Urinary tract infection in preterm infants: the protective role of breastfeeding.

Urinary tract infection (UTI) differs between preterm and older infants and children in terms of prevalence, clinical presentation, causative organism, and rate of underlying renal anomalies. Data on risk factors of UTI in preterm infants are limited. The aim of this study was to characterize UTI both clinically and microbiologically in premature infants and to define possible risk factors and the role of breastfeeding in its development. This case-control study was conducted in a tertiary-care neonatal intensive care unit (NICU) between 1995 and 2003. The study group included all premature infants (<37 weeks' gestation) diagnosed with UTI. Pre-, peri-, and postnatal data on demographic, clinical, laboratory, and imaging variables were collected from the medical records and microbiology laboratory log and compared with a gestational age- and birth weight-matched infants without UTI (control group). The ratio of control infants to cases was 2:1. Of the 6198 premature infants admitted to the NICU during the study period, 56 (0.9%) were included in the study group. The main causative organism was Klebsiella spp. Logistic regression analysis identified gender [odds ratio (OR) 2.96, 95% confidence interval (CI) 1.28-6.85, P < 0.0001] and the presence of a peripheral intravenous catheter on the day of infection to be significantly associated with UTI, while breast milk was associated with a lower risk of infection (OR 0.314, 95% CI 0.140-0.707, P < 0.009).