Teledermatology in Atopic Dermatitis: A Systematic Review

Telemedicine use has been increasing especially during the COVID-19 pandemic. Various studies have outlined benefits of telemedicine including improving health equity, reducing wait times, and cost-effectiveness. Skin diseases such as atopic dermatitis (AD) may potentially be managed via telemedicine. However, there are no evidence-based recommendations for best practices in telemedicine for assessing AD patients. The objective of this review is to assess and summarize current evidence on telemedicine modalities for AD. This review will assess patient outcomes from various telemedicine models for AD. A review protocol was developed according to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement. Two reviewers independently screened potential studies and extracted data. Studies were included if they evaluated any telemedicine assessment for AD. Of 2719 identified records, 5 reports were included. Two reports used the direct-access online model, 1 used web-based consultation, 1 used e-health through a personal eczema portal, and 1 used an online platform and mobile application. All models were variations of the asynchronous, store and forward model. In all the included reports, teledermatology for the follow-up of patients with AD was effective and equivalent when compared to in-person appointments or standard treatment for their respective key outcome measures. However, it is unclear what the most effective teledermatology model is due to significant heterogeneity between studies. Teledermatology may serve as an important tool for triaging and follow-up of patients with AD. More studies are needed to determine which teledermatology models are most effective for virtual assessment of AD.

Pharmacological Interventions for Primary Psychodermatologic Disorders: An Evidence Mapping and Appraisal of Randomized Controlled Trials

BACKGROUND

The lack of clinical guidelines for the treatment of primary psychodermatologic disorders (PPDs) hinders the delivery of optimal care to patients. The review aimed to identify, appraise, and summarize the currently available evidence about the safety and effectiveness of pharmacological management of PPDs through randomized controlled trials (RCTs).

METHODS

The Preferred Reporting Items for Systematic Review and Meta-Analyses (PRIMSA) statement and the Global Evidence Mapping Initiative guidance were followed. Medline, Embase, PsycInfo, Cochrane and Scopus were searched, and two reviewers independently completed article review, data extraction, and quality assessment.

RESULTS

Among 2618 unique studies, full texts of 83 were reviewed and 21 RCTs were included. Five PDDs were identified: trichotillomania (n = 12), pathologic skin picking (n = 5), nail biting (n = 2), delusional parasitosis (n = 1), and dermatitis from compulsive hand washing (n = 1). Seven different classes of medications were investigated: SSRIs (i.e., fluoxetine, sertraline, and citalopram), tricyclic antidepressants (i.e., clomipramine and desipramine), antipsychotics (i.e., olanzapine and pimozide), anticonvulsant (i.e., lamotrigine), N-acetylcysteine, inositol, and milk thistle. RCT-derived evidence supports the use of antidepressants in trichotillomania (sertraline and clomipramine), pathologic skin picking (fluoxetine), pathologic nail biting and dermatitis from compulsive hand washing (clomipramine or desipramine); antipsychotics in trichotillomania (olanzapine) and delusional parasitosis (pimozide); N-acetyl cysteine in trichotillomania and skin picking.

CONCLUSION

Few pharmacotherapies for primary psychodermatologic disorders are assessed through controlled trials in the literature. This review serves as a roadmap for researchers and clinicians to reach informed decisions with current evidence, and to build on it to establish guidelines in the future.

Beyond Skin Deep: case-based online modules to teach multidisciplinary care in dermatology among clerkship students

BACKGROUND

Canadian medical schools offer limited clinical dermatology training. In addition, there is a lack of educational resources that are designed specifically for clerkship students that focus on the multidisciplinary nature of dermatology.

OBJECTIVES

After developing case-based educational resources to address the lack of clinical exposure and learning of multidisciplinary care in dermatology, this study aimed to evaluate the educational intervention and gather feedback for future module development.

METHODS

Ten online interactive dermatology case-based modules involving 14 other disciplines were created. Medical students (n = 89) from two Canadian schools were surveyed regarding perceptions of the existing dermatology curriculum. Among 89 students, 46 voluntarily completed the modules, and a survey (a five-point Likert scale ratings) including narrative feedback was provided to determine an improvement in dermatology knowledge and understanding of multidisciplinary care.

