Discrepancy between minimal inhibitory concentration to enrofloxacin and mutations present in the quinolone-resistance determining regions of Mycoplasma gallisepticum field strains

Molecular characterization of the quinolone-resistance determining regions (QRDRs) of DNA gyrase and topoisomerase IV in 93 Mycoplasma gallisepticum field strains isolated in different geographic regions revealed discrepancies between minimal inhibitory concentration values and presence of amino acid substitutions within the QRDRs of GyrA and ParC in 9/93 (10%) strains. This may delimitate applicability of a gene-based assay to detect fluoroquinolone resistance in this avian pathogen.