Staphylococcus aureus Mutants Isolated via Exposure to Nonfluorinated Quinolones: Detection of Known and Unique Mutations SIDDHARTHA ROYCHOUDHURY,* TRACY L. TWINEM, KELLY M. MAKIN, MARK A. NIENABER, CHUIYING LI, TIMOTHY W. MORRIS, BENOIT LEDOUSSAL, AND CARL E. CATRENICH Procter & Gamble Pharmaceuticals, Mason, Ohio 45040 Received 16 May 2001/Returned for modification 9 July 2001/Accepted 7 September 2001
The in vitro development of resistance to the new nonfluorinated quinolones (NFQs; PGE 9262932, PGE 4175997, and PGE 9509924) was investigated in Staphylococcus aureus. At concentrations two times the MIC, step 1 mutants were isolated more frequently with ciprofloxacin and trovafloxacin (9.1 ⴛ 10ⴚ8 and 5.7 ⴛ 10ⴚ9, respectively) than with the NFQs, gatifloxacin, or clinafloxacin (
