Antimicrobial activity of propolis and essential oils and synergism between these natural products

In the present study, Apis mellifera propolis and essential oils (EOs) obtained from aromatic plants were evaluated as alternative antimicrobials. We aimed to establish the antimicrobial activity of ethanolic extracts of propolis (EEP) from Apis mellifera and of EOs from Caryophyllus aromaticus, Zingiber officinale, Cinnamomum zeylanicum and Mentha piperita against 32 Staphylococcus aureus and Escherichia coli strains from human clinical specimens. The antimicrobials were diluted in agar and the minimal inhibitory concentrations (MIC) were found whereas MIC90 percent values were calculated. Time-kill curve assays using mixtures containing one quarter of MIC90 percent for EEP with all EOs as well cinnamon EO were performed. The cinnamon EO was found to be the most efficient, with MIC90 percent values of 1.22 and 0.96 mg x mL-1 respectively against S. aureus and E. coli, whereas MIC90 percent of EEP were 1.86 and 20.12 mg x mL-1 respectively against S. aureus and E. coli. The combinations of EEP with ginger and mint EOs, and cinnamon with ginger and clove EOs, showed synergistic effects. Consequently, further studies are necessary to confirm these activities in vivo and to evaluate the phytochemical characteristics of natural products.(AU)

Detection of enterotoxin genes of Staphylococcus sp isolated from nasal cavities and hands of food handlers

Food handlers, an important factor in food quality, may contain bacteria that are able to cause foodborne disease. The present study aimed to research coagulase-negative (CNS) and -positive staphylococci (CPS) in 82 food handlers, analyzing nasal and hand swabs, with identification of 62 CNS (75.6%) and 20 CPS strains (24.4%). Staphylococcal enterotoxins genes were investigated by PCR. In 20 CPS strains, 19 were positive for one or more genes. The percentage of CNS presenting genes for enterotoxins was high (46.8%). Despite of the staphylococcal species, the most common gene was sea (35.4%), followed by seh and sej (29.2%). The detection of new staphylococcal enterotoxins (SEs) genes showed a higher pathogenic potential in this genus. The presence of these gene points out the importance of CNS not only as contaminant bacteria but also as a pathogen.

Effect of propolis extract on guines pig lung mast cell

The direct effect of ethanolic extract of propolis on guinea pig lung cell suspension containing mast cells, as well as its influence on the histamine release induced by antigen (ovoalbumin 10 mug/ml) and ionophore A 23187 (3 muM) were investigated. Propolis ethanolic extract (300 mug/ml) increased the histamine release in guinea pig lung suspension containing mast cells by a cytotoxic effect. Lower concentrations of propolis had no effect on histamine release. Our results demonstrated that propolis (3, 10, 30, and 100 mug/ml) shows no significant effect on the histamine release induced by ionophore and antigen. Based on these results, we suggest that propolis could directly activate mast cells, promoting inflammatory mediators release by cytotoxic mechanisms, what could be related to allergic processes in propolis sensitive people.(AU)

Susceptibility profile of Salmonella against the antibacterial activity of propolis produced in two regions of Brazil

Propolis antibiotic action has been widely investigated. This assay was carried out in order to observe the in vitro antibacterial activity of propolis against Salmonella enteritidis isolated from food and Salmonella typhimurium isolated from human infections. Propolis was collected by Apis mellifera in two regions of Brazil (Mossoró, Rio Grande do Norte State; and Urubici, Santa Catarina State). Both strains survival percentage decreased with time of incubation in Ethanolic Extracts of Propolis (EEP), demonstrating bactericidal effect after 24 hours. It was also observed that EEP from Mossoró was more effective than that from Urubici. The control of the propolis solvent - 70 percent ethanol - was less effective than EEP, showing only a bacteriostatic effect. We can conclude that propolis shows an activity against Gram-negative bacteria that varies according to the geographical region where it was collected by bees.(AU)