RESULTS

Among 89 surveyed students, only 17.1% agreed that their pre-clerkship dermatology education was sufficient and 10.2% felt comfortable managing patients with skin conditions in a clinical setting. Among 46 students, 95.7% of students agreed that the modules fit their learning style (4.17 ± 0.73 on Likert scale) with positive narrative feedback. 91.3% agreed or strongly agreed that the modules enhanced their dermatology knowledge (4.26 ± 0.61). 79.6% of students agreed that the modules helped with understanding the multidisciplinary nature of dermatological cases (3.98 ± 0.81). Student comfort to manage skin conditions increased 7.7 times from 10.2% to 78.3% post-module.

CONCLUSIONS

Clerkship students had limited knowledge of dermatologic conditions; the case-based modules were able to successfully address these deficits and assist students in understanding the multidisciplinary nature of dermatology.

The Global Prevalence of Primary Psychodermatologic Disorders: A Systematic Review

The management of primary psychodermatologic disorders (PPDs) (i.e., psychiatric disorders with dermatologic presentation) is challenging. The scarceness of reported prevalence hinders the development of coordinated interventions to improve healthcare delivery. This review aimed to explore the global prevalence of PPDs. The review was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analyses statement. Of the 4632 identified publications, 60 were included. Five PPDs were investigated from the included studies: delusional parasitosis (n=9), skin picking disorder (n=26), trichotillomania (n=22), tanning dependence (n=5), and repetitive nail biting (n=6). Delusional parasitosis was rare in the general population (prevalence ranging from 0.0002% to 0.03%), with higher rates in the psychiatric settings (outpatient=0.5%; inpatient=0.1%). Other pathologic or subclinical forms of PPDs had a minimum prevalence of 0.3% (median=7.0%; mean=17.0%). The distribution of the prevalence rates was highly skewed, with large differences based on the study setting (e.g., dermatologic settings, psychiatric settings, and general population). The most common condition was pathologic skin picking (prevalence, 1.2%-11.2%) in the general population. Its rates were higher in the psychiatric settings (obsessive-compulsive disorder, 38.5%; Tourette syndrome, 13.0%; body dysmorphic disorder, 26.8%-64.7%). The prevalence of trichotillomania in the general population ranged from 0.6% to 2.9%, while that of pathologic tanning and nail biting could not be ascertained as the studies were mainly in students (range; 12.0%-39.3% and 3.0%-10.1%, respectively). In conclusion, PPDs are common, especially in the dermatologic and psychiatric settings. Further population-based studies are needed to determine more accurate prevalence rates.

Psoriasis Education Tool for Patient-Physician Decision-Making About Biologics: A Pilot Study

Although biologics are well-studied, expertise regarding their use is often lacking. Many biologics have been added to the market in recent years with distinctive characteristics. This study was designed to create a tool to assist physicians involved in the care of patients with psoriasis undergoing biologic treatment. We used a quality improvement approach to develop and trial an educational visual aid to deliver comprehensive information about biologics in a convenient manner. As a pilot study, trialing this tool was carried out on a small scale to test the feasibility of both the study design and the visual aid itself, with 8 physician and 8 patients completing questionnaires evaluating the visual aid. From our results, the tool was helpful for improving patient knowledge of biologic treatment and their engagement in clinical decision-making. This visual aid may serve as a central convenient biologic resource for physicians.

Psychodermatology in Canada: A National Survey Assessment of Dermatologists' Perception, Practice Patterns, and Challenges

OBJECTIVES

We aimed to assess the perception of psychodermatology, practice patterns, and challenges reported by Canadian dermatologists.

METHODS

We designed an online questionnaire based on previous literature, including questions about practitioners' perceptions, practice patterns, training, and challenges in psychodermatology. We solicited their opinions on desired training, research needs, and clinical approach recommendations. Our survey was distributed nationally by the Canadian Dermatology Association (CDA).

RESULTS

Of the total of 78 participating dermatologists, >75% reported treating patients with psychodermatological conditions, with higher frequencies of secondary than primary psychodermatological conditions. While practitioners had some confidence in their understanding of psychodermatology (median = 4 on a 5-point scale), their comfort levels to approach these patients were lower (median = 3), and their confidence in prescribing psychotropic medication was markedly low (median = 2). A total of 50% reported that a "multidisciplinary approach" would be best for these patients. Poor access to psychiatry was the most reported (26.9%) challenge, together with time constraints, lack of training, poor communication with patients, and lack of patient insight and resources. While 46.2% reported having never participated in psychodermatology training, 55.1% expressed interest in doing so.

