Cloning and Sequence Analysis of AcrA Gene of Fluoroquinolones-resistant Salmonella Isolated from Chickens

摘要

Nine strains resistant to five fluoroquinolones ( Ciprofloxacin, Ofloxacin, Enrofloxacin, Danofloxacin, Sarafloxacin) were isolated from clinical samples and extracted the chromosomal DNA of these strains. Designed primers to amplify the whole sequnceol avrA gene, then the PCR products of strain 37, 38 and 42 were cloned and the sequences were analyzed. In comparison with the standarded strain NCTC5776, no mutation was found in acrA of strain 38, a single mutation was found at base 97 in acrA of strain 42 which changed from A to G, and several mutations were found in acrA of strain 37. The mutation of strain 42 led to an amino acid substitution of Thr29Ile and the mutations of 37 led to several amino acids substitution. The result indicated that the acrA gene has some relationship with fluoroquinolone resistance to salmonella.