Craig G. Burkhart

Microbiology's principle of biofilms as a major factor in the pathogenesis of acne vulgaris.

Propionibacterium acnes reside within the pilosebaceous unit in a biofilm. As such, they live in a community of bacteria that encase themselves within an extracellular polysaccharide lining, which the organisms secrete after adherence to the surface. This gylcocalyx polymer acts as a protective exoskeleton and serves as a physical barrier, limiting effective antimicrobial concentrations within the biofilm microenvironment. The gylcocalyx polymer secreted by P. acnes as a biofilm may explain the immunogenicity of the organism as well as the clinical course of the disease. The P. acnes’ biofilm model explains many aspects of acne pathogenesis and therapy, including why prolonged antibiotic treatment is needed, why antibiotic resistance is not a reliable assessment of treatment outcome, why accutane offers long‐lasting effectiveness, and why benzoyl peroxide radicals are beneficial. This microbiologic principle of biofilms as applied to acne leads to numerous new pathways of assessment and exploration.

Relationship of Treatment-Resistant Head Lice to the Safety and Efficacy of Pediculicides

Head lice infestation is a common and growing problem that primarily affects school-aged children. Most cases of head lice are diagnosed and treated by nonphysicians. Misdiagnosis may lead to treatment when no lice are present. Treatment failure may lead to repeated use of and improperly applied pediculicides, potentially resulting in overexposure to pesticides. These treatment failures are primarily due to the emergence of treatment-resistant lice. In regions where resistant lice are common, patients may self-treat numerous times with over-the-counter pediculicides before seeking treatment from a physician. Resistance has decreased the efficacy of lindane, a prescription pediculicide that has been used for decades. In addition, the Food and Drug Administration recently warned of potentially serious adverse effects associated with lindane and recommended strict controls for its use. Malathion, recently reintroduced in the United States as a prescription pediculicide, has not been associated with treatment resistance or notable adverse effects, although it is flammable due to its alcohol base. Because of concerns about decreasing efficacy due to resistance and safety concerns about over-the-counter products and some prescription pediculicides, a reassessment of pediculicide safety is warranted. The safety and efficacy of commonly used over-the-counter and prescription pediculicide products are discussed, along with the safety and efficacy of other treatments, such as ivermectin, that are not indicated for the treatment of head lice but are being used increasingly.

Head louse infestations: the “no nit” policy and its consequences

Health authorities in the USA, Canada and Australia recommend a “no nit” policy, i.e. the immediate dismissal of all children who have head lice, eggs and/or nits on their hair from school, camp or child‐care settings. These children would be readmitted to the institution only when all head lice, eggs and nits have been removed. The “no nit” policy assumes that all nits seen when examining the scalp are viable and therefore the infested individual should be treated for lice, and all nits must be removed from the scalp. However, it has been repeatedly shown that only a small number of children who have nits on their scalp are also infested with living lice. Accordingly, in the USA alone 4–8 million children are treated unnecessarily for head lice annually, which amounts to 64% of all lice treatments. In addition, 12–24 million school days are lost annually. The annual economic loss owing to missed workdays by parents who have to stay home with their children adds US

Clinical evidence of lice resistance to over-the-counter products.

4–8 billion to the countrys economy. The policy also results in serious psychological problems for children and their parents. Therefore, the “no nit” policy should be abandoned and alternative ways of examination and treatment for head lice should be found.

Recommendation to Standardize Pediculicidal and Ovicidal Testing for Head Lice (Anoplura: Pediculidae)

Background: Over-the-counter insecticidal solutions continue to be the mainstream treatment for most cases of head lice. Recorded insecticidal activity 15 years ago was at 100%, with ovicidal kill at 80%. Recently scattered accounts of possible resistance have surfaced. Objective: This article is to document the general consensus that head lice are becoming resistant to standard over-the-counter therapies. Methods: Direct testing of lethality of adult lice with permethrin and pyrethroid was assessed. Results: Present over-the-counter products proved to be successful in only 9 of 32 head lice tested (28% insecticidal activity). Conclusions: Our series of cases further documents that over-the-counter head lice preparations no longer achieve high levels of insecticidal activity, suggesting increased resistance to these insecticides.

