Effect of propolis in the treatment of experimental Staphylococcus aureus keratitis in rabbits

The aim of this study was to investigate the antimicrobial and anti-inflammatory properties of an ethanolic extract of propolis, a natural resin produced by honeybees, and to determine synergistic activity between ciprofloxacin and propolis in the treatment of experimental Staphylococcus aureus keratitis.

Sixteen young New Zealand white rabbits were given intrastromal injections of S. aureus strains. Twenty-four hours later, the rabbits were randomly divided into 4 groups: group 1 was treated with topical 0.3% ciprofloxacin drops along with the ethanolic extract of propolis drops; group 2 received topical 0.3% ciprofloxacin drops; group 3 was administered the ethanolic extract of propolis drops, and group 4, the control group, was treated with phosphate-buffered saline (PBS) drops. Drugs were instilled 8 times/day for 72 h. Twenty-four and 96 h after inoculation of bacteria, the eyes were examined by slit lamp to assess corneal opacity. Corneas were removed to count bacteria.

Slit lamp examination showed that the corneal opacity scores were significantly lower in eyes that received propolis plus ciprofloxacin than in those treated with ciprofloxacin (p = 0.041) or propolis (p = 0.006) or control eyes treated with PBS (p = 0.0001). There was no significant difference in eyes treated with ciprofloxacin and propolis (p = 1.00). There were significantly fewer bacteria in eyes that received propolis plus ciprofloxacin than in those treated with ciprofloxacin (p = 0.0001) or propolis (p = 0.0001) or control eyes treated with PBS (p = 0.0001). There was no significant difference in eyes treated with ciprofloxacin and propolis (p = 0.38).

Taking these findings into consideration, we suggest that the ethanolic extract of propolis has antimicrobial and anti-inflammatory properties for S. aureus keratitis. The combination of ciprofloxacin and propolis had better therapeutic effects than either agent alone.