and are opportunistic pathogens that cause a wide range of infections. Their increasing resistance to antibiotics is a serious concern and making them susceptible to treatments is now more essential than ever. There is a need to discover new biofilm inhibitors to increase the susceptibility of these bacteria to antibiotics.

To evaluate the antibiofilm activity of heather honey, propolis and medicinal plant extracts against and .

Determination of optimum biofilm growth was carried out using a time-course assay over 24 h intervals, using PA14 and NCTC 4135 strains. The inhibitory effects of all extracts were determined by biofilm inhibition assay in 24-well plates, with biofilms stained with crystal violet and de-stained with ethanol:acetone; OD were measured at 550 nm. Planktonic growth was measured at 600 nm and samples from the wells were streaked to determine bactericidal effects.

Heather honey extracts inhibited both and by 68%. At 60 μg/mL, one of the propolis extracts promoted biofilm growth of both pathogens. Two other propolis extracts also promoted growth in but inhibited biofilm formation in by 76.5% and 13.8%, respectively. Three plant extracts inhibited biofilm by 7.5%, 10.2% and 87.6% and inhibited by −34.9%, 34.7% and 19.4%, respectively.

All samples showed varying biofilm inhibition capabilities, but biofilm formation seemed to be more easily inhibited in than in .

  • This is an open-access article distributed under the terms of the Creative Commons Attribution License.

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