Other choices, such as ampicillin plus gentamicin, the aminoglycoside plazomicin (1), broad-spectrum cephalosporins (eg, ceftriaxone, cefotaxime, cefepime), aztreonam, beta-lactam / beta-lactam inhibitor combinations (ampicillin / sulbactam, ticarcillin / clavulanate, piperacillin / tazobactam), and imipenem / cilastatin, are usually reserved for patients with more complicated pyelonephritis (eg, with obstruction, calculi, resistant bacteria, or a hospital-acquired infection) or recent urinary tract instrumentation.