Overproduction of active efflux pump and variations of OprD dominate in imipenem-resistant Pseudomonas aeruginosa isolated from patients with bloodstream infections in Taiwan

Cheng Yen Kao, Shu Sheng Chen, Kuei Hsiang Hung, Hsiu Mei Wu, Po Ren Hsueh, Jing Jou Yan, Jiunn Jong Wu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

Background: The emergence of imipenem-resistant Pseudomonas aeruginosa (IRPA) has become a great concern worldwide. The aim of this study was to investigate resistance mechanisms associated with bloodstream isolated IRPA strains in Taiwan. Results: A total of 78 non-duplicated IRPA isolates were isolated from patients with bloodstream infection. The average prevalence of imipenem-resistance in those isolates was 5.9 % during a 10-year longitudinal surveillance in Taiwan. PFGE results showed high clonal diversity among the 78 isolates. VIM-2, VIM-3, OXA-10, and OXA-17 β-lactamases were identified in 2 (2.6 %), 3 (3.8 %), 2 (2.6 %), and 1 (1.3 %) isolates, respectively. Active efflux pumps, AmpC β-lactamase overproduction, and extended-spectrum AmpC cephalosporinases (ESACs) were found in 58 (74.4 %), 25 (32.1 %) and 15 (19.2 %) of IRPA isolates, respectively. oprD mutations with amino acid substitution, shortened putative loop L7, premature stop codon caused by point mutation, frameshift by nucleotide insertion or deletion, and interruption by insertion sequence were found in 19 (24.4 %), 18 (23.1 %), 15 (19.2 %), 14 (17.9 %), and 10 (12.8 %) of isolates, respectively. Conclusions: This study suggests that alterations in the OprD protein and having an active efflux pump are the main mechanisms associated with bloodstream isolated IRPA. Overproduction of AmpC, ESACs, and the presence of VIM- and OXA-type β-lactamases play additional roles in reduced susceptibility to imipenem in P. aeruginosa isolates in Taiwan.

Original languageEnglish
Article number107
JournalBMC Microbiology
Volume16
Issue number1
DOIs
StatePublished - 13 Jun 2016

Keywords

  • Efflux pump
  • Imipenem
  • OprD
  • Pseudomonas aeruginosa
  • β-lactamase

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