| This experiment aimed to study Staphylococcus aureus main biological characteris tics and the correlation of resistance with resistant genes. Staphylococcus aureus isol ated from intensive dairy farms in province of Hebei including Shijiazhuang, Baodin g, Langfang, Chengde, Xingtai, Zhangjiakou, Tangshan. By means of biochemical te sts and polymerasechain reaction(PCR) isolated and identified 109 strains of Staph ylococcus aureus bacteria. According to WHO recommended Kirby-Bauer bacteria li quid coating method, 109 strains of staphylococcus aureus were processed sensitivet est on 38 kinds of antibiotic drugs. The results indicated that 109 strains of staphyl ococcus aureus have different levels of resistance to various antibiotics, and were c haracterized by multiple drug resistance. Relatively sensitive were Cephalosporin and Aminoglycoside antibiotics, among them with Cefradine, Cefalexin, Gentamycin, Am ikacin, Cefepime, Neomycin most sensitive. To Sulfa drugs, Penicillin antibiotics, Li ncosamide antibiotics, Macrolide, Tetracycline, Antibiotics were serious drug resistan ce, Sulfafurazole, Ampicillin, Trimethoprim and Trimethoprim-sulfamethoxazole, Amo xicillin, Doxycycline, Erythromycin, Clarithromycin, Azithromycin and Clindamycin resistance most serious. Drug sensitive test provided scientific basis and medical gui dance for dairy cow mastitis treatment of Hebei. In addition, Using PCR technolog y detected 8 class antibiotic resistance genes from 109 strains of Staphylococcus au reus. Results are as follows:(1) Sulfa drug resistance gene sul1, sul2, sul3 positive rate were 45.87%, 6.42%, 1.83%, 55 strains of bacteria contain this kindof resistanc e genes, the overall detection rate was 50.46% without carrying three strains of dru g-resistant genes;(2) Tetracyclines drug-resistant genes, tet A, tet B, tet C, tet M positiv e rate was 41.28%, 18.35%, 43.12%, 18.35%, 88 strains of bacteria were cloned tet racycline resistance genes, the total separation rate was 80.73%, one strain carrying four resistance genes, 21 strains of bacteria didn’t contain any this kind of resistant genes;(3) Aminoglycoside resistance gene aac(6′)/aph(2″) the total detection rate w as 66.97% and other 36 strains of bacteria didn’t carried the drug resistant genes;(4) Beta lactam type of resistant genes mec A positive rate was 0%, but fem A was 100%, visibly derived that the resistant mechanism of test strains in beta lactam ant ibiotics is mainly mediated by fem A gene;(5) Macrolides-lincosamid drug-resistant genes erm A and erm C positive rate was 98.17% and 62.39%, all strainswere carryin g such resistance genes, and the total detection rate was 100%;(6) Quinolone resist ant gene nor A, detection rate was 59.26%, randomly selected from 30 strains of res istance to quinolones, to grl A and gyr A with QRDR gene sequence detection, found that grl A gene encoding the 80 th amino acid mutations, gyr A gene encoding the 84 th amino acid mutations, and 16 strains double mutation happened with gyr A and g rl A;(7) Chloramphenicol resistant genes cml A, cat1 and flor corresponding positive rates were 0%, 22.02%, 33.03%, 54 strains without any chloramphenicol resistant g enes, were accounting for 45.54%;(8) Being sugar peptide drug resistant genes van A,van B for testing, the positive rate was 66.97% and 63.30% respectively, there were51 strains of bacteria were living with two resistant genes, accountedfor 46.79%, wi thout any strains of drug-resistant genes had 13 strains, accounting for 11.93%. The above all kinds of drug resistant genes detection revealed the mainresistant mechani sm,and provided reference data of raw milk Staphylococcus aureus resistance epide miological investigation in Hebei province. |
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