Early treatment of urinary sepsis with surgical intervention is the superior care necessary in these patients, however, properly diagnosing the condition is somewhat difficult. Since urine and blood culture results take >24 hours to diagnose, white blood cell count (WBC) and urinalysis (UA) are used as surrogates to diagnose infection, but these methods are sometimes inaccurate due to false readings which lead to a misdiagnosis. Therefore, Dr. Whelan and his team attempted to determine whether there is a supplemental biomarker that could be used to identify ureteral tract infection (UTI) in the setting of an obstructive ureteral calculus.
Due to the previous use of procalcitonin as a marker of bacterial infection in critical care patients, the researchers set out to determine the efficacy of this amino acid in the determination of UTI’s. The researchers recruited patients who presented to the ED and were subsequently referred to urology for obstructing ureteral calculi. The standard nephrolithiasis workup was undergone by each patient, with additional c-reactive protein (CRP) tests and erythrocyte sedimentation rate (ESR) tests as well. The remaining serum collected from each patient was transferred to a -70°C freezer where procalcitonin was run in two allotments at later dates.
In this study, 149 patients were included, of which 92% were afebrile and 46% were clinically difficult. Results from the patients’ tests, including procalcitonin test (PCT), UA, WBC, CRP, neutrophils, and WBC count, are shown in Figure 1. There was no significant difference in the ESR and WBC tests between the positive and negative urine cultures (UCx). However, there was significant differences between positive and negative cultures for the UA WBC, CRP, WBC count, neutrophil %, and procalcitonin. Additionally, neutrophil % serially combined with PCT had a sensitivity of 95.1% in the clinically difficult cohort. Similarly, the clinically difficult cohort showed that UA, WBC, and neutrophil %, combined in parallel, led to a sensitivity of 95.1% as well.
Figure 1: A bar graph of the clinically difficult patients, separated by urine culture as positive versus urine culture as negative. The graph is organized by the following test result values: urinalysis (UA) white blood cell (WBC) %, erythrocyte sedimentation rate (ESR), c-reactive protein (CRP), WBC count, neutrophil %, and procalcitonin.
As he concluded his presentation, Dr. Whelan stressed that clinically difficult patients can be properly tested for UTI even with ureteral obstruction if UA, WBC, and neutrophil % are combined in parallel or PCT and neutrophil % are serially combined.
These methods can provide excellent sensitivity which could greatly aid in the diagnosis of infected ureteral stones, and thus improve patient care and safety in an emergent situation.
Presented by: Patrick Whelan, MD, Rush University Medical Center, Chicago, IL, USA
Co-Authors: Patrick Whelan1, Edward Capoccia1, Dimitri Papagiannoupolos2
Author Affiliation: 1Rush University Medical Center, Chicago, IL, USA; 2UC San Diego Health, San Diego, CA, USA
Written by: Zachary Valley Twitter: @ZacharyAValley, Department of Urology, University of California-Irvine, medical writer for UroToday.com at the 36th World Congress of Endourology (WCE) and SWL - September 20-23, 2018 Paris, France