In vitro and in vivo efficacy of vancomycin against Elizabethkingia species and the impact of increased vancomycin MICs

作者：Tzu‐Wen Huang, Teng‐Kuang Yeh, Shu-Yuan Hsu, Mei-Chen Tan, Weicheng Huang, Shu‐Chen Kuo · 发表于：Microbiology Spectrum · 年份：2025 · DOI：10.1128/spectrum.02371-25 · 被引用次数：3 · 研究领域：Infections and bacterial resistance、Streptococcal Infections and Treatments、Mycobacterium research and diagnosis

ABSTRACT This study aimed to evaluate the concordance of vancomycin susceptibility testing methods, its in vivo and in vitro efficacy, and the mechanisms underlying elevated MICs in Elizabethkingia spp. Vancomycin susceptibilities of 18 E. anophelis isolates were determined using multiple assays. The efficacy of vancomycin against five clinical isolates and one laboratory-induced mutant with an elevated vancomycin MIC was evaluated using time-kill assays and Galleria mellonella and murine models. Vancomycin MICs (16–32 mg/L) determined by broth microdilution were consistent with agar dilution, Etest, and MBC assay results. All isolates had zone diameters < 17 mm and were, thus, categorized as non-susceptible according to the CLSI criteria for Enterococcus spp. Time-kill assays of five clinical isolates demonstrated that vancomycin at a clinically relevant concentration (4 mg/L) exhibited poor bactericidal activity similar to that of teicoplanin. Vancomycin improved Galleria mellonella survival in a dose-dependent manner, whereas teicoplanin, dalbavancin, oritavancin, and daptomycin were ineffective. Murine models revealed that vancomycin at a human-equivalent dose (25 mg/kg twice daily) prolonged survival in most infections and modestly reduced bacterial load, while teicoplanin remained ineffective. Vancomycin efficacy was significantly reduced in G. mellonella and mice infected with a mutant strain exhibiting an elevated MIC (128 mg/L), which was attributable to spontaneo...