Atopic dermatitis phenotype affects expression of atopic diseases despite similar mononuclear cell cytokine response.

BACKGROUND: The atopic march refers to the coexpression and progression of atopic diseases in childhood, often beginning with atopic dermatitis (AD), although children may not progress through each atopic disease. OBJECTIVE: We hypothesized that future atopic disease expression is modified by AD phenotype and that these differences result from underlying dysregulation of cytokine signaling. METHODS: Children (n = 285) were enrolled into the Childhood Origins of Asthma (COAST) birth cohort and followed prospectively. Rates of AD, food allergy, allergic rhinitis, and asthma were assessed longitudinally from birth to 18 years of age. Associations between AD phenotype and food allergy, allergic rhinitis, asthma, allergic sensitization, exhaled nitric oxide, and lung function were determined. Peripheral blood mononuclear cell responses (IL-5, IL-10, IL-13, IFN-γ) to dust mite, phytohemagglutinin, Staphylococcus aureus Cowan I, and tetanus toxoid were compared among AD phenotypes. RESULTS: AD at year 1 was associated with an increased risk of food allergy (P = .004). Both persistent and late-onset AD were associated with an increased risk of asthma (P < .001), rhinitis (P < .001), elevated total IgE (P < .001), percentage of aeroallergens with detectable IgE (P < .001), and elevated exhaled nitric oxide (P = .002). Longitudinal analyses did not reveal consistent differences in peripheral blood mononuclear cell responses among dermatitis phenotypes. CONCLUSION: AD phenotype is associated with differential expression of other atopic diseases. Our findings suggest that peripheral blood cytokine dysregulation is not a mechanism underlying this process, and immune dysregulation may be mediated at mucosal surfaces or in secondary lymphoid organs.

Guidelines of care for the management of atopic dermatitis in adults with phototherapy and systemic therapies.

BACKGROUND: For people with atopic dermatitis (AD) refractory to topical therapies, treatment with phototherapy and systemic therapies can be considered. Multiple biologic therapies and Janus kinase (JAK)inhibitors have been approved since 2014 to treat AD. These guidelines update the 2014 recommendations for management of AD with phototherapy and systemic therapies. OBJECTIVE: To provide evidence-based recommendations on the use of phototherapy and systemic therapies for AD in adults. METHODS: A multidisciplinary workgroup conducted a systematic review and applied the GRADE approach for assessing the certainty of evidence and formulating and grading recommendations. RESULTS: The workgroup developed 11 recommendations on the management of AD in adults with phototherapy and systemic agents, including biologics, oral JAK inhibitors, and other immunomodulatory medications. LIMITATIONS: Most randomized controlled trials of phototherapy and systemic therapies for AD are of short duration with subsequent extension studies, limiting comparative long-term efficacy and safety conclusions. CONCLUSIONS: We make strong recommendations for the use of dupilumab, tralokinumab, abrocitinib, baricitinib, and upadacitinib. We make conditional recommendations in favor of using phototherapy, azathioprine, cyclosporine, methotrexate, and mycophenolate, and against the use of systemic corticosteroids.

Executive summary: Guidelines of care for the management of atopic dermatitis in adults with phototherapy and systemic therapies.

BACKGROUND: The summarized guidelines update the 2014 recommendations for the management of AD with phototherapy and systemic therapies. METHODS: A multidisciplinary workgroup conducted a systematic review and applied the GRADE approach for assessing the certainty of the evidence and formulating and grading recommendations. RESULTS: The workgroup developed 11 recommendations on the management of AD in adults with phototherapy and systemic therapies, including biologics, oral Janus Kinase inhibitors, and other immunomodulatory medications. CONCLUSIONS: The evidence supported strong recommendations for the use of dupilumab, tralokinumab, abrocitinib, baricitinib, and upadacitinib and conditional recommendations in favor of using phototherapy, azathioprine, cyclosporine, methotrexate, and mycophenolate, and against the use of systemic corticosteroids.

Incidence rates of childhood asthma with recurrent exacerbations in the US Environmental influences on Child Health Outcomes (ECHO) program.

