Molecular epidemiological study of carbapenem-resistant Escherichia coli
Objective To reveal the resistance genes prevalence and molecular epidemiological characteristics of the carbapenem-resistant Escherichia coli(CREC)isolates in three hospitals.Methods A total of 62 clinically isolated CREC strains from Wuhan No.1 Hospital,The Central Hospital of Wuhan and Huangpi District People's Hospital from July 2018 to May 2021 were collected.Fully automated bacterial identification and drug susceptibility analysis system was used to determine the drug sensitivity of bacteria.Carbapenemase Nordmann-Poirel(Carba NP)test was used to confirm carbapenicillium type.Whole-genome sequencing was used to analyze the bacterial resistance genes,plasmid carrying status,and multilocus sequence typing(MLST).Results Carba NP test results showed that the proportion of carbapenemase production by all strains was 32.3％(20/62).The 20 Carba NP test-positive strains all produced New Delhi metalloenzyme(NDM);of which,15 produced NDM-5 and 5 produced NDM-1.No other carbapenem resistance genes were detected.All strains also carried extended-spectrum β-lactamase genes(blaTEM or blaCTX-M),aminoglycoside resistance genes aacA,macrolide resistance genes(mph or mdf),trimethoprim resistance gene dfrA and tetracycline resistance gene tet.A total of 12 sequence types(ST)were detected in 20 bacterial strains,mainly ST410(n=4),ST131(n=3)and ST167(n=3),with no obvious dominant strain;all strains carried 1-6 plasmids,mostly 3-4.Conclusion NDM-producing CREC,and the blaNDM gene might coexist with clonal transmission and horizontal transmission among strains.
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