Authors : Jian Li, Dian-Hong Lu, Zhi-Jie Liu, Xiao-Hua Zhang, Fei-Long Wei, Ya-Hong Liu and Hong-Xia Jiang
Abstract: The role of mutations in genes for GyrA, GyrB, ParC and ParE in fluoroquinolone-resistance in Mycoplasma gallisepticum obtained in vitro and in vivo was studied. M. gallisepticum mutants were generated by stepwise selection in either 1/2xMIC or escalating concentration of enrofloxacin or ciprofloxacin. Seven fluoroquinolone-resistant clinical isolates of M. gallisepticum recovered from commercial poultry flocks with suspected chronic respiratory disease were recruited for the mutation detection of four target genes. The evolution of resistance in M. gallisepticum was more readily and more quickly with enrofloxacin selection than with ciprofloxacin selection. Selection with enrofloxacin gave mutations at GyrA83 (Ser→Ile) firstly and subsequent additional mutation at GyrA82 or GyrA103, combining substitution at ParC80 in association with high-level resistance to FQs. Selection with ciprofloxacin gave primary change at Gyr87 and subsequent additional alteration at ParC80, elevating the MICs for FQs significantly. The presence of alterations of both the GyrA and ParC in 7 clinical isolates of M. gallisepticum is in good agreement with the results from mutants selected in vitro. No mutations in GyrB and ParE were found in mutants selected both in vitro and in vivo.
Jian Li, Dian-Hong Lu, Zhi-Jie Liu, Xiao-Hua Zhang, Fei-Long Wei, Ya-Hong Liu and Hong-Xia Jiang, 2012. Role of Mutations in DNA Gyrase and Topoisomerase IV in Fluoroquinolones-Resistance of Mycoplasma gallisepticum Obtained in vitro and in vivo. Journal of Animal and Veterinary Advances, 11: 2327-2332.