Introduction to the revised international guidelines on breakpoints for antimicrobial susceptibility testing

Jae-Woo  Chung

doi:10.5145/ACM.2023.26.3.2

Review article

Ann Clin Microbiol 2023;26(3):51-57.

Published online: 20 September 2023

DOI: https://doi.org/10.5145/ACM.2023.26.3.2

Introduction to the revised international guidelines on breakpoints for antimicrobial susceptibility testing

Jae-Woo Chung

Department of Laboratory Medicine, Dongguk University Ilsan Hospital, Goyang, Korea

Corresponding author: Jae-Woo Chung E-mail: jwchung@dumc.or.kr

Received 13 September 2023 Revised 18 September 2023 Accepted 18 September 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Clinical and Laboratory Standards Institute (CLSI) M100 ‘Performance Standards for Antimicrobial Susceptibility Testing (AST)’ and the European Committee on AST (EUCAST) ‘Breakpoint tables for interpretation of MICs and zone diameters’ guidelines for conducting and interpreting AST are revised yearly. The 2023 CLSI guideline introduces selective and cascade reporting methods for antibacterial agents as a part of strengthening antibiotic stewardship and changes in breakpoints for aminoglycoside (AG) in Enterobacterales and AG and piperacillin in Pseudomonas aeruginosa. Main changes in EUCAST include revised breakpoints for aminopenicillins in Enterobacterales, and detailed criteria reflecting the clinical situation and antibacterial agent administration method.

Keywords: Guidelines, Antimicrobial susceptibility testing, Clinical and Laboratory Standards Institute, the European Committee on Antimicrobial Susceptibility Testing

[in Korean]

Ethics statement

It is not a human population study; therefore, approval by the institutional review board or the obtainment of informed consent is not required.

Conflicts of interest

No potential conflicts of interest relevant to this article were reported.

Funding

None.

REFERENCES

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Table 1

Breakpoints revision in CLSI M100

†agents reported only on organisms isolated from the urinary tract; ‡designated with an asterisk as ‘other’.

Abbreviations: CLSI, Clinical and Laboratory Standards Institute; MIC, minimum inhibitory concentration; S, susceptible; I, intermediate; R, resistant; O, other.

Fig. 1.

Cascade reporting examples for Enterobacterales.

Table 2

New breakpoints of aminopenicillins for Enterobacterales according to infection types and formulations in EUCAST version 13

Abbreviations: EUCAST, the European Committee on Antimicrobial Susceptibility Testing; MIC, minimum inhibitory concentration; S, susceptible; I, intermediate; R, resistant; IV, intravenous; uUTI, uncomplicated urinary tract infection; cUTI, complicated urinary tract infection.

Fig. 2.

Flowchart for implementation aminopenicillin MIC for Enterobacterales. AMC, amoxicillin-clavulanic acid; Tx, therapy; UTI, urinary tract infection; uUTI, uncomplicated UTI; MIC, minimum inhibitory concentration; S, susceptiblie; R, resistant; IV, intravenous; cUTI, complicated UTI; I, intermediate.