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Peds ID Abx QOTW #1 Answer

The correct answer is: b) Discuss with parent and provide return precautions

The core question is how to determine if a young child 2-24 months old has a UTI.  Three things guide the diagnosis of UTI:

  1. Symptoms of UTI/Pyelonephritis
  • Fever may be only presenting symptom
    • The risk for UTI in an infant with no other source but fever is about 5%.  While this is very low, risk is higher for girls > boys, and uncircumcised boys are at higher risk than circumcised boys (40x increase)
    • No other obvious cause (no URI, diarrhea, etc.)
  • Dysuria, frequency and or loss of recent bladder training may also occur but are not reliable in this age group
  • Vomiting and abdominal pain may also occur
    • These also occur in many other syndromes

Laboratory Diagnosis of UTI

  • Urinalysis that shows some evidence of pyuria or bacteriuria
    • Urine microscopy is preferred for the diagnosis
      • 10 WBC has a higher sensitivity, however >25 WBC is more specific
    • Gram Stain (GS) positive for GNR on unspun urine are suggestive,  >1,000,000 more likely to be positive
    • Nitrites may be negative in younger infants (urinate too frequently) or with GBS, as nitrites are produced by Gram negative pathogens (but not all GNRs)
  • Urine Culture (Catheterized specimens should be used, not bags)
    • >50K of urinary pathogen on catheterized specimen
    • 10-50K may represent a UTI, but is less specific, but in the presence of significant pyuria should be a consideration on catheterized specimens
    • <10K is likely not a UTI

Final Summary

  • This patient had low colony count (<50K)  and may not be a true positive, and the specimen was collected via a bag specimen with contamination from perineum
  • Patient did have a positive urine dip, but on a bag specimen this may represent fecal flora contamination from perineum
  • Patient had other symptoms that could explain fever (URI)
  • Calling the patient to determine if symptoms have resolved is the appropriate approach, further evaluation can be done if any concerns for persistent symptoms exist
  • Options for therapy are limited as well for this patient; while fosfomycin orally can be used in simple UTI, data for febrile UTI in this age group are limited

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