Study On Plasmid-mediated Resistance To β-lactamases In Clinical Isolates Of Enterobacteriaceae

Objective To study the Genotype of the clinical isolates of Enterobacteriaceae producing plasmid-mediated β -lactamases. Methods 396 enterobacteriaceae strains were performed K-B test., .ESBLs were confirmed by the nccls phenotypic confirmatory test,AmpC-like strains were tested by cefoxitin-test. drug-resistant gene were positioned by Conjugative transfer test.PCR and DNA sequencing were used to detect the genotype of ESBLs and AmpC- β -lactamases .Results 99 strains(25.0%) were confirmed ESBLs(25.0%) and 67 strains(16.7%) were AmpC-like strains. Enterobacteriaceae strains producing ESBLs strains were nearly resistanted to all antibiotics but Imipenem,and were highly multiple-drug-resistant..40 transconjugants were screened out.(40.4%) in producing ESBLs strains, 7 transconjugants were screened out (10.4%) in AmpC-like strains..Pcr experiment gave 50.0%bla_TEM,20.0% blasHV,67.5%bla_CTX-M-positive results for 40 ESBLs-like clinical strains,and 4 of 7 AmpC-like strains were DHA type. 5 PCR products were identified as TEM-1,TEM-1,SHV-12,CTX-M3 and CTX-M14. Conclusions SHV-12,CTX-M3 and CTX-M14.were prevalent in clinical Enterobacteriaceae strains in our hospital,CTX-M type is the predominant genotype of ESBLs,and there were epidemic strains producing plasmid-mediated DHA type AmpC- β -lactamases.