The Study Of Fluoroquinolone Resistance In Escherichia Coli Isolate From Chicken

Objective:The purposes of this experiment is to make use of molecular biology, to test fluoroquinolones resistance of E.coli from chicken in taiyuan area and to discuss gene mutations of Topoisomerase and OmpC,OmpF in Quinolone Resistance-Determining Regions.Methods : Using the disk diffusion tests way to screen out 12 strains of fluoroquinolones-resistant E.coli in 30 strains of E.coli gathered by farming graduate school of Shanxi province. The 12 strains fluoroquinolone isolates were exemined with polymerase chain reaction(PCR). 4 of the 12 strains were chosen for measuring genic sequence. Analysing the outer membrance protien of the 12 strains quinolone isolates with SDS-PAGE electrophoresis, and analysing the spreading trend with PFGE.Results:12 strains of E.coli that is the 40% of the sample ,were risistant to Ciprofloxacin; gyrA,gyrB,parC,parE,ompF,and ompC had formed clear aim strip in the gel in PCR experiment. SDS-PAGE experiments showed that OmpC of No.4 and No.5 were not expressed; analysis of Pulsed Field Gel Electrophoresis result showed that small-range prevalence and probability of eruption was on the lower level. The results indicated that there are alterations in GyrA located at the amino acids positions to Ser-83 and/or Asp-87 in the screend E.coli. On the side No.5 strain :Ser→80→Leu in parC; NO.6 strain : Glu→84→Lys in ParC ; No.5 strain: Ser→89→Ala in ParE.Conclusion:Having screened out the fluoroquinolone-resistant E.coli from the farming graduate school in shanxi province, The main mechanism of which was mutation which came from 83th and/or 87th amino acids of gyrase .Meanwhile, corresponding mutation from parC and parE may be the main factor that leads high level resitance to fluoroquinolones.