Synergistic antimicrobial activity by combining an allylamine with benzoyl peroxide with expanded coverage against yeast and bacterial species.

BACKGROUND: Dermatophyte infections can be polymicrobial. Topical antifungal therapies offer limited coverage of yeasts and Gram-positive and Gram-negative bacteria. Moreover, the increased usage of these topical antimicrobial agents has resulted in the development of resistant cases. Benzoyl peroxide (BP), used in concert with antimicrobial agents containing an accessible tertiary amine, has previously been shown to increase radical activity and biological effect. OBJECTIVES: To determine the applicability of using the tertiary amine terbinafine in concert with BP in dermatophyte and mixed skin infections by means of in vitro testing. METHODS: In this preliminary in vitro study, the effect of BP, alone and in combination with terbinafine, was tested against Candida albicans, Pseudomonas aeruginosa and Staphylococcus aureus isolates following a checkerboard modification of the National Committee for Clinical Laboratory Standards M27-A2 and M7-A6. The individual minimum inhibitory concentrations of terbinafine, BP, and the combination, were determined against each isolate. RESULTS: The combination of BP with terbinafine led to additive activities against the majority of Candida albicans isolates tested and additionally expanded the bacterial coverage of terbinafine. CONCLUSIONS: The combination of antifungal agents bearing a tertiary amine with BP may have benefit in polymicrobial infections, given its wider antimicrobial coverage. Further appreciation of this mechanism of catalysis of BP radical formation by certain antimicrobials and other tertiary amine-containing compounds may lead to the discovery of improved treatments for several dermatological conditions.

Cerumen composition by flash pyrolysis-gas chromatography/mass spectrometry.

OBJECTIVE: To assess the chemical composition of cerumen by flash pyrolysis-gas chromatography/mass spectrometry. STUDY DESIGN: Collected earwax specimens were fractionated into residue and supernatant by means of deoxycholate. This natural bile acid produces significantly better disintegration of earwax in vitro than do presently available ceruminolytic preparations, and also has demonstrated excellent clinical results in vivo to date. PATIENTS: The sample for analysis was obtained from a patient with clinical earwax impaction. RESULTS: The supernatant is composed of simple aromatic hydrocarbons, C5-C17 straight-chain hydrocarbons, a complex mixture of compounds tentatively identified as diterpenoids, and steroids, in particular cholesterol. The residue, on the other hand, produced simple aromatic compounds (including benzenes, phenols, and benzonitriles), C5-C25 straight-chain hydrocarbons, greater relative quantities of nitrogen compounds and phenol, and lesser importance of the (tentatively identified) diterpenoids. CONCLUSIONS: Through the use of the detergent deoxycholate, squalene and a tentatively identified diterpenoid were revealed to be present in a free, unbound state, whereas some steroids and hydrocarbons appeared to be bound to a macromolecular structure by nitrogen linkages or other bonds. Additionally, this study reintroduces detergents as a viable method of earwax removal, specifically the bile acids.

Recommendation to standardize pediculicidal and ovicidal testing for head lice (Anoplura: Pediculidae).

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.

Effects of benzoyl peroxide on lipogenesis in sebaceous glands using an animal model.

BACKGROUND: Benzoyl peroxide is the most widely used topical agent for acne since the 1960s. Concomitant treatment of benzoyl peroxide with oral, or topical antibiotics diminishes the multiplication of antibiotic-resistant strains of Propionibacteria acnes. Besides being antibacterial, the chemical also functions as a peeling agent, has comedolytic activity, reduces free fatty acid levels, and is touted to be sebosuppressive. OBJECTIVE: The purpose was to determine the ability of topically applied benzoyl peroxide to suppress lipogenesis of the sebaceous glands. METHODS: The data were obtained employing an animal model for human sebaceous glands, namely, the flank organs of female golden Syrian hamsters. RESULTS: Our results reveal no inhibition of lipogenesis in sebaceous glands by topical application of benzoyl peroxide. CONCLUSION: Despite many functions beneficial in acne therapy, benzoyl peroxide does not possess sebosuppressive capabilities. With the advent of water-soluble organic peroxides revealing similar antimicrobial activity to benzoyl peroxide, all therapeutic parameters (save for sebosuppression) will need to be assessed to weigh the benefits of these second-generation acne-fighting peroxides.

An epidemiologic and therapeutic reassessment of scabies.

Scabies is a highly contagious infestation that causes considerable discomfort. Newer information concerning therapeutics and epidemiologic dogma needs assessment. An epidemiologic evaluation of available world data is analyzed, as well as an assessment of therapeutic alternatives. Using epidemiologic techniques, the following points are proven: scabies is not primarily a sexually transmitted disease; 30-year cycles of scabies do not exist; scabies spreads in households and neighborhoods in which there is a high frequency of intimate personal contact or sharing of inanimate objects; and fomite transmission is a major factor in household and nosocomial passage of scabies. Epidemiologic evaluation proves the necessity of fomite precautions and of treatment of asymptomatic family members and physical contacts of all cases of scabies. Single oral-dose therapy of ivermectin (Stromectol) appears to be the treatment panacea for this infestation.

Scanning electron microscopic examination of the egg of the pubic louse (Anoplura: Pthirus pubis).

OBJECTIVE: The purpose of the study was to examine the eggs of pubic lice with consideration of their clinical relevance. STUDY DESIGN: Pubic lice eggs were examined by scanning electron microscopy (SEM). RESULTS: The egg is totally encased by a proteinaceous sheath, except for the operculum, by which oxygen exchange occurs. CONCLUSION: Pubic lice have proved resilient to human therapies through the ages. The anatomical target of topical insecticides for ovicidal kill is the operculum and the protective layers that surround the developing embryo. More research into these structures is warranted.

In pursuit of ceruminolytic agents: a study of earwax composition.

OBJECTIVE: To assess the protein and simple sugar content of earwax in pursuit of better ceruminolytic agents. STUDY DESIGN: Collected earwax specimens were tested in several media for dissolution before being analyzed for amino acid and carbohydrate content. PATIENTS: The samples were obtained from eight random patients requiring ear plug removal. RESULTS: The amino acid composition differs considerably from hair and stratum corneum of glabrous skin. Sugar analysis revealed high levels of galactosamine and galactose. CONCLUSIONS: This analysis of proteins and carbohydrates further characterizes earwax. Future ceruminolytic agents must dissolve lipid, keratin, and a monolayer of lipid covalently bound to the epidermal cells, which encourages cellular aggregation.