Analysis On Some Resistant Genes Of Escherichia Coli With Multiple Drug Resistance

The Escherichia coli is the most common pathogenic bacilli both on the medicineand the clinical veterinarian, the pathogenic can cause young pig's yellow diarrheaand white diarrhea,and pig's hydropsy, and so on. Along with the antibiotic'swidespread application on the veterinarian clinical, The Escherichia coli start to appearthe drug resistance, even appears the multiple drug resistance. The paper conducts theresearch mainly from three aspects, the identification of the Porcine Escherichia colifrom clinical separation, the detection on some resistant genes of Escherichia coli, andthe expression of the AcrA gene. the results are as follows:1) Twenty-seven Escherichia coli strains are affirmed by the morphological andbiochemical identification through ninety-nine pathogenic bacteria collected fromdifferent places of Hunan Province. Do antibiotics sensitivity test on the Twenty sevenEscherichia coli strains using thirty-two kinds of commonly used antibiotics, theresults show that Z16 is not sensitive to all antibiotics, and Z01, Z08, Z12, Z27, Z34are only sensitive to the polymyxin B.2) The ERIC-PCR method is used for the identification of Z16, Z01, Z08, Z12,Z27, Z34,which have different belt styles by comparing the electrophoretic picture.According to the resistant style of Z16, some resistant genes of the cephalosporin,aminolycoside and Quinolone are detected, cloned, and analyse with the determinedsequences. Results show that the ACT genotype in AmpCβ-lactamase, the aph (3')—Ⅱgene in AMEs,the gyrA and parC genes in Quinolone are all determined; bysequence comparison and found that gyrA and parC genes have 1-2 amino acidmutations both in plasmid and chromosome. Suggests that the presence of theseresistant genes and the amino acid mutations have a certain relation with the drugresistant level of Z16.3) A pair of gene-specific primers are designed to amplify the DNA fragment withlength of 696 bp. The aplified DNA were subcloned into the pET28a (+) plasmidvetor, and the transformant was efficiently expressed after being transformed into thebacterial host BL21 (DE3).Do antibiotics sensitivity test on its recombinant strains ,but no resistance of Quinolone can be found.