should be avoided In children with VUR who are toilet trained,

regular and volitional low pressure voiding with complete bladder emptying is encouraged.

Double voiding ensures emptying of the bladder of post void residual urine.

Circumcision reduces the risk of recurrent UTI in infant boys, and might therefore have benefits in patients with high grade reflux.

PREVENTION OF RECURRENT UTI

recommended for patients with (i) UTI below 1-yr of age, while awaitingimaging studies, (ii) VUR (iii)frequent febrile UTI (3 or more episodes

in a year) even if the urinary tract is normal.

Antibiotic prophylaxis

Vesicoureteric Reflux•VUR is a bladder valve defect that allows urine to reflux from the bladder through one or both ureters and up to the Kidneys.

•Febrile urinary tract infection (UTI) is the defining Symptom.

VUR is seen in 40-50% infants and 30-50% children with UTI, and resolves with age.

Its severity is graded using the International Study Classification from grade I to V, based on the appearance of the urinary tract on MCU.

The presence of moderate to severe VUR, particularly if bilateral, is an important risk factor for pyelonephritis and renal scarring, with subsequent risk of hypertension, albuminuria and progressive kidney disease.

The risk of scarring is highest in the first year of life

Grade: I II III IV V

Reflux is inherited in an autosomal dominant manner with incomplete penetrance; 27% siblings and 35% offspring of patients show VUR.

Ultrasonography is recommended to screen for the presence of reflux.

Further imaging is required if ultrasonography is abnormal

Screening of siblings and offspring: