UTI and urinary tract anomalies DR Badi AlEnazi Consultant pediatric endocrinology and diabetologist MBBS,SBP,ABP,SFPE

Introduction Urinary tract infection (UTI) is one of the most common pediatric infections. It distresses the child, concerns the parents, and may cause permanent kidney damage. Prompt diagnosis and effective treatment of a febrile UTI may prevent acute discomfort and, in patients with recurrent infections, kidney damage.

Epidemiology The incidence of UTIs varies based on age, sex, and gender. It was found that the overall prevalence of UTI in infants presenting with fever was 7.0%. the rates in girls were as follows: 0-3 months - 7.5% 3-6 months - 5.7% 6-12 months - 8.3% >12 months - 2.1% In febrile boys less than 3 months of age: 2.4% of circumcised boys . 20.1% of uncircumcised boys .

The 2 broad clinical categories of UTI are: pyelonephritis (upper UTI) cystitis (lower UTI).

Pathophysiology Typically, UTIs develop when uropathogens that have colonized the periurethral area ascend to the bladder via the urethra. From the bladder, pathogens can spread up the urinary tract to the kidneys (pyelonephritis) and possibly to the bloodstream (bacteremia).

Urine in the proximal urethra and urinary bladder is normally sterile Urine in the proximal urethra and urinary bladder is normally sterile. Entry of bacteria into the urinary bladder can result from: turbulent flow during normal voiding voiding dysfunction catheterization. More rarely, the urinary tract may be colonized during systemic bacteremia (in infancy). direct spread via the fecal-perineal-urethral route.

Etiology Bacterial infections are the most common cause of UTI, with E coli being the most frequent pathogen, causing 75- 90% of UTIs. Other bacterial sources of UTI include the following: Klebsiella species Proteus species Enterococcus species Streptococcus group B, especially among neonates Pseudomonas aeruginosa Fungi (Candida species) may also cause UTIs Adenovirus is a rare cause of UTI and may cause hemorrhagic cystitis.

Risk factors Susceptibility to UTI may be increased by any of the following factors: Anatomic anomaly Bowel and bladder dysfunction Constipation

Circumcision and UTI For male infants, neonatal circumcision substantially decreases the risk of UTI. It was found that during the first year of life, the rate of UTI was 2.15% in uncircumcised boys, versus 0.22% in circumcised boys. Risk is particularly high during the first 3 months of life.

Diagnosis The American Academy of Pediatrics (AAP) criteria for the diagnosis of UTI in children 2-24 months: are the presence of pyuria and/or bacteriuria on urinalysis and of at least 50,000 colony-forming units (CFU) per mL of a uropathogen from the quantitative culture of a properly collected urine specimen.

Urine specimen collection A midstream, clean-catch specimen may be obtained from children who have urinary control. In the infant or child unable to void on request, the specimen for culture should be obtained by suprapubic aspiration or urethral catheterization.

Suprapubic aspiration is also the method of choice for obtaining urine from uncircumcised boys,from girls with tight labial adhesions, and from children of either sex with clinically significant periurethral irritation.

Culture of a urine specimen from a sterile bag attached to the perineal area has a false-positive rate so high that this method of urine collection is not suitable for diagnosing UTI. However, a culture of a urine specimen from a sterile bag that shows no growth is strong evidence that UTI is absent.

Urinalysis Urinalysis alone is not sufficient for diagnosing UTI. Children with unexplained fever or voiding symptoms may have positive urinary cultures even when abnormal findings are not evident on complete urinalysis.

Evaluation of renal function Renal function can be measured by serum creatinine and blood urea nitrogen (BUN) levels; both may be elevated in severe disease. Electrolyte abnormalities may be present.

Imaging studies Ultrasonography Urinary ultrasonography is useful in: excluding obstructive uropathy identifying a solitary or ectopic kidney moderate renal damage caused by pyelonephritis.

indications for ultrasonography of the urinary tract after a febrile UTI in pediatric patients are as follows: Delayed or unsatisfactory response to treatment of a first febrile UTI An abdominal mass or abnormal voiding (dribbling of urine) Recurrence of febrile UTI after a satisfactory response to treatment

Performance of voiding cystourethrography (VCUG) after a first febrile UTI may be indicated if: renal and bladder ultrasonography reveal hydronephrosis, scarring, obstructive uropathy, or masses complex medical conditions are associated with the UTI.

