Extraintestinal pathogenic Escherichia coli (ExPEC) is the leading cause in humans of urinary tract infection and bacteremia. The previously published web tool VirulenceFinder ( http://cge.cbs.dtu.dk/services/VirulenceFinder/ ) uses whole-genome sequencing (WGS) data for in silico characterization of E. coli isolates and enables researchers and clinical health personnel to quickly extract and interpret virulence-relevant information from WGS data.

Emerging carbapenem resistance in Escherichia coli , including sequence type 131 (ST131), the leading cause of extraintestinal E. coli infections globally, threatens therapeutic efficacy. Accordingly, we determined broth microdilution MICs for three distinctive newer agents, i.e., cefiderocol (CFDC), ceftazidime-avibactam (CZA), and eravacycline (ERV), plus 11 comparators, against 343 carbapenem-resistant (CR) clinical E. coli isolates, then compared susceptibility results with bacterial characteristics and region.

Background: Escherichia coli ST131, mainly its H30 clade, is the leading cause of extraintestinal E. coli infections but its correlates of virulence are undefined. Materials and methods: We tested in a murine sepsis model 84 ST131 isolates that differed by country of origin (Spain vs. USA), clonal subset, resistance markers, and virulence genes (VGs). Virulence outcomes, including illness severity score (ISS) and “killer” status (>80% mouse lethality), were compared statistically with clonal subset, individual and combined VGs, molecularly defined extraintestinal and uropathogenic E. coli (ExPEC, UPEC) status, and country of origin. Results: Virulence varied widely by strain. Univariable correlates of median ISS and percent “killer” (outcomes if variable present vs. absent) included pap (ISS, 4.4 vs. 3.8; “killer”, 71% vs. 46%), kpsMII (4.1 vs. 2.3; 59% vs. 25%), K2/K100 (4.4 vs. 3.2; 77% vs. 41%), ExPEC (4.2 vs. 2.2; 62% vs. 17%), Spanish origin (4.3 vs. 3.1; 65% vs. 36%), and H30R1 subset (2.5 vs. 4.1; 35% vs. 59%). With multivariable adjustment, ExPEC status was the only consistently significantly predictive variable. Conclusion: Within ST131 the strongest predictor of experimental virulence was molecularly defined ExPEC status. Clonal subsets seemed to behave differently in the murine sepsis model by country of origin.

Emerging carbapenem resistance in Escherichia coli, including sequence type 131 (ST131), threatens therapeutic efficacy. Plazomicin (PLZ), a semisynthetic aminoglycoside approved by the FDA in 2018, overcomes the most common aminoglycoside resistance mechanisms and maintains activity against many carbapenem-intermediate or -resistant (CIR) E. coli strains. To assess plazomicin susceptibility among CIR E. coli in relation to region and multiple bacterial characteristics. We determined broth microdilution MICs for plazomicin and 11 comparators against 343 CIR clinical E. coli isolates, then compared susceptibility results by bacterial characteristics and region. The collection comprised 203 US isolates (2002–17) and 141 isolates from 17 countries in Europe, Latin America, and the Asia-West Pacific region (2003–17). Isolates were characterized for phylogenetic group, resistance-associated sequence types (STs) and subsets thereof, and relevant β-lactamase-encoding genes. Plazomicin exhibited the highest percentage susceptible (89%) after tigecycline (99%). The percentage susceptible to plazomicin varied significantly by phylogroup (63%, group B1; versus >93%, others) and ST131 subclone (92%, H30Rx; versus 87%–89%, H30R1 and non-H30), but not ST. It also varied by resistance genotype [higher with Klebsiella pneumoniae carbapenemase (KPC), lower with metallo-β-lactamases], global region [highest for Latin America (94%), lowest for Asia-West Pacific (69%)], and US region (80%, South, versus 96%–100%, others). Although reduced susceptibility to comparators often predicted reduced susceptibility to plazomicin, even among comparator-intermediate or -resistant isolates the plazomicin-susceptible fraction was ≥77%, except for amikacin (53%). The likely utility of plazomicin against CIR E. coli is high overall, but varies with region and multiple bacterial characteristics.