Objectives: This study aims to assess the prevalence of the
mcr-1 gene among carbapenem-resistant
Enterobacteriaceae (CRE) isolated from clinical specimens and to further investigate the clinical significance and microbiological characteristics of CRE carrying the
mcr-1 gene. Methods: Four hundred and twenty-three CRE isolates
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Objectives: This study aims to assess the prevalence of the
mcr-1 gene among carbapenem-resistant
Enterobacteriaceae (CRE) isolated from clinical specimens and to further investigate the clinical significance and microbiological characteristics of CRE carrying the
mcr-1 gene. Methods: Four hundred and twenty-three CRE isolates were screened for the presence of the
mcr-1 gene. After identification, their clinical significance, antibiotic susceptibility, and antibiotic resistance mechanisms including the ESBL gene, carbapenemase gene, outer membrane protein (OMP), and plasmid sequencing were assessed. Results: Only four (0.9%) isolates of carbapenem-resistant
Escherichia coli (E. coli) were found to carry the
mcr-1 gene and demonstrated different pulsed-field gel electrophoresis (PFGE) patterns and sequence types (ST). While one patient was considered as having
mcr-1-positive carbapenem-resistant
E. coli (CREC) colonization, the other three
mcr-1-positive CREC-related infections were classified as nosocomial infections. Only amikacin and tigecycline showed good in vitro activity against these four isolates, and three of them had a minimum inhibitory concentration with colistin of ≥4 mg/L. In the colistin-susceptible isolate,
mcr-1 was nonfunctional due to the insertion of another gene. In addition, all of the mcr-1-positive CREC contained various resistant genes, such as
AmpCCMY,
blaNDM,
blaTEM,
blaSHV, and
blaCTX. In addition, one strain (EC1037) had loss of the OMP.
Conclusions: The emergence of the
mcr-1 gene among CRE, especially
E. coli, remains worth our attention due to its resistance to most antibiotics, and a further national survey is warranted.
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