Dermal Microflora Restoration With Ammonia-Oxidizing Bacteria Nitrosomonas Eutropha in the Treatment of Keratosis Pilaris: A Randomized Clinical Trial

March 2018 | Volume 17 | Issue 3 | Original Article | 285 | Copyright © March 2018

Nicole Y. Lee MD MPH,a Omer Ibrahim MD,b Shilpi Khetarpal MD,c Mariya Gaber,d Spiros Jamas ScD,d Ioannis Gryllos PhD,d and Jeffrey S. Dover MD FRCPCe

aWesson Dermatology, Great Neck, NY bChicago Cosmetic Surgery and Dermatology, Chicago, IL cCleveland Clinic, Cleveland, OH dAOBiome LLC; Cambridge, MA eSkinCare Physicians, Chestnut Hill, MA

Keratosis pilaris (KP) is a common skin finding that presents as follicular hyperkeratotic papules on the proximal extremities in patients with a propensity for atopy. Although often asymptomatic, the stippled appearance is cosmetically disturbing to patients and difficult to treat as current therapies are limited in availability and efficacy. Nitric oxide (NO) has been found to be essential in basic systemic and cutaneous physiologic function, specifically in terms of its anti-microbial and anti-inflammatory properties, which evolutionarily was maintained by ammonia-oxidizing bacteria (AOB). As modern hygiene practices have improved, there has been a gradual loss of cutaneous AOB and, therefore, the availability of an important source of human physiologic NO. We propose that restoring this dermal microflora with a purified strain of AOB, Nitrosomonas eutropha (D23), may reduce the overall cutaneous inflammatory state and, thus, be a potential therapeutic option for improving the cosmetic appearance of a skin condition such as KP which is often found in association with xerosis and atopic dermatitis. Clinical trial registry number: NCT03243617

J Drugs Dermatol. 2018;17(3):285-288.


Keratosis pilaris (KP) is a skin condition that presents as hyperkeratotic, and at times erythematous, follicular papules typically found on proximal extremities of patients with a background of atopy. While a common skin finding, the available treatments are limited to minimally effective topical emollients, exfoliants, and retinoids. As such, newer, more efficacious options are needed to relieve the visual and textural abnormalities caused by this condition.In the last century, the improvement in hygiene practices and overall cleanliness of modern society has dramatically reduced exposure to diverse environmental microbiota that have traditionally assisted in immune and proliferative regulation. As a result, certain conditions such as atopic dermatitis, seasonal allergies, and asthma have increased in prevalence.1,2 Furthermore, improved societal hygiene has resulted in the near elimination of cutaneous commensal ammonia oxidizing bacteria (AOB). AOB produce nitric oxide (NO) and nitrite products through the oxidation of ammonia in sweat.1,3 NO is a ubiquitous gas that functions as a signaling and effector molecule that regulates keratinocyte proliferation, and healthy physiologic levels of NO in the skin result in decreased keratinocyte proliferation.4,5 Therefore, as the presence of AOB has essentially become nonexistent in developed societies, so has the availability of an important source of proliferation-stabilizing NO in humans. We propose that restoring this dermal microflora with a purified strain of AOB, Nitrosomonas eutropha (D23), may replenish physiologic NO levels and restore its anti-proliferative role on keratinocytes. Furthermore, as KP is primarily a disorder of hyperproliferative keratinization leading to follicular plugging, we hypothesize that D23 would be an effective treatment for this condition. 


A 4-week single-center, double-blind, placebo-controlled, split-arm study was performed to evaluate the safety and efficacy of an ammonia-oxidizing bacteria (AO+) spray-on mist for the treatment of keratosis pilaris. Enrolled subjects were aged 18-65 years with Fitzpatrick skin types I-IV and had a clinical diagnosis of keratosis pilaris involving proximal extremities. Exclusion criteria included concurrent pregnancy, prior laser therapy to the extremity in the past year, a separate on-going