Abstract: In order to survey the status quo of fish pathogens resistant to fluoroquinolones sourced from Beijing area, and provide the basis to regulate the fluoroquinolones used in fish farming,there were 16 pathogens isolated from diseased fish organs or focus with typical symtom in Beijing, and then the resistance phenotype of fish pathogens on seven kinds of fluoroquinolones were assayed by Kirby-Bauer disk diffusion method according to CLSI and the status of which carried gyrA,qnrA and qnrS genes were detected by PCR method. The data results showed that,on one hand,the rate of fish pathogens detected quinolones resistance gene-positive was higher than that of resistance phenotype,and the reason might be that the resistance genes detection were more exact than resistance phenotype tested. On the other hand, half of the fish pathogens resistant to a kind of fluoroquinolones at least, while 87.5% of the pathogens carried a quinolones resistance gene at any rate.Thereby,it was serious that the fish pathogens sourced from Beijing resistant to fluoroquinolones at genetic level, and it was necessary to strictly control these drugs used in fish farming.

Key words: Beijing; fish; pathogen; fluoroquinolone; drug-resistance