| Objective: To understand the drug sensitivity of E.coli in Luzhou,and to explore the distribution and resistant characteristics of qnrB,qnrS,qnrA genes for providing a better basis for clinical drug selection.Methods: 1.Preparation of experimental strains: 155 clinical isolates of bacteria had been recovered on the LB medium,and selected 1-2 well grown colonies to inoculate in the TSB broth nutrient solution.After 18 to 24 hours bacteria muddy had been placed in refrigerator at 4℃ and used for subsequent experiments.2.PCR detection: According to the bacterium TIANprep Mini Plasmid Kit manual,adequate bacteria was extracted plasmid DNA.Three pairs of primers and reaction solution were taken to prepare 25 ul reaction system for PCR amplification reaction.Amplified products were used for agarose gel electrophoresis,and used gel imaging analysis system to deal with and save the positive band diagram.The positive PCR products were sent to the Shanghai Sangon biotechnology companies to sequence.3.Drug sensitivity test: The K-B method(disk diffusion method)was used to test the drug sensitivity of 155 E.coli,and to observe drug resistance of antibiotics: amikacin(AMK),nalidixic acid(NA),gentamicin(GEN),ciprofloxacin(CIP),moxifloxacin(MXF),levofloxacin(LEV),cefotaxime(CTX),norfloxacin(NOR),ceftazidime(CAZ),imipenem(IPM),cefoperazone / sulbactam(SCF).4.ESBLs screening test: CTX and CTC,CAZ and CAC antibiotic disks wereused to do screening and confirmatory test,the results determine referenced NCCLS(US Committee for Clinical Laboratory Standards)Standards that the group with clavulanic acid inhibition zone diameter was greater or equal to5 mm than the group without clavulanic acid.Results: 1.PCR results: The qnr positive products had 29 strains,the detection rate was 20.65%.qnrA was detected 4,accounting for 2.58%;qnrB had 19(12.26%);qnrS had 9(5.8%).Three E.coli strains had been detected different types of qnr genes simultaneously,which were qnrA and qnrB,qnrB and qnrS,qnrA and qnrS respectively.2.Drug sensitivity test results: 1)The sensitive rate of 155 E.coli to MXF and IPM was 100%,to SCF 98.71%.The resistance rate of NA,CAZ,GEN,CTX,AMK,SCF,CIP,LEV,NOR was 70.97%,29.03%,49.03%,58.06%,2.58%,1.29%,51.61%,33.54%,54.84% respectively.2)The multi-drug resistant strains accounted for 28.39%,double resistant strains25.16%,single resistant strains 26.45%,all sensitive strains 20%.The mode of multi-resistant was mainly CAZ / CTX + GEN + NA / NOR / CIP(39,88.64%).The mode of double-resistant was mainly GEN + NA / NOR / CIP(23,58.97%).The mode of single resistant was mainly NA / NOR / CIP(25,60.98%).3.The situation of ESBLs: 97 strains were detected ESBLs(+)in 155 bacteria,accounting for 62.58%.In multi-drug resistant strains,ESBLs(+)bacteria accounted for 97.72%,double-resistant strains 89.74%,single-resistant strains 46.34%.4.Distribution of qnr genes: 1)There was no significant difference in resistant rate to 11 antibiotics(including quinolones)betweenqnr-positive strains and negative strains(P>0.05,statistically insignificant).2)The qnr genes were mainly in ESBL(+)strains.The detection rate of qnr genes was 72.41% in double-resistant strains and multi-drug-resistant strains(P <0.05,statistically significant).Conclusion: 1.The E.coli of clinical isolates to drug resistant of antibiotics are still quite serious in Luzhou.Multi-drug resistant and double resistant strains are common.2.ESBLs(+)bacteria detection rate of the clinical isolates is 62.58% in Luzhou,which mainly distributes in multi-drug-resistant and double-resistant strains.3.Detection rate of qnr gene is 20.65% in Luzhou.The qnr detection rate in ESBLs(+)bacteria is significantly higher than ESBLs(-).4.The qnr genes are mainly in multi-drug resistant and double-drug resistant strains. |
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