In vitro susceptibility of common Enterobacterales to eravacycline in Taiwan

Background: New tetracycline derivatives exhibit broad-spectrum antimicrobial activities. This study aimed to assess the in vitro activity of eravacycline against common En-terobacterales.Methods: Clinical Enterobacterales isolates were collected between 2017 and 2021. The min-imum inhibitory concentration (MIC) was determined using a broth microdilution test.Results: We identified Klebsiella pneumoniae (n = 300), Escherichia coli (n = 300), Klebsiella oxytoca (n = 100), Enterobacter cloacae complex (n = 100), Citrobacter freundii (n = 100), and Proteus mirabilis (n = 100). All P. mirabilis strains were resistant to eravacycline. Excluding P. mirabilis, the susceptibility rates to eravacycline, omadacycline, and tigecycline were 75.2%, 66.9%, and 73%, respectively. The MIC50 and MIC90 (mg/L) of eravacycline were 0.5 and 4 for K. pneumoniae, 0.5 and 1 for E. coli, 0.5 and 1 for K. oxytoca, 0.5 and 2 for E. cloacae complex, and 0.25 and 1 for C. freundii. In cefotaxime non-susceptible and meropenem sus-ceptible Enterobacterales, excluding P. mirabilis, the susceptibility rates of eravacycline, omadacycline, and tigecycline were 69.7%, 57.1%, and 66.2%. We found decreased susceptibil-ity rates of three new tetracycline derivatives against meropenem non-susceptible Enterobac-terales (eravacycline: 47.1%, omadacycline: 39.4%, and tigecycline: 39.4 %). Eravacycline showed a high susceptibility rate against cefotaxime non-susceptible and meropenem suscep-tible K. oxytoca (100%), C. freundii (93.2%), E. coli (85.9%), and meropenem non-susceptible E. coli (100%).Conclusion: This study provides the MIC and susceptibility rate of eravacycline for common Enterobacterales. Eravacycline could be a therapeutic choice for cefotaxime non -susceptible or meropenem non-susceptible Enterobacterales, especially K. oxytoca, C. freundii, and E. coli.Copyright (c) 2022, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).