Urinary tract infection (UTI) is the leading cause of fever without a source in infants younger than 3 months. This data was collected from patients who presented to the emergency department with fever without a source over a 16 year period. Out of 2850 patients, 20.8% were diagnosed with a UTI, the majority of which grew E coli. Of those patients who were diagnosed with UTI, these patients were more likely to have a history of renal/GU problems, have a fever of at least 39C (38% vs 29%) or poor feeding (13% vs 8.7%). However, 48% had none of these risk factors. Also 6.1% of patients with a febrile UTI had another invasive bacterial infection. These patients were more likely to be < 1 month, be "irritable" per parents and have an elevated procalcitonin and CRP.
Bottom line: A lack of risk factors can not exclude a UTI in febrile infants < 3 months. A diagnosis of UTI also does not definitively exclude an additional invasive bacterial infection in a subset of these children.
References
Lejarzegi, Ainara MD*; Fernandez-Uria, Amaia MD*; Gomez, Borja MD, PhD*; Velasco, Roberto MD, PhD†; Benito, Javier MD, PhD*; Mintegi, Santiago MD, PhD*. Febrile Urinary Tract Infection in Infants Less Than 3 Months of Age. The Pediatric Infectious Disease Journal ():10.1097/INF.0000000000003947, April 24, 2023. | DOI: 10.1097/INF.0000000000003947
