Emergence and rising of ceftazidime-avibactam resistant KPC-producing Pseudomonas aeruginosa in China: a molecular epidemiology study

Background Infections by Carbapenem-resistant Pseudomonas aeruginosa (CRPA) are difficult to treat and novel antibiotics are desperately needed. Till today, ceftazidime-avibactam (CAZ-AVI) has been used to treat infections caused by multidrug resistant (MDR) Gram-negative bacteria, including Klebsiella pneumoniae carbapenemase (KPC)-producing organisms. Although cases of KPC-producing P. aeruginosa (KPC-PA) have been reported sporadically, data about KPC-PA susceptibility to CAZ-AVI and its molecular characteristics are limited. Methods CRPA were collected from seven hospitals in China from 2017 to 2018. PCR was deployed to screen for the bla KPC gene. Antimicrobial susceptibility of KPC-PA was determined by broth microdilution method or agar dilution method. We combined Illumina sequencing and Nanopore long-read sequencing to elucidate the genomic characteristics of KPC-PA strains. Results KPC-PA strains were found in six out of seven hospitals. 151/374 (40.4%) CRPA clinical isolates harbored the bla KPC-2 gene. Among KPC-PA, ST463 (107/151) was predominant, followed by ST485 (14/151) and ST1212 (12/151). Approximately half of all KPC-PA (50.3%) were susceptible to CAZ-AVI. We found that the bla KPC-2 gene copy number correlated with CAZ-AVI MIC. In more than 90% (136/151) of the strains, we found plasmids that belonged to two types carrying bla KPC-2 gene. The Type 1 plasmid, predominant in East China, was identified in 118 strains and the Type 2 plasmid, belonged to a megaplasmid family spreading globally, was identified in 19 strains. In addition, we identified IS 26 -ΔTn 6296 and IS 6100 -ΔTn 6296 -Tn 1403 as two mobile genetic elements that mediated bla KPC-2 gene transmission. Conclusion Our results suggest that the bla KPC-2 gene is becoming a remarkable mediator of carbapenem resistance in P. aeruginosa in China. The emergence and spread of such KPC-PA strains poses a threat on clinical therapy as CAZ-AVI becomes inefficient. It would be beneficial to screen for the bla KPC gene in CRPA strains for antimicrobial surveillance. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study is supported by the National Natural Science Foundation of China (grant no. 81830069). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Approval was obtained from the Ethics Committee of Sir Run Run Shaw Hospital (approval/reference number: 20201118-49). This study was not considered as a human research. Therefore, no informed consent to participate was required. This study conformed to the principles of the Helsinki Declaration. All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All the sequence data were deposited at DDBJ/ENA/GenBank under the BioProject accession number PRJNA672835.