Study on molecular mechanism of carbapenem- and colistin-resistance in Escherichia coli

Abstract

To investigate the drug resistance and molecular mechanism of carbapenem and colistin-resistant Escherichia coli(E.Coli) isolated from elderly patients and provide theoretical foundation for clinical anti-infective therapy. 1028 strains of E.coli isolated from our hospital were collected. Agar dilution method was used to screen E. coli resistant to carbapenem and colistin antibiotics. Broth microdilution method was performed to confirm drug susceptibility and detect susceptibility to 9 commonly used clinical antibiotics. Carbapenem and colistin resistant genes carried by the strains were detected by PCR; Strain ST type was detected by the MLST typing method. Four samples of carbapenem and colistin-resistant E.coli were obtained by drug sensitivity test, and all four strains were isolated from elderly patients. It is a multi-drug resistant phenotype resistant to quinolones, cephalosporins, carbapenem and colistin; PCR detection found that DC632 and DC796 carry bla NDM-1 and mcr-1, DC721 and DC838 carry bla TEM-1 and mcr-1; MLST typing detection found that DC632 and DC721 were ST2 type, DC796 and DC838 were ST44 and ST31, respectively. In conclusion, Four strains of carbapenem-and colistin-resistant E.coli were isolated in this study. Although the isolation rate is low, it is still necessary to raise the awareness of clinicians on the rational use of antibiotics.