Authors: Nacke NC, et al.
A & A Practice 19(7): e02004, July 2025.
This case series explored the role of the Intensive Care Infection Score (ICIS) as a biomarker to guide infection diagnosis and antibiotic therapy in critically ill patients. ICIS integrates hematologic parameters reflecting the innate immune response, offering infection-specific insight beyond traditional inflammatory markers such as CRP, PCT, and WBC.
Three representative ICU cases were described:
-
ICIS identified poor response to initial antibiotics before PCT rose, supporting earlier escalation of therapy.
-
Persistently elevated ICIS values revealed ongoing infection despite declining CRP and PCT, prompting an antibiotic change and potentially enabling earlier de-escalation.
-
Declining ICIS values correctly indicated absence of infection, avoiding unnecessary antibiotic exposure despite elevated CRP and PCT.
Across the larger cohort study from which these cases were drawn, ICIS aligned with clinical judgment more closely than PCT or CRP, showing fewer discordant results. This suggests ICIS may improve antimicrobial stewardship by reducing both inappropriate initiation and prolonged use of antibiotics.
What You Should Know:
ICIS demonstrates promise as a real-time biomarker for distinguishing infection from sterile inflammation in the ICU. By better reflecting treatment response and infection probability, it could help clinicians avoid unnecessary antibiotics, shorten therapy, and combat antimicrobial resistance. Larger prospective studies are needed to validate cutoff values and confirm clinical impact.
References
Authors: Hassan J, et al.
Cureus 2022;11:1–13.
Authors: Nierhaus A, et al.
Inflamm Allergy Drug Targets 2012;11:109–115.
Authors: Weimann K, et al.
J Int Med Res 2015;43:435–451.
Authors: Sakr Y, et al.
Open Forum Infect Dis 2018;5:ofy313.
Thank you to A & A Practice for allowing us to use this article.