Resistance mechanisms of carbapenemresistant Enterobacteriaceae to carbapenems and cephalosporins

Abstract:

ObjectiveTo study the resistance mechanisms of carbapenemresistant Enterobacteriaceae(CRE) to carbapenems and cephalosporins, and provide molecular evidence for the treatment of CRE infection and control of healthcareassociated infection.MethodsClinically isolated bacteria in 2014-2015 were identified and performed antimicrobial susceptibility testing by MicroScan Walkaway40 plus system, encoding genes of carbapenems（blaNDM1 and blaKPC2） and encoding genes of extendedspectrum βlactamases （blaTEM, blaSHV, blaCTXM1like, blaCTXM2like, blaCTXM8like, and blaCTXM9like）were detected, multidrugresistance organismrelated class I integron encoding gene blainT1 was also detected. ResultsSeven CRE strains were isolated in 2014-2015, isolation rate was 0.30%, strain 16 was Klebsiella pneumoniae, strains 7 was Citrobacter freundii, all 7 strains were resistant to βlactamase inhibitor compound, cephalosporins, cephamicins, and carbapenems, 3 strains were sensitive to amikacin and tetracycline, 2 strains were sensitive to compound sulfamethoxazole. 3, 2, 5, 7, 1, 4, and 5 strains of CRE were detected carrying blaNDM1， blaKPC2， blaTEM， blaSHV，blaCTXM1like， blaCTXM9like，and blainT1 respectively, no strain was found to carry blaCTXM2like and blaCTXM8like genes. ConclusionblaNDM1 and blaKPC2 are important mechanisms leading to carbapenem resistance of 7 CRE strains; blaTEM, blaSHV, and blaCTXM9like are important mechanism leading to cephalosporin resistance, blainT1 plays an important role in multidrugresistance to CRE and spread of multidrugresistant genes.