P-769. Utility of Urinary Interleukin-6 to aid in the Diagnosis and to assess Prognosis in Urinary Tract Infections

TL;DR

This study shows that measuring urinary interleukin-6 (IL-6) can help diagnose and monitor urinary tract infections more effectively than traditional methods.

Contribution

The study introduces urinary IL-6 as a novel biomarker for diagnosing and tracking the progression of UTIs.

Findings

Urinary IL-6 levels significantly decrease after 72 hours of antibiotic treatment in UTI patients.

An IL-6 cutoff of 2.545 pg/mL on day 3 has 77.8% sensitivity and 77% specificity for predicting active infection.

IL-6 levels correlate with white blood cell counts and urine pus cells, indicating infection severity.

Abstract

Urinary tract infections (UTIs) are among the most common infections encountered globally. Diagnosis often relies on symptoms, pyuria, and urine cultures. However, traditional methods like urine culture are time-consuming and lack immediate applicability. This study evaluates the role of urinary IL-6 as a diagnostic and prognostic biomarker, exploring its potential to guide treatment and augment antimicrobial stewardship practices.Fig 1.Distribution pattern of isolated organismsFig 2.Distribution of Urinary IL-6 on day 0 and day 3

Distribution pattern of isolated organisms

Distribution of Urinary IL-6 on day 0 and day 3

This hospital-based observational study enrolled 88 patients aged >15 years with culture-positive UTIs. Urinary IL-6 levels were assessed before and 72 hours after antibiotic initiation. IL-6 was analysed using the Roche Elecsys® e801 automated immunoassay analyser. Clinical data, including symptoms, laboratory markers (WBC counts, urine pus cells, urine culture), and antibiotic use, were recorded. Data were analysed using SPSS v28. IL-6 cutoffs were evaluated using receiver operating characteristic (ROC) curves. Statistical significance was set at p < 0.05.Fig 3.Sensitivity and Specificity of IL-6 on day 3 predicting active infectionFig 4.Association Between Symptom Improvement on Day 3 and Percent Change in Urinary IL-6 (pg/mL)

Sensitivity and Specificity of IL-6 on day 3 predicting active infection

Association Between Symptom Improvement on Day 3 and Percent Change in Urinary IL-6 (pg/mL)

The study population had an average age of 50.26 years, with a female predominance (62.5%). The most common symptom was fever (87.5%), followed by dysuria (73.9%). E. coli was the leading pathogen (50%), followed by Klebsiella and Enterococcus (17% each) (Fig 1). Piperacillin-tazobactam was the most frequently prescribed antibiotic. Mean antibiotic duration was 9.35 days. Urinary IL-6 levels on Day 0 were significantly elevated in UTI cases (mean 223.46 pg/mL), and decreased significantly after 72 hours of antibiotic therapy (mean 24.57 pg/mL) (p< 0.001) (Fig 2). IL-6 levels correlated with WBC counts and pus cell counts, indicating its utility in monitoring infection severity. On Day 3, an IL-6 cutoff of 2.545 pg/mL showed 77.8% sensitivity and 77 % specificity for predicting active infection (Fig 3). The percentage reduction in IL-6 levels was strongly associated with symptom improvement (Fig 4).

Urinary IL-6 is a reliable biomarker for assessing UTI severity, treatment response, and infection prognosis. IL-6 levels assessed on day 3 can aid in timely de-escalation or modification of antibiotic therapy. It can complement traditional diagnostic methods and support antimicrobial stewardship practices.

All Authors: No reported disclosures

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