Aztreonam-avibactam against carbapenem-resistant Enterobacterales: Susceptibility and genomic analysis in a Chinese...

To investigate aztreonam-avibactam (AZA) susceptibility and molecular features of carbapenem-resistant Enterobacterales (CRE) at a Shenzhen hospital.

CRE isolates were collected from January 2018 to September 2025 and analysed by whole-genome sequencing, AZA disk diffusion, and clinical data review. Regional phylogenetic analysis from multiple hospitals in Guangdong Province was conducted.

Among 8655 Enterobacterales isolates, 152 (1.8%) were CRE, with prevalence increasing from 0.3% (2018) to 2.5% (2025). Isolates were predominantly carbapenem-resistant Klebsiella pneumoniae (CRKP, n = 79) and Escherichia coli (CREC, n = 43), mainly from the intensive care unit (37.5%) and elderly patients (≥60 y, 55.9%). Ceftazidime-avibactam was 45.4% resistant overall, 91.5% susceptible to bla_KPC-CRE, and 100% resistant to bla_NDM-CRE. All isolates were susceptible to AZA. CRKP was dominated by the ST11-KL64 clone (46.8%), while CREC was genetically diverse. The bla_KPC-2 predominated in CRKP (58.2%) and bla_NDM-5 prevailed in CREC (74.4%). Notably, 40 carbapenemase-negative CRE isolates accounted for 26.3% of all CRE isolates during the study period. Key resistance genes in CRKP included rmtB (58.2%), qnrS1 (72.2%), bla_CTX-M-65 (48.1%), bla_LAP-2 (57.0%), bla_SHV-134 (38.0%), and fosA6 (93.7%); those in CREC were dfrA12 (41.9%), floR (58.1%), and mphB (88.4%). Regional phylogeny demonstrated that local CRKP clustered within the provincially dominant ST11-KL64 epidemic clade, while CREC were intermixed with strains across Guangdong Province, indicating widespread regional transmission and multiple independent introduction events.

The rise of CRE driven by ST11-KL64 and a growing proportion of non-carbapenemase producers necessitates strengthened infection control. The universal in vitro AZA susceptibility offers a promising therapy.