Detection of S83V GyrA mutation in quinolone-resistant Shewanella algae using comparative genomics

Chien Hao Tseng, Jan Fang Cheng, Shi Yu Chen, Wen Huei Chen, Zhi Yuan Shi, Yu Hui Lin, Che An Tsai, Shih Ping Lin, Yung Chun Chen, Yu Chia Lin, Yao Ting Huang, Po Yu Liu

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Background: Shewanella algae is a zoonotic pathogen that poses a serious health threat to immunocompromised hosts. Treatment of S. algae infections is challenging due to the pathogen's intrinsic resistance to a variety of β-lactam antibiotics. Therapeutic options have become further limited by the emergence of quinolone-resistant strains. Currently, there are few studies concerning the genetic and molecular mechanisms underlying acquired quinolones resistance in S. algae. qnrA was once proposed as the candidate gene related to quinolones resistance in S. algae. However, recent studies demonstrated qnrA are highly conservative and does not confer resistance to quinolones in S. algae. Methods: A total of 27 non-duplicated isolates of S. algae strains were examined. MICs of ciprofloxacin were determined using Vitek 2. Whole genome sequencing was performed using MiSeq platform. Comprehensive Antibiotic Resistance Database and ResFinder were used for annotation of quinolones resistance genes. Multiple sequence alignment by EMBOSS Clustal Omega were used to identified mutation in quinolone resistance-determining regions. To investigation of the alteration of protein structure induced by mutation, in silico molecular docking studies was conducted using Accryl Discovery studio visualizer. Results: All S. algae harbored the quinolone-resistance associated genes (qnrA, gyrA, gyrB, parC, and parE) regardless its resistance to ciprofloxacin. Comparison of these genomes identified a nonsynonymous mutation (S83V) in chromosome-encoded gyrase subunits (GyrA) in quinolone-resistant strain. We found this mutation disrupts the water-metal ion bridge, reduces the affinity of the quinolone-enzyme complex for the metal ions and therefore decrease the capability of quinolones to stabilize cleavage complexes. Conclusions: The study provides insight into the quinolone resistance mechanisms in S. algae, which would be helpful for the evolution of antibiotic resistance in this bacterium.

Original languageEnglish
Pages (from-to)658-664
Number of pages7
JournalJournal of Microbiology, Immunology and Infection
Issue number4
Publication statusPublished - Aug 2021


  • DNA Gyrase
  • Quinolones
  • Shewanella algae
  • Susceptibility

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology and Microbiology(all)
  • Microbiology (medical)
  • Infectious Diseases


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