AUTHOR=Zelendova Marketa , Papagiannitsis Costas C. , Sismova Petra , Medvecky Matej , Pomorska Katarina , Palkovicova Jana , Nesporova Kristina , Jakubu Vladislav , Jamborova Ivana , Zemlickova Helena , Dolejska Monika ,  Working Group for Monitoring of Antibiotic Resistance 

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

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1147846

DOI=10.3389/fmicb.2023.1147846

ISSN=1664-302X

ABSTRACT=<p>The occurrence of colistin resistance has increased rapidly among <italic>Enterobacterales</italic> 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 <italic>mcr</italic> 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 <italic>mcr</italic> genes. Most isolates carried <italic>mcr-1</italic> (48/73) and were identified as <italic>Escherichia coli</italic> (<italic>n</italic> = 44) and <italic>Klebsiella pneumoniae</italic> (<italic>n</italic> = 4) of various sequence types (ST). Twenty-five isolates, including <italic>Enterobacter</italic> spp. (<italic>n</italic> = 24) and <italic>Citrobacter freundii</italic> (<italic>n</italic> = 1) carrying the <italic>mcr-9</italic> gene were detected; three of them (<italic>Enterobacter kobei</italic> ST54) co-harbored the <italic>mcr-4</italic> and <italic>mcr-9</italic> genes. Multi-drug resistance phenotype was a common feature of <italic>mcr</italic> 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 <italic>E. coli</italic> 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 <italic>mcr-1</italic> 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 <italic>mcr-4</italic> in three isolates, while <italic>mcr-9</italic> was carried by IncHI2/ST1 plasmids (4/73, 5%) or the chromosome (18/73, 25%). We showed an overall low level of occurrence of <italic>mcr</italic> genes in colistin-resistant bacteria from human clinical samples in the Czech Republic.</p>