Introduction: Propolis is a natural composite balsam. In the past decade, propolis has been extensively investigated as an adjuvant for the treatment of periodontitis. This study aimed to investigate antimicrobial activities of propolis solutions and plant essential oils against some oral cariogenic (Streptococcus mutans, Streptococcus mitis, Streptococcus sanguis, Lactobacillus acidophilus) and periodontopathic bacteria (Actinomyces odontolyticus, Eikenella corrodens, Fusobacterium nucleatum). Methodology: Determination of the minimum inhibitory concentration (MIC): The antimicrobial activity of propolis and essential oils was investigated by the agar dilution method. Serial dilutions of essential oils were prepared in plates, and the assay plates were estimated to contain 100, 50, 25 and 12.5 µg/mL of active essential oils. Dilutions for propolis were 50, 25, 12.5 and 6.3 µg/mL of active propolis solutions. Results: Propolis solutions dissolved in benzene, diethyl ether and methyl chloride, demonstrated equal effectiveness against all investigated oral bacteria (MIC=12.5 µg/mL). Propolis solution dissolved in acetone displayed MIC of 6.3 µg/mL only for Lactobacillus acidophilus. At the MIC of 12.5 µg/mL, essential oils of Salvia officinalis and Satureja kitaibelii were effective against Streptococcus mutans and Porphyromonas gingivalis, respectively. For the latter, the MIC value of Salvia officinalis was twice higher. Conclusions: The results indicate that propolis and plant essential oils appear to be a promising source of antimicrobial agents that may prevent dental caries and other oral infectious diseases.

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Faecal samples of 2660 domestic animals from 116 farms and 956 samples of food were examined for the presence of Shiga toxin-producing Escherichia coli (STEC). STEC was recovered from 126 (15.3%) cattle, 135 (11.3%) pigs, 135 (66.8%) sheep, 31 (73.8%) goats, 4 (1%) chicken, and 15 (1.6%) food samples. Of all STEC isolates, 21.5, 25.8 and 15% produced enterohaemolysin, alpha-haemolysin, and aerobactin respectively, 1.6% displayed localized adherence (LA) to HEp-2 cells, 27.6% were sorbitol negative, and 30% were resistant to antibiotics. Only 14 (3.1%) of the STEC isolates belonged to human infection-associated serogroups (O26, O55, O111, O128 and 0157), designated as enterohaemorrhagic E. coil (EHEC). This study revealed that STEC are prevalent in domestic animals, and to a lesser extent in food of animal origin in Serbia, but the absence of a EHEC phenotypic profile (characteristic serogroup, LA, enterohaemolysin production) in most animal STEC strains may explain the low incidence of human STEC infection in this part of the world.

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Oral infections and dental caries are still considered as a serious public health problem. Using the method of minimum inhibitory concentrations (MICs), the aim of this study was to investigate the inhibitory effects of 16 plants on the growth of Actinomyces odontolyticus, Streptococcus mitis, Streptococcus sanguinis, Eikenella corrodens, Fusobacterium nucleatum, Lactobacillus acidophilus and Streptococcus mutans. The most effective were ethanol extracts of Rosmarinus officinalis, Salvia officinalis, Thymus vulgaris, Calendula officinalis and Hypericum perforatum. The least efficiency was observed for Acorus calamus extract. Plant extracts could be used in oral health as therapeutic and prophylactic approach or in balancing oral microbiota.