A Study On PCR To Detect Streptomycin And Kanamycin Resistant Gene AadA And AadB Of Swine Salmonella

The MICs of aminoglycoside (streptomycin, kanamycin, gentamicin and neomycin) of 16 pathogenic Salmonella strains from swine were performed by the disk diffusion method. According to the guidelines setted by the national committee for clinical laboratory standard in 1994, the results of MIC showed that the resistant rates of the streptomycin kanamycin gentamicin neomycin were 61.2%, 58.75%, 18.75% and 18.75% respectively. It showed these strains have resistance to streptomycin, kanamycin, gentamicin and neomycin. Different resistance rates resist in these strains. It proved that these strains have resistance to aminoglycoside.According to the published sequences of aadA gene which confers resistance to streptomycin and aadB gene which confers resistance to kanamycin, 2 pairs of primers were designed amplify the aadA gene and aadB gene by PCR respectively. The 530bp fragments of aadA gene of 10 salmonella was obtained by PCR in the plasmid, and 330bp fragments of aadB gene of 9 salmonella was obtained in the plasmid.The aadA gene of SLPS2-2, ZGPS2-1 and GHPS1 which are from different origin were sequenced and compared with the aadA gene of Salmonella Typhimurium which registed in the GenBank. Alignment of aadA gene of SLPS2, ZGPS2-1, GHPS1 with AY125351, the homology was 97%, 95.1% and 98.2% respectively. The homology between GHPS1 and SLPS2-2, DHPS1 and ZGPS2-1, SLPS2-2 and ZGPS2-1 was 95.2%, 93.1%, 92.1% respectively. The result showed that the identity among aadA was high.Through PCR condition selection, it suggests that PCR may be a useful way for detecting the aadA and aadB gene associated the resistance to streptomycin and kanamycin in salmonella.