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NCT Number: NCT05584007

Cellulitis Optimal Antibiotic Treatment

To determine whether a short course of oral flucloxacillin (5 days) is non-inferior to a standard course (7 days) in terms of pain over days 6-14 (indicative of persistence or recurrence associated with the symptoms of most importance to patients) in adults with cellulitis of the leg presenting in primary care.

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Key information

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

Royal South Hants Hospital

Southampton, United Kingdom

Location status: Recruiting

Location contact

Ian Ward

CONTACT

Ian Ward

PRINCIPAL_INVESTIGATOR

About this study

Cellulitis is a deep infection of the skin and subcutaneous tissues and most often occurs in the legs. It is a painful condition that is associated with inflammation and swelling of the site, and often systemic symptoms such as fever, headache, muscle aches, malaise, and fatigue. Patients report feeling unwell and that it has a significant impact on their mobility and ability to carry out their usual activities. NICE guidelines recommend oral flucloxacillin 500-1000 mg four times daily for 5-7 days as first-line treatment for most patients with cellulitis in the community, but most prescriptions are dispensed for a 7-day course. We will be assessing the effectiveness and safety of a 5-day treatment vs. the standard 7-day treatment. We also aim to evaluate the cost-consequences of a shorter course from an NHS and personal perspective. Participants will be randomly allocated to one of two groups. In addition to usual care, participants will either be assigned to a 5-day oral flucloxacillin course or a standard 7-day flucloxacillin course. Participants will be prescribed a 5-day course of oral flucloxacillin, and two additional tablets will be posted to the participants which will either be the antibiotic or a placebo tablet. Participants will be asked to fill out daily questionnaires and express their experiences with the shortened course and taking part in the trial.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Must be aged 18 years or older
  • Currently showing symptoms of cellulitis (such as pain, tenderness, redness, other change in skin color, warmth to touch) in one leg for 10 days or less
  • Pain rated as 3/10 or higher on a numerical rating scale (0-10) at baseline assessment
  • Be willing to be randomized to either trial arm (5-day or 7-day treatment)
  • Able to complete trial procedures in the English language.

Exclusion criteria

  • Have penicillin allergy
  • Have bilateral cellulitis
  • Have had antibiotics for cellulitis within the past month
  • Have post-operative cellulitis (within 30 days of operative procedures on the same leg)
  • Have cellulitis resulting from human/animal bite injury
  • Have Cellulitis associated with chronic (>6 weeks) leg ulceration
  • Require immediate hospital admission or out-patient intravenous antibiotic therapy

Treatment and study plan

Flucloxacillin Only Product in Oral Dose Form

Drug

Patients will be prescribed flucloxacillin 500mg QDS for 5 days followed by blinded flucloxacillin 500mg for 2 days, reaching a total of 7 days of antibiotic treatment

Placebo Only Product in Oral Dose Form

Drug

Patients will be prescribed flucloxacillin 500mg QDS for 5 days followed by a blinded placebo for 2 days, reaching a total of 5 days of antibiotic treatment

Primary outcomes

  1. Pain assessment

    Time frame: Days 7-16

    Self-reported pain (measured using the Pain Numeric Rating Scale (0-10))

Secondary outcomes

  1. Use of additional antibiotics

    Time frame: Up to day 28

    Any reported use of antibiotics other than the initial 5 days of flucloxacillin and 2 days of IMP)

  2. Patient-reported assessment of how well they are feeling

    Time frame: Days 6-14

    Numeric rating scale NRS (0-10) and assessed as repeated measures

  3. Health related quality of life

    Time frame: Days 6-14

    EQ-5D-5L - values, and individual dimension (mobility, self-care, usual activities, pain/discomfort, anxiety/depression) level scores using repeated measures.

  4. Health related quality of life used to estimate Quality Adjusted- Life Years (QALYs)

    Time frame: Days 6-14

    EQ-5D-5L - values, and individual dimension (mobility, self-care, usual activities, pain/discomfort, anxiety/depression) level scores using repeated measures.

  5. Leg swelling and warmth

    Time frame: Day 7, 14, 21, 28

    Participant reported questionnaire

  6. Time until self-reported recovery

    Time frame: Day 7, 14, 21, 28

    Participant reported questionnaire

  7. Time until self-assessed extent of cellulitis starts to reduce (with no subsequent increase)

    Time frame: Day 7, 14, 21, 28

    Participant reported questionnaire

  8. Hospital admissions

    Time frame: 12 months

    Number of hosptial admissions since randomisation, collected from primary care notes review

  9. Recurrent cellulitis episodes over 12 months (number of episodes)

    Time frame: 12 months

    Recurrent cellulitis episodes over 12 months (number of episodes) since randomisation, collected from primary care notes review

  10. Complications over 12 months

    Time frame: 12 months

    Number of reported complications since randomisation, collected from primary care notes review

Study contacts

Contact information is provided by the study sponsor or research team.

Ella Bourke

CONTACT

[email protected]

02381550206

Sophie Varkonyi-Clifford

CONTACT

[email protected]

0 23 8059 1532

Sponsors and collaborators

Lead sponsor

University of Southampton

Other

Collaborators

  • Norfolk and Norwich University Hospitals NHS Foundation Trust
  • University Hospital Southampton NHS Foundation Trust
  • University of East Anglia
  • University of Nottingham

Registry information

Official study title

A Blinded, Non-inferiority Phase III Trial of 5 Versus 7 Days of Oral Flucloxacillin in Primary Care Patients With Lower Limb Cellulitis

Acronym: COAT

Important dates

Study start
2023
Primary completion
2026
Study completion
2027
First posted
Oct 18, 2022
Registry last updated
May 15, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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