Genomic epidemiology of colistin-resistant Enterobacterales from Dutch patients: a prospective matched case-control study

Colistin is a last-resort treatment option for infections with multidrug-resistant Gram-negative bacteria. However, colistin resistance is increasing. A six-month prospective matched case-control study was performed in which 22 Dutch laboratories with 32 associated hospitals participated. Laboratories were invited to send a maximum of five colistin-resistant Escherichia coli or Klebsiella pneumoniae (COLR-EK) isolates and five colistin-susceptible isolates (COLS-EK), matched on patient location, material of origin and bacterial species. This study shows that colistin resistance is not rare in the Netherlands and caused by the mcr gene in a minority of COLR-EK isolates.