Positive Urine Cultures for Enterococcus spp. vs. Escherichia coli in Febrile Infants Younger Than 90 Days: A Matched Cohort Study

AIM: To compare febrile infants aged 90 days or younger with Enterococcus spp. or Escherichia coli in urine cultures, overall and by urine dipstick findings. METHODS: Matched cohort study in three Spanish paediatric emergency departments (2011-2023). Infants with Enterococcus spp. were matched 1:1 by age and sex with infants with E. coli and compared using paired tests; dipstick-stratified analyses were exploratory. RESULTS: Of 4006 febrile infants, 77 (1.9%) had Enterococcus spp. Abnormal dipstick findings were less frequent than with E. coli (27.3% vs. 80.5%; p < 0.001), and blood inflammatory markers were lower, largely reflecting the higher proportion of normal dipsticks. Abnormal voiding cystourethrogram findings were more frequent with Enterococcus spp., with abnormal (70.0% vs. 27.6%; p = 0.03) and normal dipsticks (33.3% vs. 0%; p = 0.04). With abnormal dipsticks, abnormal dimercaptosuccinic acid scans (6/11 vs. 0/17; p = 0.001) and recurrent urinary tract infections (33.3% vs. 8.1%; p = 0.009) were more frequent with Enterococcus spp. CONCLUSION: In these infants, Enterococcus spp. in urine usually had a normal dipstick but was associated with more urinary tract abnormalities than E. coli. Enterococcal infections with abnormal dipsticks were associated with more renal scan abnormalities and recurrences; the significance of isolates with normal dipsticks remains uncertain.