Adaptation and validation of a method for evaluating the bactericidal activity of ethyl alcohol in gel format 70% (w/w).

Ethyl alcohol 70% (w/w) is a broad-spectrum bactericidal agent that is mandatorily marketed as a gel in Brazil since 2002. However, there is no method described for the microbiological quality control of surface disinfectants in the form of gel, which makes it impossible to monitor the effectiveness of these products by the Health Surveillance. Thus, the present study aimed to adapt an analytical method and validate it so that it is possible to evaluate the bactericidal activity of ethyl alcohol-based disinfectants at 70% (w/w) in gel form. The proposed analytical method is an adaptation of a method developed by the Association of Official Analytical Chemists (AOAC), which is currently used to evaluate the bacterial activity of disinfectants in the form of spray and aerosol. The method consisted of challenging the disinfectant by putting it in contact with 60 carriers - previously contaminated with the test microorganism - during the contact time established by the manufacturer. The bacteria used in this work were Staphylococcus aureus CBRVS 00039 ATCC 6538, Salmonella enterica CBRVS 00028 ATCC 10708, and Pseudomonas aeruginosa CBRVS 00025 ATCC 15442. The parameters chosen for the validation of the method were: matrix effect, robustness, and repeatability. The experiments performed with a disinfectant matrix showed that there is no interference of the gel on the effectiveness of alcohol. Satisfactory results regarding the evaluation of bactericidal activity were obtained for the three microorganisms tested when the volume of 100 µL of disinfectant was applied. The method also showed good repeatability, as it proved to be robust with modification of incubation times, equipment and analysts. The development and validation of this method were extremely important for the quality monitoring of these products, besides being the first method described for the evaluation of gel disinfectants.

Tolerância de Mycobacterium abscessus subsp. bolletii a desinfetantes de alto nível / Tolerance of Mycobacterium abscessus subsp. bolletii to high-level disinfectants

Mycobacterium abscessus subps. bolletii (clone BRA100), entre outras micobactérias de crescimento rápido (MCR), tem sido isolada como agente etiológico de infecções localizadas e sistêmicas no Brasil. Neste estudo, foi avaliada a suscetibilidade de MCR pelo método confirmatório para Avaliação da Atividade Micobactericida de Desinfetantes frente a produtos à base de glutaraldeído, ácido peracético e ortoftalaldeído. Todos os produtos foram utilizados nas concentrações recomendadas pelos fabricantes.Foram avaliadas cinco cepas clínicas pertencentes ao clone BRA100, juntamente com as cepas de referência M. abscessus ATCC 19977, M. chelonae ATCC 35752, M. fortuitum ATCC 6841 e M. abscessus subps.bolletii INCQS 00594. Os três desinfetantes à base de glutaraldeído não foram eficazes contra M. abscessuse M. abscessus subps. bolletii. Os desinfetantes à base de ácido peracético demonstraram eficácia para todasas micobactérias empregadas, embora as cepas do clone BRA100 tenham demonstrado suscetibilidade reduzida ao ácido peracético B. O produto à base de ortoftalaldeído foi eficaz apenas frente a M. chelonae.Visando a redução de infecções nosocomiais, sugere-se que seja suspenso o uso de produtos à base de glutaraldeído como desinfetante de alto nível para quaisquer finalidades.