BACKGROUND: Descriptive epidemiological data on incidence rates (IRs) of asthma with recurrent exacerbations (ARE) are sparse. OBJECTIVES: This study hypothesized that IRs for ARE would vary by time, geography, age, and race and ethnicity, irrespective of parental asthma history. METHODS: The investigators leveraged data from 17,246 children born after 1990 enrolled in 59 US with 1 Puerto Rican cohort in the Environmental Influences on Child Health Outcomes (ECHO) consortium to estimate IRs for ARE. RESULTS: The overall crude IR for ARE was 6.07 per 1000 person-years (95% CI: 5.63-6.51) and was highest for children aged 2-4 years, for Hispanic Black and non-Hispanic Black children, and for those with a parental history of asthma. ARE IRs were higher for 2- to 4-year-olds in each race and ethnicity category and for both sexes. Multivariable analysis confirmed higher adjusted ARE IRs (aIRRs) for children born 2000-2009 compared with those born 1990-1999 and 2010-2017, 2-4 versus 10-19 years old (aIRR = 15.36; 95% CI: 12.09-19.52), and for males versus females (aIRR = 1.34; 95% CI 1.16-1.55). Black children (non-Hispanic and Hispanic) had higher rates than non-Hispanic White children (aIRR = 2.51; 95% CI 2.10-2.99; and aIRR = 2.04; 95% CI: 1.22-3.39, respectively). Children born in the Midwest, Northeast and South had higher rates than those born in the West (P < .01 for each comparison). Children with a parental history of asthma had rates nearly 3 times higher than those without such history (aIRR = 2.90; 95% CI: 2.43-3.46). CONCLUSIONS: Factors associated with time, geography, age, race and ethnicity, sex, and parental history appear to influence the inception of ARE among children and adolescents.

Guidelines of care for the management of atopic dermatitis in adults with topical therapies.

BACKGROUND: New evidence has emerged since the 2014 guidelines that further informs the management of atopic dermatitis (AD) with topical therapies. These guidelines update the 2014 recommendations for management of AD with topical therapies. OBJECTIVE: To provide evidence-based recommendations related to management of AD in adults using topical treatments. METHODS: A multidisciplinary workgroup conducted a systematic review and applied the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) approach for assessing the certainty of evidence and formulating and grading recommendations. RESULTS: The workgroup developed 12 recommendations on the management of AD in adults with topical therapies, including nonprescription agents and prescription topical corticosteroids (TCS), calcineurin inhibitors (TCIs), Janus kinase (JAK) inhibitors, phosphodiesterase-4 inhibitors (PDE-4), antimicrobials, and antihistamines. LIMITATIONS: The pragmatic decision to limit the literature review to English-language randomized trials may have excluded data published in other languages and relevant long-term follow-up data. CONCLUSIONS: Strong recommendations are made for the use of moisturizers, TCIs, TCS, and topical PDE-4 and JAK inhibitors. Conditional recommendations are made for the use of bathing and wet wrap therapy and against the use of topical antimicrobials, antiseptics, and antihistamines.

Executive summary: American Academy of Dermatology guidelines of care for the management of atopic dermatitis in adults with topical therapies.

These guidelines update the 2014 recommendations for management of atopic dermatitis in adults with topical therapies. A multidisciplinary workgroup employed best practices for guideline development, including a systematic review of the evidence and application of the Grading of Recommendations, Assessment, Development, and Evaluation approach for assessing the certainty of the evidence and formulating and grading recommendations. The evidence on atopic dermatitis treatment supported strong recommendations for the use of nonprescription moisturizers, topical calcineurin inhibitors, topical corticosteroids, and topical PDE-4 and JAK inhibitors. Conditional recommendations are made for the use of bathing and wet wrap therapy and against the use of topical antimicrobials, antiseptics, and antihistamines.

Pernio and early SARS-CoV-2 variants: natural history of a prospective cohort and the role of interferon.

Cases of new-onset pernio and recurrences in our cohort align tightly with trends in mean 7-day COVID-19 positivity in Wisconsin and mean temperature in Madison, Wisconsin by month.

American Academy of Dermatology Guidelines: Awareness of comorbidities associated with atopic dermatitis in adults.

