Effect of Topical Endolysin Against Staphylococcus aureus

SEM of Staphylococcus aureus. X 14,000 at 4×4′. S. aureus, often referred to simply as staph, are bacteria commonly carried on the skin or in the nose of healthy people. Staph bacteria are one of the most common causes of skin infections in the United States.
Investigators examined the potential topical corticosteroid-sparing effect of topical endolysin in patients with atopic dermatitis.

Topical endolysin against Staphylococcus aureus has not demonstrated a topical corticosteroid (TCS)-sparing effect in people with atopic dermatitis, according to study results recently published in the Journal of Allergy and Clinical Immunology.

This double-blind, vehicle-controlled superiority trial included 100 adults with moderate to severe atopic dermatitis treated with TCS. A total of 87 participants completed follow-up. Of these, skin culture showed that 64.6% (n = 62) tested positive for S aureus. After a 2-week run-in period, researchers randomly assigned participants 1:1 to 12 weeks of either a vehicle or topical endolysin against S aureus, after which an 8-week follow-up period TCS-sparing effect. Data analysis was performed as intention-to-treat and per-protocol, with generalized linear mixed-effect models used to examine the primary outcome.

During the 12-week intervention period (8400 d/100 patients), the endolysin-treated cohort used TCS for more days than participants in the vehicle group (1889 days vs 1566 days, respectively). There was no statistical difference in likelihood of daily topical corticosteroid use in S aureus-positive participants (P =.08), per-protocol analysis (P =.4), or intention-to-treat analysis (P =.97). The number of physician-reported flares in the intervention period was lower in the intervention group (n = 2) compared with the vehicle group (n = 10) (P =.03); however, there was no significant difference in the reduction of S aureus.

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Limitations of this study include the possibility that participants were not recolonized with S aureus nasally, as well as a potential barrier to effectiveness created by polyethylene glycol hexadecyl, which formed the base of endolysin cream.

The study researchers concluded that “long-term targeted endolysin treatment against S aureus in this study was well tolerated but had no TCS sparing effect in patients with [atopic dermatitis]; however, an effect cannot be excluded since good compliance to the treatment and concurrent application of TCS and/or emollients may have masked a clinical benefit.”

Author van Doorn reported associations with Cutanea Life Sciences, Inc.

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de Wit J, Totté JEE, van Mierlo MMF, et al. Endolysin treatment against Staphylococcus aureus in adults with atopic dermatitis: a randomized controlled trial [published online May 27, 2019]. J Allergy Clin Immunol. doi:10.1016/j.jaci.2019.05.020