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

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What is this study about?

Women who are 75 years of age or older and develop a sudden kidney infection caused by the bacterium Escherichia coli are affected by a condition known as acute pyelonephritis. This infection can produce fever, pain in the back or side, and urinary symptoms such as burning or urgency, and it requires prompt treatment with antibiotics to prevent complications.

The study compares an oral medication called fosfomycin trometamol with other antibiotics that are commonly used for this type of infection, which may be given by mouth or through an IV line. The goal is to determine whether fosfomycin can achieve the same level of clinical cure—meaning the fever goes down and the urinary symptoms disappear—without needing additional antibiotic therapy.

Participants are assigned by chance to receive either fosfomycin or one of the standard antibiotics and receive treatment for roughly one week. After the medication course, they are checked around day 17 and again around day 37 to see if the infection has cleared, to monitor for any side effects such as confusion, falls, weight loss, or pressure sores, and to record any need for further hospital care or repeat infections.

1 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.

2 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.

3 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.

4 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.

5 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.

6 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.

7 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.

8 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.

Who Can Join the Study?

  • You must be a woman.
  • You must be 75 years old or older.
  • You must have had a fever of at least 38.0°C (100.4°F) at least once in the 72 hours before the diagnosis.
  • You must have at least one new urinary symptom, such as a sudden need to urinate (urgency), pain or burning when you pee (dysuria), urinating more often, blood in the urine (hematuria), pain in the lower back (lumbar region) or lower belly (suprapubic area), or loss of bladder control (urinary incontinence).
  • A urine test (called a urine culture) taken before starting antibiotics must show:
    • at least 10,000 white blood cells per milliliter (indicating infection),
    • only one type of bacteria, specifically E. coli, with at least 1,000 colonies per milliliter,
    • and the bacteria must be sensitive (able to be killed) by the study drug FT, the initial antibiotic you received, and at least one other oral antibiotic (such as fluoroquinolones, amoxicillin, amoxicillin‑clavulanic acid, or SMX‑TMP) or by an injectable antibiotic if no oral option is suitable.
  • You must be able to take medication by mouth (oral treatment).
  • After 3 or 4 days of the initial antibiotic, you must show a good response, meaning your fever is gone (defervescence, temperature below 38°C) and the urinary infection signs are improving or have disappeared.

Who Cannot Join the Study?

  • Having an infection in any part of the body other than the urinary system (the system that makes and stores urine).
  • Not giving written permission to join the study, or if you cannot give permission, not having a trusted person or close relative agree on your behalf.
  • Already taking part in another clinical trial that tests a new treatment.
  • Having a very severe infection such as septic shock (dangerously low blood pressure caused by infection), needing emergency surgery on the kidneys or ureters, or having a renal abscess (a pocket of pus in the kidney).
  • Having a tube that stays inside the urinary system, such as a urinary catheter, bladder catheter, ureteral catheter, or a nephrostomy tube.
  • Being unable to swallow or take medicines by mouth.
  • Having a weakened immune system (immunosuppression) because of an organ transplant, medicines that suppress the immune system, or ongoing chemotherapy (cancer treatment that kills fast‑growing cells).
  • Being allergic to or unable to use the study drug fosfomycin.
  • Having very advanced kidney disease (end‑stage chronic renal failure) with a glomerular filtration rate (a measure of how well the kidneys filter blood) less than 15 ml/min/1.73 m².
  • Not having social security coverage.
  • Being under legal protection (for example, a court has appointed a guardian to make decisions for you).

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

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Other Sites

Site Name City Country Status
Hopital Beaujon Clichy France
Hxijdsi Sldaa Abmyzby Paris France
Cqfrct Hcaczdrmqfd Vvfwuj Dsbkkh Argenteuil France
Cqi dxnewalkcrqemj Epagny Metz Tessy France
Clafzj Hbksgbdfgwg Dx Savuhwigvpb St Denis France
Ctccwa Htghakuvkvd Usjgdpjgqqwyp deauihlhu Orléans France
Ayxzoqifoe Pbpwpoyc Hrthkqfg Dk Pcvnh Paris France
Cdoddk Hjxcncovxvp Migihkzlw Sftyqr Chambery France
Cahlxi Hehziyvmdhk Udbvyisccsbrf Rncbe Reims France
Hsakyueo Fsgz Suresnes France
Ccsgqc Hxvobjattgv Udhuvkesvxgoa Df Pjrpozqw Poitiers France
Pnmtcjgby Hjgqrsul Bordeaux France
Rrqhqmmhdntjvxvd Hrikabbj Garches France
Cqms Hdkkkdpfakq Iqngxzaqg R Btyzomjzg Aulnays-Sous-Bois France

Want to learn more about this study or check if you can participate? Contact us.

