Laboratory-based surveillance of the susceptibility of carbapenemase-producing Enterobacterales to ceftazidime-avibactam: a preliminary antimicrobial stewardship initiative

Abstract

Background: In vitro susceptibility testing for the antibiotic ceftazidime-avibactam (CZA) commenced at one of the private diagnostic laboratories in South Africa (SA) in 2020. The drug was registered in SA in September 2021. While there is a paucity of quantitative data on CZA susceptibility in SA, Brink et al.11 noted increasing resistance to the drug in the country in 2022. This study provided surveillance of carbapenemase-producing Enterobacterales (CPE) susceptibility to CZA using data observed over two years.
Objective: This study aimed to determine if there is a developing trend of CPE resistance to CZA so that better stewardship and infection control measures can be implemented to safeguard the effective use of the drug.
Study design and methods: This was a longitudinal quantitative study. CZA susceptibility patterns of the OXA-48 subtype of CPE were observed and compared over two years to detect any resistance. Mass spectrometry was used to identify the isolates, and the polymerase chain reaction (PCR) assay and Kirby-Bauer (KB) methods were used to determine the carbapenemase type and CZA susceptibility, respectively.
Results: A total of 495 OXA-48 isolates were selected from 2020 and a total of 439 from 2021. Of the isolates, 6% from 2020 were resistant, while 9% from 2021 were resistant.
Conclusion: This preliminary observational study observed the beginning of a resistance trend between the years of 2020 and 2021.