Urinary tract infection Done by Dr Ali Abdul-Razak

Urinary tract infection Urinary tract infection (UTI) is one of the most common infections of childhood. It distresses the child, concerns the parents, and may cause permanent kidney damage.

Incidence During the first year of life male to female ratio is :1,this is because of periuretheral colonization with E.coli, enterococci and proteus species. The rate in uncircumcised boys is 5 to 20 times higher than in circumcised boys. Beyond 1-2 yr the male to female ratio will be 1: 10.

Causes Almost all UTIs are ascending in origin, bacteria arise from the fecal flora, colonize the perineum & enter the bladder via the urethra. In females 75-90% of infections caused by Escherichia coli, followed by Klebsiella and proteus. In male proteus commoner than E.coli, other organisms include staph. Saprophyticus.

Clinical manifestations There are three basic forms of UTI: 1.Pyelonephritis: (upper UTI) characterized by abdominal or flank pain, fever, malaise, nausea, vomiting & occasionally diarrhea. Some newborns & infants may show non specific symptoms: jaundice, poor feeding, irritability, & weight loss, or signs of septicemia.

unexplained high fever in a young child with little or no systemic symptoms and no focus of infection should rise a suspicion of UTI. The older children with pyelonephritis often have tenderness of the flank or costovertebral angle.

2.Cystitis : (lower UTI) characterized by dysuria, urgency, frequency, suprapubic pain, incontinence & malodorous urine. Cystitis does not cause fever & does not result in renal injury. The older children with cystitis may have suprapubic tenderness.

3.Asymptomatic bacteriuria : Refers to patients who have positive urine culture without any manifestations of infection & occurs almost exclusively in girls, this condition is benign & does not cause renal injury.

Risk factors for UTI 1.Female gender 2.Uncircumcised male 3.Vesicoureteric reflux 4.Toilet training 5.Voiding dysfunction 6.Obstructive uropathy 7.Anatomic abnormality (labial adhesion) 8. Urethral instrumentation 9.Wiping from back to front 10. Tight underwear 11. Pinworm infestation 12. Constipation 13. Neurogenic bladder 14. Sexual activity

Diagnosis UTI may be suspected based on symptoms or findings on urinalysis or both. The diagnosis is based on quantitative cultures of a properly collected urine specimen

 Methods of urine collection: 1.A midstream, clean-catch specimen may be obtained from children who have urinary control. 2.Urinary specimen may be collected from a sterile bag attached to the perineal area, however, the false-positive rate is so high that this method of urine collection is not suitable for diagnosing a UTI.

3. Urethral catheterization. 4.Suprapubic aspiration is the method of choice for obtaining urine from children of either sex with clinically significant periuretheral irritation.

 Quantitative Urine Culture for the Diagnosis of UTI: 1.Suprapubic aspiration If a UTI is present, bacteria are likely to be proliferating in bladder urine with growth of any organism.

 If the culture shows >100,000 colonies of a single pathogen  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  If any of these criteria are not met, confirmation of infection with a catheterized sample is recommended.

 Other tests: Urinalysis: Does not substitute for urine culture to document the presence of a UTI. Urine should be freshly voided,and well centrifuged. Pyuria suggest infection, but infection can occur in the absence of pyuria.(normal WBC in urine is< 5/mm³) Microscopic hematuria is common in cystitis, while blood cell cast suggest renal involvement.(normal RBC in urine < 5/mm³).

 Nitrites and leukocyte esterase usually are positive in infected urine.  Complete blood count: Leukocytosis, neutrophilia, increased ESR & C- reactive protein are common. Perform blood cultures in febrile infants and older patients who are clinically ill, toxic, or severely febrile.

Imaging studies: 1.Renal ultrasound should be obtained to rule out hydronephrosis & renal or perirenal abscess, obstructive uropathy, renal calculi, single or ectopic kidney and some patients with moderate renal damage caused by Pyelonephritis.

2. Renal scanning with technetium-labeled DMSA for detection of acute pyelonephritis, and presence of renal parenchymal injury (scarring)  DMSA = Dimercaptosuccinic Acid. 3. Voiding cystourethrogram (VCUG), done if there is positive DMSA scan, to look for vesicoureteric reflux.

Treatment IV antibiotics-Indications: Any patient of any age who appears clinically toxic or who has neutropenia. Infants <1 mo until bacteremia, sepsis, & meningitis ruled out. Children unable to tolerate oral antibiotics Immunocompromised patients it is reasonable to initiate treatment with IV antibiotics until these symptoms usually resolve in three days, then complete days of therapy with an oral antibiotic.

Neonates Ampicillin plus a second antibiotic (usually gentamycin or cefotaxime) to cover for GBS, Listeria, as well as gram negative organisms Vancomycin may be indicated for toxic patients or those unresponsive to initial therapy.

Older infants and children  Parenteral treatment with a third-generation cephalosporin, such as ceftriaxone or cefotaxime.  Then oral Cefixime (Suprax)  The total duration of therapy days in case of pyelonephritis.

Antibiotic Agents for Parenteral Treatment of a UTI DrugDosage and routeComment Ceftriaxone mg/kg/d IV/IM as a single dose or divided q12h Do not use in infants <6 wk of age; may displace bilirubin from albumin Cefotaxime 100 mg/kg/d IV/IM divided q6-8h Safe to use in infants <6 wk of age; used with ampicillin in infants aged 2-8 wk Ampicillin 100 mg/kg/d IV/IM divided q8h Used with gentamicin in neonates <2 wk of age; for enterococci and patients allergic to cephalosporins Gentamicin Term neonates <7 d: mg/kg/dose IV/24h Infants and children : mg/kg/dose IV q8h Monitor blood levels and kidney function if therapy extends >48 h

Antibiotic Agents for the Oral Treatment of UTI Nitrofurantoin may be used to treat lower UTIs. However, because of its limited tissue penetration, nitrofurantoin is not suitable for the treatment of kidney infection. Daily DosageAntibacterial Agent 6-12 mg/kg TMP, mg/kg SMZ divided q12h Sulfamethoxazole and trimethoprim mg/kg divided q8hAmoxicillin and clavulanic acid mg/kg divided q6hCephalexin 8 mg/kg divided q12-24hCefixime 10 mg/kg divided q12hCefpodoxime 5-7 mg/kg divided q6hNitrofurantoin *

If there is possibility of recurrent UTI follow- up urine culture should be performed periodically for 1-2 yr, even when the child is asymptomatic.

Children with cystitis : Symptomatic relief for dysuria consists of increasing fluid intake to enhance urine dilution and output, acetaminophen, and nonsteroidal anti-inflammatory drugs. A 5-day course of an oral antibiotic agent is recommended for the treatment of cystitis (trimethoprim-sulfamethoxazole (TMP-SMX), Nitrofurantoin, and Amoxicillin ). If the clinical response is not satisfactory after 2-3 days, alter therapy on the basis of antibiotic susceptibility.

Complications 1.Children with pyelonephritis may develop renal abscess. 2.Any inflammation of the renal parenchyma may lead to scar formation. 3.Long-term complications of pyelonephritis are hypertension, impaired renal function, and ESRD.