Urinary Myeloperoxidase to Creatinine Ratio as a New Marker for Diagnosis of Urinary Tract Infection

Abstract

Objective To determine whether urinary myeloperoxidase to creatinine ratio (MCR) can serve as a marker for diagnosis of urinary tract infection (UTI).Methods Patients suspected of UTI were consecutively enrolled and further divided into the culture positive and the sterile groups according to urine culture results. Subsequently, MCR, white blood cell (WBC) and bacteria in the urinary samples from patients were detected and compared between the two groups.Results Finally, 253 patients were enrolled including 157 urine culture positive patients and 96 urine culture negative patients (sterile group). After logarithmic transformation in 2 as the base, the MCR, WBC, and bacteria were separately presented as log₂ ^MCR, log₂ ^WBC(quantitative) , and log₂ ^bacteria. The values of log₂ ^MCR(8.6±2.5 vs. 5.4±1.5, t=-12.453, P=0.001), log₂ ^WBC(quantitative) (8.0±2.5 vs. 5.2±1.8, t=-10.332, P=0.001), log₂ ^bacteria (11.4±2.5 vs. 8.2±2.8, t=-9.297, P=0.001) and WBC (semi-quantitative) [2 (interquartile range 1, 3) vs. 1 (interquartile range 0.5, 1), Z=-7.580, P=0.001] showed significant difference between the urine culture positive group and the sterile group. Among the urine culture positive group, the values of log₂ ^MCR of the gram positive and gram negative subgroups were 7.2±2.5 and 9.0±2.4 (t=4.016, P=0.001), respectively. The correlation between log₂ ^MCR and log₂ ^WBC (quantitative), log₂ ^bacteria, WBC (semi-quantitative) was 0.708 (Pearson correlation, P=0.001), 0.381 (Pearson correlation, P=0.001), and 0.606 (Spearman correlation, P=0.001), respectively. Conclusions MCR is positively correlated with WBC counts and could be served as a promising biomarker for diagnosis of UTI. MCR could be even used for initial inference of infectious bacteria types of UTI.