BACKGROUND: Studies found associations between atopic dermatitis (AD) and various comorbidities. OBJECTIVE: To appraise evidence of the association between AD and comorbidities among adults. METHODS: Our multidisciplinary work group conducted a systematic review of the association between AD and selected comorbidities. We applied the Grading of Recommendations, Assessment, Development, and Evaluation for prognosis approach for assessing the certainty of the evidence, providing statements of association based on the available evidence. RESULTS: Analysis of the evidence resulted in 32 statements. Clear evidence of the association of AD in adults and select allergic, atopic, immune-mediated mental health and bone health conditions and skin infections was identified. There is some evidence supporting an association between AD and substance use, attention deficit hyperactivity disorder, and elements of metabolic syndrome. Evidence suggests a small association with various cardiovascular conditions. The association between AD in adults and autism spectrum disorders, myocardial infarction, stroke, and metabolic syndrome is inconclusive. LIMITATIONS: This analysis is based on the best available evidence at the time it was conducted. This guideline does not make recommendations for screening or management of comorbidities in adults with AD. CONCLUSIONS: Clinicians should be aware of comorbidities associated with AD. Further research is needed to determine whether screening or management of comorbidities is beneficial for adults with AD.

Real world use of peanut component testing among children in the Chicago metropolitan area.

Background: Peanut component tests (PCT) have become important in the evaluation of peanut allergy. There remains a paucity of research across the United States in investigating the utility of PCT in clinical practice in conjunction with current standards of care. Objective: The primary aims were to evaluate the performance and sensitization patterns of PCT in clinical practice when first available at our institution. Methods: We performed a retrospective chart review of 184 children with PCT and oral food challenge (OFC) results between 2012 and 2017. Simple logistic regression models assessed the associations between PCT and OFC outcomes. Receiver operator characteristic curves were constructed, and a predicted probability curve was derived for Ara h2. Results: The median (interquartile range [IQR]) age at OFC was 4 years (2-7 years), and 111 patients (60%) were boys. Ara h 2 was the most commonly sensitized PCT. Sixty-one patients (33%) reacted at OFC. Ara h 2 specific immunoglobulin E (sIgE) ≥ 0.35 kUA/L was associated with increased odds of reacting at OFC (odds ratio 5.91 95% confidence interval, 2.93-11.89; p < 0.001); however, 19 patients (37%) positive for Ara h 2 did not react. Ara h 2 sIgE of 0.49 kUA/L and 4.58 kUA/L were associated with 50% and 90% probability, respectively, of reacting at OFC. Among those sensitized only to Ara h 8 or 9 (n = 21), 86% had no reaction. There was no statistically significant association with polysensitization to Ara h 1, 2, and 3, and peanut OFC outcome. Conclusion: Although the Ara h 2 sIgE value was associated with clinical reactivity, a significant proportion of the patients sensitized to Ara h 2 tolerated peanut. OFC remains an important tool in the evaluation of peanut allergy.

Clearance of atypical cutaneous manifestations of hyper-IgE syndrome with dupilumab.

Hyper-IgE syndromes (HIES) are a heterogeneous group of rare primary immunodeficiency diseases classically characterized by the triad of atopic dermatitis, and recurrent cutaneous and pulmonary infections. Autosomal dominant, loss-of-function STAT3 pathogenic variants are the most common genetic cause, which lead to deficiency of Th17 lymphocytes, impaired interferon gamma production, and IL-10 signal transduction, and an unbalanced IL-4 state. Dupilumab, a monoclonal antibody to the IL-4a receptor, inhibits both IL-4 and IL-13, and has been shown to improve atopic dermatitis and other manifestations of HIES including asthma and allergic bronchopulmonary aspergillosis. We present a pediatric patient with HIES who presented predominantly with eosinophilic folliculitis, recurrent cutaneous infections, and other non-eczematous findings and achieved sustained clearance with dupilumab.

Private security and national security: The case of Estonia.

Most studies of private security postulate exclusively internal, primarily economic, causes of the industry's growth and regulation. In contrast, based on the case of post-Soviet Estonia, we investigate how a state's external security environment influences private security. Estonia's tense relations with neighbouring Russia and related pursuit of EU and NATO membership have generated several policies through which private security evolved from a lawless, politically contested industry to a modest, lightly regulated one: (1) the exclusion of public police from private security and an effective campaign against organized crime that together enabled an autonomous and non-criminalized security industry to emerge, (2) free-trade policies that permitted western companies to acquire Estonian security firms, and (3) an 'all-of-nation' approach to national security that promotes comprehensive state-civil society security cooperation. Estonia thus clarifies how high politics shapes private security, while also revealing the factors that make the industry relatively uncontentious in most industrialized democracies.

Quality of life is lower in adults labeled with childhood-onset food allergy than in those with adult-onset food allergy.

