Urinary Tract Infections

Risk Factors for UTI

  1. Females
    1. Sexual activity
    2. Bubble bath
    3. pinworms
    4. Sexual abuse
    5. constipation
    6. incomplete and infrequent voiding
  2. Males
    1. uncircumcised males have a 5-20x greater incidence of UTIs
  3. Males and Females
    1. reflux
    2. catheterization
    3. neurogenic bladder
  4. Urinary tract infections should be considered in any infant 2 months to 2 years who presents with a fever without localization. The earlier the diagnosis, the less risk of renal scarring and the earlier detection of anatomical abnormalities. In older children, symptoms will lead to evaluation for an infection.
Pathogenesis
  1. Escherischia coli. by far the most common organism causing UTIs. Other organism to consider are Klebsiella pneumoniae, Proteus vulgaris, and Pseudomonas aeruginosa. Gram positive organism are uncommon pathogens of UTIs in children
  2. Usually are secondary to ascending infection.
  3. Once the bladder is contaminated the risk of infection is related to the emptying of the bladder and voiding habits. Incomplete or infrequent emptying will lead to bacterial overgrowth. 
  4. Reflux allows urine to reach the kidneys and develop pyelonephritis. 
  5. Obstruction anywhere along the urinary tract 
Clinical Presentation
  1. Infants-jaundice, fever or hypothermia, septic appearance, failure to thrive, abdominal distention, poor feeding, and vomiting
  2. Toddlers and preschoolers- Strong smelling urine, fever, and failure to thrive
  3. School aged and older- fever, dysuria, frequency, urgency, daytime wetting, enuresis, abdominal pain, flank pain
  4. Pyelonephritis- indirect evidence of renal infection with fever, increased ESR and CRP, increased WBCs on CBC, decreased concentrating ability of the kidney, and CVA tenderness. These changes are not specific and sensitive when DMSA scan is done to verify kidney involvement
History
  1. Positive family history of reflux
  2. Incomplete voiding, dribbling, daytime wetting
  3. Weak urinary stream
Physical Examination Assessment
  1. Growth record 
  2. Blood pressure
  3. Abdominal exam- palpating for mass. Check for CVA tenderness.
  4. Examination of external genitalia for signs of irritation, trauma, and other abnormalities
  5. Observation of urinary stream
  6. Rectal exam to rule out impaction
Laboratory Findings
  1. Often urine will contain red blood cells, white blood cells, bacteria, and protein.
  2. Nitrite test- Best in overnight urine to allow time for bacteria to convert nitrate to nitrite in the bladder. Gram positive organisms will not give a positive nitrite test. About 50% sensitivity and 98% specific
  3. Leukocyte esterase test- 83% sensitive and 78% specific. Other conditions may cause pyuria without infection.
  4. WBCs- are markers for inflammation. Bacteriuria without WBCs of questionable significance and may obviate need for urine culture.
  5. Culture- should be fresh (<30 minutes and kept cold)
    1. A bagged urine is only significant if culture is negative
    2. Midstream urine is useful in older females and males
    3. Catheterized and suprapubic specimens are most reliable for culture.
    4. Interpretation 
      1. Suprapubic specimen
        1. any gram negative organism is positive. 
        2. more than a few thousand gram positive organisms is positive
  6. Catheterized specimen
    1. > 100,000 organisms infection likely
    2. 1000-10,000 organisms, unlikely infection. 
  7. Clean Void
    1. Boy- > 10,000 infection likely
    2. Girl 3 specimens of > 100,000 infection likely 95%
    3. 2 specimens of > 100,000 infection likely 90%
    4. 1 specimen of > 100,000 infection likely 80%
    5. 10,000-100,000 and clinical suspicion suggest repeating culture
    6. < 10,000 infection unlikely
Treatment of Positive Culture
  1. If symptoms are mild, treat with PO Bactrim or 2nd or 3rd generation Cephalosporin
  2. If symptoms are severe, use parenteral antibiotics to cover gram positive and gram negatives. Can use 2nd or 3rd generation Cephalosporin and Gentamycin. Must adjust treatment after obtaining results of the culture and sensitivity.
  3. Treat for 10-14 days
  4. Repeat culture if symptoms are persisting after two days of therapy, sensitivities not done prior to treatment, and at the end of treatment.
