Fig. 4.

Recombination-filtered core genome phylogeny for GC2 A. baumannii in the ICU. beast maximum clade credibility tree; shading indicates the period during which imipenem was used for the empirical treatment of VAP in the ICU. Isolate labels are coloured to indicate source: red, VAP; blue, asymptomatic carriage. Node bars indicate 95 % HPDs for divergence dates; node labels and branch line thickness indicate posterior support. The two main lineages (1 and 2) and five imipenem-resistant subclades (A–E) referred to in the text are labelled, arrows indicate inferred oxa23 carbapenemase acquisition events: red, Tn2006; orange, Tn2008VAR. Oxa23 gene copy number and MICs for imipenem are indicated on the right.