BACKGROUND: Immunoglobulin E-mediated food allergy (FA) affects children and adults with variable age of onset. Phenotype and quality of life (QoL) differences between childhood-onset FA (COFA) and adult-onset FA (AOFA) are not known. OBJECTIVE: To identify phenotypic and QoL differences between AOFA and COFA. METHODS: A cross-sectional study of adults (≥18 years old) seen at Northwestern Memorial HealthCare clinics between 2002 and 2017 with an International Classification of Diseases ninth and tenth revision diagnosis of FA. Subjects completed a FA history survey and a FA QoL questionnaire. FA characteristics and QoL scores were compared between groups. RESULTS: Among 294 consented subjects, 202 had a clinical history consistent with labeled immunoglobulin E-mediated FA. The onset of FA symptoms occurred before age 18 years (COFA) in 80 subjects and after age 18 years in 122 (AOFA) subjects. Shellfish reactions were most common in AOFA-labeled subjects (28%), whereas tree nut reactions were the most common in COFA-labeled subjects (55%) compared with other triggers. Hives (68% vs 52%, P = .03), facial swelling (69% vs 50%, P = .009), wheezing (56% vs 29%, P < .001), and vomiting (41% vs 22%, P = .005) were more often observed in COFA compared with AOFA. Total QoL was significantly reduced in COFA compared with AOFA (3.6 vs 3.0, P = .003) along with specific domains related to the following: allergen avoidance and dietary restriction (3.7 vs 3.1, P = .006), emotional impact (3.9 vs 3.2, P = .003), and risk of accidental exposure (3.6 vs 2.8, P = .001). CONCLUSION: There are differences in specific food triggers and symptoms in adult-onset and childhood-onset labeled FA. Adults labeled with childhood-onset FA have reduced QoL.

A randomised controlled trial comparing the efficacy of micellised and fat-soluble vitamin D3 supplementation in healthy adults.

Nanoemulsion formulation of vitamin D3 have been shown to have better bioavailability than the coarse emulsion preparation in vitro and in vivo animal studies. In the absence of randomised trial in humans, comparing the efficacy of nanotechnology-based miscellised vitamin D3 over conventional vitamin D3, we undertook this study. A total of 180 healthy adults were randomised to receive either micellised (DePura, group A) or conventional vitamin D3 (Calcirol, group B) at a monthly dose of 60 000 IU (1500µg) for 6 months. The outcome parameters were serum 25-hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH), Ca, phosphate, alkaline phosphatase and urinary Ca:creatinine ratio. A total of eighty-nine subjects in group A and seventy-seven in group B completed the trial. Subjects in both the groups had a significant increase in their serum 25(OH)D levels following supplementation (group A: 21·5 (sd 10·9) to 76·7 (sd 18·8) nmol/l (P<0·001); group B: 22·8 (sd 10·4) to 57·8 (sd 16·0) nmol/l (P<0·001)). Participants in micellised group had an additional increase of 20·2 (95 % CI 14·0, 26·4) nmol/l in serum 25(OH)D levels (P<0·001). The difference between the groups was 17·5 (95 % CI 11·8, 23·1) nmol/l, which remained statistically significant (P<0·001) even after adjustment for age and sex. Significant decline in mean serum PTH was observed in both the groups. No hypercalcaemia or hypercalciuria was noted. Although supplementation with both the preparations resulted in a significant rise in serum 25(OH)D levels, micellised vitamin D3 appeared to be more efficacious in achieving higher levels of serum 25(OH)D.

Association of food allergy and decreased lung function in children and young adults with asthma.

BACKGROUND: Food allergy (FA) appears early in the atopic march, a progression that may lead to the development of asthma. The association between FA and pulmonary function in children with and without asthma remains unknown. OBJECTIVE: To investigate the association between FA and lung function in children with and without asthma. METHODS: We enrolled 1,068 children as a part of a family-based FA cohort. We then categorized children as having FA by physician diagnosis, evidence of specific IgE, and typical symptoms within 2 hours of food ingestion. We categorized asthma by physician diagnosis. We used American Thoracic Society criteria for spirometry measurements. We assessed the effects of asthma classification and FA number on lung function using mixed-effect models. RESULTS: We enrolled 1,068 children: 417 (39%) had asthma, 402 (38%) had at least 1 FA, and 162 (15%) had 2 or more FAs. Unstratified analyses found no significant association between FA number and lung function. In children with asthma, we detected statistically significant differences in predicted forced expiratory flow at 25% to 75% between children with 2 or more FAs compared with those with none (mean [SE] ß = -7.5 [3.6]; P = .04). This effect lost significance after adjusting for aeroallergen sensitization. We detected no significant associations between FA number and predicted forced expiratory volume in 1 second, forced vital capacity, and ratio of forced expiratory volume in 1 second to forced vital capacity. CONCLUSION: Having 2 or more FAs is a potential risk factor for greater small airway airflow obstruction among children with asthma, highlighting the need for close clinical follow-up and improved intervention strategies for these patients.