CONCLUSION

We identified several challenges with knowledge, awareness, and healthcare delivery in psychodermatological practice in Canada. Increasing dermatologists' access to psychiatric consultations/services, a multidisciplinary approach with dermatologists and psychiatrists co-providing care, and more specialized training in this area are recommended to narrow the identified gaps.

Estimated Frequency of Psychodermatologic Conditions in Alberta, Canada

BACKGROUND

Psychodermatologic disorders are difficult to identify and treat. Knowledge about the prevalence of these conditions in dermatological practice in Canada is scarce. This hampers our ability to address potential gaps and establish optimal care pathways.

OBJECTIVES

To provide an estimate of the frequencies of psychodermatologic conditions in dermatological practice in Alberta, Canada.

METHODS

Two administrative provincial databases were used to estimate the prevalence of potential psychodermatological conditions in Alberta from 2014 to 2018. Province-wide dermatology claims data were examined to extract relevant International Classification of Disease codes as available. Claims were linked with pharmacy dispensation data to identify patients who received at least 1 psychoactive medication within 90 days of the dermatology claim.

RESULTS

Of 243 963 patients identified, 28.6% had received at least 1 psychotropic medication (mean age: 47.9 years; 67.5% female). Rates of concurrent psychotropic medications were highest for pruritus and related conditions (46.7%), followed by urticaria (44.5%) and hyperhidrosis (32.8%). Among patients with psychotropic medications, rates of antidepressants were highest (56.3%), followed by anxiolytics (37.1%). Across billing codes, besides hyperhidrosis (71.2%), diseases of hair (61.4%) and psoriasis (59.1%) had the highest rates of antidepressant dispensations. Patients with atopic dermatitis had the highest rates for anxiolytic prescriptions (54.3%).

CONCLUSION

In a 5-year window, more than a quarter of the identified dermatology patients in Alberta received at least 1 psychotropic medication, pointing to high rates of potential psychodermatologic conditions and/or concurrent mental health issues in dermatology. Diagnostic and care pathways should include a multidisciplinary approach to better identify and treat these conditions.

Case of giant vulvar condyloma acuminata successfully treated with imiquimod 3.75% cream: A case report

Condyloma acuminata, also known as anogenital warts, represent a cutaneous infection caused by sexual transmission of the human papilloma virus. We present a case of overwhelming condyloma acuminata that was treated successfully without surgery using only topical imiquimod 3.75% cream. The patient, a 66-year-old female, was referred to Dermatology for large protruding verrucous plaques that covered the entire surface of her external vulva, perineum and perianal area. These lesions developed after being treated for genital warts with cantharidin. Four other cases treated with imiquimod were identified in the literature but either required surgery, higher doses or longer duration of treatment or involved pediatric populations. In patients who are not amenable to surgery, topical imiquimod may be a novel standalone or an adjunctive therapy for giant condyloma acuminata.

An Approach to Minimising Risk of Adrenal Insufficiency When Discontinuing Oral Glucocorticoids

Oral glucocorticoids are commonly used across every field of medicine; however, discontinuing them in patients can be challenging. The risk of acute adrenal crises secondary to glucocorticoid withdrawal can be fatal and arises from chronic suppression of the adrenal glands. Identifying risk factors for adrenal suppression in dermatological patients, such as doses greater than 5 to 7.5 mg of prednisone equivalent, duration of glucocorticoid use greater than 3 weeks, certain medications, and comorbidities, can help risk-stratify patients. The use of adrenal gland testing such as basal cortisol levels and adrenocorticotropic hormone stimulation tests can confirm adrenal suppression in patients. This review article provides an approach that dermatologists can use to minimise the risk of adrenal insufficiency in patients discontinuing glucocorticoids and when it may be appropriate to use adrenal gland testing.

A Dermatologist’s Approach to Genitourinary Syndrome of Menopause

Background:

Genitourinary syndrome of menopause (GSM) is a debilitating condition caused by hypoestrogenism that presents with vaginal dryness and dyspareunia as well as other genital, sexual, and urinary symptoms. Previously known as atrophic vaginitis, the term GSM is now used.

Objective:

To help familiarise dermatologists with diagnosing and managing GSM.

Methods:

In total, 218 articles were identified and reviewed by 2 independent authors using PubMed. Articles included were from December 2005 to December 2015. Sixty-seven articles met our inclusion criteria.

