Abstract
Colistin resistance mediated by mobile mcr-1 gene has raised concern during the last years. After steep increase in mcr-1 reports, other mcr-gene variants (mcr-2 to mcr-5) have been revealed as well. In 2016, a clinical study was conducted on asymptomatic stool carriage of extended spectrum beta-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae among Finnish adults. All suspected ESBL producing bacterial isolates were first tested by phenotypic ESBL-confirmation methods, and then further analyzed with whole genome sequencing to identify the resistance genes. We found one study subject carrying a colistin resistant E.coli with a transferrable mcr-1 gene. This multi-drug resistant isolate, although initially suspected to be an ESBL producer, did not carry any ESBL genes, but was proven to carry several other resistance genes by using whole genome sequencing. Sequence type was ST93. The mcr-1 gene was connected to IncX4 plasmid which suggests that the colistin resistance gene locates in the respective plasmid. Here, we report the finding of a mcr-1 harboring human E.coli isolate from Finland. Clinical antimicrobial resistance (AMR) rates are low in Finland, and mobile colistin resistance has not been reported previously. This highlights the importance of AMR surveillance also in populations with low levels of resistance.
Highlights
During our clinical screening study (Ny et al unpublished data), we decided to extend our analysis by whole genome sequencing all phenotypically confirmed extended spectrum beta-lactamase (ESBL) isolates (E. coli and K. pneumoniae)
The analysis revealed that one of the E. coli isolates carried the mcr-1 gene
Mcr-1 gene and the IncX4 replicon were connected in the de Bruijn graph of the assembly which was visualized with Bandage [11]
Summary
GRO€ NDAHL-YLI-HANNUKSELA et al Southwest Finland as part of the Northern Dimension Antibiotic Resistance Study (NoDARS, http://www.nd phs.org/?database,view,project,1468). ResFinder (database version 2.1) [9] and in silico PCR, using previously reported primers [10], were used to identify the resistance genes and plasmid replicons from the WGS data. The reads of the E. coli isolate carrying mcr-1 gene have been deposited in NCBI SRA database under the accession numbers SRR6656065.
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