DHA-1 plasmid-mediated AmpC β-lactamase expression and regulation of Klebsiella pnuemoniae isolates

The present study aimed to investigate the regu- latory mechanism of the AmpC enzyme by analyzing the construction and function of AmpCR, AmpE and AmpG genes in the Dhahran (DHA)-1 plasmid of Klebsiella pneu‑ moniae (K. pneumoniae). The production of AmpC and extended-spectrum β-lactamase (ESBL) were determined following the cefoxitin (FOX) inducing test for AmpC, preliminary screening and confirmation tests for ESBL in 10 DHA-1 plasmid AmpC enzymes of K. pneumoniae strains. AmpCR, AmpD, AmpE and AmpG sequences were analyzed by polymerase chain reaction. The pACYC184-X plasmid analysis system was established and examined by regulating the pAmpC enzyme expression. The electrophoretic bands of AmpCR, AmpD, AmpE and AmpG were expressed. Numerous mutations in AmpC + AmpR (AmpCR) and in the intergenic region cistron of AmpC-AmpR, AmpD, AmpE and AmpG were observed. The homology of AmpC and AmpR, in relation to the Morganella morganii strain, was 99%, which was determined by comparing the gene sequences of Kp1 with those of Kp17 AmpCR. The specific combination of AmpR and labeled probe demonstrated a band retarded phenomenon and established a spatial model of AmpR. All the enzyme production strains demonstrated Val93→Ala in AmpG; six transmembrane domains were found in AmpE in all strains, with the exception of Kp1 and Kp4, which had only three transmembrane segments that were caused by mutation. The DHA-1 plasmid AmpC enzymes encoded by plasmid are similar to the inducible chromosomal AmpC enzymes, which are also regulated by AmpD, AmpE, AmpR and AmpG.