Session Type: ePosters
Session Title: ePosters
Authors(s): R.E. Weber (1), B. Neumann (1, 2), J.K. Bender (1), G. Werner (1)
Authors Affiliations(s): (1) Robert Koch Institute, National Reference Centre for Staphylococci and Enterococci, Division Nosocomial Pathogens and Antibiotic Resistances, Department of Infectious Diseases, Germany, (2) Institute for Hygiene, Medical Microbiology and Clinical Infectiology, University Institute of the Medical Private University, Hospital Nuremberg, Germany
Third Party Affiliation: the VRE study group
Background:
Whole-genome sequence analyses of nosocomial E. faecium isolates conducted at the German NRC for Staphylococci and Enterococci indicate a significant increase in the emergence of novel strain variants like ST117 and ST80 in recent years. In particular, isolates of ST117/CT71 show strong expansion throughout Germany. Here, we aimed to identify epidemiological trends in the dissemination of hospital-acquired strain variants in Germany by a retrospective analysis of invasive E. faecium isolates. In addition, the genetic architecture of ST117/CT71 transposon structures should be investigated to improve outbreak investigations and elucidate horizontal vanB transmission events.
Methods:Next-generation sequencing (NGS) was performed for a total of 543 invasive E. faecium isolates that were sent to the NRC between 2015 and 2019. All isolates originated from patients with blood stream infections. Genome sequences were reconstructed by the use of de novo assembly and subsequently typed by MLST and cgMLST. For the reconstruction of vanB transposon structures, we used both NGS and Nanopore long-read sequencing technology.
Results:Based on the molecular typing of invasive E. faecium isolates a sharp increase in the prevalence of vanB-type ST117/CT71 isolates was observed from 2015 onwards (2015: 1.8%), reaching percentages as high as 39% in 2019. First appearing in 2016, ST80/CT1065 has been the second most common strain type since 2018 (9%; 2019: 8%). MLST types such as ST203 or ST192, which were prominent prior to 2019 occurred only sporadically in 2019. For ST117/CT71 isolates, cgMLST provided only limited resolution, as apparently independent isolates with no epidemiological link differed only by a few alleles. Reconstruction of the Tn1549 transposon structures of 152 vanB ST117/CT71 E. faecium isolates revealed only minor sequence variations, making outbreak investigations for this strain type even more challenging.
Conclusions:Based on our studies, it could be shown that formerly prominent genetic lineages in Germany were largely displaced by isolates of ST117 CT71 in recent years. This strain variant is hardly differentiable by cgMLST and even the integration of transposon analysis does not increase discriminatory power. The factors that led to the nationwide spread and success of this strain variant are not known yet and are currently investigated.
Keyword(s): E. faecium, ST117/CT71, vanB transposonSession Type: ePosters
Session Title: ePosters
Authors(s): R.E. Weber (1), B. Neumann (1, 2), J.K. Bender (1), G. Werner (1)
Authors Affiliations(s): (1) Robert Koch Institute, National Reference Centre for Staphylococci and Enterococci, Division Nosocomial Pathogens and Antibiotic Resistances, Department of Infectious Diseases, Germany, (2) Institute for Hygiene, Medical Microbiology and Clinical Infectiology, University Institute of the Medical Private University, Hospital Nuremberg, Germany
Third Party Affiliation: the VRE study group
Background:
Whole-genome sequence analyses of nosocomial E. faecium isolates conducted at the German NRC for Staphylococci and Enterococci indicate a significant increase in the emergence of novel strain variants like ST117 and ST80 in recent years. In particular, isolates of ST117/CT71 show strong expansion throughout Germany. Here, we aimed to identify epidemiological trends in the dissemination of hospital-acquired strain variants in Germany by a retrospective analysis of invasive E. faecium isolates. In addition, the genetic architecture of ST117/CT71 transposon structures should be investigated to improve outbreak investigations and elucidate horizontal vanB transmission events.
Methods:Next-generation sequencing (NGS) was performed for a total of 543 invasive E. faecium isolates that were sent to the NRC between 2015 and 2019. All isolates originated from patients with blood stream infections. Genome sequences were reconstructed by the use of de novo assembly and subsequently typed by MLST and cgMLST. For the reconstruction of vanB transposon structures, we used both NGS and Nanopore long-read sequencing technology.
Results:Based on the molecular typing of invasive E. faecium isolates a sharp increase in the prevalence of vanB-type ST117/CT71 isolates was observed from 2015 onwards (2015: 1.8%), reaching percentages as high as 39% in 2019. First appearing in 2016, ST80/CT1065 has been the second most common strain type since 2018 (9%; 2019: 8%). MLST types such as ST203 or ST192, which were prominent prior to 2019 occurred only sporadically in 2019. For ST117/CT71 isolates, cgMLST provided only limited resolution, as apparently independent isolates with no epidemiological link differed only by a few alleles. Reconstruction of the Tn1549 transposon structures of 152 vanB ST117/CT71 E. faecium isolates revealed only minor sequence variations, making outbreak investigations for this strain type even more challenging.
Conclusions:Based on our studies, it could be shown that formerly prominent genetic lineages in Germany were largely displaced by isolates of ST117 CT71 in recent years. This strain variant is hardly differentiable by cgMLST and even the integration of transposon analysis does not increase discriminatory power. The factors that led to the nationwide spread and success of this strain variant are not known yet and are currently investigated.
Keyword(s): E. faecium, ST117/CT71, vanB transposon