Trial status

Country Status Recruitment Start
France France
Not yet recruiting
15.09.2026

Trial locations

Fosfomycin is an oral antibiotic taken as granules that dissolve in water. It is used to treat urinary tract infections, including kidney infections, by stopping bacteria from building their cell walls.

Imipenem and Cilastatin is a combination given by IV infusion for serious infections. Imipenem kills a wide range of bacteria, and cilastatin protects it from being broken down in the kidneys, allowing the drug to work longer.

Temocillin is an IV antibiotic used for infections caused by gram‑negative bacteria, especially those resistant to other drugs. It works by interfering with the bacteria’s cell wall formation.

Meropenem is a broad‑spectrum carbapenem antibiotic given intravenously for severe infections. It attacks many types of bacteria by preventing them from forming a proper cell wall.

Ciprofloxacin is an oral fluoroquinolone antibiotic that treats a variety of infections, including urinary and respiratory infections. It works by stopping bacteria from copying their DNA.

Levofloxacin is an oral fluoroquinolone used for respiratory, urinary, and skin infections. It kills bacteria by blocking the enzymes they need to replicate their DNA.

Sulfamethoxazole and Trimethoprim is an oral combination (often called co‑trimoxazole) that treats many infections such as urinary tract infections. The two drugs work together to block the bacteria’s ability to make folic acid, which they need to grow.

Cefepime is an IV cephalosporin antibiotic with a broad range of activity. It is used for serious infections and works by weakening the bacterial cell wall.

Amikacin is an IV aminoglycoside antibiotic used for serious gram‑negative infections. It kills bacteria by disrupting the production of essential proteins.

Cefoxitin is an IV cephalosporin antibiotic used for mixed infections, including those involving anaerobic bacteria. It interferes with bacterial cell wall synthesis.

Amoxicillin is an oral penicillin‑type antibiotic commonly used for ear, throat, and urinary infections. It stops bacteria from building their cell walls.

Ofloxacin is an oral fluoroquinolone antibiotic that treats urinary and respiratory infections. It works by preventing bacterial DNA replication.

Ertapenem can be given intravenously, subcutaneously, or intramuscularly and is used for a wide range of infections. It belongs to the carbapenem class and disrupts bacterial cell wall formation.

Aztreonam is an IV monobactam antibiotic that targets gram‑negative bacteria, including those resistant to other drugs. It works by weakening the bacterial cell wall.

Cefotaxime is an IV cephalosporin used for many types of infections, such as those of the lungs, urinary tract, and abdomen. It kills bacteria by damaging their cell walls.

Ceftazidime is an IV cephalosporin especially effective against Pseudomonas and other gram‑negative bacteria. It disrupts the formation of the bacterial cell wall.

Amoxicillin and Beta‑lactamase inhibitor is an oral combination (amoxicillin with clavulanic acid) that expands the range of bacteria the drug can treat. The inhibitor protects amoxicillin from being destroyed by bacterial enzymes.

Gentamicin is an IV aminoglycoside antibiotic used for serious infections, often in combination with other drugs. It kills bacteria by interfering with protein production.

Ceftriaxone is an IV or intramuscular cephalosporin antibiotic widely used for many infections, including meningitis and pneumonia. It works by weakening the bacterial cell wall.

Piperacillin and Beta‑lactamase inhibitor is an IV combination (piperacillin with tazobactam) that provides broad coverage, including Pseudomonas. The inhibitor protects piperacillin from bacterial enzymes, allowing it to kill a wider range of bacteria.

Acute pyelonephritis – A bacterial infection that begins in the lower urinary tract and spreads upward to involve the kidney tissue and renal pelvis. It causes inflammation of the kidney, leading to flank pain, fever, and urinary symptoms such as urgency and dysuria. The infection can progress from a simple bladder infection to involve the kidney, resulting in more intense pain and systemic signs. In elderly women, the condition may develop gradually, with increasing discomfort and fever as the bacteria multiply within the kidney.

Trial ID:
2025-521663-13-00
Protocol code:
APHP240802
Trial Phase:
Therapeutic confirmatory (Phase III)

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