Genomic epidemiology and ceftazidime-avibactam resistance mechanism of KPC-3-producing Pseudomonas aeruginosa: A decade retrospective study in China.
OBJECTIVES: Carbapenem-resistant Pseudomonas aeruginosa (CRPA), especially KPC-producing P. aeruginosa, is rapidly expanding and posing a serious public health threat. Here, we aim to characterise the epidemiology of KPC-3-producing P. aeruginosa in a tertiary hospital over a 10-year period and elucidate the mechanism of ceftazidime-avibactam (CZA) resistance driven by blaKPC-3 to blaKPC-267 mutations in CRPA, along with conducting a global phylogeographic analysis of KPC-3-producing P. aeruginosa. METHODS: 11 non-duplicate KPC-3-producing CRPA isolates collected over a 10-year period were characterized by antimicrobial susceptibility testing and whole-genome sequencing (WGS). The genetic context and transferability of blaKPC-3/267 and the mechanism of KPC-267-mediated CZA resistance were investigated. Global phylogenomic analysis was performed to characterize the geographic distribution and population structure of blaKPC-3-carrying P. aeruginosa. RESULTS: All 11 KPC-3-producing CRPA strains in this study belonged to ST1076 and exhibited multidrug resistance. The blaKPC-267-positive CZA-resistant strain SRMPA3523 was isolated from patient 1 after blaKPC-3-positive P. aeruginosa SRMPA1139 and SRMPA1630 were treated with CZA. WGS indicated that blaKPC-3/267 was located on the Tn6296 transposon contained in the transferable IncP-2 plasmid. KPC-267 mediates resistance to CZA by reducing the inhibitory effect of avibactam and increasing affinity for ceftazidime. Global analysis indicated that blaKPC-3-carrying P. aeruginosa were predominantly in China, America, and Colombia, with ST1076 and ST111 as dominant clones. CONCLUSIONS: This study characterised the global phylogeography of blaKPC-3-carrying P. aeruginosa and identified KPC-267 as a KPC-3-derived variant associated with CZA resistance. This finding highlighted the risk of developing CZA resistance in KPC-producing P. aeruginosa strains under therapeutic pressure.