Predominance of CTX-M-15–producing Escherichia coli belonging to MLST ST131 among ESBL isolates from asylum seekers in the Netherlands

Introduction. Numerous studies show an increased carriage rate of multi-drug resistant bacteria amongst asylum seekers. We evaluated the molecular profiles and resistomes of extended spectrum b-lactamase producing Escherichia coli (ESBL-E. coli), isolated from hospitalized asylum seekers in the Northern part of the Netherlands.Methods. Whole genome sequencing data of ESBL-E. coli isolates from asylum seekers, retrieved in routine diagnostics during 2016, were analyzed to assess MLST ST-types, fim type, phylogroup and resistance genes. Previously studied ESBL-E. coli isolates from the Dutch-German border region were used for genome comparison purposes as control group.Results. Among 112 ESBL-E. coli isolates from asylum seekers, originating mostly from Syria (n=42), Iraq (n=16) and Iran (n=12), the majority belonged to ST-131 (21.4%) and ST-10 (17.0%). The predominant gene for beta-lactam resistance was blaCTX-M-15 (67.9%), followed by the often co-detected blaTEM-1B (40.2%). No mcr or carbapenemase genes were detected. The majority of the strains belonged to phylogroups B2 (38.4%) and A (32.1%), carrying fimH27 (21.4%) and fimH30 (17.9%). CgMLST minimum-spanning tree did not reveal clusters containing strains from both the asylum seekers and control group. Five main clusters were formed within the asylum seekers group. Still, these clusters included people originating from different countries.Conclusion. The most frequently isolated clones in the study have been isolated, on a regular basis within the Dutch population, before the increase of the asylum seekers population. No mcr or carbapenemase producing clones were detected among the asylum seekers population. Minor clustering was observed amongst the asylum seekers' strains.