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Table 2 Mutations in topoisomerase IV (ParC and ParE) and gyrase (GyrA and GyrB) genes before and after cyclic exposure to ciprofloxacin, trovafloxacin, or either of these drugs plus vancomycin in a penicillin-resistant pneumococcal strain

From: Sub-inhibitory concentrations of vancomycin prevent quinolone-resistance in a penicillin-resistant isolate of Streptococcus pneumoniae

Strain ParC ParE GyrA GyrB
WB4 None none none none
WB4C Ser79 → Tyr none none Asp435 → Glu
WB4T Ser79 → Phe none Ser81 → Phe none
WB4 C+V Ser79 → Tyr none none none
WB4 T+V None none none none
  1. WB4: quinolone-susceptible but penicillin-resistant parent pneumococcus; WB4 C: ciprofloxacin-resistant derivative selected by passages on this drug; WB4 T: trovafloxacin-resistant derivative selected by passages on this drug; WB4 C+V or WB4 T+V: same as above cycled in presence of subinhibitory concentrations of vancomycin.