To Be or Not to Be Resistant: CLSI Versus EUCAST Guidelines for <i>Staphylococcus lugdunensis</i>

Abstract Introduction/Objective Staphylococcus lugdunensis is a coagulase-negative Staphyloccocus, but infections can be as severe S. aureus. Performing antimicrobial susceptibility testing (AST) paramount to appropriate treatment. Recently, the College of American Pathologists requiring clinical labs implement updated guidelines. We evaluated how Clinical and Laboratory Standards Institute (CLSI) European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines would impact our hospital’s resistance rates for lugdunensis. Methods/Case Report Cultures with isolated between 04/2018 02/2022 were included. Minimal inhibitory concentrations (MICs) (Vitek2 Microscan Walkaway) reported (clindamycin, doxycycline, daptomycin, linezolid, vancomycin) interpreted using CLSI (M100Ed32) EUCAST (v12.0) The range MICs (95% Confidence Interval) was calculated. Results (if Case Study enter NA) A total 125 isolates from 120 patients specimen types including wound (49%), tissue (42%), blood (6%), body fluid (3%) identified. Five had multiple cultures lugdunensis, four two wound/tissue sites one biopsy positive. For clindamycin (0.7-1.3 ug/mL), determined more (from wound, MIC=0.5 ug/mL) resistant. Most drastically, rate doxycycline (0.6-1.0 11% higher per (susceptible: 89% vs 100% CLSI). difference seen in &amp;gt; 2 ug/mL, all tissue. Regardless used, susceptible daptomycin (0.4-0.5 linezolid (1.2-1.4 vancomycin (0.6-0.7 ug/mL); 23% resistant oxacillin (1.7-2.0 ug/mL). Conclusion have at institution. To ensure that teams are utilizing AST results provide care, team effort consisting microbiology lab, infectious diseases physicians, antibiotic stewardship committee needed determine which should followed.