What is first line treatment for Pyelonephritis and its mode of action?

Amoxicillin clavulanate= Beta lactam antibiotic combination of amoxicillin and clavulanic acid Clavulanic acid acts to reduce drug resistance when used in combination - it has minimal antibacterial action but is a potent inhibitor of beta-lactamase produced by some bacteria Inhibits cell wall synthesis causing cell lysis = bactericidal