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Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
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Molecular characterization of quinolone-insensitive Streptococcus pneumoniae isolates from Japanese patients

Nobuko Araki1, Katsunori Yanagihara, Yoko Matsukawa

  • 1Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, Japan.

Journal of Infection and Chemotherapy : Official Journal of the Japan Society of Chemotherapy
|August 23, 2012
PubMed

Insights

Fluoroquinolone resistance in Streptococcus pneumoniae is increasing. New data show that while some fluoroquinolones maintain potent activity, mutations in parC and gyrA genes correlate with higher minimum inhibitory concentrations (MICs).

Area of Science:

  • Microbiology
  • Molecular Biology
  • Pharmacology

Background:

  • Increasing fluoroquinolone resistance in Streptococcus pneumoniae poses a significant public health challenge.
  • Understanding resistance mechanisms is crucial for effective antibiotic treatment strategies.

Purpose of the Study:

  • To investigate the susceptibility of levofloxacin-resistant Streptococcus pneumoniae isolates to other fluoroquinolones.
  • To identify genetic mutations in the quinolone resistance-determining regions of parC and gyrA genes associated with resistance.

Main Methods:

  • Sixty-one Streptococcus pneumoniae isolates with minimum inhibitory concentrations (MICs) of levofloxacin ≥ 1 μg/ml were tested.
  • Susceptibility testing was performed for ciprofloxacin, pazufloxacin, moxifloxacin, garenoxacin, and sitafloxacin.
  • Sequencing of parC and gyrA genes was conducted to identify mutations.

Main Results:

  • Increasing numbers of missense mutations in parC and gyrA correlated with elevated MIC values for all tested fluoroquinolones.
  • Moxifloxacin, garenoxacin, and sitafloxacin demonstrated potent activity against the resistant isolates.
  • Ciprofloxacin and pazufloxacin exhibited higher MICs compared to levofloxacin.

Conclusions:

  • Specific mutations in parC and gyrA are associated with fluoroquinolone resistance in Streptococcus pneumoniae.
  • Moxifloxacin, garenoxacin, and sitafloxacin represent potentially effective treatment options for levofloxacin-resistant S. pneumoniae infections.
  • Continued surveillance of fluoroquinolone resistance patterns and underlying genetic mechanisms is essential.

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