Results:

GSM is a clinical diagnosis, requiring the presence of symptoms that should be bothersome and not accounted for by another condition. A pH test may help with diagnosis as vaginal pH will be increased from acidic to neutral. The Papanicolaou test is not recommended because of poor clinical correlation. First-line treatment is low-dose local vaginal estrogen therapy, which has proven efficacy and safety. Serum estrogen levels are not significantly affected with the exception of creams containing high-dose conjugated equine estrogens. Other options have yet to be approved for use in Canada but show promise.

Conclusion:

GSM is a debilitating and common condition that suffers from barriers to diagnosis and treatment. Current treatments are well tolerated, rewarding, and effective with rapid onset.

Combination Oral Prednisone and Intravenous Immunoglobulin in the Treatment of Scleromyxedema

Background:

Scleromyxedema is a clinical variant of the rare disease papular mucinosis that has both cutaneous and systemic manifestations. Treatment options are numerous and tend to be associated with serious potential side effects and frequent relapse.

Objective:

We report a case of scleromyxedema treated with low-dose oral prednisone and intravenous immunoglobulin (IVIg). This is followed by a review of the literature.

Conclusion:

IVIg is being used for a growing number of inflammatory and immune disorders. It is being increasingly reported as a successful treatment for scleromyxedema. Although our patient succumbed to the disease, combination therapy with prednisone and IVIg provided temporary symptomatic, laboratory, and clinical improvement of the condition. Optimization of this therapeutic strategy is thus indicated for the management of scleromyxedema.

An Approach to Urinary Incontinence for Dermatologists

Incontinence-associated dermatitis (IAD) is a condition often encountered by dermatologists. IAD is an inflammatory skin condition secondary to prolonged urine exposure-it is a dermatologic sequela of urinary incontinence. Incontinence should not be dismissed simply as an age-related disorder; rather, it is due to a number of pathologic conditions that can be either reversible or manageable. It is thus critical to identify and treat the underlying causes of urinary incontinence. Clinical management of this common medical issue restores normality to patients' lives while also preventing future dermatologic complications. In this article, we aim to provide dermatologists with an overview of IAD and an approach to the diagnosis and initial management of urinary incontinence.

Evaluation of the efficacy and safety of topical imiquimod 5% for plaque-type morphea: a multicenter, prospective, vehicle-controlled trial

BACKGROUND

There is currently a lack of evidence-based therapies that are safe and effective for plaque-type morphea. We aimed to evaluate the therapeutic potential and safety profile of imiquimod 5% cream in plaque-type morphea.

METHODS

We enrolled 25 adult patients from two Canadian centers with histologically confirmed plaque-type morphea. Imiquimod 5% was applied to a representative plaque, and vehicle was applied to a control plaque for 9 months. Treatment efficacy was assessed with the Dyspigmentation, Induration, Erythema, and Telangiectasias (DIET) score, histology, and ultrasound evaluation.

RESULTS AND CONCLUSIONS

Twenty-two patients completed the entire length of the study. Imiquimod 5% was superior to vehicle in reducing DIET scores at 3, 6, 9, and 12 months (p < .05). Induration demonstrated the greatest response. Histologic evaluation showed significant improvement or resolution of disease. However, no ultrasonographic differences were found in dermal and hypodermal thicknesses between the treatment and vehicle groups (p > .05). Adverse effects were minimal and well tolerated.

Off-label uses of topical vitamin D in dermatology: a systematic review

BACKGROUND

Topical vitamin D is approved by the US Food and Drug Administration for the treatment of psoriasis but is also used off-label in the treatment of a variety of cutaneous diseases despite a lack of evidence-based guidelines.

OBJECTIVE

The objective of this study was to provide evidence-based clinical guidelines for the off-label use of topical vitamin D in the treatment of dermatologic disease.

METHODS

A systematic literature review was conducted via the MEDLINE, Embase, and CENTRAL databases for off-label uses of topical vitamin D analogues in the treatment of dermatologic disease other than psoriasis. The data were synthesized, and evidence-based recommendations were rendered according to the highest level of evidence available.

RESULTS

A total of 165 articles met the inclusion criteria. A moderate to strong recommendation was given for the use of topical vitamin D in combination with corticosteroids and phototherapy in vitiligo and as monotherapy for various ichthyoses, morphea, pityriasis alba, prurigo nodularis, and polymorphous light eruption. There is evidence showing that topical vitamin D is ineffective in the treatment of actinic keratosis, seborrheic keratosis, lichen planus, seborrheic dermatitis, alopecia areata, chemotherapy-induced alopecia, and hypertrophic scars.