VCUG is also recommended after a second episode of febrile UTI VCUG is also recommended after a second episode of febrile UTI. There is some concern, however, that without VCUG after the first documented febrile UTI, some cases of significant reflux disease will be missed

symptoms

Physical Examination Costovertebral angle tenderness Abdominal tenderness to palpation Suprapubic tenderness to palpation Palpable bladder Dribbling, poor stream, or straining to void Examine the external genitalia for signs of irritation, pinworms, vaginitis, trauma

Treatment

Criteria of Hospital Admission Usual indications for hospitalization and/or parenteral therapy include: Age <2 months Clinical urosepsis (eg, toxic appearance, hypotension, poor capillary refill) Immunocompromised patient Vomiting or inability to tolerate oral medication Lack of adequate outpatient follow-up (eg, no telephone, live far from hospital, etc) Failure to respond to outpatient therapy

Empiric therapy Early and aggressive antibiotic therapy (eg, within 72 hours of presentation) is necessary to prevent renal damage. Delayed therapy has been associated with increased severity of infection and greater likelihood of renal damage .

We suggest that empiric antimicrobial therapy be initiated immediately after appropriate urine collection in children with suspected UTI and a positive urinalysis. This is particularly true for children who are at increased risk for renal scarring if UTI is not promptly treated, including children who present with: Fever (especially >39°C [102.2°F] or >48 hours) Ill appearance Costovertebral angle tenderness Known immune deficiency Known urologic abnormality

parenteral antibiotic therapy The diagnosis in infant with a febrile UTI is usually based on fever and on positive results from a urine specimen obtained by catheterization. Infants with such findings are usually hospitalized and receive parenteral antibiotic therapy Comment Dosage and Route Drug Do not use in infants < 6 wk of age; parenteral antibiotic with long half-life; may displace bilirubin from albumin 50-75 mg/kg/day IV/IM as a single dose or divided q12h Ceftriaxone Safe to use in infants < 6 wk of age; used with ampicillin in infants aged 2-8 wk 150 mg/kg/day IV/IM divided q6-8h Cefotaxime Note: IM = intramuscular; IV = intravenous; q = every.

Comment Dosage and Route Drug Used with gentamicin in neonates < 2 wk of age; for enterococci and patients allergic to cephalosporins 100 mg/kg/day IV/IM divided q8h Ampicillin Monitor blood levels and kidney function if therapy extends >48 h Term neonates < 7 days: 3.5-5 mg/kg/dose IV q24h Infants and children < 5 years: 2.5 mg/kg/dose IV q8h or single daily dosing with normal renal function of 5-7.5 mg/kg/dose IV q24h Children ≥5 y: 2-2.5 mg/kg/dose IV q8h or single daily dosing with normal renal function of 5-7.5 mg/kg/dose IV q24h  Gentamicin Note: IM = intramuscular; IV = intravenous; q = every.

Antibiotic Agents for the Oral Treatment of Urinary Tract Infection Daily Dosage Protocol 30-60 mg/kg SMZ, 6-12 mg/kg TMP divided q12h Sulfamethoxazole and trimethoprim (SMZ-TMP) 20-40 mg/kg divided q8h Amoxicillin and clavulanic acid 50-100 mg/kg divided q6h Cephalexin 8 mg/kg q24h Cefixime 10 mg/kg divided q12h Cefpodoxime 5-7 mg/kg divided q6h Nitrofurantoin* *Nitrofurantoin may be used to treat cystitis. It is not suitable for the treatment of pyelonephritis, because of its limited tissue penetration.

The AAP guidelines for the followup of these patients can be summarized as follows: After 7 days of antimicrobial therapy, close clinical follow-up monitoring is required to help ensure that recurrent infections can be promptly diagnosed and treated Ultrasonograms of the kidneys and bladder should be obtained in order to detect anatomic abnormalities The routine use of VCUG after the first UTI is not recommended, since data do not support the use of antimicrobial prophylaxis to prevent recurrent febrile UTI in infants unless they have VUR VCUG is indicated if ultrasonograms of the kidney and bladder reveal hydronephrosis, scarring, or other signs that high-grade VUR or obstructive uropathy may be present VCUG should be performed if febrile UTI recurs, even if previous ultrasonographic findings were unremarkable

Complication

Complication of pyelonephritis : focal inflammation of the kidney (focal pyelonephritis) or renal abscess. scar formation. Approximately 10-30% of children with UTI develop some renal scarring; however, the degree of scarring required for the development of long-term sequelae is unknown. Long-term complications of pyelonephritis are hypertension, impaired renal function, and end- stage renal disease.

British Journal of Urology volume 81 Page 8 - April 1998 The Final Urological Diagnosis of 426 live-born Infants with Significant Prenatally Detected Uropathy British Journal of Urology volume 81 Page 8  - April 1998 44