Evaluation of tea tree oil physicochemical features and its antimicrobial activity against Cutibacterium acnes (Propionibacterium acnes) ATCC 6919 / [Evaluación de las características fisicoquímicas y de la actividad antimicrobiana del aceite del árbol de té contra Cutibacterium acnes (Propionibacterium acnes) ATCC 6919].

Introduction: Tea tree oil is an essential oil recognized for its antimicrobial properties. Objective: To evaluate the composition, features, and antimicrobial effect at 2% v/v, and its minimal inhibitory concentration (MIC) against Cutibacterium acnes (Propionibacterium acnes). Materials and methods: Three different batches of tea tree oil were evaluated. We characterized its chemotype by gas chromatography and its 2% v/v antimicrobial activity against C. acnes by agar diffusion assay (guide M11-A8 CLSI). Results: The three batches of oil had the chemotypes required by the ISO 4730 standard, which indicates that it is a high-quality product. Additionally, they had 30% to 40% of terpinen-4-ol, a compound that favors its antimicrobial activity. Antimicrobial activity against C. acnes for all batches had a concentration-dependent effect with microbial growth inhibitory activity in all assays at 2% v/v. The MIC obtained against C. acnes for all batches was 0.25% v/v. The antimicrobial activity of tea tree oil against this microorganism has been previously reported with a MIC between 0.05% and 1.25% v/v, a range that covers the one obtained in this study. Conclusion: These results show the high quality of the oil and its capacity as an antibacterial agent against C. acnes. New studies should be conducted to confirm its activity and that of its components in isolates of the microorganism from patients with acne vulgaris.

Introducción. El aceite del árbol de té es un aceite esencial reconocido por sus propiedades antimicrobianas. Objetivos. Evaluar la composición, características y efecto antimicrobiano del aceite al 2 % del árbol de té y su concentración inhibitoria mínima (CIM) contra Cutibacterium acnes (Propionibacterium acnes). Materiales y métodos. Se evaluó el quimiotipo en tres lotes diferentes de este aceite mediante cromatografía de gases, así como su actividad antimicrobiana en concentración al 2 % v/v y la CIM contra C. acnes mediante ensayo de difusión en agar (guía M11-A8 CLSI). Resultados. Los lotes evaluados presentaron los quimiotipos ajustados a la norma ISO 4730, lo que indicó la alta calidad del producto. Los lotes contenían de 30 a 40 % de terpinen-4-ol, compuesto que favorece la actividad antimicrobiana, la cual presentó en todos los lotes un efecto dependiente de la concentración contra C. acnes, con una inhibición del crecimiento microbiano en concentración al 2 % v/v en todas las pruebas. La concentración inhibitoria mínima fue de 0,25 % v/v. La actividad antimicrobiana del aceite del árbol de té contra este microorganismo ya ha sido reportada con una concentración inhibitoria mínima entre 0,05 y 1,25 % v/v, rango que cobija la obtenida en este estudio. Conclusiones. Los resultados evidenciaron la gran calidad de este producto y su capacidad como agente antibacteriano contra C. acnes. Se deben hacer estudios con otros aislamientos del microorganismo provenientes de pacientes con acné vulgar para confirmar su actividad general y la de cada uno de sus componentes.

Evaluation of quality of hydrogen peroxide-based antiseptic solutions available in Dar es Salaam, Tanzania.

BACKGROUND: Hydrogen peroxide solutions of low concentrations are important antiseptics and deodorants used in hospitals and as home-remedies. The preparations have the disadvantage of being unstable when exposed to sunlight and when stored for a long time. They decompose slowly, releasing oxygen and water thus decreasing the available hydrogen peroxide for antimicrobial action. OBJECTIVE: To assess the quality of hydrogen peroxide solution-based antiseptics available in Dar es Salaam. METHODOLOGY: One hundred and sixty-five samples were collected at random from pharmacies and medical stores, and analysed. One hundred and forty samples were hydrogen peroxide solutions intended for wound cleansing and 25 samples were eardrops. Among these samples, 116 were from manufacturer A, 24 from manufacturer B and 25 samples of eardrops were from manufacturer C. RESULTS: Eighteen (26%) of the samples from medical stores failed to meet specifications. Of the 70 samples from pharmacies, 20 (29%) failed to meet the BP 2005 specifications. All the 25 samples of eardrops failed to comply with specifications. The average hydrogen peroxide contents (+/-SD) of the samples from medical stores and pharmacies were 6.6 +/- 0.6%, 6.8 +/- 0.4% w/v respectively. The difference was statistically significant (P < 0.05). CONCLUSION: A significant proportion of hydrogen peroxide products in the Dar es Salaam market is of poor quality. There is a need for continuous monitoring of the quality of hydrogen peroxide available in the city.

Macaca fascicularis vs. Macaca nemestrina as a model for topical microbicide safety studies.

Preclinical studies of topical microbicide products, using appropriate animal models for assessing the safety of repeated use are essential. The pig-tailed macaque (Macaca nemestrina) model has been used to assess the safety of vaginally and rectally applied topical microbicide products. The availability of sexually mature female pig-tailed macaques has become extremely restricted. Currently, M. fascicularis is more readily available, and was therefore evaluated as an alternative model for topical microbicide pre-clinical evaluation. Twenty sexually mature M. fascicularis were assessed for feasibility to mimic the established models. The rectal and cervicovaginal microenvironments of the M. fascicularis were determined to be similar to those of M. nemestrina and humans. The gross anatomy was significantly smaller than that of the pig-tailed macaque, such that colposcopic examinations and multiple biopsies would not be possible. Thus, the M. fascicularis may not be useful for vaginally applied topical microbicide safety studies yet adequate for assessing safety of rectally applied topical microbicide products.

Antibacterial efficacy of triclosan-incorporated polymers.

Triclosan (2, 4, 4'-trichloro-2'-hydroxydiphenyl ether) is a broad-spectrum antimicrobial agent, routinely used in various personal care products.(1) It is also incorporated into polymers through melt-mixing, with the aim of providing persistent antibacterial action on the surface of the polymer.(2,3) Such triclosan-incorporated polymers can be promoted for hospital use as fabric seat covers, tables, chairs, and clothing. We assessed the antibacterial efficacy of triclosan-incorporated polymer disks against 2 bacteria cultured in liquids in contact with the polymer. In spite of the relatively high concentrations of triclosan in the polymer, only some initial slowing of the bacterial growth rates was observed, followed by the absence of an antibacterial effect over extended periods. The triclosan at the surface of the disks dissolves into the liquids, and the rest of the triclosan, immobilized in the disks, does not contribute to the antibacterial effectiveness of triclosan-incorporated polymer. In light of recent studies, which have shown that triclosan acts on a specific target within the bacterial lipid synthesis pathway, triclosan-incorporated polymers may provide the ideal setting for resistant strains of bacteria to grow and thus should be used selectively in hospital environments.

Safety and efficacy of an improved antiseptic catheter impregnated intraluminally with chlorhexidine.

The safety and efficacy of a second-generation improved antiseptic catheter impregnated with silver sulfadiazine and increased levels of chlorhexidine on its outer surface and chlorhexidine alone on its luminal surfaces was compared in vitro and in vivo to standard antiseptic catheters impregnated with these antimicrobials on their outer surfaces only. In rat and pig intravenous models, the improved antiseptic catheter was significantly more effective in resisting both outer surface and luminal colonization compared with the standard antiseptic or control catheters. There was no evidence of tissue toxicity in any group.