Combination of Tests Enhances Urinary Tract Infection Localization

Conventional serum markers for diagnosing urinary tract infection include total white blood cell count (WBC), C-reactive protein (CRP), procalcitonin (PCT), erythrocyte sedimentation rate (ESR), and interleukin (IL)-6.

Urinary tract infections (UTIs) commonly occur in young febrile children and they trigger a wide range of bacterial infections. The combination of urinary beta 2 microglobulin (urinary β2-MG) and procalcitonin (PCT) diagnosis could enhance the localization diagnostic precision of pediatric UTI compared with a single diagnosis.

Scientists at the Wuhan Women and Children's Health Care Center (Hubei, China) enrolled 85 participants, including 35 children who were diagnosed as upper urinary tract infection (UUTI) with the symptom of fever and 50 children who had lower urinary tract infection (LUTI) from August 2014 to September 2015. Levels of PCT and urinary β2-MG in both UUTI and LUTI patients were measured and compared.

Blood and urine samples were collected and stored. Enzyme-linked fluorescent analysis was carried out, in which the relevant kits were purchased from BioMérieux (Lyons, France). Quantitative measurement was conducted using a Mini VIDAS automatic quantitative fluorescence immunoassay analyzer, also from BioMérieux. The results were considered positive when the PCT concentration was higher than 0.5 ng/mL. Urinary β2-MG levels were detected using a DPC1000 automatic chemiluminescence meter (DPC Industries, Omaha, NE, USA).

The investigators found that the mean level of PCT in the UUTI group was 1.37 ± 0.67 ng/mL, whereas that in the LUTI group was 0.53 ± 0.23 ng/mL. The mean levels of urinary β2-MG in the UUTI and LUTI groups were 1.08 ± 0.73 and 0.39 ± 0.21 μg/mL, respectively. The mean levels of serum PCT and urinary β2-MG in the UUTI group were significantly higher than those in the LUTI group, respectively. The area under the curve (AUC) of urinary β2-MG ROC (sensitivity of 71.4%, specificity of 90.0%) was significantly smaller than that of PCT ROC (sensitivity of 77.1%, specificity of 96.0%) in the single diagnosis. Although in the combined diagnosis, the sensitivity and specificity increased to 88.6% and 98%, respectively.

The authors concluded the combination of urinary β2-MG and serum PCT could increase the localization diagnosis accuracy, specificity, and sensitivity of pediatric UTI. Both PCT and β2-MG could be used to localize the UTI and introducing urinary β2-MG into PCT diagnosis could increase the sensitivity and specificity of UTI lesion diagnosis in clinical practice. The study was first published online on November 1, 2016, in the Journal of Clinical Laboratory Analysis.

Related Links:
Wuhan Women and Children's Health Care Center
BioMérieux
DPC Industries