Nemonoxacin has potent activity against gram-positive, but not gram-negative clinical isolates

Objective. The aim of the current study was to analyze the susceptibility of gram-positive and -negative clinical isolates to a novel des-F(6)-quinolone (nemonoxacin) and other selected antimicrobial agents. Materials and Methods. Minimal inhibitory concentrations (MICs) were determined by the agar plate dilution method according to NCCLs. Results Nemonoxacin exhibited greater antimicrobial activity than other quinolones, such as ciprofloxacin, levofloxacin, and moxifloxacin, and other antimicrobials when tested against selected gram-positive organisms. This non-fluorinated quinolone was especially active against streptococci and staphylococci, including multi-resistant Streptococcus pneumoniae and methicillin-resistant Staphylococcus aureus (MRSA). Compared with ciprofloxacin, levofloxacin, and moxifloxacin, and other antimicrobials, nemonoxacin was not highly active against all tested gram-negative clinical isolates, with an MIC 90 of 8-32 mu g/mL. Conclusions. Nemonoxacin has powerful antibacterial activity against gram-positive strains and has value in treating quinolone-resistant clinical isolates of MSSA, MRSA, and S. pneumoniae infections. Nemonoxacin should not be the first choice to treat gram-negative clinical isolate infections.