Asymptomatic Bacteriuria or Urinary Tract Infection? New and Old Biomarkers

Abstract

Urinary tract infections (UTIs) are among the most common infective disease in the adult population. UTI diagnosis is based essentially on the presence of lower urinary tract symptoms (e.g., dysuria, urgency, and frequency) and the evidence of bacteriuria (by dipstick testing and/or urine culture). UTI diagnosis is not always easy because symptoms can be vague, or patient basal conditions can interfere negatively with the diagnostic process, whereas urine culture is still ongoing. In those cases, the differential diagnosis among UTIs and asymptomatic bacteriuria (ABU) may be challenging, while the clinician has to decide whether to start an antibiotic treatment shortly. The purpose of the present review is to analyze the biomarkers that could help in UTI diagnosis. Some biomarkers, such as procalcitonin, interleukin-6, neutrophil gelatinase-associated lipocalin, chemokines, lactoferrin, and bone morphogenetic protein-2, seem promising in UTI diagnosis, while other biomarkers failed to show any utility. Whereas a single biomarker was not enough, a combination of biomarkers could have more chances to help in the diagnosis.

Elevated UTI Biomarkers in Symptomatic Patients with Urine Microbial Densities of 10,000 CFU/mL Indicate a Lower Threshold for Diagnosing UTIs

“…The biomarkers used in this study [neutrophil gelatinase-associated lipocalin (NGAL), interleukin-8 (IL-8), and interleukin-1-beta (IL-1β)] are essential components of the constitutive immune response in the urinary tract and have been studied in association with UTIs. Importantly, these three biomarkers have also demonstrated utility for the diagnosis of UTIs [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. One of our previous studies discovered that NGAL, IL-8, and IL-1β have sensitivities of 82.6%, 91.2%, and 69.8% with specificities of 90.8%, 76.8%, and 96.9%, respectively [ 29 ].…”

Evaluation of diagnostic accuracy of urine neutrophil gelatinase-associated lipocalin in patients with symptoms of urinary tract infections: a meta-analysis

“…Their study included a review of 4 previously published studies and suggested that uNGAL offered a promising and more sensitive alternative to the LE test for diagnosing UTI. Martino et al ( 12 ) conducted a systematic review of 4 published studies in an adult population and provided a summary of the results indicating encouraging performance of uNGAL. Horvath et al ( 10 ) summarized 16 studies on uNGAL for predicting UTI in both pediatric and adult population.…”

“…The most promising biomarkers identified were neutrophil gelatinase-associated lipocalin (NGAL), matrix metalloproteinase 9 (MMP9), CXCL8 and interleukin-1β (IL-1β). While other targeted approaches over the years have additionally identified interleukin-8, tumor necrosis factor-α, and urine antimicrobial peptides ( 5 – 7 ) as putative predictors of UTI, the most promising and widely studied UTI biomarker is NGAL ( 8 – 12 ). Pre-clinical studies have established the biological, teleological, and functional roles of NGAL ( 13 – 18 ).…”

Effect of increasing age and ureteral stent implantation on urinary tract infections after kidney transplantation – update of recent literature

“…The integration of these guidelines ensures a comprehensive and tailored approach to UTI management in kidney transplant recipients. Research into novel antimicrobial agents and immunomodulatory therapies, as well as the significance of innovative nonantibiotic-based approaches, may offer more targeted and effective options, mitigating the risk of infections while minimizing adverse effects [44][45][46][47][48].…”