Determining the optimal duration of oral antibiotic cefalexin treatment for infants and young children with a clinical diagnosis of febrile urinary tract infection.

Cefalexin for UTIs – Right treatment Length in Young children (the CURLY trial). A multi-centre, randomised trial to determine the optimal duration of cefalexin therapy for the treatment of febrile urinary tract infections in children.

Status

Recruiting

Phases

Phase 4

Study type

Interventional

Source

ISRCTN

Registry ID

ISRCTN65844003

Enrollment

705

Registered

2023-09-08

Start date

2023-10-01

Completion date

Unknown

Last updated

2025-09-08

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Urinary tract infections Urological and Genital Diseases

Interventions

This trial aims to determine the optimal duration of oral cefalexin treatment for infants and young children with a clinical diagnosis of febrile urinary tract infection (UTI). The trial design is a m

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: Current participant inclusion criteria as of 07/02/2025: 1. Age 3 months to 11 years inclusive 2. Clinical diagnosis of febrile UTI at presentation to ED as defined by both: 2.1. Temperature (=38°C measured by any method OR likely fever in last 24 hours) 2.2. AND Clinical feature(s) suggestive of UTI at presentation (i.e. one or more of the following): 2.2.1. If <2 years of age: • Poor feeding • Vomiting • Irritability 2.2.2. If =2 years of age: • Vomiting • Dysuria • Urinary frequency • Urinary urgency • Abdominal or flank pain • Suprapubic or flank tenderness 3. Early urine test suggesting likely UTI as defined by any one of the following: 3.1. Dipstick: nitrite positive AND leucocyte esterase positive. 3.2. Dipstick: nitrite positive AND leucocyte esterase negative (on a fresh urine sample). 3.3. Dipstick: leucocyte esterase positive AND nitrite negative AND the treating clinician assesses there to be good clinical evidence of a UTI (e.g. obvious urinary symptoms). 3.4. Abnormal urine microscopy (bacteriuria by microscopy with Gram stain 4. Decision to treat with oral cefalexin on discharge from the ED. Previous participant inclusion criteria: 1. Age 3 months to 11 years inclusive 2. Clinical diagnosis of febrile UTI at presentation to ED as defined by both: 2.1. Temperature (=38°C measured by any method OR likely fever in last 24 hours) 2.2. AND Clinical feature(s) suggestive of UTI at presentation (i.e. one or more of the following): 2.2.1. If <2 years of age: • Poor feeding • Vomiting • Irritability 2.2.2. If =2 years of age: • Vomiting • Dysuria • Urinary frequency • Urinary urgency • Abdominal or flank pain • Suprapubic or flank tenderness 3. Early urine test suggesting likely UTI as defined by either: 3.1. Abnormal urine dipstick (both nitrite and leucocyte esterase positive) 3.2. OR Abnormal urine microscopy (bacteriuria by microscopy with Gram stain) 4. Decision to treat with oral cefalexin on discharge from the ED.

Exclusion criteria

Exclusion criteria: 1. Known congenital anomalies of the kidney and urinary tract (CAKUT), reflux nephropathy or indwelling catheter. 2. Known immune deficiency (e.g. HIV, malignancy, solid-organ transplant recipients) or currently recieving immunosuppression therapy. 3. Systemic antibiotics for any reason (treatment or prophylaxis) in the previous 14 days. 4. Weight > 50kg. 5. Known allergy to cefalexin or previous severe allergic reaction to any beta-lactam antibiotic* * e.g. ampicillin, amoxicillin, cephalosporins, co-amoxiclav, penicillin.

Design outcomes

Primary

Measure	Time frame
Clinical UTI cure rate, which will be assessed at a face-to-face follow-up assessment at 16 days post-randomisation. Clinical UTI cure is defined as those patients in whom there is (i) fever resolution and (ii) no additional systemic antibiotic prescription by 16 days post-randomisation. This primary outcome is informed by a systematic review that identified wide variation in the outcomes reported within paediatric febrile UTI trials, and proposed criteria to harmonise study design, which were endorsed by the European Medicines Agency.	—

Measure

Time frame

Clinical UTI cure rate, which will be assessed at a face-to-face follow-up assessment at 16 days post-randomisation. Clinical UTI cure is defined as those patients in whom there is (i) fever resolution and (ii) no additional systemic antibiotic prescription by 16 days post-randomisation. This primary outcome is informed by a systematic review that identified wide variation in the outcomes reported within paediatric febrile UTI trials, and proposed criteria to harmonise study design, which were endorsed by the European Medicines Agency.

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Secondary

Measure	Time frame
Clinical: 1. UTI recurrence 1.1. Relapse (recurrent infection with the original bacterial strain) up to final follow-up, 30 days post-randomisation. 1.2. Reinfection (recurrent infection with a different bacterial strain) up to final follow-up, 30 days post-randomisation. 2. Individual components of the primary outcome 2.1. Fever resolution at the primary outcome assessment visit. 2.2. No additional systemic antibiotic prescription by the primary outcome assessment visit. 3. Microbiological cure 3.1. Urine sterilisation at the primary outcome assessment visit. 4. Antibiotic-associated adverse events 4.1. Antibiotic-associated adverse events, including diarrhoea, rash, and candida infections. 5. Adherence to trial drug 5.1. No more than one missed dose from the allocated full course, as logged on the medicine tracker page of the CURLY app and no additional dose(s) beyond the assigned treatment duration. 6. Antimicrobial resistance & ESBL rates 6.1. Overall rates of antibiotic resistance of urinary pathogens within pre- and post-treatment urine samples. 6.2. Regional rates of antibiotic resistance. 6.3. Identification of ESBL-producing organisms within post-treatment urine samples. 7. Quality of life – CHU9D 7.1. Differences in quality of life (using the Child Health Utility instrument CHU9D) between the different treatment duration arms. Economic: 8. Health economics 8.1. An incremental cost-utility analysis will determine the Cost per Quality Adjusted Life Years of the different treatment durations over the follow-up period.	—

Measure

Time frame

Clinical: 1. UTI recurrence 1.1. Relapse (recurrent infection with the original bacterial strain) up to final follow-up, 30 days post-randomisation. 1.2. Reinfection (recurrent infection with a different bacterial strain) up to final follow-up, 30 days post-randomisation. 2. Individual components of the primary outcome 2.1. Fever resolution at the primary outcome assessment visit. 2.2. No additional systemic antibiotic prescription by the primary outcome assessment visit. 3. Microbiological cure 3.1. Urine sterilisation at the primary outcome assessment visit. 4. Antibiotic-associated adverse events 4.1. Antibiotic-associated adverse events, including diarrhoea, rash, and candida infections. 5. Adherence to trial drug 5.1. No more than one missed dose from the allocated full course, as logged on the medicine tracker page of the CURLY app and no additional dose(s) beyond the assigned treatment duration. 6. Antimicrobial resistance & ESBL rates 6.1. Overall rates of antibiotic resistance of urinary pathogens within pre- and post-treatment urine samples. 6.2. Regional rates of antibiotic resistance. 6.3. Identification of ESBL-producing organisms within post-treatment urine samples. 7. Quality of life – CHU9D 7.1. Differences in quality of life (using the Child Health Utility instrument CHU9D) between the different treatment duration arms. Economic: 8. Health economics 8.1. An incremental cost-utility analysis will determine the Cost per Quality Adjusted Life Years of the different treatment durations over the follow-up period.

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Countries

England, Ireland, Northern Ireland, United Kingdom

Outcome results

None listed

Source: ISRCTN (via WHO ICTRP) · Data processed: Feb 4, 2026