Antibiotics are medicines used to fight infections caused by bacteria. When used correctly, they can save lives. However, their use and misuse has led to a growing problem that has become globally relevant: the phenomenon of antibiotic resistance. Since ancient times, humans have used plants (either parts of them or their extracts) to treat all kinds of diseases, including microbial infections. Essential oils derived from plant extracts have acceptable activity against Gram-positive bacteria of interest in human and veterinary medicine, such as those of the genus Streptococcus. In vitro studies have mainly highlighted the activity of oregano, thyme, mint and cinnamon oils against these bacteria. However, a limited number of clinical isolates have been analysed in these studies and there are no studies showing the sensitivity of S. suis, an important Gram-positive swine and zoonotic pathogen associated with a wide range of diseases in pigs. The aim of this project is to evaluate the activity of different essential oils, which have been shown to be highly effective against Streptococcus spp. such as thyme, oregano, and rhodomyrtone in S. suis. The molecular effects of these compounds will also be studied at the proteomic level and the effects on the production and composition of extracellular vesicles will be examined. Furthermore, the antimicrobial activity of these products on our pathogen collections will be evaluated for future research on new antibiotic molecules and their possible synergistic effects in combination with traditional antimicrobials.
ACHIEVEMENTS:
Thyme, cinnamon and oregano essential oils have shown limited efficacy as antimicrobial agents against the two Gram-positive pathogens tested, but have produced significant synergy with conventional antibiotics. Rhodomyrtone has also been shown to be effective against S. suis. Three articles have resulted from this work, and three more are in preparation. Four Bachelor and five Master theses have been supervised, almost all jointly by professors from the two participating research groups.