Study On Genotype Characterization And Resistance Of Plasmid-Mediated AmpC Beta-lactamase In E.cloaca

Objective:In order to investigate the occurrence of infected E.cloacae AmpCβ-lactamases,the distribution and epidemic plasmid-mediated AmpC enzyme gene and the drug resistance to strain produce and no-produce enzymeand in the clinic.It is important for patient management and antimicrobial therapy.Method:A total of 161 clinical isolates of E.cloacae were collected which with the V-K Cefoxitin screen automated antimicrobial susceptibility test system to ascertain the AmpCβ-lactam phenotypes of 196 isolates of the family.Cefoxitin three-dimensional extraction test system were performed for suspicious strains of the family to confirm whether producing AmpC beta-lactamases or not.ESBLs were determined further by ceftriaxone three-dimensional extraction test system for those strains producing AmpCβ-lactamases.The plasmid was used as the template.The total reaction volume is with 80V in 30 mins after phontos.The results were expected to show positive in molecular weight strap.The drug sensitivity test was performed with Kirby-Bauer disk diffusion methods according to the standard made NCCLs 2005).All original data was analyses by Whonet 5.3 software which provided by WHO drug resistance monitoring website.The enumeration data were statistically analysis by chi-square test.Result:46 isolates were positive in three-dimensional tests in all 161 clinical isolates,and the positive rate was 42.6%.Among 46 positive isolates,38 isolates were AmpC beta-lactamase producers,so the positive rate was 23.6%;8 isolates produce both AmpC beta-lactamase and ESBLs,so the positive rate was 4.9%.46 strains which is threeidimensional test positive E.cloacae have been done plasmid extracted and 5 group AmpC in PCR.Total 15 strains are plasmid-mediated AmpC enzyme.The gene type is sole produced ACT-1,sole produced ACI-1 and DHA-1.12 strains are transferred successful.This study shows 15 strains plasmid-mediated producing AmpC enzyme E.cloacae,which are sensitive to the fourth cefalosporins(for example: Cefepime),Cefoperazone/Sulbactam and Carbopenem(Imipenem).But it resistance to the other anti-biotics.It is only sensitive to Cefoperazone/Sulbactam and Imipenem for those produce both AmpC enzyme and ESBLs E.cloacae.It is statistically significant on monitoring drug resistance rate on non-produce AmpC enzyme strain and produce AmpC enzyme,p＜0.05.Conclusion:Three-dimensional test can be used to identify clinical Gram-negative isolates whether they produce AmpC enzyme or ESBLs.Chromosome-mediated is the primary way for E.cloacae in our hospital.Most bacteria produce sole AmpC enzyme.The isolated plasmid-mediated AmpC enzyme have two genotypes:ACT-1 and DHA-1.Carbapenems and fourth-generation cefalosporins could be better choice for treatment of infections casued by AmpC enzyme producers,and could also choose levo-ofloxacin and amikacin to treat the infection of AmpC enzyme producers on the basis of susceptibility tests.