CONCLUSION

Topical vitamin D analogues have an important role in the off-label treatment of dermatologic disease, but higher quality studies are still required.

The pathogenesis of vitiligo

BACKGROUND

Vitiligo is a commonly encountered pigmentary disorder. Numerous studies and investigations from all over the world have attempted to determine the mechanisms behind this disease; however, the pathogenesis of vitiligo remains elusive.

OBJECTIVE

n this comprehensive review article, we present the findings behind the five overarching theories of what causes this disfiguring and psychologically debilitating disease.

METHOD

We begin our discussion with the role of genetic predisposition and move onward to the neural theory first proposed in the 1950s. Next we discuss the autoimmune hypothesis, followed by the reactive oxygen species model, and conclude by describing the findings of the more recent melanocytorrhagy hypothesis.

CONCLUSION

Although the exact pathogenesis of vitiligo is uncertain, each of these theories likely plays a role. Understanding each theory would pave the way for therapeutic advances for this disease.

Combination oral prednisone and intravenous immunoglobulin in the treatment of scleromyxedema

BACKGROUND

Scleromyxedema is a clinical variant of the rare disease papular mucinosis that has both cutaneous and systemic manifestations. Treatment options are numerous and tend to be associated with serious potential side effects and frequent relapse.

OBJECTIVE

We report a case of scleromyxedema treated with low-dose oral prednisone and intravenous immunoglobulin (IVIg). This is followed by a review of the literature.

CONCLUSION

IVIg is being used for a growing number of inflammatory and immune disorders. It is being increasingly reported as a successful treatment for scleromyxedema. Although our patient succumbed to the disease, combination therapy with prednisone and IVIg provided temporary symptomatic, laboratory, and clinical improvement of the condition. Optimization of this therapeutic strategy is thus indicated for the management of scleromyxedema.

First case series on the use of imiquimod for morphoea

BACKGROUND

Morphoea is characterized by fibrosis, which is mediated by cytokines including transforming growth factor (TGF)-beta.

OBJECTIVE

Our objective was to use imiquimod 5% cream (Aldara), an inducer of interferon-gamma, known to inhibit TGF-beta, to treat morphoea.

METHODS

Patients with morphoea were treated with imiquimod and evaluated during their follow-up visits to 6 months.

RESULTS

The dyspigmentation, induration and erythema of 12 patients with morphoea lesions improved. The histology of the skin also showed a decrease in dermal thickness.

CONCLUSION

This is the first case series describing the successful application of imiquimod in the management of morphoea.

Comparison of Helicobacter mustelae and Helicobacter pylori adhesion to eukaryotic cells in vitro

BACKGROUND & AIMS

Bacterial adhesion to mucosal surfaces is an important pathogenic mechanism for Helicobacter-induced gastritis. The aims of this study were to compare binding of selected Helicobacter mustelae and Helicobacter pylori strains to lipids extracted from HEp-2, Chinese hamster ovary, human embryonic lung cells, and ferret gastrointestinal tissues as well as to intact tissue culture cells and to analyze the fatty acids of the receptor.

METHODS

Thin-layer chromatography overlay binding and a receptor-based immunoassay detected adhesion of bacteria to commercial lipids and to individual species within the lipid extracts. H. mustelae binding to tissue culture cells was performed by whole cell bacterial adhesion assay.

RESULTS

H. mustelae and H. pylori both bound to phosphatidylethanolamine and lysophosphatidylethanolamine. Adhesion of H. mustelae to intact eukaryotic cells correlated with the amount of phosphatidylethanolamine. Binding of helicobacters was greater to lipids derived from ferret antrum compared with colon (P < 0.05). Biochemical analysis suggested that heterogeneity in fatty acid composition of phosphatidylethanolamine could influence the degree of Helicobacter binding.

CONCLUSIONS

Adhesion of Helicobacter strains correlates with the quantity of phosphatidylethanolamine present in the epithelial cell and with the differences in the fatty acid profile of the lipid.

