The Detection And Clinical Distribution Of Bla TEM/bla CTX-M In Multiple Drug-resistant Escherichia Coli

Objective: To investigate the drug resistance and resistance pattern of multiple drug-resistant Escherichia coli(E.coli),and to research the clinical distribution of bla TEM,bla CTX-M in multiple drug-resistant E.coli isolated from The Affiliated Hospital of Southwest Medical University.Methods: 1.The drug sensitivity test(K-B method): To detect the drug-resistance of the experimental strains to the following antibiotics:Ceftazidime(CAZ)、Ceftazidime/Clavulanic acid(CCV)、Cefotaxime(CTX)、Cefotaxime/Clavulanic acid(CTC)、 Ceftriaxone(CRO)、 Cefuroxime(CXM)、Cefazolin(CZO)、Cefoxitin(FOX)、Piperacillin(PIP)、 Piperacillin Tazobactam(TZP)、 Aztreonam(ATM)、 Imipenem(IMP)、 Moxifloxacin(MXF)、Levofloxacin(LEV)、Ciprofloxacin(CIP)、Norfloxacin(NOR)、 Nalidixic acid(NAL)、 Gentamicin(GEN)、 Streptomycin(STR)、 Amikacin(AMK)and Compound sulfamethoxazole(SMZ/TMP).2.The confirmatory test of ESBLs: The double-disk diffusion method was used for the confirmatory test of ESBLs,using two pairs of drug sensitive piece of paper CAZ/CCV,CTX/CTC,according to the CLSI2012(Clinical and Laboratory Standards Institude,the American Association of Clinical and Laboratory Standards)recommended standards.3.Polymerase chain reaction(PCR)assay: Extracted the plasmid DNA of 153 E.coli strains,PCR amplification was performed using the synthesized bla TEM and bla CTX-M primers.Agarose gel electrophoresis screened out the strains that meet the conditions of the positive band,then sent out the PCR products for sequencing,and finally confirmed the genotypes by MEGA7.0 and Bio Edit comparison.Results: 1.Drug resistance : the resistance rates of 21 antimicrobial agents were: CAZ(15.03%)、 CCV(19.61%)、CTX(47.71%)、CTC(0.65%)、CRO(44.44%)、CXM(66.67%)、CZO(63.40%)、FOX(3.92%)、 PIP(61.44%)、 TZP(3.27%)、 ATM(34.64%)、LEV(45.75%)、CIP(54.25%)、NOR(54.25%)、NAL(81.70%)、GEN(47.06%)、STR(64.05%)、AMK(3.27%)、SMZ/TMP(69.28%);No strains were detected resistant to MXF and IMP.107 strains were detected in multi-resistant strains,the detection rate was 69.93%.30 strains were found in the double-resistant strains,the detection rate was 19.61%,8 strains were detected in the single-resistant strains,the detection rate was 5.23%,and 8 strains were detected in the all-sensitive strains with a detection rate of 5.23%.2.Production of ESBLs: 92 ESBLs-positive strains were detected,the detection rate was 60.13%(92/153),82 ESBLs-positive strains were detected in multi-drug resistant strains,accounting for 76.64%(82/107),and 10ESBLs-positive strains were detected in double drug-resistant strains,accounting for 33.33%(10/30).no ESBLs-positive strains were detected in single-drug strains and all-sensitive strains.3.PCR results: 90 strains carrying bla TEM strains were detected with a detection rate of 58.82%.85 strains carrying bla CTX-M strains were detected with a detection rate of55.56%.43 strains which carrying both bla TEM and bla CTX-M were detected with a detection rate of the strain was 28.10%.21 strains(13.73%)were detected with no drug-resistant Gene mentioned this experiment.4.Detection of bla TEM and bla CTX-M in ESBLs-positive strains: 48 ESBLs positive strains carrying bla TEM were detected,the detection rate was 52.17%(48/92).85 ESBLs-positive strains carrying bla CTX-M were detected.the detection rate was 92.39%(85/92).43 ESBLs-positive strains carrying bla TEM and bla CTX-M were detected,and the detection rate was 46.74%(43/92).Two ESBLs-positive strains were detected with no bla TEM and bla CTX-M,The detection rate was 2.17%(2/92).5.Detection of bla TEM and bla CTX-M in multidrug-resistant strains: 67 bla TEM-positive strains were detected in 107multidrug-resistance strains,the detection rate was 62.62%(67/107).75 bla CTX-M positive strains were,the detection rate was 70.09%(75/107).42 strains of carring bla TEM and bla CTX-M were detected,the rate was 39.25%(42/107).Conclusions: 1.The drug-resistance situation of clinical isolated Escherichia coli strains is still serious.The strains show high resistances to antimicrobial agents commonly used in clinical.No strains is resistant to Imipenem and Moxifloxacin.The drug resistance pattern is mainly multidrug-resistance and double-drug resistance.2.The detection rate of ESBLs-positive strains is high,mainly distributed in multidrug-resistant strains and double drug-resistant strains.3.The detection rates of bla TEM and bla CTX-M are high and are mainly distributed in multidrug-resistant strains and doubledrug-resistant strains.4.The detection of bla TEM positive strains in ESBLs-positive strains and ESBLs-negative strains do not differ significantly.All bla CTX-M-positive strains were ESBLs-positive.5.In multi-resistant strains,the detection rates of ESBLs,bla TEM and bla CTX-M are high.the detection of carrying bla TEM and bla CTX-M strains is 39.25%.