More Research Needed on S aureus Colonization in Psoriasis

Controlled studies to evaluate the benefits of a universal or targeted decolonization program in patients with psoriasis is warranted.

Currently available evidence on bacterial colonization — particularly with Staphylococcus aureus — in patients with moderate to severe psoriasis is insufficient to inform clinical practice, according to the results of a prospective study published in the Journal of the American Academy of Dermatology.

A total of 50 patients with psoriasis were prospectively followed between 2015 and 2017 to quantify changes in staphylococcal colonization following a course of treatment with biologic agents (n=42) or nonbiologic agents (n=8) for 16 weeks. At enrollment, all eligible patients were assessed for initiating biologics, such as interleukin monoclonal antibodies (ustekinumab or secukinumab) or tumor necrosis factor inhibitors (adalimumab, golimumab, or etanercept) based on disease severity (Psoriasis Area and Severity Index [PASI] >10) and a lack of response or intolerance to traditional systemic therapeutic agents.

All participants were interviewed with respect to sociodemographic information, medical history, and clinical outcomes. The primary study outcome was culture-based staphylococcal colonization status of selected lesional sites. The researchers also swabbed anterior nares and nail folds of fingers to evaluate cross-site concordance.

The average age of the participants was 41 years (range, 34- 46 years), and 86% were men. A majority of the patients had had psoriasis for ≥20 years; 7 cases were newly diagnosed at study enrollment. Overall, 10 users of biologic agents were followed for an additional 8 months and appeared to be representative of the other participants.

At study enrollment, 24% (12 of 50) of patients carried S aureus in their nares and 32% (16 of 50) of patients harbored S aureus on at least 1 lesion. After 16 weeks of treatment, the mean lesional colonization decreased significantly to 5.0% (adjusted odds ratio [aOR], 0.35; P =.024), but not colonization of nares or nasal folds (P >.05), although site-specific variations did exist.

Nail fold colonization pretreatment (aOR 4.91; P =.017) and during treatment (aOR 6.20; P =.002) were associated with lesional colonization, as were active smoking (aOR 3.38; P =.019) and concurrent nasal colonization (aOR 3.68; P =.002). Patient-reported quality of life, as assessed by the Dermatology Life Quality Index (P =.008), and regular use of antiseptic-containing facial cleansers (P <.001) were significantly associated with loss of colonization. The first-time receipt of systemic therapies significantly increased the risk for lesional recolonization (P =.008).

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Results of concordance analysis demonstrated that colonization of nail folds and nares was temporally correlated (aOR 26.8; P =.003), as was colonization of nares and hairlines (aOR 4.69; P =.044). Hairline colonization was highly concordant with colonization of other skin lesions (all P ≤.022).

Although a limited power existed to compare decolonization effects of systemic agents used for the treatment of psoriasis, commensal S aureus on psoriatic lesions was decreased among patients who were receiving systemic nonbiologic agents or biologic agents.

The investigators concluded that controlled studies to evaluate the benefits of a universal (regardless of colonization status) or targeted (for confirmed colonizers) decolonization program in patients with psoriasis is warranted.


Liu S-H, Yu H-Y, Chang Y-C, et al. Host characteristics and dynamics of Staphylococcus aureus colonization in patients with moderate-to-severe psoriasis before and after treatment: a prospective cohort study [published online May 24, 2018]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2018.05.031.