Epsilon Archive for Student Projects

Abstract

Health concerns, environmental issues, resistance development of microbes and financial constraints drive hygienists to explore alternative disinfection methods to the commonly used, in order to address these issues. One possible solution may be the utilization towards that direction of materials used traditionally in food industry such as plants and herbs, directly consumed or used to flavour foods. Thymus Vulgaris, a plant with substantial antimicrobial activity, and Aloe Vera, a plant with great therapeutic capabilities, are examined in this study for their potential to be the main substance of new disinfection products, intended to be used in nosocomial environments. The extracts, obtained by hydrodistilation (thyme) and ethanol solution (Aloe), were evaluated through antimicrobial screening of their efficacy in comparison with commercial disinfectants, widely used in health care units. Their efficacy was tested against bacteria isolated from hospital environment, responsible for the half of nosocomial infections worldwide namely: Methicillin Resistant Staphylococcus Aureus, Staphylococcus Aureus, Escherichia coli, Pseudomonas aeroginosa, Klebsiella pneumoniae and Acinetobacter baumanii), diluted in deionized water and in reconstituted skim milk. The sensitivity evaluation was performed by broth dilution followed by viable count of the bacteria population after being subjected to different concentrations of the disinfectants with and without the presence of organic matter (skimmed milk). Bacteria were enumerated at time 0, 2, 5 and 10 minutes. Bacterial numbers were expressed as log10 CFU ml-1 and the log reduction was calculated. In the tested concentrations of the extracts promising results were obtained from the samples diluted in deionized water, especially from the Thymus extract. More than 2 log reduction was achieved by the thyme essential oil on four out of six tested bacteria populations from the 5.0 ml/L dilution. Similar but lower counts were obtained from the same dilution of ethanol extract of Aloe Vera (1<DR<2). However, in the presence of organic matter their antibacterial activity was greatly inhibited giving less than 1 log reduction for both extracts. Overall, comparing the tested commercial disinfectants with the natural extracts, the latter presented lower disinfection activity, which was expected taking into account the tested concentrations and their chemical complexity. These preliminary results showed that both extracts have the potential to be used as disinfectants and further studies should be conducted in higher concentrations in order to achieve 5 log reduction.