Tazarotene gel for Darier’s disease

Abstract Pediculosis capitis is a prevalent and highly communicable condition infesting millions of elementary school students annually. Topical insecticides are the present standard treatment for this condition. Because resistance of head lice to insecticides is a growing concern, assessment of efficacy of pediculicidal and ovicidal activity of the various agents is needed for public health interests. Given the number of anecdotal and market-driven reported studies, assessment of topical lice therapies requires standardized testing. Evaluations based on adaptations of World Health Organization guidelines are not ideal, whereas a protocol reflecting clinical exposure to insecticides is preferable.

Propionibacterium acnes: interaction with complement and development of an enzyme-linked immunoassay for the detection of antibody

Darier’s disease is inherited in an autosomal dominant fashion.1 Nevertheless, half of affected persons have no family history of the condition. Darier’s disease presents with scattered, greasy, keratotic papules on the face, neck, chest, back, and extremities that coalesce forming plaques. It is exacerbated by heat and sweating, and usually worsened by exposure to sunlight.1 The cause of the distorted keratinization is dissolution of desmosomal plaque proteins, specifically, desmoplakin I and II, plakoglobin, and desmoglein.2 The result of this defect is a deficiency in the tonofilament/desmosome attachment, leading to tonofilament clumping and vesicle formation. Because oral isotretinoin is effective in this condition,3 the new topical acetylenic retinoid tazarotene was tried in a patient.

The endogenous, exogenous, and latent infections with human papillomavirus

Objective To characterize the immune response to Propionibacterium acnes in acne patients.

Antibiotic‐resistant Propionibacteria acnes may not be the major issue clinically or microbiologically in acne

The human papillomavirus (HPV) consists of over 80 genotypes of species of specific DNA virus that “infect” mammalian epithelial cells causing benign proliferations of the skin known as warts or verrucae. Additionally, HPV infections have been linked to dysplasia and cancer, especially when located on mucosal surfaces such as the cervix, larynx, and rectum. The “infective” nature of this virus needs assessment, however, as HPV can establish latent infections in normal epithelia and in lymphocytes with no clinical sign of disease. 1–4

Before Using Ivermectin Therapy for Scabies

SIR, A 40-year-old man reported the slow progressive appearance, during the previous 6 years, of pruritic erythematous lesions on the trunk, buttock, abdomen, axilla, genital area and forearm (Fig. 1a). Lesions consisted of follicular papules, comedones, milia and cysts. Lesional areas were alopecic (Fig. 1b), and diffuse alopecia was also present on the scalp and beard area, along with comedones and cysts. The patient reported severe skin dryness, especially in the involved areas. No impairment of salivary or lacrimary function was noted. Serological and haematological tests were all normal or negative. Because of the diffuse presence of cysts and comedones, a diagnosis of chloracne had been made in another institution; the clinical diagnosis was confirmed histologically by the presence of infundibular cysts and a granulomatous foreign body reaction to keratin scales. A further biopsy was performed: the most striking histological feature was a lymphocytic infiltrate involving eccrine glands and coils along with a characteristic epithelial hyperplasia (Figs 1c,d). This picture fits perfectly with that reported in the literature as being characteristic of syringolymphoid hyperplasia, also known as syringotropic mycosis fungoides or syringotropic cutaneous T-cell lymphoma (CTCL). The hair follicles were involved by the lymphocytic infiltrate in a manner similar to that of the eccrine glands. Follicles were surrounded by a dense lymphocytic infiltrate, with extensive exocytosis. Occasional Pautrier microabscesses were evident in the follicular sheath. This pattern is that of pilotropic mycosis fungoides, a form of folliculotropic CTCL. Many follicles were entirely trans-