Expression of interleukin 8 and CD54 by human gastric epithelium after Helicobacter pylori infection in vitro

BACKGROUND/AIMS

Helicobacter pylori is associated with neutrophil infiltrates, although the mechanism of their recruitment is only partially defined. The aim of the study was to determine if Kato III, a human gastric epithelial cell line, expressed cytokines and the intercellular adhesion molecule 1 (ICAM-1), which could contribute to the initiation of inflammation during infection with H. pylori.

METHODS

Kato III cells were stimulated with H. pylori and were examined for evidence of infection, cytokine production, and the expression of ICAM-1.

RESULTS

The expression of interleukin 8 messenger RNA and immunoreactive protein by Kato III cells was significantly increased over constitutive levels within 3 hours of infection with H. pylori. Infected Kato III supernatants activated neutrophils as evidenced by increased CD11b/CD18 and decreased L-selectin that could be blocked by anti-interleukin 8. In contrast, Campylobacter jejuni, lipopolysaccharide, killed H. pylori, and supernatants from cultures of H. pylori did not increase interleukin 8. Interleukins 2 and 6; interferons alfa, beta, and gamma; and tumor necrosis factor were not produced by resting or H. pylori-stimulated Kato III cells. In addition to producing interleukin 8, Kato III constitutively expressed surface ICAM-1, which acts as an intercellular adhesion molecule for neutrophils.

CONCLUSIONS

Our results indicate that H. pylori stimulates the gastric epithelium to initiate inflammation and neutrophil recruitment and activation.

Signal transduction in human epithelial cells infected with attaching and effacing Escherichia coli in vitro

BACKGROUND/AIMS

Human enteropathogenic Escherichia coli infection of epithelial cells is characterized by attaching and effacing adhesion. To determine if signal transduction responses are involved in this adhesion phenotype, levels of inositol 1,4,5-triphosphate and cytosolic free calcium were measured in tissue culture cells infected with enteropathogenic E. coli strain E2348 (serotype O127:H6).

METHODS

Inositol triphosphate levels were measured by using a commercial binding assay, and intracellular calcium levels were determined by spectrofluorometry.

RESULTS

Elevated levels of both inositol triphosphate (182% +/- 52%; P < 0.05) and intracellular calcium (125% +/- 40%, mean +/- SE; P < 0.05) were seen after infection of HEp-2 cells with strain E2348. In contrast, inositol triphosphate and intracellular calcium levels were not elevated in HEp-2 cells infected with six E. coli strains that did not cause attaching and effacing lesions. Subcellular calcium localization using oxalate precipitation and electron microscopy showed calcium accumulation within the terminal web subjacent to regions of attaching and effacing adhesion. Depleting external calcium did not eliminate formation of attaching and effacing lesions, whereas treatment of HEp-2 cells with an intracellular calcium chelator prevented attaching and effacing lesions.

CONCLUSIONS

Enteropathogenic E. coli infection elevates both inositol triphosphate and intracellular calcium levels in cultured epithelial cells.

Expression and characterization of the eaeA gene product of Escherichia coli serotype O157:H7

In enteropathogenic Escherichia coli, the eaeA gene produces a 94-kDa outer membrane protein called intimin which has been shown to be necessary but not sufficient to produce the attaching-and-effacing lesion. The purpose of this study was to characterize the intimin specified by the eaeA allele of the enterohemorrhagic E. coli (EHEC) serotype O157:H7 strain CL8 and to determine its role in adherence. The carboxyl-terminal 266 amino acids of the CL8 intimin were expressed as a protein fusion with glutathione S-transferase, which was used to raise antiserum in rabbits. The antiserum reacted in Western immunoblots with a 97-kDa outer membrane protein of EHEC strains of serogroups O5, O26, O111, and O157 and enteropathogenic E. coli strains of serogroups O55 and O127. Surface labelling of CL8 with 125I showed that intimin was surface exposed. An eaeA insertional inactivation mutant of CL8 was produced and was designated CL8-KO1. Total adherence of CL8-KO1 to HEp-2 cells was not significantly different from that of CL8, but CL8-KO1 gave a negative result in the fluorescent actin staining test. The eaeA gene expressed alone in E. coli HB101 also gave a negative fluorescent actin staining test result. The eaeA gene of CL8 was able to complement the eaeA deletion mutation in CVD206. We conclude that the product of the EHEC eaeA gene is a 97-kDa surface-exposed protein and propose that it be designated intiminO157. Sherman et al. described a 94-kDa outer membrane protein which played an important role in adherence of E. coli O157:H7 (Infect. Immun. 59:890-899, 1991). Western immunoblotting and indirect fluorescent antibody studies showed that the protein described by Sherman et al. is not intimin.

