In this study, we will test the tolerance of a topical product and its efficacy in reducing the atopy crisis duration and severity. The product will be tested alone, in children and adults with acute mild to moderate AD i.e as an alternative to alternative treatments, over 6 weeks.

Atopic dermatitis is a frequent chronic inflammatory skin disease affecting up to 20% of children and 8% of adults in developed countries. The disease is often localized with predilection for the face and limb folds but can be more widespread. AD is a chronic condition with many patterns of natural history the most frequent of which starting during infancy with spontaneous resolution after several years of an evolution characterized by alternance of flares and remissions. Other natural history profiles are also frequent and the disease is prevalent in adults as well, whether as a continuation of pediatric forms or as later onset diseases. Flares and remissions may as well altern in many different ways. AD is often associated with other atopic conditions including asthma, conjunctivitis and rhinitis5. Per se, the disease generates erythematous vesiculous plaques often associated with pruritis1. With time, lesion may become thicker (i.e. lichenified) and pruritus significantly impacts quality of life and sleep quality. The chronic and recurrent evolution is also felt as a burden by many patients and parents.

Taking into account the various signs and symptoms (including itch and sleep disturbance), scores have been developed to properly assess severity and guide treatment, SCORAD being one of them used both in clinical practice and clinical research. Between flares, AD management aims at preventing recurrence by avoiding triggering factors and restoring skin barrier through daily application of emollients. During flares, topical steroids are more often used than calcineurin inhibitors mostly dedicated to sensitive areas (face, folds). More severe or resistant cases deserve phototherapy or systemic immunomodulatory treatments with many new drug candidates under clinical development. Back to topical treatments, many failures are due to improper usage of topical steroids because of corticophobia. As for calcineurin inhibitors, irritation is the main limiting factor10,11. This is where important room remains for new topical treatments with good safety and tolerance profiles leading to proper usage and good observance over time and avoiding as much as possible steroid application. Crisaborole has recently been authorized in the US and JAK inhibitors are currently under investigation which illustrates the actual need. AD pathophysiology is complex and its apprehension evolves over time. Current vision associates genetic background and environmental triggering factors. Three mains factors interact to generate AD namely 1) skin barrier defect, 2) skin inflammation driven by T lymphocytes and 3) dysbiosis through the decrease of skin microbiome diversity and staphylococcus proliferation. All three are deeply interlinked. Focusing on the latter, evidence is available that microbiome is disturbed during AD. Whether this dysbiosis is a cause or a consequence remains sometimes debated, but growing evidence suggests a causative relationship especially through S. aureus proliferation, at least as an aggravative factor. Indeed S. aureus is way more frequent on AD skin with good correlation with AD severity. Some of S aureus virulence factors (superantigens, enterotoxins, alphatoxins, proteases activators production) provide a good rational for it from a mechanistic standpoint. The decrease of the microbiome diversity, the role of which is to avoid pathogens proliferation, may play a role in S. aureus proliferation on AD skin, together with skin barrier and immune defect.

Therefore, making available well tolerated and easy to use topical products avoiding S. aureus proliferation and dysbiosis fully makes sense whether as standalone or companion products both in flares management and prevention of recurrences.

In this study, the sponsor will test a well tolerated topical product including a phage derived recombinant endolysine (Staphefekt®) with a capacity to specifically destroy S aureus regardless of its methicillin sensitivity. The product will be tested alone, in children and adults with acute mild to moderate AD i.e as an alternative to alternative treatments, over 6 weeks.

Inclusion Criteria:

Sex: female and male; Age: children from 2 to 17 years old, adults from 18 to 75 years old; Phototype: all phototypes Subjects with atopic dermatitis lesions that does not exceed 400 cm2, the studied area must be of evaluable size; 50% of the subjects having atopic dermatitis lesion mainly on the face and neck; 50% of the subjects having atopic dermatitis lesion mainly on the body (folds, trunk limbs, etc.); Subject with mild to moderate atopic dermatitis, IGA 2 (75% of the subjects) to 3 (25% of the subjects); Locally on the lesional area (face/ neck or fold): IGA 2 to 3. Subject having given his/her free informed, written consent; Subject willing to adhere to the protocol and study procedures.

Exclusion Criteria:

Subjects presenting symptoms of COVID - 19 (moderate fever, dry cough, and other symptoms as described by the World Health Organisation); Subjects with a temperature higher than 37.5°C; Subject having been tested positive for COVID-19 and without a medical certificate from the Government; For women: pregnant or nursing woman or woman planning to get pregnant during the study; Children less than two years old; Severe atopic dermatitis (IGA>3); Presenting lichenification 1 or 2 for the 25% of subjects with IGA 3; Presenting with another dermatological condition that could interfere with clinical evaluation; Presenting with a previous history of allergy to cosmetic products; Current and past (last 2 weeks) systematic use of topical or systemic antihistamines, topical or systemic steroids, cyclosporin A and other immunosuppressant, naltrexone, paroxetin, fluvoxamine, amitriptylin;

Wash-out treatment for prior or concomitant therapy:

Subjects using systemic anti-inflammatory or immunomodulatory treatments, UV phototherapy or topical high-potency corticosteroids one month prior to study inclusion; Subjects using topical medium-potency corticosteroids, topical calcineurin inhibitors, topical retinoids, topical antimycotic treatments, oral antibiotics for infected AD, within 2 weeks prior to study inclusion; Subjects having used topical low-potency corticosteroids or topical antibacterial medications within 1 week prior to Day 1; Use of topical or systemic treatment during the previous weeks liable to interfere with the assessment of the cutaneous acceptability/efficacy of the study product; Subject having undergone a surgery under general anesthesia within the previous month; Excessive exposure to sunlight or UV-rays within the previous month; Current infection of AD lesions requiring antimicrobial therapy; Current acute or chronic condition unless considered clinically irrelevant and stable by the investigator ; Inability to provide informed consent or comply with study instructions; Subject enrolled in another clinical trial during the study period.

The study took place in Mauritius. Population comes from a database of subjects registered as suffering from DA. Further to facilitate recruitment, agents were appointed to look out for subjects presenting the required condition