Precise Species Identification by Whole-Genome Sequencing of Enterobacter Bloodstream Infection, China

The clinical importance of Enterobacter spp. remains unclear because phenotype-based Enterobacter species identification is unreliable. We performed a genomic study on 48 cases of Enterobacter-caused bloodstream infection by using in silico DNA–DNA hybridization to identify precise species. Strains belonged to 12 species; Enterobacter xiangfangensis (n = 21) and an unnamed species (taxon 1, n = 8) were dominant. Most (63.5%) Enterobacter strains (n = 349) with genomes in GenBank from human blood are E. xiangfangensis; taxon 1 (19.8%) was next most common. E. xiangfangensis and taxon 1 were associated with increased deaths (20.7% vs. 15.8%), lengthier hospitalizations (median 31 d vs. 19.5 d), and higher resistance to aztreonam, cefepime, ceftriaxone, piperacillin-tazobactam, and tobramycin. Strains belonged to 37 sequence types (STs); ST171 (E. xiangfangensis) was most common (n = 6). Four ST171 strains belonged to a defined clone. Precise species identification has greater implications for epidemiology and infection control than treatment.