Effect of pH on antimicrobial activity of delafloxacin against <i>Escherichia coli</i> isogenic strains carrying diverse chromosomal and plasmid-mediated fluoroquinolone resistance mechanisms.

ABSTRACT: The aim of this study is to evaluate the pH-dependent antimicrobial activities of delafloxacin against isogenic Escherichia coli strains carrying diverse fluoroquinolone resistance mechanisms. Eighty-one isogenic E. coli strains derived from ATCC 25922 were tested, carrying various combinations of chromosomal mutations (gyrA, parC), efflux pump overexpression (marR), and plasmid-mediated quinolone resistance (PMQR) determinants (qnrA1, qnrB1, qnrC, qnrD1, qnrS1, qepA2, aac(6')-Ib-cr). Minimum inhibitory concentrations (MICs) were determined using broth microdilution at pH 7.3, 6.0, and 5.0. Time-killing assays were performed on three representative strains. Semi-mechanism-based mathematical modeling using Monolix quantified bactericidal activity through E

SUBMITTER: Alexandre K 

PROVIDER: S-EPMC12671115 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature