Abstract
OBJECTIVE: This study aimed to evaluate the clinical significance of the urine neutrophil CD64 ratio for diagnosing urinary tract infections (UTIs). METHODS: The study enrolled 106 patients suspected to have UTIs and 30 healthy controls. Based on urine culture results and clinical symptoms, 58 confirmed UTI patients with positive urine culture results and clinical symptoms were included in the urine culture positive (UCP) group, while 48 suspected UTI patients with negative urine culture results but positive clinical symptoms were included in the urine culture negative (UCN) group. Quantitative urine bacterial culture was used to identify pathogenic species and bacterial load. Urine leukocyte esterase (U-LE), urine nitrite (U-NIT), and urine leukocyte count (U-LC) were detected by an automatic urine analyzer. Neutrophil CD64 median fluorescence intensity (MFI) in urine and blood was measured by flow cytometry, and the ratio of neutrophil CD64 MFI in urine (U-nCD64) and blood (B-nCD64) was calculated. RESULTS: Among the 58 urine bacterial isolates, Gram-negative bacteria were the predominant species (74.14%), with Escherichia coli being the most common isolate (76.74%). Gram-positive bacteria (Enterococcus spp.) accounted for 25.86% of the total isolates. The U-nCD64 ratio was significantly higher in the UCP group than in the UCN group (p < 0.001). The UTI patient group had a significantly higher U-LC value than the healthy control (HC) group (p < 0.001, p < 0.001). The UCP and UCN groups had higher U-LE and U-NIT levels than the HC group. The U-nCD64 ratio was significantly positively correlated with U-LC (p = 0.0273) and U-LE (p = 0.0007). The area under the curve (AUC) value of the U-nCD64 ratio was 0.905 for diagnosing UTIs with the cutoff value, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 0.89, 81.03, 89.58, 90.38 and 79.63%, respectively. CONCLUSION: The U-nCD64 ratio has the higher auxiliary value for diagnosing UTIs and is more conducive for the screening and early diagnosis of UTIs. Thus, the U-nCD64 ratio might be a promising biomarker for auxiliary diagnosis of UTIs.