Multiple determinants of verotoxin-producing Escherichia coli O157:H7 attachment-effacement

Verotoxin-producing Escherichia coli strains of the serotype O157:H7 belong to a class of gastrointestinal pathogens that adhere to epithelial cells in a characteristic pattern known as attaching and effacing. Recent insight into the nature of E. coli O157:H7 adhesion was provided by the cloning and sequencing of the chromosomal eaeA (for E. coli attaching and effacing) gene homolog (G. Beebakhee, M. Louie, J. De Azavedo, and J. Brunton, FEMS Microbiol. Lett. 91:63-68, 1992, and J. Yu and J. B. Kaper, Mol. Microbiol. 6:411-417, 1992) and isolation of a 60-MDa plasmid referred to as pO157 (I. Toth, M. L. Cohen, H. S. Rumschlag, L. W. Riley, E. H. White, J. H. Carr, W. W. Bond, and I. K. Wachsmuth, Infect. Immun. 58:1223-1231, 1990, and S. Tzipori, H. Karch, K. I. Wachsmuth, R. M. Robins-Browne, A. D. O'Brien, H. Lior, M. L. Cohen, J. Smithers, and M. M. Levine, Infect. Immun. 55:3117-3125, 1987) and an approximately 94-kDa outer membrane protein (94-kDa OMP; P. Sherman, F. Cockerill III, R. Soni, and J. Brunton, Infect. Immun. 59:890-899, 1991). In this study, we examined the gene products of both eaeA and pO157 in relation to the 94-kDa OMP and as candidate effectors for O157:H7 attachment-effacement. Peptide sequencing and immunoassay demonstrated that the C. coli O157:H7 eaeA gene product is distinct from the 94-kDa OMP. Using ultrastructural analyses, we found that both parent and pO157 plasmid-cured O157:H7 strains demonstrated attaching and effacing adhesion to host epithelial cells and reacted equally well to rabbit antiserum raised against the 94-kDa OMP. By both transmission electron microscopy and light microscopy, E. coli HB101 transformed separately with the cloned eaeA gene and the pO157 plasmid did not form attaching and effacing lesions on cultured epithelial cells in vitro and rabbit intestinal tissues in vivo. Since additional determinants may mediate the attaching and effacing phenotype, we examined transposon TnphoA mutants constructed from E. coli O157:H7 strain CL8. Two TnphoA mutants were found deficient in bacterial factors that are necessary for O157:H7 attachment-effacement and likely distinct from the eaeA gene product.

Comparison of Helicobacter pylori and attaching-effacing Escherichia coli adhesion to eukaryotic cells

Adhesion of Helicobacter pylori was reported previously to be morphologically identical to "attaching and effacing" Escherichia coli. Therefore, the aim of the present study was to define the adhesion phenotype of H. pylori LC-11 to HEp-2, KATO-III, HEL, and CHO tissue culture cells. By using both staining of F-actin with fluorescein-labeled phalloidin and ultrastructural analysis, diffuse bacterial adhesion to discrete microvillus-denuded regions of the plasma membrane was observed in each of the infected cell lines. However, strain LC-11 did not induce formation of F-actin adhesion pedestals on the eukaryotic cells. H. pylori was negative by colony blot hybridization with an E. coli attaching and effacing gene probe. Elevations in inositol triphosphates followed infection of HEp-2 cells with H. pylori (405% of control values +/- 147%; P < 0.05). To correlate the observed histopathology with expression of the H. pylori phosphatidylethanolamine receptor, a thin-layer chromatography overlay-binding assay was used to identify receptors in each of the cell lines. H. pylori adhered to eukaryotic cells regardless of the presence (HEp-2, KATO-III, and CHO cells) or absence (HEL cells) of the lipid receptor as detected under the assay conditions. However, in comparison to cell lines that possess the phosphatidylethanolamine receptor, HEL cells demonstrated less quantitative H. pylori binding. These findings suggest that mechanisms distinct from E. coli enteropathogens underlie the adhesion of H. pylori to mucosal surfaces. In addition to the phosphatidylethanolamine H. pylori receptor, another host factor(s) likely mediates the attachment of H. pylori to human eukaryotic cells.