AUTHOR=He Long , Wang Wenji , Ma Liman , Wang Dongguo , Long Shanshan 

TITLE=Emergence of a clinical Klebsiella pneumoniae harboring an acrAB-tolC in chromosome and carrying the two repetitive tandem core structures for blaKPC-2 and blaCTX-M-65 in a plasmid

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2024.1410921

DOI=10.3389/fcimb.2024.1410921

ISSN=2235-2988

ABSTRACT=<sec><title>Objective</title><p>The emergence of clinical <italic>Klebsiella pneumoniae</italic> strains harboring <italic>acrAB-tolC</italic> genes in the chromosome, along with the presence of two repetitive tandem core structures for <italic>bla</italic><sub>KPC-2</sub> and <italic>bla</italic><sub>CTX-M-65</sub> genes on a plasmid, has presented a significant clinical challenge.</p></sec><sec><title>Methods</title><p>In order to study the detailed genetic features of <italic>K. pneumoniae</italic> strain SC35, both the bacterial chromosome and plasmids were sequenced using Illumina and nanopore platforms. Furthermore, bioinformatics methods were employed to analyze the mobile genetic elements associated with antibiotic resistance genes.</p></sec><sec><title>Results</title><p><italic>K. pneumoniae</italic> strain SC35 was found to possess a class A beta-lactamase and demonstrated resistance to all tested antibiotics. This resistance was attributed to the presence of efflux pump genes, specifically <italic>acrAB-tolC</italic>, on the SC35 chromosome. Additionally, the SC35 plasmid p1 carried the two repetitive tandem core structures for <italic>bla</italic><sub>KPC-2</sub> and <italic>bla</italic><sub>CTX-M-65</sub>, as well as <italic>bla</italic><sub>TEM-1</sub> with <italic>rmtB</italic>, which shared overlapping structures with mobile genetic elements as In413, Tn<italic>3</italic>, and Tn<italic>As3</italic>. Through plasmid transfer assays, it was determined that the SC35 plasmid p1 could be successfully transferred with an average conjugation frequency of 6.85 × 10<sup>-4</sup>.</p></sec><sec><title>Conclusion</title><p>The structure of the SC35 plasmid p1 appears to have evolved in correlation with other plasmids such as pKPC2_130119, pDD01754–2, and F4_plasmid pA. The infectious strain SC35 exhibits no susceptibility to tested antibioticst, thus effective measures should be taken to prevent the spread and epidemic of this strain.</p></sec>