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In China, clinical CR\u2010KP isolates are mainly attributed to the <jats:italic>bla<\/jats:italic><jats:sub>KPC\u20102<\/jats:sub> gene carried on plasmids, and the <jats:italic>bla<\/jats:italic><jats:sub>KPC\u20102<\/jats:sub> copy number correlates with the expression of KPC enzymes, which can cause elevated carbapenem MICs.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Thirty\u2010seven CR\u2010KP isolates were collected at the Second People\u2019s Hospital of Lianyungang City between January 2020 and March 2021, with no duplicate isolates, and were screened for the <jats:italic>bla<\/jats:italic><jats:sub>KPC\u20102<\/jats:sub> gene with PCR. Analysis of current CRKP resistance to clinically relevant antimicrobials using the bioM\u00e9rieux VITEK<jats:sup>\u00ae<\/jats:sup> 2 bacterial identification card. The multilocus sequence types of the strains were confirmed with PCR and DNA sequencing. Recombinant plasmids pET20b\u2010<jats:italic>bla<\/jats:italic><jats:sub>KPC\u20102<\/jats:sub> and pET20b\u2010CpsG were constructed, and the copy numbers of the recombinant plasmids per unit volume was calculated based on the molecular weight of the plasmids. After the genomes DNA of clinical isolates of <jats:italic>K.\u00a0pneumoniae<\/jats:italic> carrying the <jats:italic>bla<\/jats:italic><jats:sub>KPC\u20102<\/jats:sub> gene were purified, the <jats:italic>bla<\/jats:italic><jats:sub>KPC\u20102<\/jats:sub> gene relative copy number in individual <jats:italic>K.\u00a0pneumoniae<\/jats:italic> strains was indicated by the double standard curve method. Detection of MIC values changes of <jats:italic>K.\u00a0pneumoniae<\/jats:italic> under imipenem selection pressure by broth microdilution method.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Among the 37 CR\u2010KP strains isolated, only the <jats:italic>bla<\/jats:italic><jats:sub>KPC\u20102<\/jats:sub> gene was detected in 30 strains, three strains were positive for the <jats:italic>bla<\/jats:italic><jats:sub>NDM\u20101<\/jats:sub> gene, two strains carried both the <jats:italic>bla<\/jats:italic><jats:sub>KPC\u20102<\/jats:sub> and <jats:italic>bla<\/jats:italic><jats:sub>NDM\u20101<\/jats:sub> genes, and two strains without detectable carbapenem resistance genes. The ST11 clone was predominant among the 37 carbapenem\u2010resistant <jats:italic>K.\u00a0pneumoniae<\/jats:italic> isolates. Drug sensitivity testing showed that except for polymyxins (100% susceptible) and tigecycline (75.7% intermediate), the 37 CR\u2010KP strains were resistant to almost all antimicrobial drugs. The <jats:italic>bla<\/jats:italic><jats:sub>KPC\u20102<\/jats:sub> relative copy number in nine ST11 clinical isolates of <jats:italic>K.\u00a0pneumoniae<\/jats:italic> was 7.64\u00a0\u00b1\u00a02.51 when grown on LB plates but 27.67\u00a0\u00b1\u00a013.04 when grown on LB plates containing imipenem. Among these nine isolates, five CRKP strains exhibited elevated MICs to imipenem, while the remaining four strains showed unchanged MIC values to imipenem.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Carbapenem\u2010resistant <jats:italic>Klebsiella pneumoniae<\/jats:italic> isolates may have multiple pathways to achieve high levels of carbapenem resistance, and moderate carbapenem pressure can increase the copy number of KPC enzyme genes in CRKP strains and enhance the degree of carbapenem resistance in the strains.<\/jats:p><\/jats:sec>","DOI":"10.1002\/jcla.24519","type":"journal-article","created":{"date-parts":[[2022,6,20]],"date-time":"2022-06-20T05:34:44Z","timestamp":1655703284000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Carbapenem antibiotic stress increases <scp><i>bla<\/i><sub>KPC<\/sub><\/scp><sub>\u20102<\/sub> gene relative copy number and bacterial resistance 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