AUTHOR=Chen Jiawei , Zeng Yu , Zhang Rong , Cai Jiachang 

TITLE=In vivo Emergence of Colistin and Tigecycline Resistance in Carbapenem-Resistant Hypervirulent Klebsiella pneumoniae During Antibiotics Treatment

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.702956

DOI=10.3389/fmicb.2021.702956

ISSN=1664-302X

ABSTRACT=<p>Three carbapenem-resistant <italic>Klebsiella pneumoniae</italic> (CRKP; strains KP-426, KP-C76, and KP-CT77) were isolated from a patient with severe burns during the treatment of colistin and tigecycline. Single-nucleotide polymorphism typing showed that three ST11 CRKP were clonally related. Three isolates harbored the same set of antimicrobial resistance genes. <italic>bla</italic><sub>KPC-2</sub>, <italic>bla</italic><sub>SHV-12</sub>, <italic>bla</italic><sub>TEM-1</sub>, and <italic>rmtB</italic> genes were located on the same 128,928-bp IncFII/IncR plasmid. <italic>Tet</italic>(A), <italic>catA2</italic>, <italic>sul2</italic>, and <italic>dfrA14</italic> genes were located on a plasmid with an unknown Inc-type. <italic>bla</italic><sub>SHV-11</sub>, <italic>fosA</italic>, and <italic>aadA2</italic> were chromosomal genes. An IS<italic>1</italic> and an IS<italic>Kpn14</italic> were found in the promoter region of the <italic>mgrB</italic> gene of two colistin-resistant CRKP, <italic>K. pneumoniae</italic> KP-C76, and KP-CT77, respectively. A novel amino acid substitution, G300E, was identified in the type 1 Tet(A) variant of <italic>K. pneumoniae</italic> KP-CT77 which exhibited high-level tigecycline resistance compared to strains KP-426 and KP-C76 (MIC of 32, 4, and 4mg/l, respectively). Conjugation and cloning experiments confirmed that the mutated Tet(A) resulted in a 4-fold increase in tigecycline minimal inhibitory concentration (MIC) of <italic>Escherichia coli</italic>. Three CRKP belonged to the K64 serotype and possessed a similar IncHI1B/repB virulence plasmid carrying <italic>rmpA</italic>, <italic>rmpA2</italic>, and <italic>iucABCDiutA</italic>. The survival rates of <italic>Galleria Mellonella</italic> injected with <italic>K. pneumoniae</italic> KP-426, KP-C76, and KP-CT77 were 4.2, 20.8, and 8.3%, respectively. The emergence of colistin and tigecycline resistance in carbapenem-resistant hypervirulent <italic>K. pneumoniae</italic> posed a serious threat to clinical anti-infective therapy. The type 1 Tet(A) variant carrying G300E mutation, which conferred significantly elevated tigecycline MIC and was located on a conjugative plasmid, needs attention.</p>