title: In vitro activity of nemonoxacin (TG-873870), a novel non-fluorinated quinolone, against clinical isolates of Staphylococcus aureus, enterococci and Streptococcus pneumoniae with various resistance phenotypes in Taiwan.
abstract: OBJECTIVE
  The aim of this study was to assess the in vitro activities of nemonoxacin against Gram-positive cocci with various resistance phenotypes.
  
  
  METHODS
  MICs of nemonoxacin were determined for 798 recently collected (2005-07) and non-duplicate isolates of Gram-positive cocci by the agar dilution method. These isolates included: methicillin-susceptible Staphylococcus aureus (MSSA; n = 100); methicillin-resistant S. aureus (MRSA), including ciprofloxacin-susceptible (n = 50), ciprofloxacin-resistant (n = 100), vancomycin-intermediate (n = 50) and daptomycin-non-susceptible (DNS-MRSA; n = 5) isolates, and community-acquired MRSA (CA-MRSA; n = 101); invasive Streptococcus pneumoniae isolates (n = 150); levofloxacin-non-susceptible (MICs of 4-64 mg/L) S. pneumoniae isolates (n = 30); and enterococci (n = 212), including vancomycin-resistant enterococci (VRE; n = 112).
  
  
  RESULTS
  Nemonoxacin had potent activity against MSSA (MIC(90) of < or =0.03 mg/L), ciprofloxacin-susceptible MRSA (MIC(90) of < or =0.03 mg/L) and CA-MRSA (MIC(90) of 0.06 mg/L). For all invasive S. pneumoniae isolates, the activity of nemonoxacin (MIC(90) of 0.06 mg/L) was similar to that of gemifloxacin and much better than that of levofloxacin (MIC(90) of 2 mg/L) and moxifloxacin (MIC(90) of 0.25 mg/L). Nemonoxacin had a 32- to 64-fold higher activity than levofloxacin against levofloxacin-non-susceptible isolates. Nemonoxacin exerted limited activity against ciprofloxacin-resistant MRSA (MIC(90) of 1 mg/L), vancomycin-intermediate MRSA (MIC(90) of 2 mg/L), DNS-MRSA (MIC(90) of 1 mg/L), vancomycin-susceptible enterococci (MIC(90) of 2 mg/L for Enterococcus faecalis and 4 mg/L for Enterococcus faecium) and VRE (MIC(90) of 4 mg/L for E. faecalis and 16 mg/L for E. faecium).
  
  
  CONCLUSIONS
  Our findings point to a potentially useful role for nemonoxacin in the treatment of infections caused by MSSA, ciprofloxacin-susceptible MRSA and S. pneumoniae with various resistance phenotypes.
authors.affiliation: Department of Internal Medicine, Chung-Ho Memorial Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Yen-Hsu
authors.initials: YH
authors.lastname: Chen
authors.forename: Chia-Ying
authors.initials: CY
authors.lastname: Liu
authors.forename: Jang-Jih
authors.initials: JJ
authors.lastname: Lu
authors.forename: Chi-Hsin R
authors.initials: CH
authors.lastname: King
authors.forename: Po-Ren
authors.initials: PR
authors.lastname: Hsueh
mesh_terms: D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D024881:Drug Resistance, Bacterial; D016983:Enterococcus / Q000187:drug effects* / Q000302:isolation & purification; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D020125:Mutation, Missense; D015363:Quinolones / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000302:isolation & purification; D013624:Taiwan
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015363:Quinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; C543520:nemonoxacin