| contemporary diversity of β-lactamases among enterobacteriaceae in the nine u.s. census regions and ceftazidime-avibactam activity tested against isolates producing the most prevalent β-lactamase groups. | escherichia coli (328 isolates), klebsiella pneumoniae (296), klebsiella oxytoca (44), and proteus mirabilis (33) isolates collected during 2012 from the nine u.s. census regions and displaying extended-spectrum-β-lactamase (esbl) phenotypes were evaluated for the presence of β-lactamase genes, and antimicrobial susceptibility profiles were analyzed. the highest esbl rates were noted for k. pneumoniae (16.0%, versus 4.8 to 11.9% for the other species) and in the mid-atlantic and west south centr ... | 2014 | 24247134 |