Hygiene factors associated with childhood food allergy and asthma.

BACKGROUND: Childhood food allergy and asthma rates are increasing. The hygiene hypothesis has been proposed as an explanation for the increased incidence of allergic disease. OBJECTIVE: To describe the association of childhood food allergy and asthma with hygiene factors, such as the number of siblings, antibiotic use, infection history, pet exposure, child care exposure, and maternalchild factors. METHODS: Children ages 021 years old (N = 1359) were recruited for a cross-sectional family-based study, including children with food allergy and children without food allergy, and their siblings. We assessed the associations between childhood food allergy and asthma with hygiene factors. RESULTS: Of the 1359 children, 832 (61.2%) had food allergy, and 406 (30%) had asthma. In the adjusted analysis, the prevalence of food allergy was increased if there was a history of skin infection (prevalence ratio [RRR] 1.12 [95% confidence interval {CI}, 1.011.24]) or eczema (RRR 1.89 [95% CI, 1.702.10]). The prevalence of asthma was increased with a history of respiratory syncytial virus infection (RRR 1.60 [95% CI, 1.341.90]) or eczema (RRR 1.54 [95% CI, 1.271.86]). A greater number of siblings were associated with a decreased prevalence of food allergy (RRR 0.79 [95% CI, 0.750.84]) and asthma (RRR 0.82 [95% CI, 0.740.91]). CONCLUSION: Our findings supported the accumulating evidence of an association between skin infections and eczema with food allergy. Because these results could be subject to recall bias, additional prospective studies are needed to substantiate these findings.

The future of biologics: applications for food allergy.

Allergic diseases affect millions worldwide, with growing evidence of an increase in allergy occurrence over the past few decades. Current treatments for allergy include corticosteroids to reduce inflammation and allergen immunotherapy; however, some subjects experience treatment-resistant inflammation or adverse reactions to these treatments, and there are currently no approved therapeutics for the treatment of food allergy. There is a dire need for new therapeutic approaches for patients with poorly controlled atopic diseases and a need to improve the safety and effectiveness of allergen immunotherapy. Improved understanding of allergy through animal models and clinical trials has unveiled potential targets for new therapies, leading to the development of several biologics to treat allergic diseases. This review focuses on the mechanisms that contribute to allergy, with an emphasis on future targets for biologics for the treatment of food allergy. These biologics include immunotherapy with novel anti-IgE antibodies and analogs, small-molecule inhibitors of cell signaling, anti-type 2 cytokine mAbs, and TH1-promoting adjuvants.

Effect of early ultrasound-guided femoral nerve block on preoperative opioid consumption in emergency patients with hip fracture: a randomized trial.

