Clinical isolates of Streptococcus pneumoniae resistant to levofloxacin contain mutations in both gyrA and parC genes

Xiaotian Zheng*, Crystal Johnson, Yuanan Lu, Richard Yanagihara, Susan Hollingshead, Marilyn Crain, William Benjamin, Ken B. Waites

*Corresponding author for this work

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Thirty Streptococcus pneumoniae clinical isolates resistant to levofloxacin were analyzed for the quinolone resistance-determining DNA sequences to identify point mutations and were tested for in vitro susceptibility to multiple drug classes. Of these isolates, 29 had mutations in both gyrA and parC genes of DNA gyrase and topoisomerase IV, respectively. In GyrA, an amino acid change from Ser-81→Phe was detected in 27 isolates and a Glu-85→Lys change was found in the remaining three. Of the 29 isolates for which ParC data were available, Ser-79→Tyr or Phe were the predominant mutations observed. MICs for levofloxacin were 4-16 mg/l, whereas those for moxifloxacin were 1-2 mg/l. Twenty-four (80%) isolates were susceptible to erythromycin, 25 (83%) to azithromycin, 26 (87%) to clarithromycin, 27 (90%) to clindamycin, 20 (67%) to penicillin, 21 (70%) to ceftriaxone and 30 (100%) to amoxycillin/clavulanate. These results confirm the presence of double mutations among clinical isolates of S. pneumoniae from diverse geographical regions of North America and also suggest that quinolone resistance may develop independently of resistance to other drug classes.

Original languageEnglish (US)
Pages (from-to)373-378
Number of pages6
JournalInternational Journal of Antimicrobial Agents
Volume18
Issue number4
DOIs
StatePublished - Nov 10 2001

Keywords

  • Fluoroquinolones
  • QRDR
  • Serotypes
  • Streptococcus pneumoniae
  • Susceptibility testing

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)

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