Phenotypic and genotypic characterization of extended-spectrum b-lactamases producing Escherichia coli and Klebsiella pneumoniaein a tertiary care hospital in Riyadh, Saudi Arabia. (2015). Phenotypic and genotypic characterization of extended-spectrum b-lactamases producing Escherichia coli and Klebsiella pneumoniaein a tertiary care hospital in Riyadh, Saudi Arabia. Annals Of Saudi Medicine, 35(6).