Focused Commentary; About Revision of CLSI Antimicrobial Breakpoints, 2018-2021

Abstract

In recent years, antimicrobial resistance has been on the rise and infectious disease specialists and other clinicians face several challenges when treating patients with antimicrobial resistant infections. Clinical and Laboratory Standards Institute (CLSI) annually publishes guidelines for antimicrobial resistance tests, including revised antimicrobial breakpoints, because of the rise in antimicrobial resistance and changes to nomenclature owing to advances in whole genome sequencing technology. However, many laboratories use historical guidelines and do not follow the revised breakpoints. Moreover, the current breakpoints have limitations. This study evaluated the changes in antimicrobial breakpoints over the last 4 years, from 2018 to 2021. Here, I describe the microbiological and clinical background of the CLSI breakpoint revision and evaluate the advantages and limitations of new breakpoints with a review of large study data. In addition, I reviewed problems associated with each antimicrobial breakpoint and made suggestions for how they might be improved, for example, increasing or decreasing the minimum inhibitory concentration (MIC) or zone diameter, deleting or adding an S, I, or R category, introducing new concepts (such as susceptible-dose dependent (SDD)), and requesting more evaluation methods. Conclusions; CLSI annually publishes guidelines for antimicrobial resistance tests. I reviewed problems associated with each antimicrobial breakpoint for last 4 years, and made suggestions for how they might be improved.

Characterization of β-lactamase and virulence genes in Pseudomonas aeruginosa isolated from clinical, environmental and poultry sources in Bangladesh

“…The Kirby-Bauer agar disk diffusion method was used to test the susceptibility of the confirmed P . aeruginosa isolates to different antibiotics in accordance with the guidelines recommended by the Clinical and Laboratory Standards Institute (CLSI, 2021) to determine the sensitivity or susceptibility [ 27 ]. The antibiotic disks (Liofilchem ® , Italy) used in this study included Ciprofloxacin (CIP, 5 g/disc), Gentamicin (GEN, 10 g/disc), Levofloxacin (LEV, 5 g/disc), Penicillin-G (P, 10 g/disc), Aztreonam (ATM, 30 g/disc), Imipenem (IMP, 10 g/disc), Amikacin (AK, 30 g/disc), Ceftazidime (CAZ, 30 g/disc), Doripenem (DOR, 10 g/disc), and Cefepime (CPM, 0 g/disc).…”

Genomic insights into antibiotic resistance genes in Leuconostoc citreum strains isolated from artisanal buffalo milk curd in Bangladesh through whole-genome sequencing

“…After performing partial 16S rRNA gene sequencing ( 7 ), 27 isolates were identified as Leuconostoc citreum . This study aimed to sequence the genomes of two Leuconostoc citreum strains, BSMRAU-M1L6 and BSMRAU-M1L13, and they were found to be multidrug-resistant (MDR; resistant to eight antibiotics) in disk diffusion tests according to CLSI 2021 ( 8 ). The Nextera DNA Flex Library Prep Kit (Illumina, USA) was used to generate libraries from 1 ng of DNA, extracted from BSMRAU-M1L6 and BSMRAU-M1L13 strains as described earlier.…”

Characterization of β-lactamase and virulence genes inPseudomonas aeruginosaisolated from clinical, environmental and poultry sources in Bangladesh

“…The Kirby-Bauer agar disk diffusion method was used to test the susceptibility of the confirmed P. aeruginosa isolates to different antibiotics in accordance with the guidelines recommended by the Clinical and Laboratory Standards Institute (CLSI, 2021) to determine the sensitivity or susceptibility [25]. The antibiotic disks (Liofilchem ® , Italy) used in this study included Ciprofloxacin (CIP, 5 g/disc), Gentamicin (GEN, 10 g/disc), Levofloxacin (LEV, 5 g/disc), Penicillin-G (P, 10 g/disc), Aztreonam (ATM, 30 g/disc), Imipenem (IMP, 10 g/disc), Amikacin (AK, 30 g/disc), Ceftazidime (CAZ, 30 g/disc), Doripenem (DOR, 10 g/disc), and Cefepime (CPM, 0 g/disc).…”