Study On Drug Resistance Of Salmonella And E.coli From Swine And Chicken And Detection Of Ⅰ Integron

Salmonella and E.coli are the most popular pathogeny bacteria in clinic with serious harm to human' health and the development of husbandry.As antibacterial is widely used ,the problem of drug-resistance increased seriously. Study on drug-resistance of Salmonella and E.coli ,amplifying I integron can help us make clear of the mechanism of drug-resistance transferring in gene level.According to the method of K-B,we mensurated drug-resistance rate of 42 Salmonella strains from Swine ,19 Salmonella strains from Chicken and 48 E.coli strains from Swine which are resistant to amikacin, kanamycin, gentamicin,neomycin, streptomycin,tetracycline, doxycycline,sulfuamethoxazole,cloramphenicol,amplocilin, cefepine, cefalexin, norfloxacin. Drug resistance was determined by the standard of NCCLS(2004) .Results showed that 61 Salmonella and 48 E.coli were highly resistant to tetracycline, doxycycline and sulfuamethox-azole,the resistance rate was between 89.58%~98.36%;the rate of drug-resistance to streptomycin and amplocilin exceeded 80%.Tested strains presented on multi-drug resistance, strains resistanting three medicines have reached 56 and 48 in 61 Salmonella and 48 E.coli.The multi-drug resistance rate of Salmonella and E.coli were 91.80% and 100%.According to the genes sequence published in Genbank ,we analysed the value of Tm ,content of G+C, oligonucleotide dimer by DNAStar and Primer 5.0 software, and according to the construction of I integron ,we designed 3 pairs of primers to amplify intIl gene ,variable segment ,3'-conserved segment for detectting Salmonella and E.coli's I integron.As a result , aimed genes were amplified and sequenced;The detection rate of I integron of 61 Salmonella and 48 E.coli were 81.97% and 66.67%.Among 56 multi-drug resistance strains of Salmonella , I integron was detected in 50 strains ,the detection rate was 89.29%,and no I integron was detected in 5 nonmulti-drug resistance strains.Among 48 multi-drug resistance strains of E.coli , I integron was detected in 32 strains ,the detection rate was 66.67%.We use endonuclease Hinfl to digest PCR products of the variable segment ,the result was that the variable segment with the same length has the same cleavage map,the different length has different cleavage map .The results showed that the variable segment with same length carrying the same gene cassette.We mensurated the sequence of different length of variable region PCR products,using Blastn in Genbank to analysis the gene cassettes that variable region carried ,the results show-...