Fluoroquinolone-nonsusceptible Streptococcus pneumoniae isolates from a medical center in the pneumococcal conjugate vaccine era

Hsin Hang Chen, Hsin Chieh Li, Lin Hui Su*, Cheng Hsun Chiu

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

9 Scopus citations


Background/Purpose Streptococcus pneumoniae is one of the most common pathogens to cause mucosal and invasive infection in humans. Resistance to fluoroquinolones (FQ) is associated with clinical failure when treating pneumococcal diseases and increase of mortality. Methods We collected clinical isolates of S. pneumoniae from January 2011 to July 2015 at Chang Gung Memorial Hospital, Taoyuan, Taiwan. Susceptibility to FQ was examined by disk diffusion method. Levofloxacin or moxifloxacin-nonsusceptible S. pneumoniae isolates were analyzed by serotyping, multilocus sequence typing, and sequencing of the quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC, and parE. Results During the study period, 42 FQ-nonsusceptible pneumococcal isolates were identified. The rate increased from 1.6% of total pneumococcal isolates (2 of 127) in 2011 to 4.6% (13 of 283) in 2014, then decreased to 1.5% (3 of 202) in the first half of 2015. These isolates belonged to 13 serotypes, and serotype 14 (12 of 42, 33.3%) was the most prevalent. Most of the isolates belonged to international clones or their variants. After QRDR analysis, there were 19 isolates in five clusters that shared both the same sequence type and QRDR mutation. Conclusions FQ resistance initially emerged in either vaccine or nonvaccine serotypes. The majority of isolates were international clones or related variants, suggesting that resistance was disseminated through clonal spread. The wide use of pneumococcal conjugate vaccine since 2013 appears to have reduced the spread of FQ-nonsusceptible pneumococci.

Original languageEnglish
Pages (from-to)839-845
Number of pages7
JournalJournal of Microbiology, Immunology and Infection
Issue number6
StatePublished - 12 2017

Bibliographical note

Publisher Copyright:
© 2016


  • Fluoroquinolone
  • Streptococcus pneumoniae
  • pneumococcal conjugate vaccine
  • resistance


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