MUTATIONS IN THE GYRA AND PARC GENES ASSOCIATED WITH FLUOROQUINOLONE RESISTANCE IN CLINICAL ISOLATES OF CITROBACTER-FREUNDII

We determined partial sequences of the gyrA and parC genes of Citrobac ter freundii type strain, and then examined 38 C. freundii clinical st rains isolated from patients with urinary tract infections for the ass ociation of alterations in GyrA and ParC with susceptibility to fluoro quinolones. Our results suggest that in C. freundii DNA gyrase may be a primary target of quinolones, that an amino acid change at Thr-83 or Asp-87 in GyrA is sufficient to decrease susceptibility to fluoroquin olones, and that accumulation of changes in GyrA with the simultaneous presence of an alteration at Ser-80 or Glu-84 in ParC may be associat ed with the development of high-level fluoroquinolone resistance in C. freundii clinical isolates.