Levofloxacin treatment failure in a patient with fluoroquinolone-resistant Streptococcus pneumoniae pneumonia

Pharmacotherapy. 2002 Mar;22(3):395-9. doi: 10.1592/phco.22.5.395.33185.


The frequency of fluoroquinolone-resistant Streptococcus pneumoniae has increased as fluoroquinolone administration for treatment of respiratory tract infections has increased. Levofloxacin treatment failed in a patient who had pneumococcal pneumonia and had received three previous courses of levofloxacin therapy. Susceptibility testing revealed high-level resistance to levofloxacin (minimum inhibitory concentration [MIC] > 32 microg/ml), and cross-resistance to moxifloxacin (MIC 4 microg/ml), trovafloxacin (6 microg/ml), and gatifloxacin (12 microg/ml). Sequencing of the quinolone-resistance determining region revealed a mutation of serine-81 to phenylalanine (Ser81-->Phe) in the gyrA region of DNA gyrase and a Ser79-->Phe mutation in the parC region of topoisomerase IV The patient was treated successfully with intravenous ceftriaxone followed by oral cefprozil. Clinicians must be aware of local resistance patterns and the potential for fluoroquinolone treatment failures in patients with infections caused by S. pneumoniae.

Publication types

  • Case Reports

MeSH terms

  • Anti-Infective Agents / therapeutic use*
  • Colony Count, Microbial
  • DNA Gyrase / genetics
  • DNA Topoisomerase IV / genetics
  • Drug Resistance / genetics
  • Drug Resistance, Microbial / genetics
  • Humans
  • Levofloxacin*
  • Male
  • Middle Aged
  • Mutation
  • Ofloxacin / therapeutic use*
  • Pneumonia, Pneumococcal / drug therapy*
  • Streptococcus pneumoniae / drug effects*
  • Streptococcus pneumoniae / isolation & purification
  • Treatment Failure


  • Anti-Infective Agents
  • Levofloxacin
  • Ofloxacin
  • DNA Topoisomerase IV
  • DNA Gyrase