[Etiology and clinical course of urinary tract infections in infants less than 3 months-old].

BACKGROUND: Infants less than 3 months of age with urinary tract infection are usually hospitalized. Recent studies show that a less aggressive management for those patients aged ≥ 29 days may be feasible.

OBJECTIVES: To determine the complication rate in infants<3 months of age with urinary tract infection, and to identify the causative agents and their antibiotic susceptibility.

METHODS: A retrospective study was conducted on infants<3 months of age with positive urinalysis results, together with a positive urine culture from a catheterized specimen and seen in the Emergency Department from 2007 to 2012. Demographics, clinical and microbiology (microorganism isolated and antibiotic susceptibility) data were collected. The complications rate (bacteremia, bacterial meningitis, renal abscess, surgical intervention, Intensive Care Unit admission, or death) were calculated for the overall sample and for different age groups (<29, 29-60, and 61-90 days).

RESULTS: A total of 460 patients are included; 137 (29.8%)<29, 166 (36.1%) 29-60, and 157 (34.1%) 61-90 days of age. Twenty four (5.4%; 95% CI: 3.6-7.8) had bacteremia; 15 (10.9%; 95% CI: 6.7-17.3) were<29 days; 8 (4.9%; 95% CI: 2.5-9.4) were 29-60 days, and one (0.7%; 95% CI: 0.1-3.7) was 61-90 days of age (P<.001). One neonate (0.8%; 95% CI: 0.1-4.1) had bacterial meningitis, and 2, renal abscess. Escherichia coli was the common pathogen identified (87.2%) in the urine culture, with a susceptibility to amoxicillin-clavulanate, gentamicin, and cefixime of 89.2, 97.0, and 96.0%, respectively.

CONCLUSION: Complications are low in infants<3 months of age with UTI, especially in those ≥ 29 days of age. The identification of patients at very low risk for complications would allow a less aggressive management. Escherichia coli antibiotic susceptibility remains stable, but continuing careful surveillance is essential to optimize empirical antibiotic treatment.