ena-STUDY-Universitaetsklinikum Freiburg-05-03-2019-15:25:20:348-132
Molecular characterization of carbapenem-resistant Acinetobacter baumannii using whole-genome sequencing revealed missed transmission events, Germany, 2012-2015
Infection and colonization with multi-resistant Acinetobacter baumannii causes therapeutic and economic problems in the nosocomial setting. Due to the sensitivity issue of screening schemes for A. baumannii, it is difficult to implement adequate transmission prevention measures. The high discriminatory power of whole genome sequencing for transmission-chain analysis provides us with the necessary tool to study and identify transmission events. We retrospectively sequenced and analyzed 39 A. baumannii isolates from 2012-2015 to search for possible missed transmission events.A database search of the laboratory information system was performed to identify patients with A. baumannii colonization and infection, along with antibiotic resistance data and relevant clinical information.Between July 2012 and September 2015, A. baumannii was isolated from 268 patients of which 16% (42/268) were carbapenem resistant. 39 of these isolates were recoverable and sequenced. 21% (8/39) of these were resistant to all antibiotics tested. Most isolates belong to the circulating IC2 clonal type. SNP analysis revealed 4 suspicious clusters. Two of these clusters showed high concordance with the local spatio-temporal epidemiology, suggesting that transmission events were very likely.  Our data suggest that there were two independent transmission events, which would have been missed by conventional MLST typing due to high clonality. The routine implementation of WGS can optimize surveillance and initiation of suitable containment measures. In addition, emerging resistance to salvage therapy is a major therapeutic problem and should be monitored closely.
Infection and colonization with multi-resistant Acinetobacter baumannii causes therapeutic and economic problems in the nosocomial setting. Due to the sensitivity issue of screening schemes for A. baumannii, it is difficult to implement adequate transmission prevention measures. The high discriminatory power of whole genome sequencing for transmission-chain analysis provides us with the necessary tool to study and identify transmission events. We retrospectively sequenced and analyzed 39 A. baumannii isolates from 2012-2015 to search for possible missed transmission events.A database search of the laboratory information system was performed to identify patients with A. baumannii colonization and infection, along with antibiotic resistance data and relevant clinical information.Between July 2012 and September 2015, A. baumannii was isolated from 268 patients of which 16% (42/268) were carbapenem resistant. 39 of these isolates were recoverable and sequenced. 21% (8/39) of these were resistant to all antibiotics tested. Most isolates belong to the circulating IC2 clonal type. SNP analysis revealed 4 suspicious clusters. Two of these clusters showed high concordance with the local spatio-temporal epidemiology, suggesting that transmission events were very likely.  Our data suggest that there were two independent transmission events, which would have been missed by conventional MLST typing due to high clonality. The routine implementation of WGS can optimize surveillance and initiation of suitable containment measures. In addition, emerging resistance to salvage therapy is a major therapeutic problem and should be monitored closely.