By means of mathematical modeling methods, we analyzed the relationship between the resistance to fluoroquinolones and GyrA mutation of Salmonella from animal isolates. We found that considering the influence of the resistance to ciprofloxacin hydrochloride, enrofloxacin, ofloxacin, pefloacin mesylate and norfloxacin nicotinate of the five types of fluoroquinolones to GyrA mutation of animal Salmonella, the resistance of pefloacin mesylate had the most significant effect, while the resistance of ciprofloxacin hydrochloride and enrofloxacin were the least significant factors. Nearly half of the Salmonella supports such a rule that the MIC of norfloxacin nicotinate reaching 64 or 128 might lead to the mutation Ser83→Phe, MIC exceeding 512 might lead to the mutation Ser83→Gly; 60% of the sample supported that the MIC of enrofloxacin reaching 32 or 64 might lead to the mutation Asp87 →Asn. 80% of them agreed to the fact that the MIC of neither ciprofloxacin hydrochloride under 64 nor pefloacin mesylate below 512 might result in the gene mutation in 119 site. All Salmonella isolates supported the conclusion that the mutation Alal19→Val took place, if and only if the MIC of norfloxacin nicotinate exceeded 512.
