HD5 Levels in Catheter Versus Bag Urine Specimens in Young Children for the Diagnosis of UTI
HD5 Levels in Catheter Versus Bag Urine Specimens in Young Children for the Diagnosis of UTI
Urinary tract infections (UTIs) are a common cause of bacteremia and serious bacterial
 infections in young children (2-24 months of age). Because these children are usually unable
 to say what symptoms they are experiencing, UTIs are diagnosed through testing. Current
 testing of urine samples require a catheter or suprapubic aspiration performed for urine
 collection for infections markers to be reliable. Bag specimens often have varying results
 that can be poor in sensitivity and specificity depending on what component of the urine test
 one is looking at. Catheter and aspiration testing can be anxiety-provoking to parents, be
 painful for patients and even introduce bacteria into the bladder. An antimicrobial peptide
 called alpha human defensin-5 (HD5) is produced by the uroepithelium in response to
 infection. HD5 has been studied in the urine and does increase in actual UTIs. This study
 will look at children 1 to 24 months of age and again study levels of HD5 in culture positive
 UTIs versus urine negative for UTI. This study will also determine if collection method
 alters HD5 levels. We will measure HD5 levels in the urine from a bag specimen and a catheter
 specimen in the same patient.

 Our primary objective is to determine the sensitivity and specificity of HD5 measured in
 urine collected by bag and catheter in the same patient for the diagnosis of UTI in children
 between the age 1 to 24 months presenting with febrile illness and suspected UTI.
Pediatric urinary tract infections (UTIs) are a common diagnosis and account for greater than
 500,000 emergency department (ED) visits each year in the US. Although prevalence varies by
 age, gender, ethnicity and circumcision status, the overall prevalence is cited between 5% to
 13.8%. UTIs also account for a large number of pediatric hospital admissions with up to
 50,000 children admitted per year, 40% of which occurring in children under the age of 1
 year. In children under the age of two, diagnosis of UTI is difficult as patients are unable
 to verbalize complaints and often present with only fever or other nonspecific symptoms such
 as vomiting. UTIs are the leading cause of occult bacteremia and serious bacterial infection
 in the 2-24 month age range.

 A definitive diagnosis of UTI is made when a patient has pyuria and/or bacteriuria with a
 positive urine culture. For non-toilet trained children who have urine collected by either
 suprapubic aspiration (SPA) or bladder catheterization, a urine culture is considered
 positive if a single uropathogenic organism of at least 50,000 colony forming units (CFU) per
 mL is recovered. Identification of a uropathogen by culture can take up to 48 hours to be
 completed which delays treatment and risks progression of infection if antibiotics are not
 given empirically. Commonly, clinicians use urine microscopy and dipstick for quick diagnosis
 to enable early empiric treatment of UTIs. However, the components of the urinalysis are
 limited in sensitivity and specificity even for specimens of high quality such as those
 obtained by catheterization or suprapubic tap. The main components of urine dipstick testing
 are leukocyte esterase (LE) and nitrite levels in urine. The LE test has a sensitivity of 94%
 when combined with clinical suspicion for UTI, but a specificity of only 83%. False positives
 for UTI occur when LE is positive in the child who has pyuria for other reasons besides
 infection, for example, in urethritis or Kawasaki disease. False negatives can occur in young
 children because the pattern of more frequent urination allows less time to mount an adequate
 inflammatory response to bacteria. Nitrites have a low sensitivity in young children (53%)
 due to frequent voiding not allowing sufficient time (up to 4 hours) for production of
 nitrites by bladder-dwelling bacteria; however, specificity is high (98%) making this a good
 test to rule in UTI. Sensitivity and specificity of urine microscopy for WBCs and bacteria
 are worse than for LE with pyuria (5 or more WBC/high power field on a spun sample or >10
 WBC/hpf on an un-spun sample) having a sensitivity and specificity of 73% and 81%
 respectively. Presence of bacteria on microscopy has a sensitivity and specificity of 81% and
 83% respectively. The resulting over- and under-treatment for false positive and negative
 urinalyses leads to increased costs, antibiotic resistance and unnecessary adverse events
 from antibiotics. The inaccuracy of the traditional urinalysis on bagged urine samples is
 much greater than for catheter specimens. These specimens suffer from false positives results
 for leukocyte esterase and cultures at rates up to 75-88% because of contamination by
 urogenital flora and white blood cells present on the perineum.

 As a result of the poor performance characteristics of routine urinalyses on bag specimens, a
 sample obtained by catheterization in children who are not yet toilet-trained is required
 even for UTI screening. This is invasive and painful for the child, causes anxiety for the
 family, leads to urethral trauma and can even introduce bacteria into the urinary system.
 Recent research describes a new two-step technique of obtaining urine samples of screening
 for UTI on these young patients. First, a bagged urine sample is taken, and if suspicious for
 UTI by urinalysis, the patient then is catheterized for culture. One study showed that this
 technique decreased the number of catheterizations by 33%; however, given the low specificity
 of the urinalyses on bag specimens, there is still substantial room for reductions in
 unnecessary bladder catheterizations.

 New urinary biomarkers hold promise to improve screening accuracy for UTIs. Watson et al.
 investigated antimicrobial peptides (AMPs) as urinary biomarkers of UTIs in children. One
 specific AMP, derived from the epithelium, is human alpha-defensin 5 (HD5). This AMP is
 produced by intestinal Paneth cells, the female genital tract and the uroepithelium. HD5 was
 found to have mean concentration significantly higher in the urine from culture-positive
 compared to culture-negative specimens. When used in combination with LE, HD5 increased the
 specificity of the LE-only test by 6% without decreasing the sensitivity (97% for LE >
 trace). This study determined the optimal cut-off value of 174 pg/mg creatinine to declare
 sample positive. Because HD5 is not derived from white blood cells, its presence is not
 affected by the presence or absence of WBCs in the urine to accurately identify urinary
 inflammation. While the authors of this study examined results from both clean-catch and
 catheterized specimens, they did not analyze samples collected by both techniques from the
 same patient.

 Identification and validation of biomarkers with improved performance characteristics could
 reduce over-treatment of UTIs; validating such biomarkers on bag urine specimens has the
 further benefit of reducing the need for catheterization to provide urine to screen for UTI
 in a relatively unselected population of young children who have fever without a focus. We
 propose to compare the use of HD5 in bag versus catheter urine samples on children 1 to 24
 months of age to determine if the biomarker has similarly high sensitivity and specificity to
 the original study in both specimen types. Eliminating the need for urine culture would also
 save on costs for children whose rapid testing does not suggest UTI. Reducing the number of
 catheterizations performed on young children will decrease the number of painful procedures,
 prevent introduction of bacteria in the urinary tract and decrease parental anxiety.
Inclusion Criteria:

 Patient is between 1 to 24 months of age Patient has reported or measured fever >38.5
 degrees C (101.3 degrees F)

 Exclusion Criteria:

 RSV Positive at time of urine collection Flu Positive at time of urine collection Known GU
 abnormality Neurogenic bladder Frequent catheterizations Indwelling catheter Antibiotics in
 the last 7 days