Monitoring Rational Antimicrobial Use Through the Antimicrobial Spectrum Score (Asi): An Automated Approach in Clinical Stewardship

Days of Therapy (DOT) counts each antibiotic (ATB) administered per day, while LOT (Length of Therapy) considers only total therapy duration, regardless of the number of drugs used. Thus, we adapted and automated, in the SACIH+ system, the Antimicrobial Spectrum Score (ASI), which complements DOT and LOT by quantifying the number of microorganism groups covered by each ATB. The objective of this work is to present an automated method for analyzing escalation and de-escalation of ATBs, based on ASI. ASI assigns 1 point for each group of microorganisms susceptible to an ATB, resulting in scores from 1 to 14 for ATBs. Fourteen target groups were considered: methicillin-susceptible S. aureus (MSSA), Enterococcus sp., B. fragilis, Moraxella sp/H. influenzae, E. coli/Klebsiella sp, Enterobacter spp/Serratia spp/Citrobacter spp, extended-spectrum beta-lactamase producers (ESBL), P. aeruginosa, methicillin-resistant S. aureus (MRSA), penicillin-resistant pneumococcus, vancomycin-resistant Enterococcus sp (VRE), atypicals (such as Mycoplasma sp, Chlamydophila sp and Legionella sp), and multidrug-resistant microorganisms (MDRO). Summing the ASIs of all ATBs prescribed each day allows classification of spectrum evolution as escalation. Fifty-three different ATBs received ASI scores from 1 to 14, and four antifungals had spectrum scores: Liposomal Amphotericin B (7), Fluconazole (3), Micafungin (4) and Voriconazole (5). It is possible to quantify antimicrobial coverage day by day and classify whether de-escalation occurred, in an automated way. The tool can identify subtle or explicit changes in spectrum. For example, if an initial prescription begins with [Azithromycin] + [Amoxicillin + Potassium Clavulanate], with ASI = 10, and ends with [Amoxicillin + Potassium Clavulanate], with ASI = 6, or changes from [Cefepime], ASI = 6, to [Vancomycin], ASI = 5, this constitutes de-escalation, as does changing [Vancomycin] + [Cefepime] = 11 to [Cefepime] = 6. If [Vancomycin] = 5 changes to [Piperacillin/Tazobactam] = 8, or from [Ertapenem] = 9 to [Meropenem] + [Vancomycin] = 15, this constitutes escalation. Automated use of ASI via SACIH+ was effective in evaluating prescribing quality, with de-escalation practices. This methodology improves measurement of rational ATB use and adds value to stewardship programs, overcoming limitations of traditional metrics.