In vitro susceptibility of common Enterobacterales to eravacycline in Taiwan

Abstract

Abstract Background: New tetracycline derivatives exhibit broad-spectrum antimicrobial activities. This study aimed to assess the in vitro activity of eravacycline against common Enterobacterales. Methods: Clinical Enterobacterales isolates were collected between 2017 and 2021. The minimum inhibitory concentration (MIC) was determined using a broth microdilution test. Results: We identified Klebsiella pneumoniae (n Z 300), Escherichia coli (n Z 300), Klebsiella oxytoca (n Z 100), Enterobacter cloacae complex (n Z 100), Citrobacter freundii (n Z 100), and Proteus mirabilis (n Z 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 susceptible Enterobacterales, excluding P. mirabilis, the susceptibility rates of eravacycline, omadacycline, and tigecycline were 69.7%, 57.1%, and 66.2%. We found decreased susceptibility rates of three new tetracycline derivatives against meropenem non-susceptible Enterobacterales (eravacycline: 47.1%, omadacycline: 39.4%, and tigecycline: 39.4%). Eravacycline showed a high susceptibility rate against cefotaxime non-susceptible and meropenem susceptible 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 nonsusceptible or meropenem non-susceptible Enterobacterales, especially K. oxytoca, C. freundii, and E. coli.