Rationale for oral antibiotic therapy for acute pyelonephritis in nonpregnant adults

See Approach to managing acute pyelonephritis in nonpregnant adults for principles of antibiotic choice.

At the time of writing, approximately 10 to 15% of Escherichia coli urine isolates from adults in the community in Australia are resistant to amoxicillin+clavulanate and ciprofloxacinAustralian Commission on Safety and Quality in Health Care (ACSQHC), 2023. These drugs achieve adequate concentrations to effectively treat infections in blood and kidney tissue, as well as urine.

It is the consensus of the Antibiotic Expert Group thatHeil, 2021Mponponsuo, 2023Nelson, 2024:

• oral amoxicillin+clavulanate can be used empirically to treat nonpregnant patients with acute pyelonephritis, despite limited published clinical data
• higher dosages of oral beta-lactam antibiotics should be used to ensure adequate antimicrobial exposure and activity against Enterobacterales (eg E. coli).

The efficacy of oral ciprofloxacin for acute pyelonephritis has been demonstrated in published clinical studies. Ciprofloxacin is recommended for patients with acute pyelonephritis who have hypersensitivity to penicillin. See Practical information on using quinolones for information on adverse effects of quinolones.

Oral nitrofurantoin, fosfomycin or norfloxacin are not recommended for empirical treatment of pyelonephritis because these drugs do not achieve adequate concentrations in blood or kidney tissueBonkat, 2024Gupta, 2011.