  5. Child should be on prophylaxis awaiting imaging studies. Acceptable drugs include Bactrim, Nitrofurantoin, Sulfisoxazole, Nalidixic Acid
  6. Treatment of young infants with fever and UTI- a recent study has demonstrated that oral treatment with Cefixime is as effective as intravenous treatment with Cefotaxime and there was no increase of renal, scarring, length of fever, time to sterilize the urine, and reinfections.
Imaging Studies
  1. Imaging studies are necessary to demonstrate the urinary tract anatomy and functional status. There are differing opinions on who and when they should be performed.
  2. Ultrasound and voiding cystourethrogram (VCU) should be done after the first UTI. May do the US immediately especially in neonates, infants, sick children, and boys to demonstrate possible obstruction. If the US shows obstruction, renal imaging studies should be done. The VCU can be done while the patient is being treated for UTI. 
  3. If need follow-up VCU, usually do nuclear cystogram to decrease radiation exposure.
  4. The presence of a normal fetal ultrasound may obviate the need for further imaging studies. This is presently under study.
Follow-up
  1. May follow urines at home with nitrite reagent sticks
  2. Refer to pediatric urologist if there are recurrent infections associated with anatomic defects or obstruction. 
Prevention
  1. Prevent urethral colonization by avoiding bubble baths, good local hygiene, increase bathing
  2. Prevent bladder colonization by encouraging frequent and complete voiding
  3. Circumcision
  4. Front to back wiping in females
  5. Proper catherization technique with neurogenic bladders
References
  1. Committee on Quality Improvement. Subcommittee on Urinary Tract Infection. The Diagnosis,Treatment, and Evaluation of the Initial UTI in Febrile Infants and Young Children. Pediatrics. April 1999.
  2. Goldman M et al. Imaging after Urinary Tract Infection in Male Neonates. Pediatrics. 2000; 105(6):1232-1235.
  3. Heldrich FJ. UTI Diagnosis: Getting it right the first time. Contemporary Pediatrics. Feb 1995.
  4. Hellerstein, S Urinary Tract Infections-old and new concepts. Pediatric Clinics of N America. 1995; 42: 1433-57.
  5. Hoberman, A et al. Oral Versus Inital Intravenous Therapy for Urinary Tact Infection in Young Febrile Children. Pediatrics  Pediatrics. 1999; 104(1):79-86.
  6. Hoberman and Wald. UTI in young children. New light on old questions. Contemporary Pediatrics. November 1997.
  7. Johnson CE. New Advances in Childhood Urinary Tract Infections. Pediatrics in Review. 1999; 20:335-342.
  8. McDonald A et al. Voiding Cystourethrograms and Urinary Tract Infections: How Long to Wait? Pediatrics. 2000; 105(4):e50.
  9. Roberts KB. A Synopsis of the American Academy of Pediatrics' Practice Parameters on the Diagnosis, Treatment and Evaluation of the Initial Urinary Tract Infection in Febrile Infants and Young Children. Pediatrics in Review. 1999; 20:344-347.
  10. Rushton HG. Urinary Tract Infections in Children: Epidemiology, Evaluation and Management. Pediatric Clinics of North America. 1997; 44(5):1133-1169.
  11. Shaw KN and Gorelick MH. Urinary Tract Infections in the Pediatric Patient. Pediatric Clinics of North America. 1999; 46(6):1111-1124.
  12. Todd, JK Management of Urinary Tract Infections: Children are Different. Pediatrics in Review Vol 16 no. 5. May 1995 190-196.
  13. Fihn Stephen. Acute Uncomplicated Urinary Tract Infection in Women. NEJM Vol 349 NO. 3 Page 259 July 17, 2003
  14. Hoberman A. et al. Imaging Studies after First Febgrile Uinary Tract Infection in Young Children. NEJM Vol 348 No. 3 Page 195.  Janulary 18 2003
  15. Zamir G. et al. Urinary Tract Infection: Is there a Need for Rooutine Renal Ultrasonography? Arch Dis Child. 2004;89:466
  16. Zorc J.J. et al. Urinary Tract Infection in Young Febrile Infants. Pediatrics Sept. 2005
  17. Raszka W. and Khan O. Pyelonephritis. Pediatrics in Review October 2005
  18. Oreskovic N, Sembrano E. Repeat Urine Cultures in Children Who Are Aadmitted with Urinary Tract Infections.  Pediatrics Feb 2007 e325
  19. Cystitis Pediatrics in Review December 2007