Emergence of a high-risk multidrug-resistant Acinetobacter baumannii clone ST697 in nosocomial settings

作者：Jing Guan, Huiqi Qu, Yu Lin, Weilong Li, Garnet Eister, Håkon Håkonarson, S Y Li · 发表于：Microbiology Spectrum · 年份：2026 · DOI：10.1128/spectrum.02293-25 · 被引用次数：1 · 研究领域：Antibiotic Resistance in Bacteria、Infections and bacterial resistance、Nosocomial Infections in ICU

ABSTRACT Acinetobacter baumannii is a critical opportunistic pathogen increasingly linked to hospital-acquired infections due to its ability to acquire multidrug resistance (MDR). Its persistence in clinical environments and resistance to nearly all major antibiotic classes make it a formidable challenge for infection control and treatment. This study investigated the molecular epidemiology and therapeutic strategies for A. baumannii across three hospital campuses. A total of 148 clinical MDR A. baumannii isolates were collected, mostly recovered from respiratory tract specimens in ICU settings. All isolates underwent whole-genome sequencing (WGS), antibiotic susceptibility testing against 16 antibiotics, and in vitro evaluation of 14 antibiotic combinations. WGS confirmed 140 clinical isolates as A. baumannii, and 42.3% were classified as extensively drug-resistant (XDR). High resistance rates were observed for carbapenems (98.6%), fluoroquinolones (100%), and aminoglycosides (91.4%), while susceptibility to polymyxin B (PMB) and tigecycline (TGC) remained largely preserved. Four antibiotic combinations, TGC + cefoperazone/sulbactam (CSL), TGC + PMB, PMB + CSL, and minocycline (MNO) + CSL, demonstrated strong synergistic effects (>90%). The efficacy and safety of the MNO + CSL combination were preliminarily assessed in the mouse model. Genome sequence typing revealed ST2 as the dominant clone (92.9%), while a novel XDR clone, ST697, was identified. Genomic and virulence p...