PM2038: Urinary Tract Infections in Infants (≤ 60 Days) and Clinical Outcomes with Short Duration of Parenteral Antibiotics (≤ 3 Days): A Retrospective Study at a Canadian Tertiary Hospital

Background: Urinary tract infections (UTIs) are the most common bacterial infections in infants under two months of age. Guidelines on the appropriate time to switch from parenteral to oral antibiotics are lacking in this age group. Recent systematic reviews have shown no significant difference in recurrence rate for infants with UTIs treated for ≤ 3 days of intravenous (IV) antibiotics compared to ≥4 days.

Methods: This retrospective cohort study compared outcomes between patients receiving short (≤3 days) and long (≥ 4 days) duration of parenteral antibiotics. The study was approved by local research ethics board (H21-02632).

Using UTI diagnostic codes, we identified patients 60 days or younger at time of presentation. Patients were included if they had a significant growth of a single organism obtained from an appropriate sample. We excluded patients with presumed meningitis, prematurity, or severe genitourinary abnormalities previously diagnosed, and those transferred from outside hospitals. Antibiotic duration was measured in calendar days.

The primary outcome was UTI recurrence with the same organism within 30 days. Secondary outcomes included hospital length of stay (LOS), all cause readmission and presentation with a UTI caused by a different organism within 30 days.

Results: We identified 94 eligible patients, with a median age of 33.5 days (range: 5-59). The majority of the cohort were male (N=75, 79.8%), and admitted to hospital (N= 87, 92.6%), for a median of 6 days (range: 0-15). E. coli was the most commonly identified organism, isolated in 82 patients (87.2%).

A blood culture was collected in 92 patients (97.9%) and was positive in 5 (5.3%). A renal bladder ultrasound (RBUS) was obtained in 66 (70.2%) prior to discharge, and in 26 (27.7%) as outpatient. Of those, 29 patients (30.9%) had abnormal findings.

Fifteen patients (16%) received a short duration of parenteral antibiotics, all of whom were above one month of age and non-bacteremic. A short duration of parenteral treatment was associated with a shorter LOS (median: 3 vs. 6 days, p< 0.001). There was no significant difference in UTI recurrence, re-presentation to ED, or hospital readmission. UTI recurrence within 30 days was identified in 5 patients, all of whom had received a longer course of parenteral antibiotics. Eight patients with long duration of parenteral antibiotics were readmitted to hospital, compared to none in the short duration arm.

Conclusion: A short course of IV antibiotics was associated with a shorter LOS, without an increase in negative clinical outcomes. Despite mounting evidence of the safety, only a minimal number of patients under 60 days have been treated with shorter duration of parenteral antibiotics. Quality improvement measures are required to assess for barriers, develop a standardized local pathway, and safely reduce hospital length of stay.