Febrile Urinary Tract Infection With Negative Initial Urine Culture.

Area of Science:

• Pediatrics
• Infectious Diseases
• Urology

Background:

• Febrile urinary tract infection (UTI) is a frequent bacterial infection in young infants.
• Diagnosis typically relies on urine culture meeting specific bacterial colony count thresholds.
• An initial low count may lead to underdiagnosis, particularly in early fever stages.

Purpose of the Study:

• To investigate infants with febrile UTI initially presenting with sub-threshold urine culture counts.
• To identify clinical characteristics of infants with delayed positive urine cultures during the same febrile episode.

Main Methods:

• Retrospective review of infants diagnosed with febrile UTI.
• Analysis of patients with multiple urine cultures during a single febrile episode.
• Comparison of initial sub-threshold cultures with subsequent positive cultures.

Main Results:

• Five infants with febrile UTI had initial low urine colony counts followed by positive cultures during the same fever.
• Initial samples were often collected within hours of fever onset.
• Risk factors included known vesicoureteral reflux, prior UTI history, and age under 3 months.

Conclusions:

• Febrile UTI diagnosis in infants should not be excluded based solely on an initial low urine culture count.
• Early-phase fever urine samples may yield false-negative results.
• Consider repeat urine cultures for infants with suspected UTI despite initial low counts.