Author(s): Machado, Daniela Marlene da Silva ; Alves, Patrícia Maria ; Sousa, Cláudia ; Oliveira, J. Martinez de ; Salgueiro, L. ; Oliveira, A. Palmeira de ; Cerca, Nuno
Date: 2013
Persistent ID: http://hdl.handle.net/1822/28728
Origin: RepositóriUM - Universidade do Minho
Subject(s): Bacterial vaginosis; Gardnerella vaginalis; Essential oils; Novel antimicrobial agent
Bacterial vaginosis (BV) is the most common gynecological clinical condition in women in reproductive age, and has been associated with an increased risk of development of preterm labor, spontaneous abortion, and several sexually transmitted diseases such as HIV [1]. BV is not only a condition that involves excessive growth of anaerobic microorganisms, but also involves the presence of an adherent biofilm [2]. Despite its high prevalence, the aetiology of BV remains unknown, but frequently Gardnerella vaginalis is the main microorganism associated with this disorder [3], that is often the main species in biofilms presented in BV [4]. These results led to the theory that the microorganisms that form biofilms may be relevant for the aetiology of BV [5]. Traditionally, the treatment of BV involves the antibiotics metronidazole, clindamicin or tinidazole [6]. However, the recurrence rate remains high and this can be related to the biofilm-forming ability of G. vaginalis [5]. In this context, recently it was reported that natural compounds, such as Thymbra capitata essential oil, can reduce the activity of biofilms [7]. To test if T. capitata could be used in the treatment of BV, we determined the biofilm-forming ability and the effect of essential oil in seven strains of G. vaginalis isolated from women with BV. Thus, the biofilm-forming ability was assessed under anaerobic conditions for 48 hours, allowing each strain to form biofilm. These assays revealed that in fact, G. vaginalis strains produced moderate to tenacious biofilm. We then determined the sensibility of the tested bacteria to the common antibiotics used to treat BV. Not surprisingly, most of strains were resistant of metronidazole and tinidazole which are more commonly administered. However half of strains were sensitive to clindamicin. We then evaluated the antibacterial activity of essential oil upon G. vaginalis strains, determining minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC). The T. capitata essential oil exhibited a potent anti-G. vaginalis effect, which was confirmed by the low values of MIC (0.16 µL.mL-1) and MLC (0.16 - 0.31 µL.mL-1). To conclude, these results showed that T. capitata essential oil presents a strong antibacterial activity upon antibiotic resistant and biofilm forming of G. vaginalis strains, reinforcing the potential interest of this essential oil as antimicrobial agent in the treatment of BV.
