Neonatal Nephrology/AKI
Neonatal Nephrology/AKI 1
Tahagod Mohamed, MD
Assistant Professor
Nationwide Children's Hospital
Columbus, Ohio, United States
Urinary tract infections (UTIs) are a common comorbidity in hospitalized neonates. The current UTI diagnostics have several limitations including invasive collection of urinary samples to ensure sterility, risk of contamination and lack of consensus definitions of UTI based on urine culture. Antimicrobial peptides (AMPs) have been recently utilized as novel biomarkers to improve the diagnostic efficiency and accuracy of pediatric UTI. However, the expression of AMPs in neonatal urine is not well-defined.
Objective:
To determine baseline expression of two AMPs, Ribonuclease 7 (RNase 7) and Beta Defensin-1 (BD-1) and to define the relationship between AMP concentration and gestational age (GA).
Design/Methods: Urine from neonates admitted to a single level IV neonatal intensive care unit was obtained urine samples were collected via cotton balls placed in the patient’s diaper. Urine was tested via commercial ELISAs to quantify HBD-1 (Peprotech, Rocky Hill, NJ) and RNase 7 (Cloud Clone Corp, Katy, TX). Those samples whose ELISA results interpolated with the standard curves for each AMP were included for statistical analysis. AMP levels (ng/ml) were normalized to urine creatinine (UCr, mg/ml) to control for differences in urine concentration.
Results: RNase 7 and BD-1 were expressed in neonatal urine (n=80) regardless of GA and as early as 22 weeks gestation. Urinary concentrations of both AMPs decreased as GA and birthweight increased. The overall median urinary RNase 7 and BD-1 values were 5026.26 ng/mg, and 116.36 ng/mg, respectively. The median and IQR urinary concentrations of RNase 7 for infants born at < 27, 27-32, 33-35 and ≥ 36 weeks were 11,160 (216.79 - 38,665.98), 5877.19 (181.46 - 26,289.2), 4943.67 (246.32 – 26,026.86) and 2324.24 (188.07 – 18,330.47) ng/mg respectively. Similarly, the concentrations of BD-1 at these GA were 165.93 (98.61, 2258.6), 115.01 (19.79, 207.79), 107.94 (67.11, 674.94) and 14.08 (6.49, 201.49) ng/mg, respectively, Table 1.
Conclusion(s): Baseline neonatal urinary expression of two AMPs (RNase 7 and BD-1) and the variation by GA were identified. This is an essential first step toward the potential utilization of AMPs in improving neonatal UTI diagnostics.