Practice of standardization of CLSI M45 A3 antimicrobial susceptibility testing of Infrequently Isolated or Fastidious Bacteria strains isolated from blood specimens in Guangdong Province 2017-2021

Nanhao He; Xu Yang; Anwarul Haque; Jiakang Chen; Yingyi Guo; Jiahui Li; Likang Yao; Chuyue Zhuo; Jiong Wang; Yijing Wang; Mingxin Li; Yexin Lin; Shunian Xiao; Chao Zhuo

doi:10.3389/fmicb.2024.1335169

Practice of standardization of CLSI M45 A3 antimicrobial susceptibility testing of Infrequently Isolated or Fastidious Bacteria strains isolated from blood specimens in Guangdong Province 2017-2021

Front Microbiol. 2024 Apr 29:15:1335169. doi: 10.3389/fmicb.2024.1335169. eCollection 2024.

Authors

Nanhao He^#¹, Xu Yang^#¹, Anwarul Haque², Jiakang Chen¹, Yingyi Guo³, Jiahui Li¹, Likang Yao¹, Chuyue Zhuo¹, Jiong Wang¹, Yijing Wang¹, Mingxin Li¹, Yexin Lin¹, Shunian Xiao¹, Chao Zhuo¹

Affiliations

¹ Department of Guangdong Antimicrobial Resistant Bacteria Monitoring and Quality Control Center, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
² Department of Infectious Diseases, School of Medicine, International University of Health and Welfare, Narita, Japan.
³ Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Laboratory, Guangzhou Medical University, Guangzhou, China.

^# Contributed equally.

Abstract

The concentration of antimicrobial agents in environments like water and food has increased rapidly, which led to a rapid increase in antimicrobial resistance levels in the environment. Monitoring of bacterial resistance levels is considered as a necessary means to control the bacterial resistance. Reference standards are critical for antimicrobial susceptibility testing. CLSI M45 A3 standard defines pathogenic microorganisms that cause infections less frequently than those covered by CLSI M02, M07, and M100 as Infrequently Isolated or Fastidious Bacteria and specifies antimicrobial susceptibility testing methods. Our study investigated the epidemiology and antimicrobial susceptibility testing data of Infrequently Isolated or Fastidious Bacteria strains isolated from blood specimens in 70 hospitals in Guangdong Province between 2017 and 2021. We defined testing methods other than those specified in CLSI M45 A3 as "Non-Standardized." The proportion of standardized antimicrobial susceptibility testing for penicillin increased significantly (Corynebacterium spp. 17.4% vs. 50.0% p < 0.05; Micrococcus spp. 50.0% vs. 77.8% p < 0.05; Abiotrophia spp. and Granulicatella spp. 21.4% vs. 90.9% p < 0.001), while for cefotaxime (Corynebacterium spp. 0.0% vs. 45.2% p < 0.05; Abiotrophia spp. and Granulicatella spp. 0.0% vs. 14.3% p = 0.515) and vancomycin increased finitely. Non-standardized methods were used for all other antimicrobials. Due to limitations in the economic and medical environment, some clinical laboratories are unable to fully comply with CLSI M45 A3 standard. We recommend that CLSI should add breakpoints for disk diffusion method to improve the standardization of antimicrobial susceptibility testing.

Keywords: CLSI M45 A3; Infrequently Isolated or Fastidious Bacteria; bloodstream infections; clinical laboratories; standardization.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was funded by Special Foundation for National Science and Technology Basic Research Program of China 2019FY101200. The funders had no role in the design, conduct, analysis or interpretation of the study.