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 blaNDM-1 and mcr-1, DC721 and DC838 carry blaTEM-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.
Highlights
Escherichia coli (E.coli) is a common gram-negative pathogen in the clinic, which can cause intestinal infections, urinary tract infections and bloodstream infections (Kaper et al, 2004)
In order to elucidate the underlying mechanism for the resistance to carbapenem and colistin, we performed polymerase chain reaction (PCR) reactions to detect and analyze the presence of carbapenem and colistin resistant genes in these strains
As showed in Table.3, we found that DC632 and DC796 carry blaNDM-1 and mcr-1, while DC721 and DC838 carry blaTEM-1 and mcr-1
Summary
Escherichia coli (E.coli) is a common gram-negative pathogen in the clinic, which can cause intestinal infections, urinary tract infections and bloodstream infections (Kaper et al, 2004). Carbapenemases catalyze the hydrolysis of Carbapenem and other β-lactam antimicrobials, and this resistance mechanism poses a greater threat, as these enzymes may inactivate many other β-lactams (Little et al, 2012; Yang et al, 2009) They are encoded by genes carried on transposons, plasmids or other mobile genetic elements, which can be horizontally transferred to other bacterial species (Yang et al, 2009; Tzouvelekis et al, 2012; Stapleton et al, 1999). With the first discovery of plasmid-mediated colistin resistance gene-mcr-1 by Chinese scientists in 2015 (Liu et al 2016), there are more and more reports about colistin-resistant E.coli in various regions of the world (Schembri et al, 2015) These cases have greatly attracted the attention of scientists, governments and media, as they brought new challenges to the clinical application of colistin. Preliminary research on the characteristics and underlying mechanisms of drug-resistant E. coli is carried out, which will provide guidance for clinical anti-infection treatment
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