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In vitro Quinolones Susceptibility Analysis of Chinese Mycoplasma bovis Isolates and their Phylogenetic Scenarios based upon QRDRs of DNA Topoisomerases Revealing a Unique Transition in ParC
Riaz Mustafa1,2,3, Jingjing Qi1,2, Xiaoliang Ba1,2, Yingyu Chen1,4, Changmin Hu1,2, Xiaole Liu1,2, Lingling Tu5, Qingjie Peng5, Huanchun Chen1,2 and Aizhen Guo1,2*
1State Key Laboratory of Agriculture Microbiology, Huazhong Agriculture University, Wuhan 430070, China; 2College of Veterinary Medicine, Huazhong Agriculture University, Wuhan 430070, China; 3Department of Pathology, Faculty of Veterinary Science, University of Agriculture, Faisalabad-38040, Pakistan; 4College of Animal Science, Huazhong Agriculture University, Wuhan 430070, China; 5Wuhan Keqian Animal Biological Products Co Ltd, Wuhan 430070, China *Corresponding author:


Mycoplasma bovis can cause different systemic problems in cattle, and recently has been resulted in huge economic losses in China. In vitro susceptibilities of 26 twice sub-cultured Chinese M. bovis field isolates were determined at physiological pH including PG45 through broth micro-dilution method. Except Huanggang isolate, all isolates and PG45 were in the sensitive range for levofloxacin, lomefloxacin and ciprofloxacin, whereas, for norfloxacin and nalidixic acid, they had shown intermediate resistant and complete resistant patterns, respectively. The multiple sequence analysis revealed point mutations in QRDRs of gyrA and parC genes of Huanggang isolate resulting in amino acid substitutions at positions 83 (S-F) in GyrA (E. coli numbering) and 80 (S-I) in ParC proteins, the latter is reported for first time in M. bovis. Conclusively, fluoroquinolones are the potential veterinary therapeutic agents for mycoplasmosis in China and resistance to these agents comes through point mutations in QRDRs of gyrA and parC genes with ParC and GyrA mutation orientation.

Key words: Huanggang, MICs, Mollicutes, QRDRs, Quinolones, Topoisomerases


ISSN 0253-8318 (Print)
ISSN 2074-7764 (Online)