Predictive value of urinary interleukin‐6 for symptomatic urinary tract infections in a nursing home population

Abstract

Objectives: To study urinary interleukin-6, interleukin-8 and pyuria during episodes of asymptomatic bacteriuria and symptomatic urinary tract infection in the institutionalized elderly, and to investigate the role of interleukin-6 as a biomarker for differential diagnosis. Methods: Levels of interleukin-6, interleukin-8 and pyuria were assessed in 35 older adults with asymptomatic bacteriuria and symptomatic urinary tract infection to define possible diagnostic thresholds. In a two-phase intervention study, the antibiotic treatment for urinary tract infection before and after introduction of urinary interleukin-6 as a biomarker was then assessed. Results: Asymptomatic bacteriuria patients had no or low levels of interleukin-6, and low levels of interleukin-8 and pyuria. Women had lower interleukin-6 and interleukin-8 than men (P = 0.05). Interleukin-6 was the only marker showing significant increases during urinary tract infection episodes in patients with both asymptomatic bacteriuria and urinary tract infection, in pooled (P = 0.042) and in paired intra-individual (P = 0.017) comparisons. In the intervention study lectures, the increased use of urine cultures and the introduction of interleukin-6 as a biomarker reduced antibiotic treatments by 20%. Antibiotic-treated urinary tract infection episodes had increased interleukin-6 as compared with urinary tract infection episodes not treated (P = 0.02), and as compared with asymptomatic bacteriuria patients (P < 0.0001). The sensitivity and specificity of interleukin-6 (cut-off 25 pg/mL) differentiating asymptomatic bacteriuria from urinary tract infection was 57% and 80%, respectively. Conclusions: Urinary interleukin-6 shows promise as a biomarker to detect the transition from asymptomatic bacteriuria to symptomatic urinary tract infection in older adults. Further larger studies with robust methodology are warranted to determine whether development for near to patient testing would be worthwhile.

Editorial Comment from Dr Cai to Predictive value of urinary interleukin‐6 for symptomatic urinary tract infections in a nursing home population

“…1 In the case of UTI development, there is an increase of IL-6 levels and its levels are related with the severity of the infection; in contrast, the IL-6 secretion is mostly not detectable or very low in the case of ABU. For all these reasons, we need to improve all available tools for diagnosing symptomatic UTI in order to reduce inappropriate antibiotic use and to diffuse the need for antibiotic stewardship.…”

“…1 They showed that ABU patients had no or low levels of IL-6, and low levels of IL-8, and that IL-6 was the only marker showing significant increases during UTI episodes in patients with both ABU and UTI. In their intervention study lectures, the increased use of urine cultures was seen, and the introduction of IL-6 as a biomarker reduced antibiotic treatments by 20%.…”

“…1 They highlighted two important issues in the management of UTI patients: (i) the need for a thoughtful approach to UTI patients for reducing the spread and inappropriate use of antibiotics; and (ii) the need for new markers to use for optimizing the diagnostic method in patients suspicious of symptomatic UTI. First of all, the current increasing rate of fluoroquinolone-resistant organisms has become a significant contemporary health crisis.…”

“…First of all, the current increasing rate of fluoroquinolone-resistant organisms has become a significant contemporary health crisis. 1 This emergency is due both to the abuse and overprescription of antibiotics, and the limited development of new molecules with a subsequent reduced number of new antibiotics in the pipelines of pharmaceutical companies. 2 Furthermore, even if ABU treatment is considered a dangerous practice, its treatment is, today, a common practice among clinicians.…”

“…1 Other studies suggest that the levels of pro-inflammatory cytokines, like IL-6, in the urine, can be used to assess the severity of inflammatory changes in the kidney and to monitor the effectiveness of anti-inflammatory therapy. 2 Also, other studies suggest that advanced grade of urothelial bladder carcinoma is significantly associated with elevated urinary levels of pro-inflammatory cytokines; results suggested that urinary IL-6 and CK-18 might benefit as noninvasive biomarkers for early detection as well as histopathological subtyping of urothelial carcinoma, and can be used to assess the severity of inflammatory changes in the kidney and to monitor the effectiveness of anti-inflammatory therapy.…”