Kim JH, Lee J, Kim DH, et al. - Of infantile urinary tract infection (UTI) cases studied, approximately one-fourth were found to be extended-spectrum beta-lactamase (ESBL)-positive. Prenatal antibiotic exposure of mothers and Klebsiella species were shown to be linked with community-acquired UTI due to ESBL-positive bacteria.

• This is a retrospective review of 265 infants aged < 1 year with first UTI from 2018 to 2019 at two tertiary centers in Korea.

• A diagnosis of first UTI caused by ESBL-positive bacteria was received by 23.4% of these at the median age of 3.6 (interquartile range (IQR) 2.3–5.4) months.

• Factors that were significantly related to ESBL-positive UTIs and continued to be valid in the multivariate analysis were: maternal use of antibiotics during pregnancy (29.0 vs 10.3%) and Klebsiella species (19.4% vs 4.9%), with odds ratios 3.40 and 5.26, respectively.

• There was no significant difference between ESBL-positive and ESBL-negative groups in terms of previous antibiotic exposure of patients, previous hospitalization, prematurity, delivery mode, milk type, and use of postpartum care center.

• A higher number of blood leukocytes and longer hospital stay were noted in the ESBL-positive group vs the ESBL-negative group.