Fosfomycin trometamol versus drug combination for treating acute E. coli pyelonephritis in women aged 75 years and older

Randomization and start of study medication

After joining the study you will be assigned by a computer to receive either fosfomycin trometamol or one of several commonly used antibiotics. the assignment is random and you will not know which medication you will receive until it is given to you.

The study medication will be started as soon as possible after randomization.

Administration of fosfomycin trometamol (if assigned)

Fosfomycin trometamol is taken by mouth as a solution that you dissolve in water.

The prescribed dose is 3 g (three grams) taken once daily.

The treatment period lasts for the number of days specified by the study protocol, typically up to day 7.

Administration of comparator antibiotic (if assigned)

If you are assigned to a comparator antibiotic, one of the following may be used; each has its own dose, route, and schedule:

imipenem and cilastatin: 3 g given intravenously, usually once daily;

temocillin: 6 g given by infusion, usually once daily;

meropenem: 6 g given intravenously, usually once daily;

ciprofloxacin: 1 g taken orally, usually once daily;

levofloxacin: 500 mg taken orally, usually once daily;

sulfamethoxazole and trimethoprim: 1600 mg taken orally, usually once daily;

cefepime: 4 g given by infusion, usually once daily;

amikacin: 15 mg per kilogram of body weight given intravenously, usually once daily;

cefoxitin: 6 g given intravenously, usually once daily;

amoxicillin: 3 g taken orally, usually once daily;

ofloxacin: 400 mg taken orally, usually once daily;

ertapenem: 1 g given intravenously, subcutaneously, or intramuscularly, usually once daily;

aztreonam: 6 g given intravenously, usually once daily;

cefotaxime: 3 g given by infusion, usually once daily;

ceftazidime: 3 g given by infusion, usually once daily;

amoxicillin and beta‑lactamase inhibitor: 3 g taken orally, usually once daily;

gentamicin: 3 mg per kilogram of body weight given intravenously, usually once daily;

ceftriaxone: 1 g given by infusion, usually once daily;

piperacillin and beta‑lactamase inhibitor: 12 g given intravenously, usually once daily.

Daily symptom and temperature monitoring

You will be asked to check your body temperature each day and record any urinary symptoms such as pain, urgency, or frequency.

A temperature of 38 °C (100.4 °F) or higher that is not related to another cause will be noted as a fever.

End‑of‑treatment assessment (day 7)

On day 7, after completing the assigned antibiotic course, you will have a clinical evaluation.

The doctor will check that your temperature is below 38 °C and that urinary infection symptoms have resolved.

Any need to start a new antibiotic targeting the original bacteria will be recorded.

Primary endpoint evaluation (day 17)

On day 17, you will be seen again to confirm the primary outcome.

The assessment includes confirming that you have no fever (temperature <38 °C) and no urinary infection symptoms, and that no additional antibiotic targeting the original bacteria has been started since the end of treatment.

Follow‑up assessment (day 37)

On day 37, a final follow‑up visit will be performed.

The evaluation will include checking for any recurrence of urinary infection, measuring functional independence using the ADL (activities of daily living) scale, and recording any geriatric complications such as confusion, falls, weight loss, or pressure ulcers.

Hospitalization days after randomization, mortality, and colonization with antibiotic‑resistant bacteria will also be documented.

Adverse event reporting throughout the trial

Any side effects or unwanted medical events you experience at any time during the study must be reported to the study team.

The severity of each event will be graded using a standard scale that classifies events from mild to severe.