A 42-year-old man from Mumbai with a history of diabetes mellitus type 2 (HbA1c 9.2%) presents with fever (39.5°C), right flank pain, and costovertebral angle tenderness. Urinalysis shows pyuria, bacteriuria, and WBC casts. Blood culture and urine culture are sent. A Gram stain of urine shows Gram-negative rods that are oxidase-negative, indole-positive, and ferment lactose. The organism produces extended-spectrum beta-lactamase (ESBL). Which antibiotic is most appropriate for empirical therapy of this ESBL-producing organism pending susceptibility results?