The intestinal carriage of plasmid‐mediated colistin‐resistant enterobacteriaceae in tertiary care settings

Abstract

Background: In order to estimate the prevalence of plasmid borne colistin resistance and to characterize in detail the mcr‐positive isolates, we carried out a sentinel testing survey on the intestinal carriage of plasmid‐mediated colistin‐resistant Enterobacteriaceae in hospitalized patients. Methods: Between June 2018 and September 2019, 1922 faecal samples from hospitalised patients were analysed by selective culture in presence of colistin (3.5 mg/L), and in parallel by direct detection of the mcr‐1 to mcr‐8 genes by qPCR. The mcr‐positive isolates were characterised by whole‐genome sequencing. Results: The prevalence of the mcr‐1 gene was 0.21% (n = 4/1922); the mcr‐2 to 8 genes were not detected. The mcr‐1 gene was found to be localised in the IncX4 (n = 3) and IncHI2 (n = 1) plasmid type. One Escherichia coli isolate was susceptible to colistin due to the inactivation of the mcr‐1 gene through the insertion of the IS2 element; however, the colistin resistance was inducible by culture in low concentrations of colistin. One human mcr‐1 positive E. coli isolate was related genetically to the mcr‐1 E. coli isolate derived from turkey meat of Czech origin. Conclusions: mcr‐mediated colistin resistance currently poses little threat to patients hospitalised in Czech healthcare settings. The presence of the mcr‐1 gene in the human population has a possible link to domestically produced, retail meat.