Propolis as an antimicrobial agent in treating vulvovaginal dysbiosis

Propolis resin is under investigation for its antimicrobial properties, and use in treating antibiotic-resistant strains of microbes. This includes some of the microbes that cause yeast infections, bacterial vaginosis and aerobic vaginitis, and vaginal dysbiosis, amongst others.

Propolis is antioxidant, antimicrobial, antibacterial, antiviral, antiparasitic, immunostimulating, and antifungal. Propolis is believed to be safe and non-toxic to humans, however there remains a small risk of allergic reaction like contact dermatitis, as reported by beekeepers.

Why isn’t propolis already used by medicine?

Propolis is known to have been used as a medicine by ancient human civilisations, and while some favour has been lost over the centuries, renewed interest in this resinous substance is occurring in western medicine pharmacy.

Because of the variability in propolis products naturally, scientific research has been slow to develop and approve products for medical complaints – standardising is an issue when it comes to potency. When a substance contains many different active parts, it can be difficult to isolate them, and we know from experience that sometimes the compounds work together, and not separately.

Traditional use has been for both internal and external complaints.

What is propolis?

Propolis is a substance produced by honey bees (bee glue), collected from living plants, used to construct and augment hives. Propolis has been demonstrated to possess antibacterial, antiviral and antifungal properties. Studying propolis has had varying results, since the plants that the bees collect the resins from varies from location to location depending on local flora.

These differences in flora change the properties of the resin, making it more or less effective against various microbes, however it seems that variations in effect are minor. The type of bee doing the collecting also appears to make a difference in how potent the propolis is.

Propolis is a combination of two Greek words

Pro – in defence of Polis – the city

Meaning, in defence of the city, or beehive. Propolis keeps a beehive sterile and protected, having many effects on potential invading fungi (moulds and yeasts), bacteria, viruses and parasites. Invaders are also mummified with propolis if they are too big/heavy to take out of the hive.

What propolis is made up of

Propolis is used by bees mixed with wax to seal up the hive, fix cracks, keep moisture and temperature levels stable, and smooth the walls. It is typically made up of half plant resins, 30 per cent waxes, 10 per cent essential and aromatic oils, and five per cent each of pollen and other organic substances.

Colour varies depending on the wide range of plants used. Propolis can’t be used raw; it must be extracted and the non-useful debris and wax removed. Alcohol is most often used in this process. 

Extracted propolis contains high levels of polyphenolic components, with over 500 compounds identified so far. These include:

• Polyphenols – flavonoids, phenolic acids and aldehydes, simple phenols (and esters), coumarins, stilbenes and lignans
• Terpenes
• Fatty/waxy substances
• Beeswax
• Vitamins
• Proteins
• Amino acids
• Sugars

Comparisons between studies have proven difficult due to variations in composition of the propolis. Drug resistance in microbes has not proved to be a barrier to successful treatment with propolis.

There isn’t just one component of propolis that offers its antimicrobial effects, and due to the local variances in flora, the mixture is always a bit different.

Propolis is most effective against gram-positive bacteria and yeasts, while gram-negative bacteria are less susceptible – but generally still susceptible. Some gram-positive bacteria and some yeasts are less susceptible, for example Enterococcus faecalis, Candida albicans, and Salmonella species. Research has demonstrated that using propolis with antibiotics has a synergistic effect, enhancing both the action of antibiotics and antifungals.

Bacteria that propolis is effective against:

• Aeromonas hydrophila (aerobic gram-negative)
• Actinomyces naeslundii (anaerobic gram-positive, vagina-related)
• Actinobacillus actinomycetemcomitans (anaerobic gram-negative)
• Bacillus cereus (aerobic gram-positive)
• Bacillus subtilis (aerobic gram-positive, vagina-related)
• Brucella abortus (aerobic gram-negative)
• Capnocytophaga gingivalis (anaerobic gram-negative)
• Corynebacterium species (aerobic gram-negative, vagina-related)
• Corynebacterium pseudotuberculosis (aerobic gram-negative)
• Enterococcus faecalis (aerobic gram-positive, vagina-related)
• Escherichia coli (aerobic gram-negative, vagina-related)
• Fusobacterium nucleatum (anaerobic gram-negative, UTI and vagina-related)
• Helicobacter pylori (aerobic gram-negative, vagina-related)
• Klebsiella pneumoniae (aerobic gram-negative, UTI and vagina-related)
• Lactobacillus acidophilus (anaerobic gram-positive, probiotic, vagina-related)
• Micrococcus luteus (aerobic gram-positive, UTI-related)
• Nocardia asteroids (aerobic gram-positive)
• Peptostreptococcus micros (anaerobic gram-positive, vagina-related)
• Porphyromonas species (anaerobic gram-negative, vagina-related)
• Porphyromonas anaerobius (anaerobic gram-negative, vagina-related)
• Porphyromonas gingivalis (anaerobic gram-negative, vagina-related)
• Pseudomonas aeruginosa (aerobic gram-negative, UTI and vagina-related)
• Proteus species (aerobic gram-negative, vagina-related)
• Proteus mirabilis (aerobic gram-negative, UTI and vagina-related)
• Proteus vulgaris (aerobic gram-negative, UTI and vagina-related)
• Prevotella species (anaerobic gram-negative, vagina-related)
• Prevotella intermedia (anaerobic gram-negative, vagina-related)
• Prevotella melaninogenica (anaerobic gram-negative)
• Prevotella oralis (anaerobic gram-negative)
• Rhodococcus equi (a.k.a. Corynebacterium equi) (aerobic gram-positive, possibly urinary tract-related)
• Salmonella species (aerobic gram-negative)
• Salmonella enteritidis (aerobic gram-negative)
• Salmonella typhi (aerobic gram-negative)
• Salmonella typhimurium (aerobic gram-negative)
• Shigella dysenteriae (aerobic gram-negative, vagina-related)
• Staphylococcus aureus (aerobic gram-positive, vagina-related)
• Staphylococcus auricularis (aerobic gram-positive)
• Staphylococcus capitis (aerobic gram-positive)
• Staphylococcus epidermis (aerobic gram-positive)
• Staphylococcus haemolyticus (aerobic gram-positive)
• Staphylococcus hominis (aerobic gram-positive)
• Staphylococcus mutans (aerobic gram-positive)
• Staphylococcus warneri (aerobic gram-positive)
• Streptococcus cricetus (aerobic gram-positive)
• Streptococcus faecalis (aerobic gram-positive)
• Streptococcus pneumoniae (aerobic gram-positive, vagina-related)
• Streptococcus pyogenes (group A strep) (aerobic gram-positive, vagina-related)
• Streptococcus beta-haemolyticus (aerobic gram-positive)
• Streptococcus mutans (aerobic gram-positive, vagina-related)
• Streptococcus sobrinus (aerobic gram-positive)
• Streptococcus viridans (aerobic gram-positive)
• Veillonella parvula (anaerobic gram-negative, vagina-related)

References

1. Srdjan Stepanovića Nataša AntićaIvana Dakića Milena Švabić-Vlahovića, 2003, In vitro antimicrobial activity of propolis and synergism between propolis and antimicrobial drugs. Microbiological Research Volume 158, Issue 4, 2003, Pages 353-357.
2. José M. Alvarez-Suarez, Editor, Bee Products – Chemical and Biological Properties