Fluoroquinolone Resistance inStreptococcus pyogenes

Abstract
Streptococcus pyogenes isolated from blood and urine samples obtained from a 78-year-old woman was tested for susceptibility, and fluoroquinolone resistance (minimum inhibitory concentration of levofloxacin, 16 μg/mL) was found. DNA amplification and sequencing revealed a serine81→tyrosine substitution in gyrA and 2 substitutions in parC: serine79→phenylalanine and alanine121→valine. This is the second report of a clinical isolate of S. pyogenes with high-level fluoroquinolone resistance.