BACKGROUND AND IMPORTANCE: Ultrasound-guided femoral nerve block (FNB) could be used as part of a multimodal preoperative pain management for patients with hip fracture. Evidence of the effects of its early implementation in the emergency room as an immediate alternative to intravenous morphine titration is sparse. OBJECTIVE: To investigate the effect of an early ultrasound-guided FNB performed by emergency physicians on preoperative opioid consumption, compared to standard pain management. DESIGN, SETTING, AND PARTICIPANTS: This open randomized controlled trial was conducted in the Emergency Department of a French hospital with patients with neck or trochanteric femoral fracture who had a pain score ≥7 out of 10 points at triage. INTERVENTION: Patients were randomized to receive an initial analgesia with an early ultrasound-guided FNB or with standard pain management. The continuation of pain treatment followed standardized pain control guidelines until hospital discharge in both groups. OUTCOME MEASURE AND ANALYSIS: The primary outcome was preoperative opioid consumption truncated 48h after triage time, and converted in morphine milligram intravenous equivalents (MME). Secondary outcomes were time to pain relief, time for regaining walk, opioid consumption and occurrence of opioid and FNB adverse effects during the hospital stay. Exploratory outcomes included ease and duration of the procedure. MAIN RESULTS: We randomized 35 patients: 17 to standard pain management and 18 to ultrasound-guided FNB, among whom 30 patients completed the protocol. The median of preoperative opioid consumption was reduced by 60% in the ultrasound-guided FNB group compared to standard group [6 MME (3-9) vs. 15 MME (11-18)], with a consumption difference of 9 MME (95% CI: 3-14, P  < 0.001). Throughout hospital stay, opioid consumption was reduced by 56% in the ultrasound-guided FNB group compared to standard group, with a consumption difference of 11.5 MME (95% CI: 0.5-22).Times to pain relief and for regaining walk did not differ between groups. Opioid adverse events occurrence were reduced by 40% (95% CI: 5.1-74.9) in the ultrasound-guided FNB group compared to standard group. No adverse effects of FNB have been detected. CONCLUSION: Early ultrasound-guided FNB resulted in reducing preoperative opioid consumption, without delaying time to pain relief.

Prevalence and Characteristics of Accidental Ingestions Among Pediatric Food Allergy Patients.

BACKGROUND: Despite a known diagnosis of food allergy, accidental ingestions continue to occur. OBJECTIVE: To characterize accidental ingestions, including prevalence, risk factors, food allergen triggers, and severity of reactions. METHODS: A prospective monthly survey developed by the Food Allergy Consortium at Northwestern University was administered to parents of food-allergic children between April 2015 and April 2017. The monthly survey included questions on any allergic reactions experienced in the previous month. In addition, chart reviews of 100 pediatric participants from Lurie Children's Hospital of Chicago allergy clinics (typical clinical encounters) were compared with the prospective survey results. RESULTS: A total of 196 survey participants and 100 retrospective review subjects were analyzed-31.1% of participants from the surveyed cohort and 19.0% of participants from the retrospective review reported at least 1 accidental ingestion over 1 year. The rate of accidental ingestions reported in the prospective survey was high: 10% to 25% of participants each month reported an accidental ingestion, and multiple ingestions were common. Common triggers were milk, wheat, and tree nuts. In the retrospective cohort, the highest rate of accidental ingestion (25.0%) occurred for milk, followed by sesame (20.0%) and egg (18.8%). Rates of anaphylaxis after exposure were high in both the prospective and retrospective cohorts (33.1% and 16.7%, respectively). CONCLUSIONS: Accidental ingestion rates were high among food-allergic patients. Multiple exposures, especially to milk, were common. Incidence of anaphylaxis was also high, suggesting that ongoing patient education on allergen avoidance and accidental exposure is imperative.

Combined metagenomic- and culture-based approaches to investigate bacterial strain-level associations with medication-controlled mild-moderate atopic dermatitis.

Background: The skin microbiome is disrupted in atopic dermatitis (AD). Existing research focuses on moderate to severe, unmedicated disease. Objective: We sought to investigate metagenomic- and culture-based bacterial strain-level differences in mild, medicated AD and the effects these have on human keratinocytes (HKs). Methods: Skin swabs from anterior forearms were collected from 20 pediatric participants (11 participants with AD sampled at lesional and nonlesional sites and 9 age- and sex-matched controls). Participants had primarily mild to moderate AD and maintained medication use. Samples were processed for microbial metagenomic sequencing and bacterial isolation. Isolates identified as Staphylococcus aureus were tested for enterotoxin production. HK cultures were treated with cell-free conditioned media from representative Staphylococcus species to measure barrier effects. Results: Metagenomic sequencing identified significant differences in microbiome composition between AD and control groups. Differences were seen at the species and strain levels for Staphylococci, with S aureus found only in participants with AD and differences in Staphylococcus epidermidis strains between control and AD swabs. These strains showed differences in toxin gene presence, which was confirmed in vitro for S aureus enterotoxins. The strain from the participant with the most severe AD produced enterotoxin B levels more than 100-fold higher than the other strains (P < .001). Strains also displayed differential effects on HK metabolism and barrier function. Conclusions: Strain-level differences in toxin genes from Staphylococcus strains may explain varying effects on HK, with S aureus and non-aureus strains negatively affecting viability and barrier function. These differences are likely important in AD pathogenesis.