Local phylogeny of carbapenem-susceptible and -nonsusceptible Citrobacter spp. from UPMC. A phylogenetic tree of 102 local Citrobacter sp. genomes (82 carbapenem-susceptible and 20 carbapenem-nonsusceptible isolates) was generated based on an alignment of 1,606 core genes using RAxML (28). The tree was visualized and annotated using Interactive Tree of Life (iTOL) (29). The tree is annotated based on species, facility source, carbapenem susceptibility phenotype, and carbapenemase genes identified, if any, in the genome of each isolate.