Rationale for empirical antibiotic therapy for acute cystitis in adults
See Approach to empirical antibiotic choice for UTI in adults for principles of antibiotic choice.
At the time of writing, less than 5% of Escherichia coli urine isolates from adults in the community in Australia are resistant to nitrofurantoin and less than 5% are resistant to fosfomycinAustralian Commission on Safety and Quality in Health Care (ACSQHC), 2023. Nitrofurantoin is recommended as first-line empirical treatment for acute cystitis in female1 and male2 patients. Although there have been concerns about serious adverse effects with nitrofurantoin, these adverse effects are associated with long-term use; nitrofurantoin is safe and effective for short-term treatment of acute cystitis in patients with a glomerular filtration rate (GFR) of 30 mL/min or higherCunha, 2017Geerts, 2013Nelson, 2024Santos, 2016Singh, 2015. Fosfomycin is recommended second-line for females with cystitis because a head-to-head randomised controlled trial showed lower efficacy when compared to nitrofurantoinHuttner, 2018Shafrir, 2023Ten Doesschate, 2020Tutone, 2022; data are lacking for fosfomycin in male patients with cystitisBouiller, 2022.
Trimethoprim is no longer the first-line empirical recommendation for acute cystitisAustralian Commission on Safety and Quality in Health Care (ACSQHC), 2023. Although, trimethoprim is well tolerated and effective for acute cystitis if the pathogen is susceptible, the rates of trimethoprim resistance among E. coli urine isolates in Australia have been increasing and are now above 20%Australian Commission on Safety and Quality in Health Care (ACSQHC), 2023.
Pivmecillinam3 is an effective option for cystitis in nonpregnant adult females and malesJansaker, 2019; however, pivmecillinam is not currently registered in Australia.
Amoxicillin+clavulanate has an unnecessarily broad spectrum of activity for empirical treatment of cystitis. The use of broad-spectrum antibiotics selects for antibiotic-resistant organisms and increases the risk of Clostridioides difficile (formerly known as Clostridium difficile) infection.
Quinolones (eg ciprofloxacin) are not recommended for empirical treatment of cystitis because of their potential adverse effects (see Practical information on using quinolones) and association with the development of resistance; they are the only oral drugs available for infections caused by Pseudomonas aeruginosa and some multidrug-resistant bacteria.