Comparative efficacy of eravacycline and tigecycline in addressing multidrug-resistant Gram-negative bacteria

Abstract

The rise in antibiotic resistance among Gram-negative bacteria poses significant challenges to global health. This study evaluates the in vitro efficacy of tigecycline, omadacycline, and eravacycline against clinical isolates harboring the mobile tigecycline resistance genes tet(X4) and tet(A). A total of 175 clinical strains collected between 1999 and 2023 were analyzed. Resistance genes, including tet(X4) and tet(A), were determined using Polymerase chain reaction (PCR). Minimum inhibitory concentrations (MICs) were determined using the broth microdilution method. Eravacycline exhibited significantly lower MIC values than those of tigecycline for Escherichia coli carrying tet(X4) (P < 0.0001), despite similar resistance rates. Omadacycline consistently displayed the highest MIC values, indicating reduced potency. In contrast, Klebsiella pneumoniae carrying tet(A) showed higher MIC values for eravacycline than tigecycline. Universal resistance was observed in Enterobacter cloacae carrying tet(A). Eravacycline demonstrated superior in vitro efficacy, particularly against E. coli carrying tet(X4), underscoring its potential as a therapeutic option for multidrug-resistant infections. MIC values should complement resistance rates in clinical decision-making, and further studies are warranted to validate eravacycline’s clinical utility.