Tigecycline-non-susceptible hypervirulent Klebsiella pneumoniae strains in Taiwan

Yi Hsiang Cheng, Tzu Wen Huang, Chih Han Juan, Sheng Hua Chou, Yao Yi Tseng, Ting Wen Chen, Tsuey Ching Yang, Yi Tsung Lin*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

21 Scopus citations


Objectives: Emergent antimicrobial-resistant hypervirulent Klebsiella pneumoniae (hvKp) is an important public health issue. We aimed to investigate resistance mechanisms and hypervirulent traits among tigecycline-non-susceptible (TNS) K. pneumoniae clinical strains, focusing on one hvKp strain with in vivo evolution of tigecycline resistance. Methods: TNS K. pneumoniae strains causing invasive diseases in a medical centre in Taiwan between July 2015 and April 2018 were collected. Resistance mechanisms were determined and hvKp strains were defined as rmpA/rmpA2-carrying strains. Isogenic strains with and without tigecycline resistance were subjected to WGS and in vivo virulence testing. Further, site-directed mutagenesis was used to confirm the resistance mechanism. Results: In total, 31 TNS K. pneumoniae strains were isolated, including six hypervirulent strains. Tigecycline resistance mechanisms were mostly caused by overexpression of AcrAB and OqxAB together with up-regulation of RamA or RarA, respectively. One TNS hypervirulent strain (KP1692; MIC=6 mg/L) derived from its tigecycline-susceptible counterpart (KP1677; MIC=0.75 mg/L) showed acrAB overexpression. WGS revealed four genetic variations between KP1677 and KP1692. In addition, using site-directed mutagenesis, we confirmed that a 1 bp insertion in the ramA upstream region (RamR-binding site), leading to ramA and acrAB overexpression in KP1692, was responsible for tigecycline resistance. The in vivo virulence experiment showed that the TNS hvKp strain KP1692 still retained its high virulence compared with KP1677. Conclusions: hvKp strains accounted for 19.4% among TNS strains. We identified alterations in the ramA upstream region as a mechanism of in vivo tigecycline resistance development in an hvKp strain.

Original languageEnglish
Pages (from-to)309-317
Number of pages9
JournalJournal of Antimicrobial Chemotherapy
Issue number2
StatePublished - 01 02 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019 The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: [email protected].


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