Impact of CLSI and EUCAST breakpoint discrepancies on reporting of antimicrobial susceptibility and AMR surveillance

Time to switch from CLSI to EUCAST? A Southeast Asian perspective

“…S1 and Supplementary Table S1 ) identified 101 articles in PubMed reporting on EUCAST implementation ( n = 8), specific methodological discrepancies between CLSI and EUCAST ( n = 20), and comparisons of CLSI and EUCAST breakpoints for susceptibility interpretation ( n = 73). The susceptibility comparisons generally reported higher resistance rates with EUCAST breakpoints, which our own findings supported [10] , and all articles about EUCAST implementation were from Europe, focusing mainly on the history and structure of EUCAST, organizational differences with CLSI, and EUCAST breakpoint-setting and disk-diffusion methodologies. One recent article [14] proposes a roadmap for transitioning from CLSI to EUCAST in Spanish laboratories, providing useful general recommendations and highlighting differences between CLSI and EUCAST such as antimicrobial disk contents and media.…”

“…Using the Enterobacteriaceae as an example, 64/69 (93%) of CLSI breakpoints included an intermediate category compared to 24/48 (50%) with EUCAST, and EUCAST resistance cut-offs were higher in 26/33 directly comparable zone diameter breakpoints. Our susceptibility interpretation comparison [10] demonstrated that these discrepancies would have significantly increased reported co-amoxiclav and ciprofloxacin resistance rates amongst clinical isolates of E. coli and Klebsiella pneumoniae had EUCAST 2018 breakpoints been used. It must be noted that from 1st January 2019, EUCAST changed its definition of the intermediate category to ‘Susceptible, increased exposure’ [11] for when there is a high likelihood of therapeutic success because exposure to the agent is increased by adjusting the dosing regimen or by its concentration at the site of infection.…”

“…Clinical breakpoints from both organizations from 2018 [5] , [6] and disk-diffusion AST guidelines from 2018 from CLSI [7] and from 2017 from EUCAST [8] , [9] were assessed for significant differences. We also examined the impact of discrepancies in CLSI and EUCAST zone diameter breakpoints on the interpretation of antimicrobial susceptibility of frequently isolated Gram-negative organisms at one of our sites—the Mahosot Microbiology Laboratory, Vientiane, Laos—in 2017, as reported in this issue of CMI [10] . Although a formal cost analysis was not performed, major additional expenses or savings associated with adopting EUCAST were estimated where possible.…”

Antimicrobial Susceptibility Testing of Antimicrobial Peptides to Better Predict Efficacy

“…Different documents describe breakpoints for bacteria, yeasts, filamentous fungi (moulds) and other microorganisms ( Table 1 ). Despite many similarities and agreements, there remains some lack of harmonisation between AST methods from different organisations (Pfaller et al, 2011 , 2014 ; Chowdhary et al, 2015 ; Kahlmeter, 2015 ; Brown et al, 2016 ; Sanguinetti and Posteraro, 2018 ; Simjee et al, 2018 ; Cusack et al, 2019 ). Interpretive categories most commonly assigned are susceptible (S), indicative of a high probability of a successful outcome, and resistant (R), indicative of a low probability of a successful outcome, although in less common cases other categories include; non-susceptible, intermediate, susceptible-dose dependent and area of technical uncertainty (See the documents in Table 1 for details about these interpretive categories).…”

Coagulase-negative staphylococci in outpatient routines: the implications of switching from CLSI to BrCAST/EUCAST guidelines

“…CLSI and EUCAST susceptibility profiles have been compared in studies, and significant changes have been reported concerning certain pathogens [21][22][23][24][25][26]. Due to its more restrictive breakpoints, lower susceptibility rates have been observed for EUCAST [21].…”