Plasmid-mediated colistin resistance among human clinical isolates: national surveillance in the Czech Republic.

The occurrence of colistin resistance has increased rapidly among around the world. We performed a national survey of plasmid-mediated colistin resistance in human clinical isolates through a retrospective analysis of samples from 2009 to 2017 and a prospective sampling in 2018-2020. The aim of this study was to identify and characterize isolates with genes from various regions of the Czech Republic using whole genome sequencing (WGS). Of all 1932 colistin-resistant isolates analyzed, 73 (3.8%) were positive for genes. Most isolates carried (48/73) and were identified as ( = 44) and ( = 4) of various sequence types (ST). Twenty-five isolates, including spp. ( = 24) and ( = 1) carrying the gene were detected; three of them ( ST54) co-harbored the and genes. Multi-drug resistance phenotype was a common feature of isolates and 14% (10/73) isolates also co-harbored clinically important beta-lactamases, including two isolates with carbapenemases KPC-2 and OXA-48. Phylogenetic analysis of ST744, the dominant genotype in this study, with the global collection showed Czech isolates belonged to two major clades, one containing isolates from Europe, while the second composed of isolates from diverse geographical areas. The gene was carried by IncX4 (34/73, 47%), IncHI2/ST4 (6/73, 8%) and IncI2 (8/73, 11%) plasmid groups. Small plasmids belonging to the ColE10 group were associated with in three isolates, while was carried by IncHI2/ST1 plasmids (4/73, 5%) or the chromosome (18/73, 25%). We showed an overall low level of occurrence of genes in colistin-resistant bacteria from human clinical samples in the Czech Republic.